Design of Machine Elements

1

PBR VISVODAYA INSTITUTE OF TECHNOLOGY

AND SCIENCE

Course File

Design of Machine Elements – 1

III Year B.Tech (ME) – I Semester

2

Contents

1. Syllabus

2. Objective

3. Lesson Plan

4. Question Papers – Mid-semester

examinations

5. Question Bank

6. Previous years’ question papers – JNTUA

3

Syllabus

2009-10

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR

III Year B.Tech. M.E. – I Semester T P C

4 0 4

(9A03504) DESIGN OF MACHINE ELEMENTS - I

UNIT – I

INTRODUCTION: General considerations of design, design process. Selection of Engineering Materials - properties –Manufacturing considerations in the design. BIS codes of materials. Preferred numbers.

UNIT – II

STRESSES IN MACHINE MEMBERS: Simple stresses – Combined stresses – Torsional and bending Stresses – impact stresses – stress -strain relation – Various theories of failure – factor of safety – Design for strength and rigidity. Concept of stiffness in tension, bending, torsion and Combined cases.

UNIT – III

STRENGTH OF MACHINE ELEMENTS: Stress concentration –notch sensitivity – Design for fluctuating stresses – Endurance limit – Estimation of Endurance strength – Goodman’s line – Soderberg’s line.

UNIT – IV

RIVETED JOINTS: Types of riveted joints, design of riveted joints. Boiler shell riveting, eccentric loading.

UNIT –V

BOLTED JOINTS – Forms of Screw threads. Stresses in Screw fasteners. Design of bolts with pre-stresses – Design of joints under eccentric loading– Bolts of uniform strength.

UNIT – VI

COTTERS AND KNUCKLE JOINTS: Design of Cotter joints: spigot and socket, sleeve and cotter, jib and cotter joints- Knuckle joints.

UNIT – VII

SHAFTS: Design of solid and hollow shafts for strength and rigidity – Design of shafts for combined bending and axial loads – Shaft sizes – BIS code.

UNIT – VIII

KEYS AND COUPLINGS: Design of Rigid couplings: Muff, Split muff and Flange couplings-Flexible couplings.

TEXT BOOKS:

1. Machine design / Schaum Series. 2. Machine design – Pandya& shah.

REFERENCES:

1. Machine design- J.E.Shigley

2. Machine design- R S Khurmi and J K Gupta

3. Design Of Machine Elements - M.F.Spotts-PHI

4. Machine Design - Kannaiah/ Scietech.

NOTE: Design data books are not permitted in the examinations. The design must not only satisfy strength criteria but also

rigidity criteria.

Question Paper Pattern: 5 questions to be answered out of 8 questions- Each question should not have more than 3 bits.

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Objective

This course “Design of Machine Elements -1” is designed with the following objectives in mind: 1. The student shall gain appreciation and understanding of the design function in mechanical engineering, the steps involved in designing and the relation of design activity with manufacturing activity. 2. Shall be able to choose proper materials to different machine elements depending on their physical and mechanical properties. Thus he shall be able to apply the knowledge of material science in real life usage. 3. Student shall gain a thorough understanding of the different types of failure modes and criteria. He will be conversant with various failure theories and be able to judge which criterion is to be applied in which situation. 4. Student shall gain design knowledge of the different types of elements used in the machine design process. Eg., fasteners, shafts, couplings etc. and will be able to design these elements for each application.

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PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE, KAVALI Department of Mechanical Engineering

Class: III B.Tech ME ( I SEM )LESSON PLAN 2012-13 Subject: DME–I C.M.M. Rao

Text Book :Machine Design – Khurmi and Gupta Ref. Books :1) Mech.Engg.Design - JE Shigley; 2) Machine Design - Bhandari

Head of the department

S.NO Duration No.of

periods

UNIT

No. of

Classes TOPIC

No.of

periods

per unit

1. 5 I

1 2 4 2 1

Introduction; What is design? General considerations in design Engg. materials & their properties and applicatios Manufacturing considerations. Preferred numbers Engineering standards, BIS codes.

10

2. 5

3. 4

II

2 2 2 3 3

Simple stresses in machine parts – combined stresses Stress strain relation, Factor of safety, thermal stresses Torsion & bending stresses – strength vs rigidity Various theories of failures Stiffness in tension, bending, torsion &combined situations

12

4. 8

5. 2

III

3 3 4

Stress concentration in machine elements Theoretical fatigue stress concentration factor, Notch sensitivity, fluctuating stresses, endurance limit Estimation of endurance strength, Good man’s, Soderbergs line, modified Goodman’s line

10

6. 8

7. 4

IV

2 2 2 2

Types of riveted joints Design of riveted joints Riveted joints for boilers Design based on eccentric loading

9 8. 5

9. I mid exams

10. 1 V

2 2 1 2

Screw thread forms and stresses in fasteners Design of bolted joints with initial stresses Pre stress in bolted joints, bolts of uniform strength Bolted joints under eccentric loading

7 11.

6

12. 7

1 2 2 2

Design of cotter joints Spigot-socket joint & Sleeve and cotter joints Jib and cotter joints Knuckle joints

7

13. 5

VII

3 3 3 1

Design of shaft for strength & rigidity, hollow shafts Design of shafts for combined loads Numerical problems on shafts, Shaft sizes, BIS codes

10

14.

5

15. 5

VIII

3 2 2 2

Design of keys Rigid couplings –muff couplings Split muff couplings Flange couplings Flexible couplings

09 16.

4

17. II mid exams

6

Question Papers

Mid-semester examinations

7

PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE, KAVALI

DEPARTMENT OF MECHANICAL ENGINEERING

III B.Tech – Mech (I sem) Mid Exam – I (objective) Max. Marks : 20

Date : 05-09-2012 (FN) Time : 30 min DESIGN OF MACHINE ELEMENTS – I

Answer all questions 1. According to Indian standard specifications, a grey case iron designated by ‘FG 200’ means that

the [ ]

a) carbon content is 2% b) maximum compressive strength is 200 N/mm2

c) minimum tensile strength is 200 N/mm2 d) maximum shear strength is 200N/mm2

2. According to Indian standard specification, a plain carbon steel designated by

40C8 means that [ ]

a) carbon content is 0.04 percent and manganese is 0.08 percent

b) carbon content is 0.4 percent and manganese is 0.8 percent

c) carbon content is 0.35 to 0.45 percent and manganese is 0.60 to 0.90 percent

d) carbon content is 0.60 to 0.80 percent and manganese is 0.8 to 1.2 percent

3. According to Indian standards, total number of tolerance grades are [ ]

a) 8 b) 12 c) 18 d) 20

4. According to Indian standard specification, 100 H6/g5 means that [ ]

a) tolerance grade for the hole is 6 and for the shaft is 5

b) tolerance grade for the shaft is 6 and for the hole is 5

c) tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7

d) tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7

5. The energy stored in a body when strained within elastic limit is known as [ ]

a) resilience b) proof resilience c) strain energy d) impact energy

6. If the elongation is less than ------------- %, the material is considered brittle [ ] 7. If σ is the yield stress, modulus of resilience is proportional to [ ] a) σ b) σ2 c) σ3 d)√σ 8. Two shafts A and B are made from the same material; B has double the diameter of A. The torque B can carry is -------------- times that A can carry. [ ] a) 2 b) 4 c) 8 d) 16 9. Sresses in X and Y directions in a body are σX = 200 MPa and σY= 100 MPa; The maximum principal stress in the body is [ ] a)50 MPa b) 100 MPa c) 150 MPa d) 200 MPa 10. σ1 andσ2 are principal stresses. Maximum shear stress will be [ ] a) σ1 b) σ2 c) σ1 - σ2 d) (σ1 - σ2)/2 11. Factor of safety in fatigue loading is the ratio of [ ] a) yield stress to working stress b) ultimate stress to working stress c) Endurance limit to working stress d) yield stress to endurance limit

12. The ratio of endurance limit in shear to endurance limit in flexure is [ ] a) 0.45 b) 0.65 c) 0.55 d) 0.70

13. Soderberg and Goodman’s equations are meant for determining [ ]

a) endurance limits for ductile materials c) yield stress for elastic materials

14. In static loading, stress concentration is more serious for a) ductile materials

15. For steel, the ratio of endurance limit and ultimate strength can be taken as [ ] a) 0.4

16. Distance between a line joining the centers of rivets and parallel to the edge ofthe plate is known as (a) back pitch

17. The objective of caulking in a riveted joint is to make (a) free from corrosion (c) free from stresses

18. A double strap butt joint with equal straps is always in (a) single shear (b) double shear (c) triple shear (d) no shear failure

19. Efficiency of the riveted joint is the ratio of ………….. to the tensile strengthof un riveted plate (a) tensile strength of perforated plate (b) shear strength or crushing strength of rivets

(c) minimum of the above three strengths (d) maxim

20. According to Indian Boiler Regulations, for double shear , the shear strength of rivet may be taken as……

(a) 2*(π/4)d2 * τ



III B.Tech – Mech (I sem)Mid Exam

Date : 05-09 DESIGN OF MACHINE ELEMENTS

Answer any THREE questions.

1. Enumerate the most commonly used engineering materials and state at least one important property and application of each.2. (a) Explain the term interchangeability.

(b) Explain the hole basis and shaft basis system as they apply to different fits.3. A mild steel shaft of 60 mm diameter is subjected to a bending mome torque T. If the yield point of steel in tension is 200 MPa, find the maximum value of this torque without causing yielding of the shaft according to i) maximum principal stress ii) Maximum shear stress and theories of failure. 4. (a) Define stress concentration factor. (b) A hot rolled shaft is subjected to torsional load that varies from 320 Nm clockwise to 120Nm anti-clockwise and 200Nm. The shaft is of uniform cross section. Determine the required shaft diameter. The material has an ultimate strength of 560MPa and yield strength of 420 MP safety to be 2.

5. (a) What is the difference between Caulking and fullering? Explain with the help of neat sketches.

(b) A double riveted double cover butt joint is made in 12mm thick plates with 18mm diameter rivets. Find the efficiency of the joint for a pitch of 80mm, if σt = 115MPa; τ = 80MPa; and σc = 160Mpa.

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ce limits for ductile materials b) endurance limit for brittle materialsc) yield stress for elastic materials c) factor of safety under variable stresses

14. In static loading, stress concentration is more serious for a) ductile materials b) brittle materials c) elastic materials d) all materials

15. For steel, the ratio of endurance limit and ultimate strength can be taken as [ ]b) 0.5 c) 0.55 d ) 0.70

stance between a line joining the centers of rivets and parallel to the edge of

(b) marginal pitch (c) gauge line

17. The objective of caulking in a riveted joint is to make it (b) stronger in tension

(d) leak- proof

A double strap butt joint with equal straps is always in (b) double shear (c) triple shear (d) no shear failure

Efficiency of the riveted joint is the ratio of ………….. to the tensile strength

(a) tensile strength of perforated plate (b) shear strength or crushing strength of rivets

(c) minimum of the above three strengths (d) maximum of the above three strengths

According to Indian Boiler Regulations, for double shear , the shear strength of rivet may be taken as…… (τ = shear stress of a rivet material )

(b) 1.875*(π/4)d2 *τ (c) 0.5*(π/4)d2 *τ



Mech (I sem)Mid Exam – I (Descriptive) Max. Marks : 20

09-2012 (AN) Time : 90 min

DESIGN OF MACHINE ELEMENTS – I


1. Enumerate the most commonly used engineering materials and state at least one importanterty and application of each.

2. (a) Explain the term interchangeability.

(b) Explain the hole basis and shaft basis system as they apply to different fits.3. A mild steel shaft of 60 mm diameter is subjected to a bending mome

torque T. If the yield point of steel in tension is 200 MPa, find the maximum value of this torquewithout causing yielding of the shaft according to i) maximum principal stress ii) Maximum shear stress and

4. (a) Define stress concentration factor.

(b) A hot rolled shaft is subjected to torsional load that varies from 320 Nm clockwise to 120Nmclockwise and an applied bending moment at a critical section varies from 400Nm to

200Nm. The shaft is of uniform cross section. Determine the required shaft diameter. Thematerial has an ultimate strength of 560MPa and yield strength of 420 MP

5. (a) What is the difference between Caulking and fullering? Explain with the help of neat

(b) A double riveted double cover butt joint is made in 12mm thick plates with 18mm diameterrivets. Find the efficiency of the joint for a pitch of 80mm, if σt = 115MPa; τ = 80MPa; and

σc = 160Mpa.

b) endurance limit for brittle materials c) factor of safety under variable stresses

[ ] b) brittle materials c) elastic materials d) all materials

15. For steel, the ratio of endurance limit and ultimate strength can be taken as [ ]

stance between a line joining the centers of rivets and parallel to the edge of [ ]

(d) pitch line

[ ]

[ ] (b) double shear (c) triple shear (d) no shear failure

Efficiency of the riveted joint is the ratio of ………….. to the tensile strength [ ]


um of the above three strengths

According to Indian Boiler Regulations, for double shear , the shear strength of rivet (τ = shear stress of a rivet material ) [ ]

*τ (d) 4*(π/4)d2 *τ



I (Descriptive) Max. Marks : 20

2012 (AN) Time : 90 min

1. Enumerate the most commonly used engineering materials and state at least one important [16]

(b) Explain the hole basis and shaft basis system as they apply to different fits. [6+10] 3. A mild steel shaft of 60 mm diameter is subjected to a bending moment of 3000 N-m and a

torque T. If the yield point of steel in tension is 200 MPa, find the maximum value of this torque

i) maximum principal stress ii) Maximum shear stress and iii) Maximum distortion energy [16]

(b) A hot rolled shaft is subjected to torsional load that varies from 320 Nm clockwise to 120Nm an applied bending moment at a critical section varies from 400Nm to

200Nm. The shaft is of uniform cross section. Determine the required shaft diameter. The material has an ultimate strength of 560MPa and yield strength of 420 MPa. Assume factor of

[6+10]

5. (a) What is the difference between Caulking and fullering? Explain with the help of neat

(b) A double riveted double cover butt joint is made in 12mm thick plates with 18mm diameter rivets. Find the efficiency of the joint for a pitch of 80mm, if σt = 115MPa; τ = 80MPa; and

[6+10]

9



III B.Tech – Mech (I sem)Mid Exam –II (objective) Max. Marks : 20

Date : 03-11-2012 (FN) Time : 30 min DESIGN OF MACHINE ELEMENTS – I Answer all questions 1. In a steam engine the piston rod is usually connected to the cross head by means of a [ ] a) knuckle joint b) universal joint c) flange coupling d) cotter joint 2. A key made from the circular disc having segmental cross section, is known as [ ] a) feather key b) gib head key c) Woodruff key d) flat saddle key 3. A feather key is generally [ ] a) loose in shaft and tight in hub b) tight in shaft and loose in hub c) tight in both shaft and hub d) loose in both shaft and hub 4 A keyway reduces [ ] a) the strength of the shaft b) the rigidity of the shaft c) both the strength and rigidity of the shaft d) the ductility of the material of the shaft 5 The following can connect only perfectly aligned shafts [ ] a) flange coupling b) muff coupling c) Oldham coupling d) flexible coupling 6. Oldham coupling is used to connect two shafts [ ] a) which are perfectly aligned b) which are not in exact alignment c) which have lateral misalignment d) whose axes intersect at a small angle 7. A cotter is used to transmit [ ] a) axial tensile load only b) axial compressive load only c) combined axial land twisting loads d) axial tensile or compressive loads 8. In designing a sleeve and cotter joint for a shaft of diameter ‘d’ , the outside diameter of the sleeve is taken as………. [ ] a) 1.5 d b) 2.5 d c) 3 d d) 4d 9. The following is the application of knuckle joint [ ] a) link of a cycle chain b) valve rod joint with eccentric rod c) tension link in bridge structure d) all the above 10. Two shafts A and B are made of the same material. The diameter of the shaft A is twice as that of shaft B. the power transmitted by the shaft A will be ………. of the shaft B. [ ] a) twice b) four times c) eight times d) sixteen times 11. When a nut is tightened by placing a washer below it, the bolt will be subjected to………… stress [ ] a) tensile b) compressive c) bending d) shear . 12. Railway carriage coupling have [ ] a) square threads b) acme threads c) knuckle threads d) buttress threads 13. A bolt of uniform strength can be developed by [ ] a) keeping the core diameter of the threads is equal to the diameter of the un-threaded portion of the bolt. b) keeping the core diameter of the threads smaller than the diameter of the un-threaded portion of the bolt. c) keeping the nominal diameter of the threads is equal to the diameter of the un-threaded portion of the bolt. d) none of the above 14. Resilience of a bolt may be increased by [ ] a) increasing its shank diameter b) increasing its length c) decreasing its shank diameter d) decreasing its length 15. A bolt of M 24X2 means that [ ] a) the pitch of the thread is 24 mm and depth is 2mm. b) cross sectional area of the thread is 24mm2 c) the nominal diameter of the bolt is 24mm and pitch is 2mm. d) the effective diameter of the bolt is 24mm and there are two threads per 2cm.

16. When a bolt is very yielding when compared with a) Either the external load or the initial tightening load, whichever is greaterb) Infinity c) External load onlyd) Initial tightening load only 17. When its connecting members are very yielding whena) zero b) Approximately the sum of external load and the initial tightening loadc) External load onlyd) Initial tightening load only 18. When a mating part, eg. Pulley has to slide on a shaft, the key used is a) Woodruff key b) Kennedy key c) feather key c) saddle key 19. The following key is used for heavy torquesa) Saddle key b) Kennedy key c) sunk key d) woodruff key 20. Locking device extensively used in automobile industry is a) Jam nut b) ring nut



III B.Tech

Date

DESIGN OF MACHINE ELEMENTS


1. (a) An eye bolt is to be used for lifting a load of 60 KN. Find the nominal diameter of the bolt, ifthe tensile stress is not to exceed 100 MPa. Assume coarse threads. (b) Two shafts are connected by means of a flange coupling to transmit torque of 25NThe flanges of the coupling are fastened by four bolts of the same material at a radius of 30 m.m. Find the size of the bolts if the allowable shear stress for the bolt material is 30 MPa. 2. (a) What are the applications of a cotter jo

(b) Design a cotter joint to transmit a load of 60kN in tension or in compression.Take the stresses as : allowable tensile stress =60 N/mmcrushing stress =110 N/mmdimensions. 3. (a) Explain the reasons for preferring hallow shafts over solid shafts

(b) A shaft, 2m long between bearings, carries a 900N pulley at its mid point. Through a belt drive, the shaft receives 25 kW at 180 rpm. The belt drive is horizontal and the sum of the belt tensions is 7 kN. Determine the diameter of the shaft and angle of twist, the shaft undergoes. Take G = 80 GN/mm 4. Design a clamp coupling completely for a shaft be transmitted by this coupling taking in to account overloading is 140Nm. The number of bolts used is 4 and the allowable stress in the material of the bolt is limited to 70 N/mmThe coefficient of friction belevation of the designed clamp coupling. 5. Design a cast iron protective type flange coupling to connect two shafts in order to transmit 7.5kW at 720rpm. The following permissible stresses may be used: Permissible shear stress for shaft, bolt and key material=33MPa; Permissible crushing stress for shafmaterial=60MPa; Permissible shear stress for cast iron=15MPa.

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When a bolt is very yielding when compared with connecting members, the resultant load is

Either the external load or the initial tightening load, whichever is greater

External load only Initial tightening load only

When its connecting members are very yielding when compared with a bolt, the resultant load is

Approximately the sum of external load and the initial tightening loadExternal load only Initial tightening load only

When a mating part, eg. Pulley has to slide on a shaft, the key used is Woodruff key b) Kennedy key c) feather key c) saddle key

The following key is used for heavy torques Saddle key b) Kennedy key c) sunk key d) woodruff key

Locking device extensively used in automobile industry is b) ring nut c) screw nut



III B.Tech – Mech (I sem)Mid Exam – II (Descriptive) Max. Marks : 20

: 03-11-2012 Time : 90 min

DESIGN OF MACHINE ELEMENTS – I


eye bolt is to be used for lifting a load of 60 KN. Find the nominal diameter of the bolt, iftensile stress is not to exceed 100 MPa. Assume coarse threads.

(b) Two shafts are connected by means of a flange coupling to transmit torque of 25Ne flanges of the coupling are fastened by four bolts of the same material at a radius of 30 m.m. Find

the size of the bolts if the allowable shear stress for the bolt material is 30 MPa.

(a) What are the applications of a cotter joint?

(b) Design a cotter joint to transmit a load of 60kN in tension or in compression.Take the stresses as : allowable tensile stress =60 N/mm2.allowable shear stress =48 N/mmcrushing stress =110 N/mm2. Sketch a `sectional elevation of the

(a) Explain the reasons for preferring hallow shafts over solid shafts

(b) A shaft, 2m long between bearings, carries a 900N pulley at its mid point. Through a belt receives 25 kW at 180 rpm. The belt drive is horizontal and the sum of the belt tensions is

7 kN. Determine the diameter of the shaft and angle of twist, the shaft undergoes. Take G = 80 GN/mm

Design a clamp coupling completely for a shaft diameter of 50mm. The torsional moment tobe transmitted by this coupling taking in to account overloading is 140Nm. The number of bolts used is 4 and the allowable stress in the material of the bolt is limited to 70 N/mmThe coefficient of friction between the shaft and muff material is 0.3. Draw sectional elevation of the designed clamp coupling.

a cast iron protective type flange coupling to connect two shafts in order to transmit 7.5kW at 720rpm. The following permissible stresses may be used: Permissible shear stress

for shaft, bolt and key material=33MPa; Permissible crushing stress for shafmaterial=60MPa; Permissible shear stress for cast iron=15MPa.

connecting members, the resultant load is [ ]

Either the external load or the initial tightening load, whichever is greater

compared with a bolt, the resultant load is [ ]

Approximately the sum of external load and the initial tightening load

When a mating part, eg. Pulley has to slide on a shaft, the key used is [ ] Woodruff key b) Kennedy key c) feather key c) saddle key

[ ] Saddle key b) Kennedy key c) sunk key d) woodruff key

[ ] d)castle nut



II (Descriptive) Max. Marks : 20

2012 Time : 90 min

eye bolt is to be used for lifting a load of 60 KN. Find the nominal diameter of the bolt, iftensile stress is not to exceed 100 MPa. Assume coarse threads.

(b) Two shafts are connected by means of a flange coupling to transmit torque of 25N-m. e flanges of the coupling are fastened by four bolts of the same material at a radius of 30 m.m. Find

the size of the bolts if the allowable shear stress for the bolt material is 30 MPa.

(b) Design a cotter joint to transmit a load of 60kN in tension or in compression. .allowable shear stress =48 N/mm2; allowable

. Sketch a `sectional elevation of the joint to a suitable scale giving all the

(a) Explain the reasons for preferring hallow shafts over solid shafts


7 kN. Determine the diameter of the shaft and angle of twist, the shaft undergoes. Take G = 80 GN/mm2

diameter of 50mm. The torsional moment to be transmitted by this coupling taking in to account overloading is 140Nm. The number of bolts used is 4 and the allowable stress in the material of the bolt is limited to 70 N/mm2.

etween the shaft and muff material is 0.3. Draw sectional elevation of the designed clamp coupling.

a cast iron protective type flange coupling to connect two shafts in order to transmit 7.5kW at 720rpm. The following permissible stresses may be used: Permissible shear stress

for shaft, bolt and key material=33MPa; Permissible crushing stress for shaft, bolt and key material=60MPa; Permissible shear stress for cast iron=15MPa.

eye bolt is to be used for lifting a load of 60 KN. Find the nominal diameter of the bolt, if

e flanges of the coupling are fastened by four bolts of the same material at a radius of 30 m.m. Find

; allowable joint to a suitable scale giving all the


.

11

QuestionBank

12

Design Of Machine elements -1

Objective Type Question Bank UNIT – I

1. Which of the following material has the maximum ductility? [ ]

a) mild steel b) copper c) zinc d) aluminum

2. According to Indian standard specifications, a grey case iron designated by ‘FG 200’

means that the [ ]

b) carbon content is 2% b) maximum compressive strength is 200 N/mm2

c) minimum tensile strength is 200 N/mm2 d) maximum shear strength is 200 N/mm2

3. According to Indian standard specification, a plain carbon steel designated by 40C8 means

that [ ]

d) carbon content is 0.04 percent and manganese is 0.08 percent

e) carbon content is 0.4 percent and manganese is 0.8 percent

f) carbon content is 0.35 to 0.45 percent and manganese is 0.60 to 0.90 percent

d) carbon content is 0.60 to 0.80 percent and manganese is 0.8 to 1.2 percent

4. The material commonly used for machine tool bodies is [ ]

a) mild steel b) aluminium c) brass d) cast iron

5. The material commonly used for crane hooks is [ ]

a) cast iron b) wrought iron c) mild steel d) aluminum

6. The steel widely used for motor car crankshafts is [ ]

a) nickel steel b) chrome steel c) nickel-chrome steel d) silicon steel

7. 18/8 steel contains [ ]

a) 18 percent nickel and 8 percent chromium b) 18 percent chromium and 8 percent nickel c)18

percent nickel and 8 percent vanadium d) 18 percent vanadium and 8 percent nickel

8. Ball bearing are usually made from [ ]

a) low carbon steel b) high carbon steel c) medium carbon steel d) high speed steel

9. The metal suitable for bearings subjected to heavy loads is [ ]

a) silicon bronze b) white metal c) monel metal d) phospher bronze

10. The metal suitable for bearings subjected to light loads is [ ]

a) silicon bronze b) white metal c) monel metal d) phospher bronze

11. In a unilateral system of tolerance, the tolerance is allowed on [ ]

a) one side of the actual size b) one side of the nominal size

c) both sides of the actual size d) both sides of the nominal size

12. The algebraic difference between the maximum limit and the basic size is called [ ]

a) actual deviation b) upper deviation c) lower deviation d) fundamental deviation

13. A basic hole is one whose [ ]

a) Lower deviation is zero b) upper deviation is zero

c) Lower and upper deviations are zero d) none of these

14. According to Indian standards, total number of tolerance grades are [ ]

a) 8 b) 12 c) 18 d) 20

15. According to Indian standard specification, 100 H6/g5 means that [ ]

e) tolerance grade for the hole is 6 and for the shaft is 5

f) tolerance grade for the shaft is 6 and for the hole is 5

g) tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7

h) tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7

16. Hooke’s law holds good up to [ ]

a) yield point b) elastic limit c) plastic limit d) breaking point

13

17. The energy stored in a body when strained within elastic limit is known as [ ]

a) resilience b) proof resilience c) strain energy d) impact energy

Bit questions Units 2 & 3

1. Permissible stress considered for ductile materials is [ ] a) Yield stress / FS b) ultimate stress / FS c) allowable stress/FS 2. Permissible stress considered for brittle materials is [ ] b) Yield stress / FS b) ultimate stress / FS c) allowable stress/FS 3. If the elongation is less than ------------- %, the material is considered brittle [ ] 4. If σ is the yield stress, modulus of resilience is proportional to b) σ b) σ2 c) σ3 d)√σ 5. Two shafts A and B are made from the same material; B has double the diameter of A. The torque B can carry is -------------- times that A can carry. [ ] b) 2 b) 4 c) 8 d) 16 6. Two shafts A and B are made from the same material; B has double the diameter of A. The power B can transmit is -------------- times that A can transmit. [ ] a) 2 b) 4 c) 8 d) 16 7. Two shafts A and B are made from the same material; B has double the diameter of A. The shear stress in A is -------------- times that in B under the same load. [ ] a) 2 b) 4 c) 8 d) 16 8. Strength to weight ratio of a solid shaft of diameter d carrying torque is directly proportional to [ ] a) √d b) d c) d2 d) d3 9. Sresses in X and Y directions in a body are σX = 200 MPa and σY= 100 MPa; The maximum principal stress in the body is [ ] a)50 MPa b) 100 MPa c) 150 MPa d) 200 MPa

10. σ1 andσ2 are principal stresses. Maximum shear stress will be [ ] a) σ1 b) σ2 c) σ1 - σ2 d) (σ1 - σ2)/2

11. Rankine’s theory is used for the following type of materials [ ] a) brittle b) ductile c)elastic d) plastic

12. Guest’s theory is used for the following type of materials [ ] a) brittle b) ductile c)elastic d) plastic

13. The following theory is most widely used for structural analysis of steel parts [ ] a) Rankine’s b) Guest’s c)St. Venant’s d) Von Mises’

14. Guest / Coulomb / Tresca proposed the following criterion of failure [ ] a)max principal stress b) max shear stress c)max strain energy d) max distortion energy

15. Von Mises / Hencky proposed the following criterion of failure [ ] a)max principal stress b) max shear stress c)max strain energy d) max distortion energy

16. Factor of safety in fatigue loading is the ratio of [ ] a) yield stress to working stress b) ultimate stress to working stress c) Endurance limit to working stress d) yield stress to endurance limit

17. The ratio of endurance limit in shear to endurance limit in flexure is [ ]

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a) 0.45 b) 0.65 c) 0.55 d) 0.70

18. In static loading, stress concentration is more serious for [ ] a) ductile materials b) brittle materials c) elastic materials d) all materials

19. For steel, the ratio of endurance limit and ultimate strength can be taken as [ ] a) 0.4 b) 0.5 c) 0.55 d ) 0.70

20. Soderberg and Goodman’s equations are meant for determining [ ] a) endurance limits for ductile materials b) endurance limit for brittle materials c) yield stress for elastic materials c) factor of safety under variable stresses

Unit-IV

Bit Questions on Riveted Joints

1. A rivet is specified by [ ]

(a) shank diameter (b) length of rivet (c)type of head (d) length of tail

2. The diameter of rivet hole is usually…………..the nominal diameter of the rivet

(a) equal to (b) less than (c) more than (d) twice [ ]

3. The rivet head used for boiler plate riveting is usually [ ]

(a) snap head (b) pan head (c) counter sunk head (d) conical head

4. According to Prof. UnWin’s formula, the relation between the diameter of rivet hole (d) and the thickness of the plate (t) is given by [ ]

(a) d = t (b) d = 6*t1/2 (c) d = 2t (d) d = 6t

5. Distance between a line joining the centers of rivets and the edge of the plate is known as

(a) back pitch (b) marginal pitch (c) gauge line (d) pitch line [ ]

6. The center to center distance between two consecutive rivets in a row, is called

(a) back pitch (b) marginal pitch (c) diagonal pitch (d) pitch [ ]

7. The objective of caulking in a riveted joint is to make it [ ]

(a) free from corrosion (b) stronger in tension (c) free from stresses (d) leak- proof

8. A riveted lap joint is always in…………… [ ]

(a) single shear (b) double shear(c) triple shear(d) no shear failure

9. A double strap butt joint with equal straps is always in [ ]

(a) single shear (b) double shear(c) triple shear (d) no shear failure

10. Which of the following riveted butt joints with double straps should have the highest efficiency as per Indian Boiler Regulations [ ]

(a) single riveted (b) double riveted (c) triple riveted (d) quadruple riveted

11. If the tearing efficiency of the riveted joint is 50%, then the ratio of the diameter of the rivet hole to the pitch of the rivets [ ]

(a) 0.20 (b) 0.30 (c) 0.50 (d) 0.60

12. The strength of the unriveted or solid plate per pitch length is equal to [ ]

15

(a) p *d*σt (b) p *t*σt (c) (p – t) *d*σt (d) (p – d)t*σt

13. The longitudinal joint in boilers is used to get the required [ ]

(a) length of the boiler (b) diameter of the boiler (c) Length and diameter of the boiler (d) efficiency of the boiler

14. For longitudinal joint in boilers, the type of joint used is [ ]

(a) lap joint with one ring overlapping the other(b) butt joint with single cover plate

(c) butt joint with double cover plate (d) any of these

15. Lozenge joint is name adapted for [ ]

(a) longitudinal butt joint of a boiler (b) circumferential lap joint of a boiler

(c) Diamond riveting of structures (d) eccentric loading of structures.

16. Efficiency of the riveted joint is the ratio of ………….. to the tensile strength of un riveted plate [ ]


(c) minimum of the above three strengths (d) maximum of the above three strengths

17. According to Indian Boiler Regulations, for double shear , the shear strength of rivet

( Ps ) may be taken as…… (τ – shear stress of a rivet material ) [ ] (a) 2*(π/4)d2 * τ (b) 1.875*(π/4)d2*τ (c) 0.5*(π/4)d2 *τ (d) 4*(π/4)d2 *τ

18. For circumferential joint in boilers, the type of joint used is [ ]

(a) lap joint with one ring overlapping the other (b) butt joint with single cover plate

(c) butt joint with double cover plate (d) any of these

19. The circumferential joint in boilers is used to get the required [ ]

(a) length of the boiler (b) diameter of the boiler (c) length and diameter of the boiler (d).efficiency of the boiler

20. According to Indian standards , the diameter of rivet hole for a 24mm diameter of rivet, should be (a) 23mm (b)24mm (c) 25mm (d) 29mm. [ ]

BIT-QUESTION BANK (UNITS - V,VI, VII & VIII)

………………………………………………………………………………………………………………

1. The usual proportion for the width of the key is [ ] a) d/8 b) d/6 c) d/4 d) d/2 3. A key made from the circular disc having segmental cross section, is known as [ ] a) feather key b) gib head key c) Woodruff key d) flat saddle key 3. A feather key is generally [ ] a) loose in shaft and tight in hub b) tight in shaft and loose in hub c) tight in both shaft and hub d) loose in both shaft and hub 4. the type of stresses developed in a key is/are [ ] a) shear stress alone b) bearing stress alone c) both shear and bearing stresses d) shearing, bearing and bending stresses 5. for a square key made of mild steel, the shear and crushing strengths are [ ] a) shear strength = crushing strength b) shear strength > crushing strength c) shear strength < crushing strength d) none of the above 6. A keyway reduces [ ]

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a) the strength of the shaft b) the rigidity of the shaft c) both the strength and rigidity of the shaft d) the ductility of the material of the shaft 7. the sleeve or muff coupling is designed as [ ] a) thin cylinder b) thick cylinder c) solid shaft d) hollow shaft 8. The stress developed in the bolts of a split muff coupling is [ ] a) tensile b) compressive c) shear d) bending 9. The following can connect only perfectly aligned shafts [ ] a) flange coupling b) muff coupling c) Oldham coupling d) flexible coupling 10. Oldham coupling is used to connect two shafts [ ] a) which are perfectly aligned b) which are not in exact alignment c) which have lateral misalignment d) whose axes intersect at a small angle 11. a cotter is used to transmit [ ] a) axial tensile load only b) axial compressive load only c) combined axial land twisting loads d) axial tensile or compressive loads 12. the taper on cotter varies from [ ] a) 1 in 15 to 1 in 10 b) 1 in 24 to 1 in 20 c) 1 in 32 to 1 in 24 d) 1 in 48 to 1 in 24 13. The following cotter joint is used to connect strap end of a connecting rod [ ] a) socket and spigot cotter joint b) sleeve and cotter joint c) gib and cotter joint d) none of these 14. In designing a sleeve and cotter joint for a shaft of diameter ‘d’ , the outside diameter of the sleeve is taken as………. [ ] a) 1.5 d b) 2.5 d c) 3 d d) 4d 15. The length of cotter, in a sleeve and cotter joint, is taken as [ ] a) 1.5 d b) 2.5 d c) 3 d d) 4d 16. In a gib and cotter joint, the thickness of gib is……….thickness of cotter [ ] a) more than b) less than c) equal to d) there is no relation 17. When one gib is used in a gib and cotter joint, then the width of the gib should be taken as……….(B- total width of gib and cotter ) [ ] a) 0.45 B b) 0.55 B c) 0.65 B d) 0.75 B 18. In a steam engine the piston rod is usually connected to the cross head by means of a [ ] a) knuckle joint b) universal joint c) flange coupling d) cotter joint 19. In a steam engine the valve rod is connected to an eccentric by means of a ………. [ ] a) knuckle joint b) universal joint c) flange coupling d) cotter joint 20. The following is the application of knuckle joint [ ] a) link of a cycle chain b) valve rod joint with eccentric rod c) tension link in bridge structure d) all the above 21. The following is the material used for a cotter [ ] a) mild steel b) aluminium c) brass d) C.I 22. Which end of the connecting rod is usually provided with gib and cotter joint? [ ] a) small end b) big end c) both the ends d) none of the ends

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23. Two shafts A and B are made of the same material. The diameter of the shaft A is twice as that of shaft B. the power transmitted by the shaft A will be ………. of the shaft B. [ ] a) twice b) four times c) eight times d) sixteen times 24. When a shaft is subjected to combined B.M. ‘M’ and T.M. ‘T’, then the equivalent twisting moment is equal to [ ] a) M + T b) M2 + T2 c) √ (M2 + T2) d) √ (M2 - T2) 25. Following is the material used for shafts [ ] a) mild steel b) Ni- Cr steel c) Ni – V steel d) all the above 26. Short shaft that imparts motion to a cutting tool or to a work piece [ ] a) axle b) spindle c) long slender shaft d) strut 27. Transmission shaft is generally subjected to [ ] a) only twisting moment b) only bending moment c) both twisting and bending moment d) none of the above. 28. Maximum shear stress theory is used for …………….materials [ ] a) brittle b) ductile c) plastic d) non-ferrous. 29. Shafts made of brittle materials are to be designed according to [ ] a) Guest’s theory b) Von Mises’ theory c) Rankine’s theory d) St. Venant’s theory 30. Axle is used for the transmission of [ ] a) only twisting moment b) only bending moment c) both twisting and bending moment d) none of the above. 31. Product of Young’s modulus (E) and moment of inertia (I), in the flexural equation is Called [ ] a) stiffness b) rigidity c) section modulus d) strength 32. The following must be considered in the design of long slender shaft [ ] a) stress concentration factor b) load factor c) column factor d) all the above. 33. Maximum Normal stress theory is used for …………….materials [ ] a) brittle b) ductile c) plastic d) non-ferrous. 34. process used for manufacturing of shaft [ ] a) forging b) hot rolling c) cold rolling d) all the above. 35. A screw is specified by its [ ] a) major diameter b) minor diameter c) pitch diameter d) pitch 36. Railway carriage coupling have [ ] a) square threads b) acme threads c) knuckle threads d) buttress threads 37. A bolt of uniform strength can be developed by [ ] a) keeping the core diameter of the threads is equal to the diameter of the un-threaded portion of the bolt. b) keeping the core diameter of the threads smaller than the diameter of the un-threaded portion of the bolt. c) keeping the nominal diameter of the threads is equal to the diameter of the un-threaded portion of the bolt. d) none of the above 38. Resilience of a bolt may be increased by [ ] a) increasing its shank diameter b) increasing its length c) decreasing its shank diameter d) decreasing its length

18

39. when a nut is tightened by placing a washer below it, the bolt will be subjected to………… stress [ ] a) tensile b) compressive c) bending d) shear 40. A bolt of M 24X2 means that [ ] a) the pitch of the thread is 24 mm and depth is 2mm. b) cross sectional area of the thread is 24mm2 c) the nominal diameter of the bolt is 24mm and pitch is 2mm. d) the effective diameter of the bolt is 24mm and there are two threads per 2cm. 41. A bolt with left hand threads matches with a nut with the following threads [ ] a) Right hand of same pitch b) left hand of same pitch c) Right hand of fine pitch d) left hand of fine pitch 42. When a bolt is very yielding when compared with its connecting members, the resultant load is [ ] e) Either the external load or the initial tightening load, whichever is greater f) Infinity g) External load only h) Initial tightening load only 43. When its connecting members are very yielding when compared with a bolt, the resultant load is [ ] e) zero f) Approximately the sum of external load and the initial tightening load g) External load only h) Initial tightening load only 44. When a mating part, eg. Pulley has to slide on a shaft, the key used is [ ] b) Woodruff key b) Kennedy key c) feather key c) saddle key 45. The following key is used for heavy torques [ ] b) Saddle key b) Kennedy key c) sunk key d) woodruff key 46. Locking device extensively used in automobile industry is [ ] b) Jam nut b) ring nut c) screw nut d) castle nut

Question Bank – Units 1&2

Introduction, Materials and manufacturing, simple stresses

1. (a) Enumerate various factors influencing selection of materials.

(b) A cast iron pulley transmits 20Kw at 300RPM. The diameter of pulley is 0.55 metre of elliptical cross section in which major axis is twice minor axis, find dimensions of arm if the allowable bending stress is 15 MPa

2. (a) Discuss the factors to be considered in the selection of engineering materials.

(b) The crank pin of an engine sustains a maximum load of 35kN due to steam pressure. If the allowable bearing pressure is 7MPa, find the dimensions of the pin. Assume length of pin is 1.2 times diameter of pin.

3. (a) List out and discuss the general considerations in the design of machine members. (b) A square tie bar of 20mm side section is attached to a bracket by 6 pins and carries a load. Calculate the diameter of pin, if the maximum stress in tie bar is 150MPa and in pins 75MPa.

4. (a) Enlist the manufacturing considerations in design of machine members.

(b) The diameter of a piston of steam engine is 300mm and the maximum permissible steam

19

pressure is 0.7MPa. If the maximum permissible compressive stress for the piston rod material is 40MPa, find the size of the piston rod.

5. (a) What are the factors to be considered in determination of factor of safety?

(b) Find the minimum size of the hole that can be punched in a 20mm thick steel plate, having an ultimate tensile strength of 600MPa. The maximum permissible compressive stress in the punch material is 1200MPa. Assume ultimate shear strength of plate material is half its ultimate tensile strength.

6. Enumerate the most commonly used engineering materials and state some important properties and their engineering applications. [16]

7. (a) What is an Engineering design.

(b) Explain the stages in the design of machine members. [4+12]

8. (a) What is conceptual design.

(b) Explain the manufacturing consideration in the design. [4+12]

9. (a) Explain the concept of philosophy of engineering design.

(b) Explain the following terms: i. Conceptual design ii. Innovative design. [8+8] 10. Explain the stress-strain diagram indicating various points on it. [16]

11. (a) Explain the term interchangeability.

(b) Explain the hole basis and shaft basis system as they apply to different fits. [6+10]

12. (a) Define the terms load, stress and strain. Discuss the various types of stresses and strains.

(b) Explain the difference between linear and lateral strain. [10+6]

13. (a) Classify the various types Machine Design.

(b) What is the procedure adopted in the design of Machine elements. [6+10]

14. (a) What are the various phases in general design procedure?

(b) Discuss various cast irons and its applications in design.

15. (a) What are the factors considered while selection of engineering materials.

(b) What are factors to be considered while selecting factor of safety in design?

16. (a) What are the general considerations in engineering design?

(b) What are applications of steels in design?

17. (a) Discuss standardization and effect of Preferred Numbers on it.

(b) What are the properties and applications of Non-metals in design?

18. (a) Classify Machine Design.

(b) What is the procedure adopted in the design of Machine elements. [6+10] 19. What are the factors to be considered for the selectors of materials for the design of machine elements. Discuss.

20. (a) Discuss the factors to be considered in the selection of engineering materials.

(b) The crank pin of an engine sustains a maximum load of 35kN due to steam pressure. If the allowable bearing pressure is 7MPa, find the dimensions of the pin. Assume length of pin is 1.2 times diameter of pin.

21. (a) List out and discuss the general considerations in the design of machine members.

20

(b) A square tie bar of 20mm side section is attached to a bracket by 6 pins and carries a load. Calculate the diameter of pin, is the maximum stress in tie bar is 150MPa and in pins 75MPa.

22. (a) Enlist the manufacturing considerations in design of machine members.

(b) The diameter of a piston of steam engine is 300mm and the maximum permissible steam pressure is 0.7MPa. If the maximum permissible compressive stress for the piston rod material is 40MPa, find the size of the piston rod.

23. (a) What are the factors to be considered in determination of factor of safety?

(b) Find the minimum size of the hole that can be punched in a 20mm thick steel plate, having an ultimate tensile strength of 600MPa. The maximum permissible compressive stress in the punch material is 1200MPa. Assume ultimate shear strength of plate material is half its ultimate tensile strength.

24. Enumerate the most commonly used engineering materials and state at least one important property and application of each.

Principal stresses, Combined bending, axial and torsional stresses

1. (a) Derive expressions used for principal stresses.

(b) The crankpin of a engine sustains a max load of 35 KN due to steam pressure. If the allowable bearing pressure is 7N/mm find the dimensions of pin. Assume the length of pin equal to 1.2 times diameter of pin.

2. A cast iron pulley transmits 20 KW at 300 RPM. The diameter of pulley is 550 mm and has four straight arms of elliptical cross section in which major axis is twice the minor axis. Find the dimensions of the arm, if the allowable bending stress is 15 MPa. 3. (a) Explain the salient features of the maximum principal stress theory and indicate under what conditions such a theory is useful?

(b) A shaft is designed based on maximum distortion energy theory with a factor of safety of 2.0. The material used is 30C8 steel with a yield stress of 310 MPa. It is subjected to an axial load of 40 kN. Determine the maximum torque capacity. Diameter of the shaft is 20 mm.

4. A mild steel shaft of 60 mm diameter is subjected to a bending moment of 3000 N-m and a torque T. If the yield point of steel in tension is 200 MPa, find the maximum value of this torque without causing yielding of the shaft according to i) maximum principal stress ii) Maximum shear stress and iii) Maximum distortion energy theories of failure. 5. A cantilever shaft of length 300 mm and diameter 60 mm is subjected to the following loads at its free end: A vertical bending load of 5 kN, pure torque of 1600 N-m and an axial pulling force of 20 kN. Calculate the stresses at the fixed end of the shaft.

Question Bank: Unit III - Variable stresses

1. (a) Explain fatigue stress concentration factor and notch sensitivity.

(b) Determine the size of a piston rod subjected to fluctuation of loads from 15KN (compression) to 25KN (tension). The endurance limit is 360MPa and yield strength is 400MPa. Take the impact factor =1.25. Factor of safety=1.5. Surface factor=0.88. Stress concentration factor =2.25.

2. (a) Differentiate between endurance limit and endurance strength.

(b) Determine the diameter of a circular rod made of ductile material with fatigue strength of 280 MPa and yield strength of 350MPa. The member is subjected to a varying axial load

21

from 700kN to-300kN. Assume Kt=1.8 and FS=2.

3. (a) Define ‘form stress concentration factor’ and notch sensitivity.

(b) Determine the size of a piston rod subjected to a total fluctuations between 15KN m. Compression and 25KN in tension. The endurance limit is 360 MPa and yield strength 400MPa. The FS=1.5; surface factor =0.88. Stress factor = 2.25.

4. (a) Illustrate the methods of reducing stress concentration.

(b) A simply supported shaft between bearings carries a load at 15KN at the centre. The span of beam is 500mm. The load varies to a maximum value of 30KN. Find the diameter of the shaft if its endurance limit is 600MPa and surface factor is 0.88, size factor is 0.8 and FS=1.6.

5. (a) What are the various factors influencing endurance strength.

(b) Find the diameter of a shaft to transmit twisting moments varying from 800 Nm to 1600Nm. The ultimate tensile strength for the material is 600MPa, and yield stress is 400MPa. Assume the stress concentration factor=1.2; surface finish factor =0.8 and size factor =0.85.

6. (a) Explain the effect of the following factors on the type of fatigue failure. i. Type of material ii. Stress distribution

(b) A shaft made of steel having ultimate tensile strength of 700 MPa and yield point 420 MPa is subjected to a torque of 2000 N m clockwise to 600 N m anti-clockwise. Calculate the diameter of the shaft if the factor of safety is 2 and it is based on the yield point and the endurance strength in shear. [4+12]

7. (a) Explain the effect of the following factors on the type of fatigue failure. i. Range of imposed stress ii. strain rate

(b) A rotating shaft carries a 18 KN pulley at the center of a 0.75m simply supported span. The average torque is 230 N m. Assume the torque range to be 10 % of the average torque. The material has yield point of 770 MPa and the endurance limit of 450MPa.

Determine the required diameter of the shaft based on i. Maximum stress theory and ii. distortion energy theory. Stress concentration factor may be taken as 1.5 and a factor of safety 2. [4+12]

8. (a) Define stress concentration factor.

(b) A hot rolled shaft is subjected to torsional load that varies from 320 Nm clockwise to 120Nm anti-clockwise and an applied bending moment at a critical section varies from 400Nm to 200Nm. The shaft is of uniform cross section. Determine the required shaft diameter. The material has an ultimate strength of 560MPa and yield strength of 420 MPa. Assume factor of safety to be 2. [6+10]

9. (a) Explain the effect of the following factors on the type of fatigue failure. i. Stress distribution ii. Surface treatment

(b) Determine the maximum load for a simply supported beam of 0.4m length if the load at the mid-span varies cyclically from 2P to 4P. The size of the beam is 0.05m diameter. The endurance limit for reversed bending is 350 MPa and the yield point in tension is 520 MPa. Take Size correction factor = 0.85 and Surface correction factor = 0.9. Design factor of safety may be taken as 1.9. [4+12]

10. (a) Discuss the effects of the following factors on endurance limit. i. Load factor ii. Surface finish factor iii. size factor.

(b) A circular bar of 500 m.m length is supported freely at it two ends. It is acted upon by a central concentrated cyclic load having a minimum value of 20 kN and a maximum value of 50 kN. Determine the diameter of the bar by taking a factor of safty of 1.5, size effect of

22

0.85, surface finish factor of 0.9. The material properties of bar are given by: ultimate strength of 650 Mpa, yield strength of 500 Mpa and endurance strength of 350 Mpa. [6+10]

11. A hot rolled steel shaft is subjected to a torsional moment that varies from 330 N-m clockwise to 110 N-m counterclockwise and an applied bending moment at a critical section varies from 440 N-m to -220 N-m. The shaft is of uniform cross- section and no key way is present at the critical section. Determine the required shaft diameter. The material has an ultimate strength of 550M N/m2 and a yield strength of 410M N/m2. Take the endurance limit as half the ultimate strength, factor of safty of 2, size factor of 0.85 and surface finish factor of 0.62. [16]

12. (a) Explain the Soderberg method for combination of stresses.

(b) A steel rod is subjected to a reversed axial load of 180 kN. Find the diameter of the rod for a factor of safty of 2. Neglect column action. The material has an ultimate tensile strength of 1070 Mpa and yield strength of 910 Mpa. The endurance limit is reversed bending may be assumed to be one half of the ultimate tensile strength. The correction factors are as follows. Load factor =0.7; surface finish factor=0.8; Size factor =0.85; stress concentration factor = 1. [6+10]

13. (a) Discuss fatigue and endurance limit.

(b) Determine the diameter of a circular rod made of ductile material with a fatigue strength (complete reversal), σe = 265 Mpa and tensile yield strength of 350 Mpa. The member is subjected to a varying axial load from Wmin = -300 kN to Wmax =700 kN and has a stress concentration factor=1.8. Use factor of safty as 2. [6+10]

14. (a) Discuss maximum shear stress theory.

(b) A steel connecting rod is subjected to completely reversed axial load of 160 KN. Suggest a suitable diameter of rod, using a factor of safety 1.5. The ultimate tensile strength 1100 MPa; yield strength of 930 MPa. Neglect stress concentration.

15. (a) Discuss methods of minimizing stress concentration.

(b) A cast iron pulley transmits 10 KW at 400 RPM. The diameter of pulley is 1.2 m and has four straight arms of circular cross section. Determine the dimensions of the arm if the allowable bending stress is 15 MPa.

16. (a) Describe maximum strain energy theory with its limitations.

(b) Find the diameter of shaft made of steel with ultimate tensile strength of 600 MPa and yield stress 440 MPa. The shaft is subjected to completely reversed axial load of 200 KN. Assume surface factor of 0.85 and factor of safety as 1.5.

17. (a) Discuss distortion energy theory.

(b) Find the diameter of shaft to transmit varying moment of 800 Nm to 1600 Nm. The ultimate tensile strength of material is 600 MPa and yield stress is 450 MPa. Assume a stress concentration factor of 1.2; surface factor of 0.8 and a size factor of 0.85.

18. (a) Discuss factors affecting stress concentration.

(b) A shaft is transmitting 100 KW at 800rpm. If the allowable shear stress 60 MPa, find the suitable diameter of shaft. The shaft is not to twist more than 10 for a length of 3 meters. Take C=80GPa.

19. (a) Discuss maximum principal stress theory.

(b) Determine diameter of circular rod of steel with fatigue strength of 280 MPa; and a tensile strength of 350 MPa. The member is subjected varying axial load from 700 KN to -300KN. Assume Kt = 1.8 and FOS=2.0.

20. (a) Explain stress concentration with suitable examples.

23

{b) A steel link having a rectangular section is subjected to a repeated axial load of 50,000 N with a medium shock. Determine the section if the endurance limit be 250 MPa with a design factor 1.5. Take side ratio as 2:1. Size factor may be taken as 0.85 and surface finish factor as 0.88. [6+10] 21. (a) Explain the effect of the following factors on the type of fatigue failure i. Stress distribution ii. Range of imposed stress

(b) A hot rolled steel shaft is subjected to a torsional load that varies from 300 N m clockwise to 100 N m anti-clockwise as an applied bending moment at a critical section varies from 400 N m to - 200 N m. Suggest the suitable size for the shaft if the material has an ultimate strength of 560 MPa and a yield strength of 420 MPa. Take the factor of safety as 2. The shaft is of uniform diameter and no keyway is present at the critical section.

22. (a) Differentiate between endurance limit and endurance strength.

(b) Determine the diameter of a circular rod made of ductile material with fatigue strength of 280 MPa and yield strength of 350MPa. The member is subjected to a varying axial load from 700kN to-300kN. Assume Kt=1.8 and FS=2.0

23. (a) Define ‘form stress concentration factor’ and notch sensitivity.

(b) Determine the size of a piston rod subjected to a total fluctuations between 15KN m. Compression and 25KN in tension. The endurance limit is 360 MPa and yield strength 400MPa. The FS=1.5; surface factor =0.88. Stress factor = 2.25.

24. (a) Illustrate the methods of reducing stress concentration.

(b) A simply supported shaft between bearings carries a load at 15KN at the centre. The span of beam is 500mm. The load varies to a maximum value of 30KN. Find the diameter of the shaft if its endurance limit is 600 MPa and surface factor is 0.88, size factor is 0.8 and FS=1.6.

25. (a) What are the various factors influencing endurance strength.

(b) Find the diameter of a shaft to transmit twisting moments varying from 800 Nm to 1600Nm. The ultimate tensile strength for the material is 600MPa, and yield stress is 400MPa. Assume the stress concentration factor=1.2; surface finish factor =0.8 and size factor =0.85.

26. (a) Explain the following methods of reducing stress concentration i. Drilled holes ii. Using large fillet radius iii. Added grooves

(b) A shaft is made of steel [ultimate tensile strength 700 MPa and yield point 420 MPa] is subjected to a torque varying from 200N-m anti-clockwise to 600 N-m clockwise. Calculate the diameter of the shaft if the factor of safety is 2 and it is based on the yield point and the endurance strength in shear.

Question Bank- Unit IV: Riveted Joints

1. (a) Explain caulking and fullering.

(b) Two plates of mild steel tie rod are connected with width 200 mm and thickness 12.5mm are to be connected by means of a butt joint with double cover plates. Design the joints if safe stresses are 80MPa in tension; 65MPa in shear ; and 160MPa in crushing. Make sketch of a joint.

2. Design a double riveted butt joint with two cover plates, for the longitudinal seam of a boiler shell 1.5m diameter subjected to a steam pressure of 0.9MPa. Assume the joint efficiency as 75%, allowable tensile stress in plate 90MPa, compressive stress 140MPa; and shear stress in the rivets is 56 MPa.

4. A double riveted lap joint with zig-zag riveting is to be designed for 13mm plates. Assume permissible stresses in tension, shear and compression are 80MPa, 60MPa and 120MPa respectively. Find the efficiency of the joint and state how the joint will fail.

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5. Design the longitudinal joint for a 1.25m diameter steam boiler to carry a steam pressure of 2.5 N/mm2. The ultimate strength of the boiler plate may be assumed as 420MPa, crushing strength as 650MPa and shear strength of 300MPa. The joint efficiency as 80%. The FOS=2.0.

6. Two plates of 8mm thickness each are to be joined by a single riveted double strap butt joint. Design the joint with working stresses in tension and shearing and compression are 80MPa, 60MPa and 100MPa respectively.

7. A bracket is riveted to a column by 6 rivets (A,B,C,D,E and F) of equal size as shown in Figure 3. The centres of rivets A,B,C are on the same vertical line and the centres of E , F are on the another vertical line. The centres of B, D are on the same horizontal line. The centres of A, E are on one horizontal line and the centres of C,F are on another horizontal line. The vertical distance between A,B and B,C are 75 mm and 75 mm respectively. The horizontal distance between B,D and C,F are 75 mm and 150 mm respectively. It carries a load of 100 KN at a horizontal distance of 250 mm from the central line of rivet D. If the maximum shear stress in the rivet is limited to 63 MPa, find the diameter of the rivet. [16]

8. (a) What are the relative advantages and disadvantages of welded joints over riveted joints?

9. A double riveted butt joint in which the pitch of the rivets in the outer rows is twice that in the inner rows, connects two 16mm thick plates with two cover plates each 12mm thick. The diameter of rivets is 22mm. Determine the pitches of the rivets in the two rows if the working stresses are not to exceed the following limits. Tensile stress in plates = 100 MPa Shear stress in rivets = 75 MPa; Bearing stress in rivets and plates = 150 MPa Make a fully dimensioned sketch of the joint by showing at least two views. [16]

10. (a) Classify the rivet heads according to Indian Standard Specification.

(b) A double riveted lap joint is made between 15mm thick plates. The rivet diameter and pitch are 25mm and 75mm respectively. If the ultimate stresses are 400 MPa in tension and 320 MPa in shear and 640 MPa in crushing, find the minimum force per inch, which will rupture the joint. If the above joint is subjected to a load such that the factor of safety is 4, find out the actual stresses developed in the plates and the rivets. [6+10]

11. (a) What is the difference between Caulking and fullering? Explain with the help of neat sketches.

(b) A double riveted double cover butt joint is made in 12mm thick plates with 18mm diameter rivets. Find the efficiency of the joint for a pitch of 80mm, if σt = 115MPa; τ = 80MPa; and σc = 160Mpa. [6+10]

12. Discuss the design procedure of eccentrically loaded riveted joints.

13. (a) Enumerate the different types of riveted joints.

(b) Two plates 16 mm thick are joined by a double riveted lap joint. The pitch of each row of rivets is 90 mm. The rivets are 25 mm in diameter. The permissible stresses are 140 MPa in tension, 80 MPa in shear and 160 MPa in crushing. Find the efficiency of the joint.

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[8+8]

14. (a) Show by neat sketches the various modes of failure of riveted joints.

15. Design a double riveted butt joint with two cover plates, for the longitudinal seam of a boiler shell 1.5m diameter subjected to a steam pressure of 0.9MPa. Assume the joint efficiency as 75%, allowable tensile stress in plate 90MPa, compressive stress 140MPa; and shear stress in the rivets is 56 MPa.

16. A double riveted lap joint with zig-zag riveting is to be designed for 13mm plates. Assume permissible stresses in tension, shear and compression are 80MPa, 60MPa and 120MPa respectively. Find the efficiency of the joint and state how the joint will fail.

17. Design the longitudinal joint for a 1.25m diameter steam boiler to carry a steam pressure of 2.5 N/mm2. The ultimate strength of the boiler plate may be assumed as 420MPa, crushing strength as 650MPa and shear strength of 300MPa. The joint efficiency as 80%. The FOS=2.0.

18. Two plates of 8mm thickness each are to be joined by a single riveted double strap butt joint. Design the joint with working stresses in tension and shearing and compression are 80MPa, 60MPa and 100MPa respectively.

19. (a) Explain the following terms in connection with riveted joints i. Pitch ii. Back pitch iii. Diagonal pitch iv. Margin

(b) A double riveted butt joint, in which the pitch of the rivets in the outer rows is twice that in the inner rows, connects two 16 mm thick plates with two cover plates each 12 mm thick. The diameter of the rivets is 22 mm. Determine the pitches of the rivets in the two rows if the working stresses are not to exceed the following limits: Tensile stress in plates = 100 MPa, Shear stress in rivets = 75 MPa and bearing stresses in rivets and plates = 150 MPa. Make a fully dimensioned sketch of the joint showing at least two views.

20. (a) Enumerate the different types of riveted joints.

(b) Two plates 16 mm thick are joined by a double riveted lap joint. The pitch of each row of rivets is 90 mm. The rivets are 25 mm in diameter. The permissible stresses are 140 MPa in tension, 80 MPa in shear and 160 MPa in crushing. Find the efficiency of the joint.

[8+8]

Question Bank: Unit-VThreaded Joints 1. (a) Explain design of bolted joints with combined pre-load and external loads.

(b) A steam engine cylinder has an effective diameter of 350mm and maximum steam pressure is 1.25 MPa. Calculate the member and size of studs required to fix the cylinder cover assuming permissible stress in the studs as 33MPa. 2. (a) Enumerate various stresses due to initial tightening of screwed fasteners.

(b) The cylinder head of effective diameter 300 mm for a steam engine is subjected to 1.2MPa. It is held in position by means of 12 studs. A soft copper gasket is used to make joint leak proof. Determine the size of bolts or studs, so that the stress should not exceed 100MPa. 3. (a) Enumerate various types of locking devices, seals and thread forms.

(b) The cylinder head of a steam engine is subjected to 1.0MPa. It is held in position by means of 12 studs. The effective diameter is 300mm. A soft copper gasket is used to make joint leak proof. Determine the size of the bolts or studs, so that bolt stress should not exceed 100MPa. 4. (a) Explain what are bolts of uniform strength.

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(b) The cylinder head of a steam engine is subjected to a steam pressure of 0.7MPa. It is held in position by 12 studs. A soft copper gasket is used to make the joint leak proof. The effective diameter of cylinder is 300mm. Find the size of the bolts, so that the stress is limited to 100MPa. 5. Discuss the design procedure of eccentrically loaded bolted joints. 6. Discuss stresses subjected to bolted joints. (a) When tightened only. (b) When externally loaded. (c) Combined initial load with external loads. 7. A steam engine of effective diameter 300 mm is subjected to a steam pressure of 1.5 MPa. The cylinder head is connected by 8 bolts having yield point 330 MPa and endurance limit at 240 MPa. The bolts are tightened with an initial preload of 1.5 times the steam load. A soft copper gasket is used to make the joint leak-proof. Assuming factor of safety 2, find the size of the bolt required. The stiffness factor for copper gasket may be taken as 0.5. [16] 8. (a) Sketch various types of threads giving their applications.

(b) A lever loaded safety valve has a diameter of 100 mm and the blow off pressure is 1.6N/mm2. The fulcrum of the lever is screwed into the cast iron body of the cover. Find the diameter of the threaded part of the fulcrum, if the permissible tensile stress is limited to 50 MPa and the lever ratio is 8. [8+8] 9. (a) An eye bolt is to be used for lifting a load of 60 KN. Find the nominal diameter of the bolt, if the tensile stress is not to exceed 100 MPa. Assume coarse threads.

(b) Two shafts are connected by means of a flange coupling to transmit torque of25 N-m. The flanges of the coupling are fastened by four bolts of the same material at a radius of 30 mm. Find the size of the bolts if the allowable shear stress for the bolt material is 30 MPa. [8+8] 10. (a) Write a short note on bolts of uniform strength.

(b) The cylinder head of a steam engine is subjected to a steam pressure of0.7N/mm2. It is held in position by means of 12 bolts. A soft copper gasket is used to make the joint leak-proof. The effective diameter of cylinder is 300mm. Find the size of the bolt so that the stress in the bolts is not to exceed 100 MPa. [6+10] 11. (a) List out the advantages and disadvantages of screw joints.

(b) A mild steel cover plate is to be designed for an inspection hole in the shell of a pressure vessel. The hole is 120 mm in diameter and the pressure inside the vessel is 6N/mm2. Design the cover plate along with the bolts. Assume the allowable tensile stress for mild steel on 60 MPa and for bolt material as40 MPa. [6+10] 12. (a) Define the following terms with necessary sketch. i. Major diameter ii. Minor diameter iii. Pitch iv. Lead.

(b) Derive an expression for the maxim load in a bolt. When a bracket with a circular base is bolted to a wall by means of four bolts. [8+8] 13. (a) Define the following terms related to screw fastenings: i. Stress area ii. Major diameter iii. Minor diameter.

(b) A punching press is required to punch a maximum hole size of 20 m.m diameter in a material having ultimate shear strength of 300N/m.m2. If the thickness of the sheet is 5 mm, design the screw and the nut. [6+10] 14. The cylinder head of a 200 mmx350 mm compressor is secured by means of 12 studs of rolled mild steel. The gas pressure is 1.5 N/mm2 gauge. The initial tension in the bolts, assumed to be equally loaded

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such that a cylinder pressure of 1.2 N/mm2 gauge is required for the joint to be on the point of opening. Suggest the suitable size of the studs in accordance with Soderberg’s equation assuming the equivalent diameter of the compressed parts to be twice the bolt size and factor of safety 2. The stress concentration factor may be taken as 2.8 and the value of endurance strength for reversed axial loading is half the value of ultimate strength. [16]

Question Bank- Unit VI: Cotter & knuckle Joints

1. Design a spigot and socket type cotter joint to carry a load of 25kN. The stress induced is limited to 50MPa in tension; 35MPa in shear and 90MPa in crushing.

2. Design a knuckle joint to connect two rods to carry a load of 100KN. The design stresses may be taken as 75MPa in tension; 60MPa in shear; and 100MPa in crushing.

3. Design a Gib and Cotter joint to carry a pull of 35KN. The stress in the materials are limited to 20MPa in tension; 15MPa in shear; and 30MPa in crushing.

4. Design a Gib and Cotter joint with two gibs to carry a load 30KN. All the components are made of same material with limiting stresses in tension 20MPa; in shear 15MPa and in crushing 30MPa. 5. Design a knuckle joint to carry a load of 140 KN. The design stresses may be taken as 75 MPa intension; 60 MPa in shear and 90 MPa in crushing

6. Design a single Gib and Cotter joint to carry a load of 50KN. The permissible stresses in tension=60 MPa; in crushing=90 MPa and in shear=50 MPa.

7. Design a Socket and Spigot Cotter joint to connect two rods for a pull of 15 KN. The stresses are limited to tensile at 50 MPa; shear at 40 MPa and crushing at 80 MPa.

8. Design a sleeve and cotter joint for a pull of 50 KN. The permissible stresses are 60 MPa tensile; 50 MPa in shear and 120 MPa in crushing.

9. (a) Differentiate between a cotter joint and a knuckle joint. (b) The cotter joint is commonly used for long pump rods and similar machine members. Design this joint to support a load varying from 28kN in compression. The material for all the components of the joint is steel with the allowable stresses in tension, compression and shear as 50N=mm2, 60N=mm2 and 35N=mm2respectively. [4+12]

10. (a) Explain the bending failure of cotter and knuckle pin?

(b) Two steel rods are to be connected by means of a sleeve, and two steel cotters. The rods are subjected to a tensile load of 40kN. Design the joint, using the permissible stress in tension as 60MPa, in shear as 50MPa, and in crushing as120MPa. [6+10]

11. Design and sketch a cotter joint for fastening the piston rod to the cross head ofthe engine having cylinder diameter 250mm and steam pressure 1.05N/mm2.The thickness of the cotter is to be 0.3 times piston rod diameter at the pointwhere cotter is located. Allowable stresses in tension, shear and compression are 50 N/mm2, 40N/mm2 and 84 N/mm2 respectively. 12. (a) Differentiate between a cotter and a key.

(b) Design a gib and cotter joint to resist safely a tensile load of 40kN. The material of the gib, cotter and rods is same for which the allowable safe stresses are: σc=60 N/mm2, σt=25 N/mm2 and τs =20 N/mm2. [4+12]

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13. Design a gib and cotter joint to connect square rods with a side of the square as 25mm. Consider σt = 60MPa σc = 90MPa and τ = 40MPa. The joint hasto carry a load of 35kN. (t=8mm, B=55(30+25)mm and length of the tail ofthe rod is 12mm. [6+10]

14. (a) Describe the design procedure of Sleeve & Cotter joint.

(b) Design a cotter joint with two gibs to transmit an axial force of 130 kN. The permissible stresses are 165 MPa in tension; 100 MPa in shear and 180 M Pain crushing. [6+12]

15. (a) How is the slipping of the cotter avoided? Explain by two methods.

(b) Design a knuckle joint to transmit 120 kN, with permissible stresses in tension, shear and compression are 75 Mpa; 60 Mpa and 150 Mpa respectively. [4+12]

16. (a) Describe the design procedure of Sleeve & Cotter joint.

(b) Design a cotter joint with two gibs to transmit an axial force of 130 kN. The permissible stresses are 165 MPa in tension; 100 MPa in shear and 180 M Pain crushing. [6+12]

Question Bank – Unit VII:Shafts

1. Find the diameter of a solid steal shaft to transmit 20KW at 200RPM. The ultimate shear stress for the steel may be taken as 360MPa and a factor of safety of 8. If a hollow shaft is used in place of solid shaft find the inside and outside diameters if their ratio is 0.6

2. A hollow shaft is subjected to torque of 2 KNm and bending moment of 3KNm and axial load of 10KN. Assume that the load is applied gradually and the ratio of diameters is 0.6 and if the outer diameter is 80mm, find the shear stress induced in the shaft. If a solid shaft is replaced for hollow shaft, what is its diameter? 3. A line shaft is driven by means of a motor placed vertically below it. The pulley on the line shaft is 1.5 metre in diameter and has belt tensions 5.8 KN and 1.2 KN on the tight side and slack side of the belt respectively. Both these tensions may be assumed vertical. The pulley is overhung on a shaft with a distance of 500mm. Find the diameter of shaft. The shear stress is limited to 42MPa. 4. A hollow shaft with 0.8 and 0.6m as diameters, transmits 5000 KW at 200 RPM. The shaft is mounted on bearings 6 metre apart. The thrust on shaft is 500KN and shaft weighs 70KN. Determine maximum shear stress in the shaft and angular twist between bearings. 5. A mild steel rod transmits 100 KW at 300 RPM. Length of shaft=3m. It carries two pulleys each weighing 1.5 KN supported at a distance of 1 meter from each ends respectively. Assume safe stress of 70 MPa in shear for shaft, find its diameter.

6. A mild steel shaft transmits 20 KW at 200 RPM. It carries a central load of 1 KN and supported between bearings 3 m apart. Determine the size of the shaft, if the allowable stress in shear is 42 MPa and in tension is 56 MPa. What is the size of the shaft if it is subjected to gradually applied load. 7. Find the diameter of a solid steel shaft to transmit 25 KW at 240 RPM. The ultimate shear stress for steel is 360 MPa with a factor of safety=8. If a hollow shaft is to be used in place of solid shaft and if the ratio of inside to outside diameters is 0.6, find its diameters. 8. A hollow shaft of 0.6 m outside diameter and 0.4 m inside diameter is used to drive a propeller of a marine vessel. The shaft is mounted on bearings 6 m apart and transmits 5000 KW at 150 RPM. The thrust on propeller is 500 KN and shaft weighs 70 KN. Determine: (a) Maximum shear stress in shaft. (b) Angular twist between bearings.

9. (a) Define the terms: i. equivalent bending moment, and

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ii. equivalent twisting Moment.

(b) A shaft, 2m long between bearings, carries a 900N pulley at its mid-point. Through a belt drive, the shaft receives 25kW at 180 r.p.m. The belt drive is horizontal, and the sum of the belt tensions is 7kN. Determine the shaft diameter and angle of twist the shaft undergoes. Take G= 80GN/m

2. [6+10] 10. A shaft of 30kW, 710 rpm motor is 40mm in diameter and is supported in Bearings500 mm apart. Calculate,

(a) stress due to bending if the armature weighing 10,000 N concentrated at the centre acting vertically (b) Stress due to torsion (c) Equivalent shear stress and tensile stress due to bending moment and torque.[16] 11. (a) What are the causes of failure of shaft?

(b) A hollow shaft 0.5m outside diameter and 0.3m inside diameter is supported by two bearings 6m apart, the shaft is driven by a flexible coupling at one shaft end and drives a ship’s propeller at 10.5 rad/sec. The maximum thrust on the propeller is 540kN when the shaft is transmitting 5885kW. The shaft weightis 67.5kN. Determine the maximum shear stress in the shaft considering the weight of the shaft and the column effect. Assume Kb= 1.5 and Ks=1.0. [4+12] 12. A shaft is supported on two bearings 1800mm apart and rotates at 800 rpm. Two pulleys B and C are located on the shaft at distance of 600mm and 1350 mm respectively to the right of the left bearing. The distance of the pulleys B and C are 750 mm and 600 mm respectively. 50kW power is supplied to the shaft through pulley B and output is through pulley C. The drive to pulley B is vertically downward while from C the drive is downward at an angle of 600 to the horizontal. In both cases the tension ratio is 2 and the angle of lap is 1800. The combined fatigue and shock factors for tensions and bending may be taken. Working stresses to be 40N/mm2 in shear and 80N/mm2 in tension. [16]

13. (a) Explain the reasons for preferring hollow shafts over solid shafts.

(b) A shaft, 2m long between bearings, carries a 900N pulley at its mid-point. Through a belt drive, the shaft receives 25kW at 180 r.p.m. The belt drive is horizontal, and the sum of the belt tensions is 7kN. Determine the shaft diameter and angle of twist, the shaft undergoes. Take G= 80GN/m2. [4+12]

14. A shaft is supported on bearings A and B, 0.1m between centers. A 200 straight tooth spur gear having 0.75m pitch diameter, is located 0.35m to the right of the left hand bearing A and a 0.85 m diameter pulley is mounted 0.22m towards left of bearing B. The gear is driven by a pinion with a downward tangential force while the pulley drives a horizontal belt having 180o angle of wrap. The pulley also serves as a flywheel and weighs 2.2 kN. The maximum belt tension is 3.5kN and The tension ratio is 3:1. Determine the maximum bending moment and the necessary shaft diameter if allowable shear stress of the material is 45 N/mm2. [16]

15. A hollow shaft carries a 90cm diameter CI pulley which is driven by another pulley mounted on a shaft placed below it through belt drive. The belt ends are parallel and vertical. The ratio of tensions in the belt is and H.P. transmitted is 50 at400rpm. The pulley mounted on the hollow shaft weighs 800N and overhangs the nearest bearing by 25cm. Calculate the diameter of the hollow shaft when the ratio of inside diameter to outside diameter is 0.5, when permissible shear stress for the shaft material is limited to 200N/mm2. [16]

Question Bank - Unit VIII: Keys & Couplings

1. Design a muff coupling to connect two shafts to transmit 40KW at 350 RPM. The shear stress and crushing stress for the shaft and key material are 40MPa and 80MPa respectively. The material for the muff is cast iron for which shear stress is limited to 15 MPa.

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2. Design a cast iron protective type flange coupling to transmit 15KW at 900RPM. The maximum load is 35% more than mean value on shaft. The limiting stresses are 40MPa in shear for shaft, bolt and key material; 80MPa in crushing for bolt and key; and 8MPa in shear for cast iron. 3. Design a split muff coupling to transmit 25KW at 200 RPM. The allowable shear stress for the shaft and key is 40MPa and number of bolts connecting two halves are six. The permissible tensile stress for the bolts is 70MPa. The coefficient of friction between the muff and shaft surface is 0.3. 4. Design a protective type flange coupling for C.I. flange to connect two steel shafts to transmit 15KW at 200RPM, with shear stress limited to 40MPa for steel. The working stress in the bolts not to exceed 30MPa. Assume that the same material is used for key, shaft and bolts and the crushing stress is twice shear stress. The maximum torque is 25% greater than full torque. The shear stress for cast iron is 14MPa. 5. Design a Split Muff Coupling to transmit 30KW at 100 RPM. The allowable shear stress for shaft and key=40MPa. The number of bolts are six. The tensile stress in bolts not to exceed=70MPa: The coefficient friction=0.25. 6. Sketch i. Woodruff key. ii. Kennedy key. 7. Design a Muff Coupling to transmit 15 KW at 800 RPM. The shear stress for shaft and key=40 MPa and shear stress for muff=8 MPa; The crushing stress for key=60 MPa. Draw sketch of the coupling. 8. Sketch a i. Gib head key. ii. Lewis key. 9. Design a protective type Flange Coupling to transmit 15 KW at 900 RPM. The following stresses are permitted: Shear stress for shaft, bolt and key=40 MPa Crushing stress for bolt and key=80 MPa shear stress for cast iron=8 MPa. Draw sketch of Coupling. 10. Sketch a i. Rectangular key. ii. Gib head key. 11. Design a Rigid flange coupling to transmit 20 KW at 900 RPM. The service factor is 1.35 for coupling motor. The shear stress for shaft, bolt and key=40 MPa; crushing stress for bolt and key=80 MPa; the shear stress for flange=8 MPa. Draw sketch of the coupling. 12. Sketch a i. Spline. ii. Square key. 3. Design a rigid sleeve coupling to connect two shafts, transmitting 18.75kW at 1000rev/min. The allowable shear stress in the material of the shaft is 55 N/mm2. The material of the shaft and key is same and the coupling is required to transmit 20% overload. The material of the sleeve is cast iron, the allowable shear stress for which is16 N/mm2. Make a neat sketch of the designed sleeve coupling showing side view and sectional elevation. [16] 14. A sleeve coupling is used to connect two 75mm shafts whose shearing stress is 70N/mm2. (a) What torque is transmitted by the shafting? (b) To what torsional moment is the coupling subjected? (c) Find the diameter and the length of the coupling. (d) What will be the induced stress in the sleeve if the diameter of the part (c) is used. (e) If cast iron sleeve with ultimate shearing stress of 140 N/mm2 is used. What is the numerical value of the factor of safety? [16] 15. A belt pulley is fastened to a 70mm dia shaft running at 200 r.p.m by means of a key, 20mm wide and 120mm long. Permissible stresses for the shaft and key materials are 50 and 90MPa respectively Determine the power that can be transmitted at 240 r.p.m also determine the thickness of the key.

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16. Design a clamp coupling completely for a shaft diameter of 50mm. The torsional moment to be transmitted by this coupling taking in to account overloading is140Nm. The number of bolts used is 4 and the allowable stress in the material of the bolt is limited to 70 N/mm2. The coefficient of friction between the shaft and muff material is 0.3. Draw sectional elevation of the designed clamp coupling. [16] 17. (a) The bolt in the flange coupling should be made weaker than the other components of coupling, Why? (b) In a flange shaft coupling having 37.5mm bore it is desired that torsional stress in the shaft will not exceed 25 N/mm2. The outside diameter of the coupling limited by space is 200mm. There are three 15mm bolts on a bolt circle diameter of 140mm. The radial flange thickness is 18mm. Determine the following: i. The power that may be transmitted at 600 rev/min. ii. The shearing stress in the bolts. iii. The bearing pressure on the bolts. [4+12]

18. What is a key? Where it is used? In what basis it is selected?

19. A plane flange coupling for a 75mm shaft has the following dimensions: bore of flange =75mm, hub diameter =135mm, hub length=100mm, flange diameter=250mm, flange thickness=28mm, bolt circle diameter=200mm, bolt diameter=19mm,number of bolts=6, and the key size is 18mm square. All the parts are made of carbon steel having a shearing strength of 400N/mm2 and a tensile strength of650N/mm2. This coupling is rated at 37.3kW power at 100rev/min. (a) Determine the shearing ,bearing and tensile stresses in all parts of the coupling. (b) What F.O.S does this coupling have? (c) Is there a possibility of the flange shearing off at the hub? Assume perfect shaft alignment. [16]

20. A propeller shaft is made-up by joining together number of solid shafts. The joint is made by forging the ends of the shaft in the form of a flange, and bolting the flanges together by means of 8 bolts. If the shaft transmits 60kW at 120 rpm, determine the size of the shaft, the diameter and thickness of the flange and the diameter and pitch circle diameter of bolts. Permissible stresses are τ=35MPa ; σc=45MPa. [16]

21. Design a bushed pin flexible coupling for connecting a motor shaft to a pump shaft for the following service conditions: H.P to be transmitted=25 rpm of the motor shaft=1440 Diameter of the motor shaft=60mm Diameter of the pump shaft=50mm Bearing pressure on the rubber bush=0.4N/mm2 Allowable stress in the pins=20N/mm2. [16]

22. (a) What are the various types of keys? Discuss their merits and demerits? (b) Select a key for a 100mm dia shaft transmits 750kW at 1000r.p.m. The allowable shear stress in the key is 100MPa and the a allowable compressive stress is 200MPa. What type of key should be used if the allowable shear stress is30MPa and the compressive stress is 120 MPa. [8+8] 23. Design a bushed-pin type flexible coupling for connecting a motor shaft to a pump shaft, with the following service conditions: Power to be transmitted=40kW Speed of the motor shaft=1000rpm Diameter of motor and pump shafts=45mm Bearing pressure on the rubber bush=0.7N/mm2 Allowable stress in the pins=60MPa. [16] 24. Design a bushed -pin type flexible couplings to transmit 25kW at 960rpm. Use the following stress values: Shear stress =50MPa(shaft and key), 30MPa(pin) Crushing stress =90MPa (key) Bearing pressure=0.45N/mm2(rubber bush). [16]

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Previous years’ Question papers of

JNTUA

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Code:R7310305 R7 III B.TechISemester(R07)SupplementaryExaminations,May2011 DESIGNOF MACHINEMEMBERS-I (MechanicalEngineering) Time:3hours MaxMarks: 80 Answer any FIVE questions All Questions carry equal marks 1. (a)Enumerate various factors influencing selection of materials.

(b)Acastironpulleytransmits20Kwat300RPM.Thediameterofpulleyis0.55metreof elliptical

Cross section in which major axis is twice minor axis find dimensions of armif the allowablebendingstressis15MPa.

2. (a) Explain fatigue stress concentration factor and notch sensitivity.

(b)Determine the size of a piston rod subjected to fluctuation of loads from 15KN (compres sion)to25KN(tension).The endurance limitis 360MPa and yield strength is 400MPa. Take the impact factor=1.25.Factorofsafety=1.5.Surfacefactor=0.88.Stressconcentration factor=2.25.

3. (a)Explain caulking and fullering.

(b)Twoplatesofmildsteeltierodareconnectedwithwidth200mmandthickness12.5mm aretobeconnectedbymeansofabuttjointwithdoublecoverplates.Designthejoints if safe stresses are 80MPa in tension;65MPa in shear ;and160MPa in crushing. Make sketch of a joint.

4. (a)Describe bolts of uniform strength.

(b)The cylinder head of a steam engine is subjected to a steam pressureof1N/mm2. If is held in position by means of 12 bolts. A soft copper gasket is used to make the joint leak proof. Thee effective diameter of cylinder is 300mm. Find the size of bolts, so that the stress in the bolts is not to exceed100MPa.

5. (a)Discuss the effect of keyway on a shaft.

(b)Design Gib and Cotter joint to carry 35000N.Assume the gib, cotter and rods are made of same material with safe stresses in tension 20MPa; Shear15MPa and crushing of 50MPa respectively. 6.Design a shaft to transmit power from motor to a lathe head stock through a pulley by means of a belt drive. The pulley weighs 200N and is located at 300mm from the centre of bearing. The diameter of pulley is 200mm and maximum power transmitted is 1kW at 120RPM. The angle of lap of belt is1800 and coefficient of friction between belt and pulley is 0.3.The shock and fatigue factors for bending and twisting are 1.5and 2.0 respectively. The allowable shear stress in the shaft is 40 MPa.

7. Design and draw a cast iron flange coupling for mild steel shaft transmitting 90KW at 250

RPM. The allowable shear stress in the shaft is 40MP a and angle of twist is not to exceed 10 In a length of 20 diaeters. The safe shear stress in coupling bolts is 30MPa. 8. Write design procedure for: (a)Compression springs (b)Torsional helical springs. ***********

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B.Tech. III-I Sem (M.E) (9A03505)

HEAT TRANSFER

UNIT – I

Introduction: Modes and mechanisms of heat transfer – Basic laws of heat transfer – General applications of heat transfer. Conduction Heat Transfer: Fourier rate equation – General heat conduction equation in Cartesian, Cylindrical and Spherical coordinates. UNIT – II

Simplification and forms of the field equation – steady, unsteady and periodic heat transfer – boundary and Initial conditions. One Dimensional Steady State Heat Conduction: in Homogeneous slabs, hollow cylinders and spheres – overall heat transfer coefficient – electrical analogy – Critical radius/thickness of insulation-with Variable Thermal conductivity –with internal heat sources or Heat generation. Extended surface (fins) Heat Transfer – Long Fin, Fin with insulated tip and Short Fin, Application to errors in Temperature measurement. UNIT III

One Dimensional Transient Heat Conduction: in Systems with negligible internal resistance – Significance of Biot and Fourier Numbers - Chart solutions of transient conduction systems- Problems on semi-infinite body. UNIT – IV

Convective Heat Transfer: Dimensional analysis–Buckingham π Theorem and its application for developing semi – empirical non- dimensional correlations for convective heat transfer – Significance of non-dimensional numbers – Concepts of Continuity, Momentum and Energy Equations. UNIT – V

Forced convection: External Flows: Concepts of hydrodynamic and thermal boundary layer and use of empirical correlations for convective heat transfer for flow over-Flat plates, Cylinders and spheres.. Internal Flows: Division of internal flow through Concepts of Hydrodynamic and Thermal Entry Lengths – Use of empirical relations for convective heat transfer in Horizontal Pipe Flow, annular flow. Free Convection: Development of Hydrodynamic and thermal boundary layer along a vertical plate – Use of empirical relations for convective heat transfer on plates and cylinders in horizontal and vertical orientation. UNIT VI

Heat Transfer with Phase Change: Boiling: Pool boiling – Regimes, determination of heat transfer coefficient in Nucleate boiling, Critical Heat flux and Film boiling. Condensation: Film wise and drop wise condensation –Nusselt’s Theory of Condensation on a vertical plate - Film condensation on vertical and horizontal cylinders using empirical correlations. UNIT VII

Heat Exchangers:

Classification of heat exchangers – overall heat transfer Coefficient and fouling factor – Concepts of LMTD and NTU methods - Problems using LMTD and NTU methods.

UNIT VIII

Radiation Heat Transfer

Emission characteristics and laws of black-body radiation – Irradiation – total and monochromatic quantities– laws of Planck, Wien, Kirchoff, Lambert, Stefan and Boltzmann– heat exchange between two black bodies – concepts of shape factor – Emissivity – heat exchange between gray bodies – radiation shields– electrical analogy for radiation networks. TEXT BOOKS:

1. Fundamentals of Engg. Heat and Mass Transfer, R.C. Sachdeva, 3/e, New Age International 2. Fundamentals of Heat and Mass Transfer, M.Thirumaleswar, Pearson Edu. REFERENCE BOOKS:

1. Heat Transfer, P.K.Nag, 2/e, TMH, 2010 2. Heat Transfer, Holman.J.P, 9/e, TMH, 2010 3. Heat and Mass Transfer, R.K.Rajput, S.Chand & Company Ltd. 4. Fundamentals of Heat and Mass Transfer, Kondandaraman, C.P., 3/e, New Age Publ. 5. Fundamentals of Heat Transfer, Incropera, 5/e, Wiley India. 6. Heat Transfer, Ghoshdastidar, Oxford Univ. Press, 2004 7. Thermal Engineering Data Book, B.S.Reddy and K.H.Reddy Rev/e, I.K. International

35

Importance of the Subject

Heat transfer has emerged as a central discipline in contemporary engineering science. The research activity of a few decades ago—the material reviewed in the first handbooks—has distilled itself into textbook concepts and results. Heat transfer has become not only a self-standing discipline in the current literature and engineering curricula, but also an indispensable discipline at the interface with other pivotal and older disciplines. For example, fluid mechanics today is capable of describing the transport of heat and other contaminants because of the great progress made in modern convective heat transfer. Thermodynamics today is able to teach modeling, simulation, and optimization of “realistic” energy systems because of the great progress made in heat transfer. Ducts, extended surfaces, heat exchangers, and other features that may be contemplated by the practitioner are now documented in the heat transfer literature. To bring this body of results to the fingertips of the reader is one of the objectives of this new handbook. The more important objective, however, is to inform the reader on what has been happening in the field more recently. In brief, heat transfer marches forward through new ideas, applications, and emerging technologies. The vigor of heat transfer has always come from its usefulness. For example, the challenges of energy self-sufficiency and aerospace travel, which moved the field in the 1970s, are still with us; in fact, they are making a strong comeback. Another example is the miniaturization revolution, which continues unabated. The small-scale channels of the 1980s do not look so small anymore. Even before “small scale” became the fashion, we in heat transfer had “compact” heat exchangers. The direction for the future is clear. The importance of optimizing the architecture of a flow system to make it fit into a finite volume with purpose has always been recognized in heat transfer. It has been and continues to be the driving force. Space comes at a premium. Better and better shapes of extended surfaces are evolving into networks, bushes, and trees of fins. The many surfaces designed for heat transfer augmentation are accomplishing the same thing: They are increasing the heat transfer rate density, the size of the heat transfer enterprise that is packed into a given volume. The smallest features are becoming smaller, but this is only half of the story. The other is the march toward greater complexity. More and more small-scale features must be connected and assembled into a device whose specified size is always macroscopic. Small-scale technologies demand the optimization of increasingly complex heat-flow architectures. A highly distinguished group of colleagues who are world authorities on the frontiers of heat transfer today have contributed to this new handbook. Their chapters provide a bird’s-eye view of the state of the field, highlighting both the foundations and, especially, the edifices that rest on them. Because space comes at a premium, we have allocated more pages to those chapters dedicated to current applications. The latest important references are acknowledged; the classical topics are presented more briefly. One feature of the handbook is that the main results and correlations are summarized at the ends of chapters. This feature was chosen to provide quick access and to help the flow of heat transfer knowledge from research to computer-aided design. It is our hope that researchers and practitioners of heat transfer will find this new handbook inspiring and useful. Adrian Bejan acknowledges with gratitude the support received from Professor Kristina Johnson, Dean of the Pratt School of Engineering, and Professor Kenneth Hall, Chairman of the Department of Mechanical Engineering and Materials Science, Duke University. Allan Kraus acknowledges the assistance of his wife, who has helped in the proofreading stage of production. Both authors acknowledge the assistance of our editor at John Wiley, Bob Argentieri, our production editor, Milagros Torres, and our fantastic copy editor, known only to us as Barbara from Pennsylvania.

36

PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI

LESSON PLAN

CLASS : III B.Tech BRANCH : Mechanical Engineering

SEMESTER: I SUBJECT : Heat Transfer

LECTURER: Z.TRIVENI YEAR : 20012-2013

S. no DATE TOPIC

NO. OF

Hours

TOTAL

HOURS

Introduction to Heat transfer Modes and mechanism of HT - basic laws of heat transfer - applications of HT Fourier rate equation General heat conduction equation in Cartesian coordinates

1 2 1

8

UNIT-I

Fourier rate equation General heat conduction equation in cylindrical coordinates General heat conduction equation in spherical coordinates

3

UNIT-II

Simplification and forms of field equation, Steady, unsteady and periodic heat transfer, initial and boundary conditions, One dimensional steady state HT for homogenous slabs, plane slabs One dimensional HT for hollow cylinders and spheres, electrical analogy Critical radius of insulation

1

2

2

1

11

Variable thermal conductivity - systems with internal heat generation Extended surfaces - long fin, fin with insulated tip and short fin-error measurement of temperature

2 3

UNIT-III

One dimensional transient conduction HT Systems with negligible internal resistance Significance of Biot & Fourier numbers

1 31

8 Chart solutions - Problems

Concept of functional body 2 1

U

NIT -IV

Classifications of flow, condition & configuration of flow, medium of flow Dimensional analysis, Buckingham Pi theorem non dimensional correlation for convective HT significance of non dimensional numbers

1 1 1 1

. 13

Concept of Continuity, momentum & energy equations Forced convection - hydrodynamic & thermal Boundary layer, use of empirical relations for convective HT over external surfaces, flat plates and cylinders

1

2

2

Internal flow -Empirical relations for horizontal pipes and annulus flow -numerical

4

I Mid exams

UNIT

-V Free convection - development of hydrodynamic and

thermal boundary layer along a vertical plate, Use of empirical relations for vertical plates and pipes

3 3

6

UNIT

-VI

Boiling- Pool boiling - regimes Nucleate boiling- critical heat flux and film boiling

1 2

Problems 2

37

Film wise & drop wise condensation, Nusselt's theory of condensation on vertical plate Film condensation on vertical and horizontal cylinders using empirical correlation

1 2 2

10

UNIT

-VII

Classification of heat exchangers, overall heat transfer coefficient and fouling factor

2 8

Concept of LMTD & NTU -methods 2

Problems using LMTD & NTU -methods

4

UNIT

-VIII

Emission characteristics - laws of black body Radiation

1

10

Irradiation - total and monochromatic quantities 1

Laws of Plank, Wien's, Kirchoff, Lambert, Stefan and Boltzmann

3

Heat exchange between two back bodies, Concept of shape factor

3

Emissivity -heat exchange between grey bodies -radiation shields -electrical analogy for radiation networks

2

Revision 2 2

Total Expected hours 76

Text books:

1. Heat transfer – J.P.HOLMAN 2. Heat Transer - R.K. RAJPUT/S.CHAND Fundamentals of Heat and Mass Transfer - INCROPERA & DEWITT/ JOHN WILEY 3. Heat Transfer -P.K. NAG/TMH

38

PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE-KAVALI III-B.Tech I-sem MECHANICAL ENGINEERING I-MID Dt:- 5-9-2012 A.N Time : 90 mints HEAT TRANSFER Max marks 20

Answer any Three of the following Use of HEAT TRANSFER DATA BOOK is permitted

1. (a) State the Fourier’s law of heat conduction. Give the physical significance of the term (b) Derive a general equation for heat conduction in 3D – cylindrical coordinate system. 2. (a) Explain the following: i. Efficiency of fin. ii. Effectiveness of fin. (b) A steel rod (K = 32 W/mk), 12mm in diameter and 60mm long, with an insulated is to be sed as a spine. It is exposed to surroundings with a temperature of 600C and a heat transfer coefficient of 55 W/m2k. The temperature at the base of fin is 950C. Determine i). Efficiency of fin. ii). Heat dissipation of the fin 3. (a) Explain lumped parameter analysis of heat conduction in solids. (b) Using lumped system analysis, determine the time required for solid steel ball of diameter 5cm, density 7,833 kg/m3, specific heat 465 J/kg 0C, thermal conductivity 54 W/m 0C, to cool from 6000C to 2000C, if it is exposed to an air stream at 500C having a heat transfer coefficient h=100 W/m2 0C. 4. (a) The expression (hl/k) gives the biot number as well as Nusselt number what is the difference between the two. (b) What is meant by dimensional homogeneity? Explain some of it’s applications. 5. In quenching process a copper plate of 3mm thickness is heated up to 3500C and is suddenly dipped into water bath and cooled to 250C. Calculate the time required for the plate to reach the temperature of 500C. The heat transfer coefficient on the surface of the plate is 28 W/m2-K. The length and width of the plates are 40cm and 30cm respectively. The properties of copper are as follows: specific heat=380.9 J/Kg-K, density 8800 kg/m3 and thermal conductivity 385 W/m-K. PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE-KAVALI III-B.Tech I-sem MECHANICAL ENGINEERING II-MID Dt:- 3-11-2012AN Time : 90 mints HEAT TRANSFER Max marks 20

Answer any Three of the following Use of THERMAL ENGINEERING DATA BOOK and STEAM TABLES are permitted

1. (a) Explain briefly the condensation mechanism? (b) Determine the stable film boiling heat transfer co-efficient for the film boiling of saturated water At atm pressure on an electrically heated1.6mm diameter horizontal platinum wire with a temperature difference of Ts-Tsat=2550c. What would be the power dissipation per unit length of the heater? 2. (a) Explain the terms : fouling factor, effectiveness, NTU and LMTD. (b) A heat exchanger of total outside surface are of 17.5m2 is to be used for cooling oil at 2000c with a mass flow rate of 2.77Kg/s having specific heat of 1.9KJ/KgK. Water at a flow rate of 0.83 Kg/s is available at 200C as a cooling agent. Calculate the exit temperature of the oil if the heat exchanger is operated in a) parallel flow mode and b) counter flow mode. Take U = 300 W/m2 0K 3. (a) What is meant by a hydrodynamic boundary layer? Explain the formation of hydrodynamic boundary layer over a flat plate. (b) Air at 200C and 1 atmosphere flows over a flat plate at 35 m/s. The plate is 75 cm long and is maintained at 600C. Calculate the heat transfer from the plate per unit width of the plate. Also calculate the turbulent boundary layer thickness at the end of the plate assuming it to develop from the leading edge of the plate. 4. (a) Derive an expression for the effectiveness of heat exchanger using NTU method of a parallel – flow heat exchangers. (b) A one shell pass, two tube pass heat exchanger has a total surface area of 5 m2 and its overall heat transfer coefficient based on that area is found to be 1400 W/m2K. If 4500 kg/h of water enters the shell side at 315 0C while 9000 kg/h of water enters the tube side at 400

C, find the outlet temperatures using (a) The correction factor LMTD method and (b) Effectiveness-NTU method. Take cp for both fluid streams as 4.187 kJ/kg K 5. (a) What is meant by thermal radiation? Which part of electro magnetic spectrum belongs to it ? (b) A pipe carrying steam having an outside diameter of 20cm runs in a large room and is exposed to

39

air at a temperature of 300c. The pipe surface temperature is 4000

c. Calculate the loss of heat to surroundings per meter length of pipe due to thermal radiation. The emissivity of the pipe surface is 0.8 . HT question bank

Unit-I

1. (a) Write the Fourier rate equation for heat transfer by conduction. Give the physical significance of each term. (b) Determine the steady heat transfer per unit area through a 3.8 cm thick homogeneous slab with its two faces maintained at uniform temperatures of 350C and 250C. The thermal conductivity of wall material is 1.9 x 10¡4 kW/m-K. 2. Derive a three dimensional generalized heat conduction equation in rectangular coordinates. 3. Derive a three dimensional generalized heat conduction equation in cylindrical co-ordinates. 4. Derive a three dimensional generalized heat conduction equation in spherical co-ordinates. 5. (a) What are the various modes of heat transfer explain with its mechanisms (b) Determine the study state heat transfer rate through wall, 5m long x 4m high x 0.25m thick, with its two faces maintained at uniform temperatures of 100oC and 30oC. The wall is made of fire brick having thermal conductivity equal to 0.7 W/m-K. 6. (a) What are the basic laws of heat transfer. (b) Determine the heat transfer rate through a spherical copper shell of thermal conductivity 386 W/m.K, inner radius of 2-mm and outer radius of 60 mm. The inner surface and outer surface temperatures are 2000C and 1000C respectively. Unit-II

1. (a) Explain the following: i. Efficiency of fin. ii. Effectiveness of fin. (b) A steel rod (K = 32 W/mk), 12mm in diameter and 60mm long, with an insulated is to be used as a spine. It is exposed to surroundings with a temperature of 600C and a heat transfer coefficient of 55 W/m2k. The Temperature at the base of fin is 950C. Determine i). Efficiency of fin. ii). Heat dissipation of the fin. 2. (a) Derive an expression for the temperature distribution in a solid sphere of radius R with uniform heat generation q' and constant surface temperature Tw. (b) Derive an expression for heat flow through a composite cylinder taking into account the film heat transfer co-efficients on the inside and outside surface of the cylinder. 3. A plane wall 10 cm thick generated heat at the rate of 4×104W/m3. When an electric current is passed through it. The convective heat transfer co-efficient between each face of the wall and the ambient air is 50 W/m2k. Determine I) The surface temperature ii) The maximum temperature in the wall. Assume the ambient air temperature to be 200C and the thermal conductivity of the wall material to be 15 W/mK. 4. (a) Explain the concept of critical radius of insulation. (b) A long cylinder rod of radius 50 cm with thermal conductivity of 10w/mk contains radioactive material, which generates heat uniformly within the cylinder at rate of 3 x 105 W/m3. The rod is cooled by convection from its cylindrical surface into the ambient air at 500c with a heat transfer -efficient of 60w/m2. Determine the temperature at the end center and the outer surface of the cylindrical rod.. 5. (a) Derive the expression for heat transfer for the case of a straight rectangular fin of uniform cross section when the tip of the fin is end insulated. (b) Aluminum fins of rectangular profile are attached on a plane wall with 5 mm spacing. The fins have thickness 1 mm, length = 10 mm and the normal conductivity K = 200 W/mk. The wall is maintained at a temperature of 2000C and the fins dissipate heat by convection into ambient air at 400C, with heat transfer coefficient = 50 W/m2k. Find the heat loss. 6. (a) Sketch various types of fin configurations?. (b) Derive an expression for 1- Dimensional, steady state heat conduction state, with internal heat generation for plane wall. Unit-III

1. (a) What are Biot and Fourier numbers? Explain their physical significance. (b) A slab of Aluminum 10cm thick is originally at a temperature of 5000C. It is suddenly immersed in a liquid at 1000C resulting it a heat transfer coefficient of 1200 W/m2k. Determine the temperature at the centerline and the surface 1 min after the immersion. Also the total thermal energy removal per unit area slab during this period. The properties of aluminum for the given condition are: γ = 8.4 x 10-5m2 /s, K=215 W/mk, ρ = 2700 kg/m3, Cp= 0.9 kJ/kg.

40

2. (a) Explain lumped parameter analysis of heat conduction in solids. (b) Using lumped system analysis, determine the time required for a solid steel ball of diameter 5cm, density 7,833 kg/m3, specific heat 465 J/kg 0C, thermal conductivity 54 W/m 0C, to cool from 6000C to 2000C, if it is exposed to an air stream at 500C having a heat transfer coeffcient h=100 W/m2 0C. 3. A large slab of aluminum at a uniform temperature of 2000C is suddenly exposed to a convective surface environment of 700C with a heat transfer coefficient of 525 W/m2k .Estimate time required for a point 4cm from the surface to come up to a temperature level of 1200C. (Take k = 215 W/mk, h = 8.4 x10-5 m2/s). 4. (a) Discuss the concept of transient heat conduction in semi- infinite solids. (b) On a hot summer,s day a concrete high way reach a temperature of 55oc. Suppose that a stream of water is directed on the high way so that the surface temperature is suddenly lowered to 30oc .How long will it take to cool the concrete to 45oc at a depth of 5cm from the surface. 5. In quenching process a copper plate of 3mm thickness is heated up to 3500C and is suddenly dipped into water bath and cooled to 250C. Calculate the time required for the plate to reach the temperature of 500C. The heat transfer coefficient on the surface of the plate is 28 W/m2-K. The length and width of the plates are 40cm and 30cm respectively. The properties of copper are as follows: specific heat=380.9 J/Kg-K, density 8800 kg/m3 and thermal conductivity 385 W/m-K. 6. The initial uniform temperature of a thick concrete wall of thermal diffusivity=1.6x10-3

m2/s, k=0.94W/mo C of a jet engine test cell is 25oc .The surface temp of the wall suddenly rises to 340oc when the combination of exhaust gases from the turbojet and spray of cooling water occurs. Determine, (a) The temp. at a point 80mm from the surface after 8 hours. (b) The instantaneous heat flow rate at the specified plane and at the surface itself at instant mentioned above . Unit-IV 1. (a) Discuss the advantages and limitations of dimensional analysis. (b) Neglecting viscous dissipation, the convective heat transfer co-efficient is anticipated to depend upon following parameters-Fluid viscosity µ, fluid density ρ, fluid thermal conductivity K, Fluid specific heat Cp, flow velocity V, and significant length L. Considering mass, length, time and temperature as the significant dimensions, set up a suitable correction in terms of non-dimensional numbers for the heat flow .Use Buckingham-π method of analysis. 2. (a) The expression (hl/k) gives the biot number as well as Nusselt number what is the difference between the two. (b) What is meant by dimensional homogeneity? Explain some of it’s applications. 3. Explain the significance of the following dimensionless numbers (a) Re (b) Pr (c) Nu (d) Gr 4. What thermo -physical variables are involved in the equations describing the phenomenon of free convection? Apply dimensional analysis to these variables and develop a generalized correlation between certain non – dimensional parameters .Discuss the physical significance of those parameters. 5. Describe the Rayleigh’s method for dimensional analysis. 6. Describe the Buckingham Pi- theorem for dimensional analysis

UNIT-V

1. (a) What is meant by a hydrodynamic boundary layer? Explain the formation of hydrodynamic boundary layer over a flat plate. (b) Air at 200C and 1 atmosphere flows over a flat plate at 35 m/s. The plate is 75 cm long and is maintained at 600C. Calculate the heat transfer from the plate per unit width of the plate. Also calculate the turbulent boundary layer thickness at the end of the plate assuming it to develop from the leading edge of the plate. 2. (a) Define Rayleigh number. What is the approximate value of the Rayleigh number at which the transition from laminar to turbulent takes place in a free convection boundary layer past a vertical flat plate? (b) 100Kg of water per minute is heated from 150C to 250C by passing through a pipe of 2.5cm in diameter. The pipe outer surface temperature is maintained at 1400C. Calculate the length of the pipe required. 3. A thin flat plate has been placed longitudinally in a steam of air at 200C and while flows with undisturbed velocity of 7.5 m/s. The surface of plate is maintained at a uniform temperature of 1200C. a. calculate the heat transfer coefficient 0.8m from the leading edge of the plate,

41

b. Also calculate the rate of heat transfer from one side of the plate to the air over the first 0.8 m length. Assume unit width of the plate. 4. In a nuclear reactor core, parallel vertical plates each 2.5 m high and 1.5m wide, heat liquid Bismuth by natural convection. Maximum temperature of the plate should not exceed 755oC and lowest allowable temperature of Bismuth is 320 0C. Calculate the maximum heat dissipation from both sides of each plate. 5. (a) A horizontal pipe of 6 cm diameter is located in a room, whose temperature of air is 200C. The surface temperature of the pipe is 140 0 C. Calculate the free convection heat loss per meter length of the pipe. (b) Distinguish between bulk mean temperature and film temperature. (c) Define the local and average skin friction (drag) coefficient for a flat smooth plate at zero Incidence 6. (a) Explain for fluid flow along a flat plate. a. Velocity distribution in hydrodynamic boundary layer. b. Temperature distribution in thermal boundary layer. c. Variation of local heat transfer co-efficient along the flow. (b) A vertical plate is at 960C in an atmosphere of air at 200C. Estimate the local heat transfer coefficient at a distance of 20 cm from the lower edge and the average value over the 20 cm length. UNIT-VI

1. (a) Explain the various regimes of pool boiling heat transfer. (b)Water is boiled at a rate of 30kg/hr in a copper pan,30cm in diameter, at atmospheric Pressure. Estimate the temperature of the bottom surface of the pan assuming nucleate boling conditions. 2. (a) what do you meant by sub-cooled boiling? (b) The outer surface of a vertical cylinder drum of 350mm diameter is exposed to saturated steam at 2 bar for condensation. If the surface temperature of drum is maintained at 800c , calculate (i) the length of the drum (ii) the thickness of the condensate layer to condense 70kg/hr of steam. 3. (a) How does radiation play an important role in boiling heat transfer? (b) Saturated steam at 1100c condenses on the outside of a bank of 64 horizontal tubes of 25mm outer diameter, 1m long arranged in a 8X8 array. Calculate the rate of condensation If the tube surface is maintained at 1000c. Had the condenser been vertical, what would be the rate of condensation? 4. (a) Explain briefly the condensation mechanism? (b) Determine the stable film boiling heat transfer co-efficient for the film boilng of saturated water At atm pressure on an electrically heated1.6mm diameter horizontal platinum wirewith a temperature difference of Ts-Tsat=2550c. What would be the power dissipation per unit length of the heater? 5. (a) Differentiate between the mechanism of filmwise condensation and dropwise condensation? (b) Saturated steam at 900c condenser on the outer surface of a 2.5cm diameter, 1.2m long horizontal Pipe which is maintained at a uniform temperature of 800c. calculate (a) average heat transfer co-efficient (b) The total rate of steam condensation UNIT-VII

1. (a) How heat exchangers are classiffed? Discuss briefy different types of heat exchangers. (b) Water is evaporated continuously at 100 0 C in an evaporator by cooling 500 kg of air per hour from 2600

C to 1500C. Calculate the heat transfer surface area required and the steam

evaporation per hour, if the liquid enters at 1000C. Take Uo = 46 W/m2K and cp of air 1.005

kJ/kgK. At 1000C, hfg = 2257 kJ/kg.

2. (a) Write an expression for overall heat transfer coeficient (U) for double pipe heat exchanger. (b) Water at a rate of 7500 kg/h enters a counter flow heat exchanger at 150

C to cool 8000 kg/h of air at 1050

C. The overall heat transfer coefficient is 145 W/m2 K and the exchanger area is 20m 2. Find the exit temperature of air. 3. (a) Explain the terms : fouling factors, effectiveness, NTU and LMTD. (b) A heat exchanger of total outside surface are of 17.5m2 is to be used for cooling oil at 2000c with a mass flow rate of 2.77Kg/s having specific heat of 1.9KJ/KgK. Water at a flow rate of 0.83

42

Kg/s is available at 200C as a cooling agent. Calculate the exit temperature of the oil if the heat exchanger is operated in a) parallel flow mode and b) counter flow mode. Take U = 300 W/m2 0K 4. (a) What do you mean by fouling factor? What are the causes of fouling? (b) A one shell pass, two tube pass heat exchanger has a total surface area of 5 m2 and its overall heat transfer coefficient based on that area is found to be 1400 W/m2K. If 4500 kg/h of water enters the shell side at 315 0C while 9000 kg/h of water enters the tube side at 400

C, find the outlet temperatures using (a) The correction factor LMTD method and (b) Effectiveness-NTU method. Take cp for both fluid streams as 4.187 kJ/kg K. 5. (a) A double pipe heat exchanger is constructed of a stainless steel ( k = 15.1 W/mK) inner tube of Di = 15mm and Do = 19 mm and the outer tube of diameter 32 mm. The convective heat transfer coefficient is given to be hi = 800W/m2K and ho = 1200W/m2K. For a fouling factor of Rfi = 0. 0004m2K/W on the tube side and Rfo = 0.0001m2K/W on the shell side, determine i. The total thermal resistance ii. Ui and iii.Uo of the heat exchanger. (b) What is the limitation of the LMTD method? How is NTU method superior to correction factor LMTD method? 6. (a) Derive an expression for the LMTD of a counter - flow heat exchangers. State clearly the assumptions. (b) Derive an expression for the effectiveness of heat exchanger using NTU method of a parallel – flow heat exchangers. UNIT-VIII

1.(a) Distinguish between black colour and radiation black bodies? (b) A 3mm thick glass window transmits 90 percent of the radiation between λ=0.3&3µm and is essentially opaque for other wave lengths .Determine the rate of radiation through a 2mX2m glass window from a black body source at 5000k. 2. (a) Define intensity of radiation? (b)The filament of a 40w bulb is radiating into a black enclosure at 700

c The filament is a wire of 0.1mm. diameter and 3cm length . Assume filament as a black body. find the temperature of the Filament. 3. (a) Define absorptivity, reflectivity and transitivity of radiant energy. (b) 300 watts of energy is incident on aglass plate per unit area out of which 200 watts is transmitted and 20 watts is absorbed .Calculate absorptivity, reflectivity and transitivity of the glass plate. 4. (a) What is meant by thermal radiation? Which part of electromagnetic spectrum belongs to it? (b) A pipe carrying steam having an outside diameter of 20cm runs in a large room and is exposed to air at a temperature of 300

c. The pipe surface temperature is 4000c. Calculate the loss

of heat to surroundings per meter length of pipe due to thermal radiation. The emissivity of the pipe surface is 0.8 . 5.(a) State Plank’s law of monochromatic radiation. What is its significance? (b) Two black square plates of size 1.0 by 1.0m are placed parallel to each other at a distance of 0.4m. One plate is maintained at a temperature of 9000 c and the other at 4000c. Find net Exchange of Energy due to radiation between the two plates.

43

OBJECTIVE TYPE QUESTIONS

UNIT-1 1. Heat transfer takes place by the process of (a) conduction (b) convection (c) radiation (d) all of the above. 2. The rate of heat transfer is constant if (a) temperature decreases with time (b) temperature increases with time (c) temperature is constant with time (d) none of the above.

3. The rate of heat transfer is variable if (a) temperature decreases with time (b) temperature increases with time (c) temperature is constant with time (d) temperature changes with time.

4. If the rate of heat transfer is constant, it is known as (a) steady-state heat transfer (b) unsteady-state heat transfer (c) uniform heat transfer (d) non-uniform heat transfer.

5. If the rate of heat transfer is variable, it is known as

(a) steady-state heat transfer (b) unsteady-state heat transfer (c) uniform heat transfer (d) non-uniform heat transfer.

6. The process of heat transfer, from one particle of the body to another without actual motion of the particle, is called (a) radiation (b) convection (c) conduction (d) none of the above. 7, The process of heat transfer, from one particle of the body to another by the actual motion of the heated particles, is called (a) radiation (b) convection (c) conduction (d) none of the above

8. The process of heat transfer, from a hot body to a cold body in a straight line without affecting the intermediate medium, is called (a) radiation (b) convection (c) conduction (d) none of the above 9. Heat energy can be obtained from other type of energy is the statement of (a) zeroth law of thermodynamics (b)first law of thermodynamics (c) second law of thermodynamics (d) Fourier's law.

10. The heat transfer takes place according to

(a) first law of thermodynamics (b)zeroth law of thermodynamics (b) second law of thermodynamics (d) Fourier's law.

11. The basic law of heat conduction is called (a) Newton's law of cooling (b) Fourier's law (c) Kirchhoff's law (d) Stefan's law.

12. The rate of heat transfer from a solid surface to a fluid is obtained from (a) Newton's law of cooling (b) Fourier's law (c) Kirchhoff's law (d) Stefan's law.

13. Fourier's law is based on assumption that (a) heat flow through a solid is one-dimensional (b) heat flow is in steady-state (c) both (a) and (b) (d) none of the above. 14. The co-efficient of thermal conductivity is defined as the heat flow per unit time (a) through unit thickness (b) when temperature difference of unity is maintained between opposite faces (c) when temperature gradient is unity (d) across unit area when temperature gradient is unity.

15. The thermal conductivity in S.I. units is expressed as (a) J/m2 °K (b) W/m °K (c) W/m °K sec (d)Wm/°K

44

UNIT-II

1. The unit of overall heat transfer co-efficient is (a) W/m3k (b) W/m2k (c) W/m2 (d) W/mk. 2. The concept of log mean area is normally used in the analysis of (a) composite plane surfaces (c) spherical surfaces (b) cylindrical surfaces (d) Any plane surface 3. A composite wall is made of two different materials of same thickness with thermal conductivities k1, k2 respectively. The equivalent thermal conductivity of slab is (a) k1+k2 (b) k1+k2 /( k1k2 ) (c) k1k2 (d) 2k1k2/ (k1+k2 ). 4. Why fins are provided on heat transferring surface (a) To increase temperature gradient (b) To increase heat transfer co-efficient (c) To increase heat transfer area (d) all of the above 5. For spheres, the critical thickness of insulation is given by (a) h/2k (b) 2k/h (c) k/h (d) k/2πh. 6. The temperature distribution for a plane wall, for steady state heat flow and constant value of therml conductivity, is (a) linear (b) parabolic (c) logarithmic (d) any of the above. 7. If k, is the thermal conductivity, ρ is the mass density and C is the specific heat then the thermal diffusivity of substance is given by (a) ρC/k (b) k/ ρC (c) kC/ ρ (d) kρ/C 8. In heat flow equation Q=kA(t1-t2)/x, the term (t1-t2)/x is called (a) Thermal conductivity (b) Thermal co-efficient (c) Thermal resistance (d) Temperature gradient. 9. In heat flow equation Q=kA(t1-t2)/x, the term (x/kA) is called (a) Thermal conductivity (b) Thermal co-efficient (c) Thermal resistance (d) Temperature gradient. 10. What does transient conduction mean? (a) Heat transfer for a short time (b) Very little heat transfer (c) Conduction when the temperature at a point varies with time.

(d) Heat transfer with a very small temperature difference

11. The critical radius of insulation for sphere is ………………times to that of cylinder. (a) 2 (b) 3 (c) 4 (d) 5 12. The unit of thermal resistance is (a) W/m3 oc (b) W/m2 oc (c) W/m2 (d) oc/W. 13.The temperature distribution of infinite length fin is (T-T∞)/(To-T∞) (a) e-mx (b) cosh m(l-x)/cosh ml (c) Tanh ml (d) None.

14. In a plate which is not generating heat ,the temp. distribution is a curve, then thermal conductivity is given by

(a) k=koα T (b) k=ko (1+α T ) (c) k=ko +α T (d) k=ko -α

T

15. The fin efficiency is defined as

(a) √(hp/kA) (b) Tanh ml/ml (c) Tanh ml (d) √(kA/hp)

45

UNIT-III

1. In transient heat conduction, the two significant dimensionless parameters are…………….number and ……………..number. (a) Fourier, Reynolds. (b) Biot ,Fourier (c) Reynolds, Biot (d) Biot, prandtl 2. Lumped parameter analysis for transient heat conduction, is essentially valid for (a) Bi<0.1 (b) 0.1< Bi<100 (c) 1< Bi<10 (d) Bi�∞ 3. In case of infinite solid the Biot number value is (a) Bi<0.1 (b) 0.1< Bi<100 (c) 1< Bi<10 (d) Bi�∞

4. In case of semi- infinite solid the Biot number value is (a) Bi<0.1 (b) 0.1< Bi<100 (c) 1< Bi<10 (d) Bi�∞

5. In lumped parameter analysis, which is used for transient heat conduction , the assumption is (a) k of solid is zero (b) the temp. gradient in the solid does not effect. (c) The conduction resistance is maximum. (d) k of the solid is ∞.

6. The temperature variation with time, in the lumped parameter model, is (a) Linear (b) parabolic (c) logarithmic (d) exponential 7. The lumped parameter analysis, should be used when

(a) The convective heat transfer co-efficient is low (b) The thermal conductivity is high (c) The characteristic dimension is small (d)all of the above. 8. The dimensionless number relevant in transient heat conduction is, (a) Grashof number (b) Weber number (c) Fourier number (d) Reynolds number. 9. The characteristic length in Biot number is the ratio of (a) Volume of solid to it’s surface area (b) surface area to perimeter of the solid (c) perimeter to surface area of the solid (d) Volume of solid to it’s length. 10. Heisler charts are used to determine the transient heat flow rate and distribution when

(a) Internal conduction resistance is higher than surface convective resistance

(b) Internal conduction resistance is lower than surface convective resistance

(c) Both the resistances are same

(d) Solids posses infinitely large thermal conductance. 11. The temperature distribution in case of infinite sold body (T-T∞)/(To-T∞) is a function of (a)Bi, Fo, x/l (b) Bi, Fo (c) Bi, x/l (d) Fo, x/l 12. The temperature distribution in case of semi-infinite sold body (T-T∞)/(To-T∞) is (a)erf(Bi, Fo, x/l) (b) erf(Bi, Fo) (c) erf(Bi, x/l) (d) erf(x/2√(αT)

Where ‘erf ‘ is error function

13. The characteristic length (L c ) of sphere is ………………

(a) R/2 (b) R/ 3 (c)R/4 (d) R Where ‘R ‘ is radius of sphere.

14. The characteristic length (L c ) of cylinder is ………………

(a) R/2 (b) R/ 3 (c)R/4 (d) R Where ‘R ‘ is radius of cylinder.

46

15. The Non dimensional factor (hL c /k ) is called……………… (a) Biot number (b) Weber number (c) Fourier number (d) Reynolds number.

UNIT-IV

1. Which of the following dimensionless number has a significant role in forced convection. (a) Pr (b) Re (c) Mach (d) Gr

2. Which of the following dimensionless number has a significant role in free convection. (a) Pr (b) Re (c) Mach (d) Gr 3. The dimensions of thermal diffusivity in M-L-T-θ system (a) L2T -1 (b) LT -1 θ-1 (c) ML2T -1 (d) L2T -1 θ-1

4. The dimensions of heat transfer co-efficient is

(a) ML2T -1 (b) MT -3 θ-1 (c) ML2T -1 (d) M2T -1 θ-1

5. The dimensions of thermal conductivity is

(a) ML2T -3 (b) MT -3 θ-1 (c) MLT -3 θ-1 (d) MLT -3

6. The dimensions of the specific heat is

(a) L2T -1 θ-1 (b) L2T -2 θ-1 (c) L2T 2 θ-1 (d) L2T -1 θ

7. Which of the following dimensionless number can provide the relation among Nu, Re and Pr

(a) Bi (b) Fo (c) Wb (d) St 8. The units of Nusselt number is (a) meter (b) kj/mok (c) W/m2 ok (d) No units 9. The ratio of kinematic viscosity to thermal diffusivity is…………

(a) Re (b) Nu (c) Gr (d) Pr 10. If there are ‘n’ variables in a dimensionally homogeneous equation and in which there are ‘m’ primary dimensions, then the variables can be grouped into…………….. dimension less group.

(a) m (b) n (c) m x n (d) m/n (e)n-m

11. State the methods of dimensional analysis

12. Reynolds number is the ratio of ……………and …………………..

(a) Inertia force, viscous force (b) viscous force, inertia force

(c) Buoyancy force, viscous force (d) viscous force, buoyancy force

13. The quantities mass, length, time are called………………………

(a) Fundamental quantities (b) Derived quantities

(c) Secondary quantities (d) any one of the above.

14.The pecelt number can be written as

(a) Re. Pr (b) Nu.Re (c) Gr .Nu (d) Pr. Gr

15.The stanton number can be written as

(a) Nu/(Re x Pr) (b) (NuxRe)/Pr (c) Gr / (Re x Pr) (d) Pr /(NuxRe)

47

UNIT-V

1. For free convection the Nusselt number is a function of (a) Grashof number, prandtl number (b) Grashof number, reynolds number (c) Fourier number , Reynolds number (d) Reynolds number, prandtl number 2. For forced convection the Nusselt number is a function of (a) Grashof number, prandtl number (b) Grashof number, reynolds number (c) Fourier number , Reynolds number (d) Reynolds number, prandtl number 3. Kinematic viscosity is defined as: (a) dynamic viscosity/density (b) dynamic viscosityXdensity (c) dynamic viscosity/ pressure (d) dynamic viscosityX pressure 4. The bulk mean temperature of a fluid moving through a tube at a given cross-section is the (a) Temperature of the fluid at the tube surface (b) Temperature of the fluid at the center of the tube (c) Temperature midway between the centre and surface of the tube (d) Mean Temperature of the fluid. 5. Nusselt number may be characterized as (a) The non- dimensional velocity gradient at the surface (b) The dimensionless temperature gradient at the surface (c) The ratio of viscous to inertia forces (d) The ratio of convective to conductive resistances. 6. Reynolds analogy is true only when (a) flow is laminar (b) flow is turbulant (c) flow is partly laminar and partly turbulant (d) Prandtl number is near about 1. 7. The thickness of thermal boundary is equal to that of hydrodynamic boundary layer when prandtl number is (a) 0 (b) 0.1 (c) 0.5 (d) 1.0 8……………………number has a significant role in forced convection. (a) mach (b) reynolds (c) prandtl (d) grashof 9. The ratio of hydrodynamic to thermal boundary layer thickness (a) varies as one-third power of prandtl number (b) varies as two-third power of prandtl number (c) varies as two-third power of stanton number (d) varies as root of Prandtl number . 10. The temperature gradient in the fluid flowing over a heated plate will be (a) zero at the top of thermal boundary layer (b) very steep at the surface (c) zero at the plate surface (d) positive at the surface.

48

UNIT-VI 1. In film and dropwise condensation which one is effective? (a) film condensation (b) dropwise condensation (c) both (d) None of the above 2.The critical Reynolds number for condensation around…………………………… (a)1800 (b)2000 (c) 25000 (d)2500 3. The maximum heat flux point in pool boiling is known as………………………… 4. Depending on saturation temperature of liquid the boiling may classified into………………….and……………………. (a) pool boiing and film boiling (b) sub cooled boiing and bulk boiling (c) pool boiing and bulkboiling (d) None of the above 5. Write various regimes of pool boiling? 6.What is meant by excess temp. in pool boiling? (a)Ts- Tsat (b) Tsat- Ts (c) Tsat (d) Ts 7. In pool boiling, the heat flux becomes maximum towards the end of (a)Free convection boiling regime (b) Stable film boiling regime (c) Nucleate boiling regime (d) unstable film boiling regime 8. If the excess temperature is below 50c, then the regime is called as, (a)Free convection boiling regime (b) Stable film boiling regime (c) Nucleate boiling regime (d) unstable film boiling 9. If the excess temperature is in between 50c and 500c, then the regime is called as, (a)Free convection boiling regime ( b) Stable film boiling regime (c)Nucleate boiling regime (d) unstable film boiling regime 10. The maximum value of heat flux in pool boiling is expected to be………………. (a) 1MW/m2 ( b) 2MW/m2 (c) 1KW/m2 (d) 2KW/m2

UNIT-VII

1. In heat exchangers (a) Temperature of the hot fluid increases (b) Temperature of the cold fluid decreases (c) Temperature of the hot fluid decreases (d) Temperatures of both fluids increase 2. In a heat exchanger, Ui = U o due to (a) Negligible convective resistances (b) Negligible tube wall resistances (c) Negligible inner film resistances (d) all of the above 3. In a heat exchanger the overall heat transfer co-efficient(U) is given by

(a) ��.��

(b)��

(c)√ℎ. ℎ� (d) 4 ��.��

4.The concept of fouling factor is applicable to

(a)Fresh heat exchanger (b)All heat exchangers (c)Dirty heat exchanger (b) Multipass heat exchangers

49

5. LMTD of a parallel flow heat exchanger is given by_________________________ 6. LMTD of a counter flow heat exchanger is given by_________________________

7. The concept of LMTD correction factor is used in

(a) parallel flow heat exchanger (b) counter flow heat exchangers (c) Multipass heat exchangers (d) all of the above

8. NTU of a heat exchanger stands for (a) Number of Transfer Units (b) Number of TemperatureUnits

(c) Number of Terminal Units (d) None 9. The NTU of a heat exchanger represents it’s

(a) size ( b) performance (c) mode of operation (d) None

10. The effectiveness of heat exchanger is given by (a)Q/Qmax ( b)Qmax /Q (c) 1-( Q/Qmax) (d) 1-( Qmax/Q)

11.The effectiveness of a parallel flow heat exchanger in terms of NTU is given by______________ 12. The effectiveness of a counter flow heat exchanger in terms of NTU is given by______________

13. The temperature ratio of heat Exchanger is given by

(a) � ��

( b) ��

(c) � ��

(d)��

Where Thi and Tho are the inlet and outlet temperatures of hot fluid and

Tci and Tco are the inlet and outlet temperatures of cold fluid 14. The LMTD of a counter flow heat exchanger as compared to parallel flow heat exchanger will be

(a) more ( b) less (c) approximately equal (d) Exactly equal

15. The overall heat transfer co-efficient in a fouled heat exchanger in comparison with that of a clean exchanger is (a) more ( b) less (c) equal (d) Negligible.

UNIT-VIII

1. Radiation is believed to be____________

(a) a molecular phenomenon (b) a wave phenomenon (c) a bulk phenomenon (d) all of the above

2. For a transparent body

(a)τ =1 (b)α =1 (c)ρ =1 (d)ε =1 3. .For a opaque body

(a) τ =0 (b) α =1 (c) ρ =1 (d) ε =0 4. The units of emissivity is (a) W (b) W/m2k (c) W/m2 (d) None 5. Radiation shields are used to (a) increase the heat transfer (b) control the heat transfer (c) decrease the heat transfer (d) all of the above 6. The sum of reflectivity, absorptivity and transmitivity is (a) 1 (b) 0 (c) 0.5 (d) 0.2

7 .The units of plank’s constant are

(a) J (b)JS (c) J (d) J/s2 8. The reciprocity theorem is expressed as

50

(a) A 1F 21=A 2F12 (b) A 1F 12=A 2F21 (c) F 21= F12 (d) ��

= ��

��

9. Plank’s distribution law is applicable only to

(a) gray surfaces (b) black surfaces

(c) real surfaces (d) all of the above 10. Kirchoff’s law of radiation is applicable only to

(a) gray surfaces (b) black surfaces (c) real surfaces (d) all of the above

51

Code: 9A03505 R09 III B. Tech I Semester (R09) Supplementary Examinations, May 2012 HEAT TRANSFER (Mechanical Engineering) Time: 3 hours Max Marks: 70 Answer any FIVE questions All questions carry equal marks 1 (a) Define heat flux and thermal diffusivity and explain its importance in conduction mode of heat

transfer. (b) A plane wall 80 mm thick (K=0.15 W/mK) is insulated on one side while the other is exposed

to environment at 900C. If the convective heat transfer coefficient between the wall and the environment is 560 W/m2 K, determine the temperature at the surface of the wall will be subjected.

2 Determine the rate of heat flow through a spherical boiler wall which is 2 m in diameter and 2 m thick steel (k = 58 W/m K). The outside surface of boiler wall is covered with asbestos (k = 0.116 W/m K) 5 mm thick. The temperature of outer surface and that of fluid inside are 500C and 3000C respectively. Take inner film resistance as 0.0023 K/W.

3 (a) Sheets of brass and steel, each of thickness 1 cm, are placed in contact. The outer surface of brass is kept at 1000C and the outer surface of steel is kept at 00C. What is the temperature of the common interface? The thermal conductivities of brass and steel are in the ratio of 2:1.

(b) How long will it take to form a thickness of 4cm of ice on the surface of a lake when the air temperature is -60C? K of ice = 1.675 W/m K and its density = 920 kg/m3. Take the latent heat of fusion of ice as 335 kJ/kg.

4 Starting with the two dimensional Navier Stokes equation, listing all assumptions, and performing an order of magnitude analysis, show that for flow over a flat plate, the pressure is a function of x alone. (Please proceed systematically for full credit. Brute force application of known result will yield zero credit).

5 (a) Estimate the heat transfer from a 40 W incandescent bulb at 127oC to 27oC quiescent air. Approximate the bulb as a 50 mm diameter sphere. What percentage of the power is lost by free convection?

(b) What is the boundary layer thickness? What do you mean by laminar and turbulent boundary layers? What is laminar sub layer?

6 (a) Explain the flow regimes in two phase flow through a tube. What is the difference between slug flow regime and annular flow regime?

(b) Saturated steam at atmospheric pressure condenses on a horizontal copper tube of 25 mm inner diameter and 29 mm outer diameter through which water flows at the rate of 30 kg/min entering at 320C and leave at 720C. Calculate: (a) the condensing heat transfer coefficient, (b) the inside heat transfer coefficient and (c) the length of the tube.

7 (a) Define heat exchanger effectiveness and explain its significance. (b) In a counter flow double pipe heat exchanger water is heated from 400C to 800C with oil

entering at 1050C and leaving at 700C.Taking the overall heat transfer coefficient as 300 W/m2k and the water flow rate as 0.1Kg/s. Calculate the heat exchanger area

8 Explain the following laws relevant to radiation heat transfer: (i) Kirchhoff’s law. (ii) Wien’s displacement law. (iii) Planck’s law. (iv) Lambert Law.

52


B.Tech. III-I Sem (M.E) T P C

4 0 4

(9A03503) MACHINE TOOLS

UNIT – I

Elementary treatment of metal cutting theory – Elements of cutting process – Geometry of single point tooland angles chip formation and types of chips – built up edge and its effects, chip breakers. Mechanics ofOrthogonal cutting –Merchant’s Force diagram, cutting forces – cutting speeds, feed, depth of cut, tool life,coolants, machinability –economics- Tool materials. UNIT – II

Engine lathe – Principle of working, specification of lathe – types of lathes – work holders, tool holders – BoxTools, Taper turning, thread turning and attachments for Lathes. Turret and capstan lathes – collet chucks – other work holders – tool holding devices – box and tool layout. Principal features of automatic lathes – classification – Single spindle and multi-spindle automatic lathes– tool layout and cam design. UNIT – III

Shaping, Slotting and Planning machines – their Principles of working – Principal parts – specification, classification,Operations performed. Kinematic scheme of the shaping slotting and planning machines, machining time calculations. UNIT – IV

Drilling and Boring Machines – Principles of working, specifications, types, operations performed – tool holding devices – twist drill – Boring machines – Fine boring machines – Jig Boring machine. Deep hole drilling machine. Kinematics scheme of the drilling and boring machines UNIT – V

Milling machine – Principles of working – specifications – classifications of milling machines – Principal features of horizontal, vertical and universal milling machines – machining operations, Types and geometry of milling cutters– methods of indexing – Accessories to milling machines. UNIT –VI

Grinding machine –Theory of grinding – classification of grinding machine – cylindrical and surface grinding machine – Tool and cutter grinding machine – special types of grinding machines – Grinding wheel:Different types of abrasives – bonds, specification and selection of a grinding wheel UNIT - VII

Lapping, Honing and Broaching machines – comparison of grinding, lapping and honing. Lapping, Honing and Broaching machines: Constructional features, speed and feed Units, machining time calculations UNIT - VIII

Principles of design of Jigs and fixtures and uses. Classification of Jigs & Fixtures – Principles of location and clamping – Types of clamping & work holding devices. Typical examples of jigs and fixtures. TEXT BOOKS :

1. Production Technology, R.K. Jain and S.C. Gupta. 2. Workshop Technology – Vol II, B.S. Raghuvamshi. REFERENCES :

1. Machine Tools, C.Elanhezhian and M. Vijayan, Anuradha Agencies Publishers.

53

2. Manufacturing Technology, Kalpakzian, Pearson 3. Production Technology, H.M.T. (Hindustan Machine Tools). 4. Introduction to Manufacturing Technology, Date, Jaico Publ. House Question Paper Pattern: 5 questions to be answered out of 8 questions. Each question should not have more than 3 bits

MACHINE TOOLS

OBJECTIVES OF THE COURSE:

At the end of the course the student will be able to

• Understand the significance of machining.

• Appreciate the difference between Orthogonal and Oblique Cutting.

• Understand forces acting in metal cutting.

• Know about different types of machines viz. Lathe, Shaper, Slotter, Planer, Borer, Drill Press, Milling

Machine, Grinding Machine, Lapping, Honing and Broaching Machines.

• Must be able to understand parts, specifications, classification, working principle, operations

performed on different machine tools.

• Must be able to select a machine for the job.

• Should be able to understand the difference between a jig and a fixture.

54

P.B.R.VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI

DEPARTMENT OF MECHANICAL ENGINEERING LESSON PLAN FOR THE ACADEMIC YEAR 2012-2013 Class / Semester: III B.Tech. I Semester Subject: Machine Tools

Unit Week No.of

Hours

Topic to be covered No.of Hours

per Week

No.of Hours per Unit

I

2

3

Elements of cutting process, Methods of cutting

Geometry of single point cutting tool, Chip formation 5

14

2

3

Types of chips, Chip Breakers

Merchant’s Force diagram, Cutting parameters 4

3

2

Tool life, coolants

Machinability, Economics of machining, Tool Materials 5

II

2

3

Engine Lathe : Principle of working, Specification, Types

Work holders, Tool holders, Box tools

5

13 3

2

Taper turning, Thread cutting and attachments for lathes

Turret and Capstan Lathes, Tool and work holders 5

3

Box and tool layout, Automatic lathes : Types, Single Spindle and Multi Spindle, Tool layout and cam design

3

III

2

2

Shaping : Principle of working, Parts, Specification, Types, Operations Performed, Kinematic schemes

Slotting : Principle of working, Parts, Specification, Types, Operations Performed, Kinematic schemes

4

08

2

Planning : Principle of working, Parts, Specification, Types, Operations Performed, Kinematic schemes

Machining time calculations

4

55

2

IV

2

1

2

Drilling Machines : Principle of working, Parts, Specification, Types, Operations Performed

Tool holders, Twist drill, kinematic schemes

Boring Machines : Fine Boring , Jig Boring, Kinematic schemes

5 05

V

3 Milling Machines : Principle of working, Parts, Specification, Types, Operations Performed, Kinematic schemes

3 08

2

3

Types and geometry of milling cutters

Methods of indexing, Accessories 5

VI

2

2

Grinding Machines : Principle of grinding, Types

Cylindrical and Surface grinders, Tool and cutter grinders, Special types

4

09

3

2

Grinding Wheel : Types of abrasives and bonds

Selection and specification of a grinding wheel 5

VII

2

2

Lapping Machines

Honing Machines 4

08

2

2

Broaching Machines, Comparison

Speed and Feed Units, Kinematic schemes, Machining Time calculations

4

VIII

3

2

Jigs and Fixtures : Design , Types

Location and Clamping : Principles

5 10

56

2

Types of locating pins, supporting pins

2

3

Examples of jigs and fixtures 3

Total Expected Hours 75

TEXT BOOKS:

1. Production Technology by R.K.Jain and S.C. Gupta 2. Work Shop Technology Vol-II by B.S. Raghu Vamshi REFERENCES:

1. Manufacturing Technology by Kalpakjian 2. Production Technology by HMT 3. Work Shop Technology Vol-II by Hajra Choudhury



Class : III B.Tech., ME (I sem)

Date : 04-09-2012 AN

MACHINE TOOLS

Answer any THREE questions

1. With neat sketches explain the nomenclature of single point cutting tool.

2. Draw Merchant’s circle diagram and derive the expressions to show the relationships among the

different forces acting on the cutting tool.

3. Define taper. Explain taper turning methods with neat sketches.

4. With neat sketches explain the various operations pe

5. With a neat sketch explain sensitive drill press.

*********ALL THE BEST********* PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE, KAVALI

DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech., ME (I sem) Date : 02-10-12 AN

MACHINE TOOLS

Answer any THREE questions 1. With neat sketches explain column and knee type milling machines.

2. Explain the different types of bonds used in grinding wheel. Also mention their merits and de merits.

3. With a neat sketch explain the principle of centre less grinding.

4. With neat sketches explain the principle of broaching.

5. Explain the principles of design of jigs

* * * * *

57



Class : III B.Tech., ME (I sem) Mid Exam – I (Descriptive type) Max. Marks

Duration

With neat sketches explain the nomenclature of single point cutting tool.

Draw Merchant’s circle diagram and derive the expressions to show the relationships among the

different forces acting on the cutting tool.

Define taper. Explain taper turning methods with neat sketches.

With neat sketches explain the various operations performed on Shaper.

With a neat sketch explain sensitive drill press.

*********ALL THE BEST*********


DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech., ME (I sem) Mid Exam – II(Descriptive type)

MACHINE TOOLS

With neat sketches explain column and knee type milling machines.

the different types of bonds used in grinding wheel. Also mention their merits and de merits.

With a neat sketch explain the principle of centre less grinding.

With neat sketches explain the principle of broaching.

Explain the principles of design of jigs and fixtures.


Max. Marks : 20

Duration : 90 min

Draw Merchant’s circle diagram and derive the expressions to show the relationships among the


Max. Marks : 20 Duration : 90 min

the different types of bonds used in grinding wheel. Also mention their merits and de merits.


DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech., ME (I sem) Date : 04-09-2012 A.N

Name :

1. Metal cutting processes are also known as(A) Chip forming processes (C) Both A & B 2. Segmental chips are produced while(A) Brittle materials (B) Ductile materials(D) Both A & C 3. ------------ is not an example for multi point cutting tool (A) Drill bit (B) Broaching tool 4. The following Lathe is used for precision work on tools and dies (A) Center (B) Tool Room (C) Bench 5. The following is the operation of enlarging an already drilled hole through a certain distance(A) Drilling (B) Reaming (C) Boring6. ------------ is the velocity of the cutting tool relative to the work piece and is parallel to the generated surface (A) Cutting Velocity (B) Shear Velocity7. ---------------- is a reciprocating type of machine tool(A) Shaper (B) Slotter (C) Planer8. The following drilling machine is used for drilling holes in rifle barrels(A) Radial (B) Gang (C) Multiple Spindle9. In which type of Planer, fo(A) Open Side (B) Double Housing10. The following Mandrel is used to support work pieces having internal threads(A) Step (B) Collar (C) Screwed11. --------------------- is used wh12. In slotter, the ram holding the tool reciprocates in 13. The value of chip thickness ratio is always

14. --------------------------------------------------

15. ---------------------------------------------------16. Apron in a shaper consists of clapper block, clapper box and tool post17. In oblique cutting, the cutting edge of the tool is at right angles to the tool feed.18. Capstan Lathe is also known as Ram Type Lathe19. Work done in cutting is given by the sum of work done in shear and work done in frictio

[TRUE / FALSE] 20. Shaping width = Width of the work piece + 2 x Allowance

58


DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech., ME (I sem) Mid Exam – I (Objective Type) Max. Marks

Duration

MACHINE TOOLS

Roll No. :

Metal cutting processes are also known as (B) Chip less processes (D) None of these

Segmental chips are produced while machining (B) Ductile materials (C) Ductile materials at low speed

is not an example for multi point cutting tool (C) Turning tool (D) Milling cutter

following Lathe is used for precision work on tools and dies (C) Bench (D) Capstan & Turret

The following is the operation of enlarging an already drilled hole through a certain distance(C) Boring (D) Counter-boring [

is the velocity of the cutting tool relative to the work piece and is parallel to the generated [ ]

(B) Shear Velocity (C) Chip flow velocity (D) None of thesereciprocating type of machine tool

(C) Planer (D) All of these The following drilling machine is used for drilling holes in rifle barrels

(C) Multiple Spindle (D) Deep Hole In which type of Planer, four tool heads can be accommodated

(B) Double Housing (C) Pit (D) Divided Table The following Mandrel is used to support work pieces having internal threads

(C) Screwed (D) Gang is used when the length is 10 to 12 times the diameter of work piece.

In slotter, the ram holding the tool reciprocates in ------------------------------------The value of chip thickness ratio is always -----------------------------------------than one.

--------------------------------------------- chuck is a self centering chuck

--------------------------------------------------- is used to measure the cutting forces. Apron in a shaper consists of clapper block, clapper box and tool post [TRUE / FAIn oblique cutting, the cutting edge of the tool is at right angles to the tool feed.Capstan Lathe is also known as Ram Type Lathe [TRUE / FALSE]Work done in cutting is given by the sum of work done in shear and work done in frictio

Shaping width = Width of the work piece + 2 x Allowance [TRUE / FALSE]



[ ]

[ ]

[ ]

[ ]

The following is the operation of enlarging an already drilled hole through a certain distance ]

is the velocity of the cutting tool relative to the work piece and is parallel to the generated

(D) None of these [ ]

[ ]

[ ]

[ ]

en the length is 10 to 12 times the diameter of work piece. ------------------------------------axis.

than one.

is used to measure the cutting forces. [TRUE / FALSE]

In oblique cutting, the cutting edge of the tool is at right angles to the tool feed. [TRUE / FALSE] [TRUE / FALSE]

Work done in cutting is given by the sum of work done in shear and work done in friction

[TRUE / FALSE]


DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech, ME (I sem) Date : 02-10-12 AN MACHINE TOOLS

Name :

1. If the size of the shanks of the milling cutter is smaller than that of the hole in the spindle nose,then --------------------- are used to hold the cutters.(A) Adaptors (B) Arbors 2. ------------- is the process employed for machining a flat surface which is at right angles to the axis of the cutter (A) Face Milling (B) Plain Milling3. Side milling cutters are also called as (A) Straddle Mills (B) Face Mills4. ---------------- abrasive is made from sili(A) SiC (B) Al2O3 5. ------------ is the base material for silicate bond(A) Silicate of soda (B) Felspar6. -------------- is the operation of running two mating parts or shapes together with an abrasive in between them (A) Equalising Lapping (B) Form Lapping7. ------------- is a device used to hold and locate the wonormally not fixed to the machine table(A) Jig (B) Fixture (C) Both A & B8. The type of locating device and locating method to be used in a particular jig or a fixture is based (A) Shape and size of work piece (C) Degree of accuracy and surface finish9. The following is a fixed bed type milling machine (A) Universal (B) Duplex Head10. For vitrified bond, the inside temperature of kiln is (A) 600C (B) 2600C 11. In ---------------------------- type of grinding machines, the work piece is usually hel12. The material used for making a lap should be easily embedded into its surface.13. All locating and supporting surfaces of a jig or a fixture should be made of are not quickly worn out. 14. Honing tool is a bonded abrasive stone made in the form of a 15. ------------------------------------------16. For cleaning laps, naphtha is commonly used.17. In all jigs or fixtures, the inserts or pads are made of soft material18. In column and knee type milling machines, the work is support[TRUE/FALSE] 19. Sand stone is a natural abrasive

59


DEPARTMENT OF MECHANICAL ENGINEERING Class : III B.Tech, ME (I sem) Mid Exam – II Max. Marks

12 AN Duration MACHINE TOOLS

Roll No:

If the size of the shanks of the milling cutter is smaller than that of the hole in the spindle nose,are used to hold the cutters.

(C) Shank (D) Sleeve is the process employed for machining a flat surface which is at right angles to the

(B) Plain Milling (C) Form Milling (D) None of these

Side milling cutters are also called as ----------------------- when used in pairs (B) Face Mills (C) End Mill (D) None of these

abrasive is made from silicon dioxide, coke , saw dust and salt (C) Both A & B (D) None of these

is the base material for silicate bond (B) Felspar (C) Oxides and Chlorides of Mg (D) None of these

is the operation of running two mating parts or shapes together with an abrasive in between (B) Form Lapping (C) Both A & B (D) None of these

is a device used to hold and locate the work piece, guide the cutting tool to work and is normally not fixed to the machine table

(C) Both A & B (D) None of these 8. The type of locating device and locating method to be used in a particular jig or a fixture is based

(B) Type of operation (C) Degree of accuracy and surface finish (D) All of these

9. The following is a fixed bed type milling machine----------------------------------- lex Head (C) Omniversal (D) All of these

10. For vitrified bond, the inside temperature of kiln is (C) 12600C (D) None of these

type of grinding machines, the work piece is usually held between two centers.12. The material used for making a lap should be ------------------------- so that the abrasive grains can be

easily embedded into its surface. 13. All locating and supporting surfaces of a jig or a fixture should be made of ----------------------

14. Honing tool is a bonded abrasive stone made in the form of a ---------------------------------------------------------------------------------- type milling machine carries two horizontal and one vertical spindle.

16. For cleaning laps, naphtha is commonly used. [TRUE/FALSE]17. In all jigs or fixtures, the inserts or pads are made of soft material [TRUE/FALSE]18. In column and knee type milling machines, the work is supported on a knee like casting.

[TRUE/FALSE]



If the size of the shanks of the milling cutter is smaller than that of the hole in the spindle nose, [ ]

is the process employed for machining a flat surface which is at right angles to the [ ]



[ ] (D) None of these

is the operation of running two mating parts or shapes together with an abrasive in between [ ]

(D) None of these rk piece, guide the cutting tool to work and is

[ ]

8. The type of locating device and locating method to be used in a particular jig or a fixture is based on----

[ ] [ ]

[ ] (D) None of these

d between two centers. so that the abrasive grains can be

----------------------so that they

----------------------------------------. al and one vertical spindle.

[TRUE/FALSE] [TRUE/FALSE]

ed on a knee like casting.

[TRUE/FALSE]

20.In broaching, the sum of thicknesses of all layers taken together is called as feed per tooth. [TRUE/FALSE]

PBR VISVODAYA INSTITUTE OF TECHN


MACHINE

UNIT -I

6. (a) Explain the basic elements of machining with a neat sketch. (b) Bring out the differences between orthogonal and oblique cutting.

7. Draw Merchant’s circle diagram and derive the expressions to show the relationships among the different forces acting on the cutting tool.8. With neat sketches explain the nomenclature of single point cutting tool.9. (a) With neat sketches explain the different typ(b) Explain the need for chip breaking. Explain the different types of chip breakers.

10. Derive the velocity relationships in metal cutting.11. Define tool life. Explain the factors affecting tool life.UNIT - II

1. With a neat sketch explain the princi2. Define taper. Explain taper turning methods with neat sketches.3. Explain thread cutting operation with a neat sketch.4. Explain with neat sketches 5. With a neat sketch explain turret 6. Give the classification of automatic lathes. With a neat sketch explain 6automatic lathe. UNIT - III

1. With a neat sketch explain the working and basic parts of a shaper.2. Give the classification of shaper.3. With neat sketches explain the operations performed on shaping machine.4. With a neat sketch explain the basic parts of a planer.5. Give the specifications of slotter and planer.6. Explain the different types of planerUNIT - IV

1. With a neat sketch explain sensitive 2. With a neat sketch explain radial drilling machine.3. With a neat sketch explain deep hole drilling machine4. With neat sketches explain the operations performed on drilling machine.

60

20.In broaching, the sum of thicknesses of all layers taken together is called as feed per tooth.



MACHINE TOOLS DESCRIPTIVE TYPE QUESTIONS

(a) Explain the basic elements of machining with a neat sketch. (b) Bring out the differences between orthogonal and oblique cutting.

Merchant’s circle diagram and derive the expressions to show the relationships among the different forces acting on the cutting tool.

With neat sketches explain the nomenclature of single point cutting tool. (a) With neat sketches explain the different types of chips

(b) Explain the need for chip breaking. Explain the different types of chip breakers.

Derive the velocity relationships in metal cutting. Define tool life. Explain the factors affecting tool life.

With a neat sketch explain the principle of working and basic parts of Lathe. Define taper. Explain taper turning methods with neat sketches. Explain thread cutting operation with a neat sketch.

(A) Rests (B) Box Tools (C) Chucks With a neat sketch explain turret tooling layout. Give the classification of automatic lathes. With a neat sketch explain 6- Spindle progressive action

With a neat sketch explain the working and basic parts of a shaper. Give the classification of shaper.

at sketches explain the operations performed on shaping machine. With a neat sketch explain the basic parts of a planer. Give the specifications of slotter and planer. Explain the different types of planer

With a neat sketch explain sensitive drill press. With a neat sketch explain radial drilling machine. With a neat sketch explain deep hole drilling machine With neat sketches explain the operations performed on drilling machine.

20.In broaching, the sum of thicknesses of all layers taken together is called as feed per tooth.

OLOGY AND SCIENCE, KAVALI

Merchant’s circle diagram and derive the expressions to show the relationships among the

Spindle progressive action

61

5. With neat sketches explain the nomenclature of twist drill. 6. With a neat sketch explain the basic parts of a jig boring machine UNIT – V

1. With neat sketches explain column and knee type milling machines. 2. With neat sketches explain the operations performed on milling machines. 3. Bring out the differences between up and down milling 4. With neat sketches explain various types of milling cutters UNIT – VI 1. Explain the different types of bonds used in grinding wheel. Also mention their merits and de merits. 2. With a neat sketch explain the principle of centre less grinding. 3. What are natural and artificial abrasives? Explain 4. Explain the procedure of specification of grinding wheel. UNIT - VII

1. With neat sketches explain the principle of broaching. 2. Explain the methods of lapping. Explain the advantages. 3. With a neat sketch explain honing tool. 4. Explain Push and Pull Braoching. UNIT – VIII 1. Explain the principles of design of jigs and fixtures. 2. With neat sketches explain various supporting devices. 3. With neat sketches explain various locating devices. 4. Explain the factors to be considered for designing jigs and fixtures.



MACHINE TOOLS

UNIT-I

1. Metal cutting processes are also known as(A) Chip forming processes

(C) Both A & B

2. Segmental chips are produced while machining(A) Brittle materials (B) Ductile materials(D) Both A & C 3. ------------ is not an example for multi point cut (A) Drill bit (B) Broaching tool

4. ------------ is the velocity of the cutting tool relative to the work piece and is parallel to the generated surface (A) Cutting Velocity (B) Shear Velocity

5. The value of chip thickness ratio is always (A) Greater (B) Less (C) Equal to

6. ---------------------- is an element of cutting process (A) Work piece (B) Tool (C) Chip 7. ------------- is the curved portion at the bottom of the tool, where the base and flank of the tool meet (A) Face (B) Shank 8. When the face of the tool is so ground that it slopes upwards fro(A) Back rake (B) Side rake (C) Negative rake9. ------------- type of chip breaker is commonly used with carbide tipped tools (A) Step (B) Groove (C) Secondary Rake 10. -------------- is the ability of the tool material to retain its hardness even at elevated temperatures (A) Wear Resistance (B) ToughnessUNIT-II 1. The following Lathe is used for precision work on tools and dies (A) Center (B) Tool Room (C) Bench 2. The following is the operation of enlarging an already drilled hole through a certain distance(A) Drilling (B) Reaming (C) Boring3. Facing operation results in reduction of (A) Diameter (B) Length (C) Both4. Turning operation results in reduction of (A) Diameter (B) Length (C) Both5. In a Lathe, Bed is made of (A) Alloy Steel (B) Mild Steel 6. ------------------- is the operation of cutting the work piece after it is being machined to the required shape and size

62



MACHINE TOOLS OBJECTIVE TYPE QUESTIONS

Metal cutting processes are also known as (B) Chip less processes

(D) None of these

Segmental chips are produced while machining (B) Ductile materials (C) Ductile materials at low speed

is not an example for multi point cutting tool (C) Turning tool (D) Milling cutter

is the velocity of the cutting tool relative to the work piece and is parallel to the generated [ ]

(B) Shear Velocity (C) Chip flow velocity (D) None of these

The value of chip thickness ratio is always -------------------------------than one. (C) Equal to (D) None of these

is an element of cutting process (C) Chip (D) All of these

is the curved portion at the bottom of the tool, where the base and flank of the tool meet (C) Heel (D) Corner [

When the face of the tool is so ground that it slopes upwards from the point is said to contain(C) Negative rake (D) Positive rake [

type of chip breaker is commonly used with carbide tipped tools (C) Secondary Rake (D) Clamp

ability of the tool material to retain its hardness even at elevated temperatures(B) Toughness (C) Hot Hardness (D) All of these

The following Lathe is used for precision work on tools and dies (C) Bench (D) Capstan & Turret

The following is the operation of enlarging an already drilled hole through a certain distance(C) Boring (D) Counter-boring [

Facing operation results in reduction of ------------------------------ (C) Both (D) None of these

Turning operation results in reduction of ------------------------------ (C) Both (D) None of these

In a Lathe, Bed is made of ------------------ material (C) Cast Iron (D) Aluminium

is the operation of cutting the work piece after it is being machined to the required [ ]


[ ]

[ ]

[ ]

is the velocity of the cutting tool relative to the work piece and is parallel to the generated

(D) None of these

[ ]

[ ]

is the curved portion at the bottom of the tool, where the base and flank of the tool meet ]

m the point is said to contain ]

[ ]

ability of the tool material to retain its hardness even at elevated temperatures (D) All of these

[ ]

The following is the operation of enlarging an already drilled hole through a certain distance ]

[ ]

[ ]

[ ]

is the operation of cutting the work piece after it is being machined to the required

63

(A) Forming (B) Grooving (C) Parting -Off (D) Chamfering 7. For making the nut to pass freely on the threaded portion -------------- operation may be carried out. (A) Forming (B) Grooving (C) Parting -Off (D) Chamfering[ ] 8. The following Mandrel is used to support work pieces having internal threads [ ] (A) Step (B) Collar (C) Screwed (D) Gang 9. ------------- is used when the length is 10 to 12 times the diameter of work piece. [ ] (A) Rests (B) Mandrels (C) Chucks (D) Face Plate 10. ------------------------- chuck is a self centering chuck [ ] (A) Three Jaw (B) Four Jaw (C) Magnetic (D) None of these UNIT-III 1. ---------------- is a reciprocating type of machine tool [ ] (A) Shaper (B) Slotter (C) Planer (D) All of these 2. In which type of Planer, four tool heads can be accommodated [ ] (A) Open Side (B) Double Housing (C) Pit (D) Divided Table 3. In slotter, the ram holding the tool reciprocates in -----------------------axis. [ ] (A) Horizontal (B) Vertical (C) Inclined (D) None of these 4. In ------------ type of shaper return stroke is the cutting stroke [ ] (A) Push (B) Draw (C) Horizontal (D) None of these 5. Apron in a shaper consists of [ ] (A) Clapper block (B) Clapper box (C) Tool Post (D) All of these 6. By giving -----feed any irregular shape may be machined by using slotting machine[ ] (A) Longitudinal (B) Cross (C) Rotary (D) All of these 7. External keyways are cut on --------------- [ ] (A) Gears (B) Pulleys (C) Shafts (D) All of these 8. In slotter, longitudinal feed is achieved by moving [ ] (A) Saddle (B) Cross slide (C) Table (D) All of these 9. In ---- planer, the table is stationery and the column carrying the cross rail reciprocates [ ] (A) Open Side (B) Double Housing (C) Pit (D) Divided Table 10. In shaper, length of stroke is --------------- than length of work piece [ ] (A) Longer (B) Shorter (C) Equal (D) None of these UNIT-IV 1. The following drilling machine is used for drilling holes in rifle barrels [ ] (A) Radial (B) Gang (C) Multiple Spindle (D) Deep Hole 2. ------------ drilling machine is used to drill a number of holes in a piece of work simultaneously and to reproduce the same pattern of holes in a number of identical work pieces [ ] (A) Radial (B) Gang (C) Multiple Spindle (D) Deep Hole 3. ------------ is used when the tapered tool shank is larger than spindle taper [ ] (A) Sleeve (B) Socket (C) Chuck (D) Special Attachment 4. ---------------- is the operation of smoothing and squaring the surface around the hole for the seat for a nut or a head of a screw [ ] (A) Counter boring (B) Countersinking (C) Spot Facing (D) Drilling 5. -------------- is the operation of producing a hole in the work piece [ ] (A) Counter boring (B) Countersinking (C) Spot Facing (D) Drilling 6. The small diameter cylindrical portion that separates body and shank of the drill is [ ] (A) Neck (B) Tang (C) Point (D) Shank

64

7. ---------- is the portion of the drill which is gripped in the holding device [ ] (A) Neck (B) Tang (C) Point (D) Shank 8. The maximum size of the drill that can be accommodated by a portable drilling machine is [ ] (A) 18 mm (B) 30 mm (C) 40 mm (D) 50 mm 9. In Plain radial drilling machine, ----------- principal movements are possible [ ] (A) Two (B) Three (C) Four (D) Five 10. --------- is the operation of finishing an already drilled hole [ ] (A) Drilling (B) Boring (C) Reaming (D) Tapping UNIT - V 4. If the size of the shanks of the milling cutter is smaller than that of the hole in the spindle nose, then --------------------- are used to hold the cutters. [ ] (A) Adaptors (B) Arbors (C) Shank (D) Sleeve 5. ------------- is the process employed for machining a flat surface which is at right angles to the axis of the cutter [ ] (A) Face Milling (B) Plain Milling (C) Form Milling (D) None of these 6. Side milling cutters are also called as ----------------------- when used in pairs [ ] (A) Straddle Mills (B) Face Mills (C) End Mill (D) None of these 4. The following is a fixed bed type milling machine----------------------------------- [ ] (A) Universal (B) Duplex Head (C) Omniversal (D) All of these 5. Triplex head fixed bed type milling machine carries two horizontal and one vertical spindle. 6. In column and knee type milling machines, the work is supported on a knee like casting. 7. Universal machine vice is best suited for tool room work and should not be used where heavy cuts are to be employed. 8. Circular milling attachment is employed for indexing as well as providing continuous rotary motion to the work. 9. In Up or Conventional Milling, the cutter rotates in a direction opposite to that in which the work is fed. 10. Corner rounding milling cutters are used for milling the edges and corners of the jobs to required radius. UNIT – VI 1. ---------------- abrasive is made from silicon dioxide, coke , saw dust and salt [ ] (A) SiC (B) Al2O3 (C) Both A & B (D) None of these 2. ------------ is the base material for silicate bond [ ] (A) Silicate of soda (B) Felspar (C) Oxides and Chlorides of Mg (D) None of these 3. For vitrified bond, the inside temperature of kiln is [ ] (A) 600C (B) 2600C (C) 12600C (D) None of these 4. In Plain Cylindrical type of grinding machines, the work piece is usually held between two centers. 5. Sand stone is a natural abrasive [TRUE/FALSE] 6. Artificial Abrasives are manufactured under controlled conditions in closed electric furnaces in order to avoid the introduction of impurities and to achieve necessary temperature for chemical reactions to take place.

7. The common trade names for aluminium oxide are Alundum, Aloxite, Borolon. 8. Structure is the term used for denoting the space between the abrasives. 9. The principle of centerless grinding can be employed for both external and internal grinding.

65

10. According to the table movement, the surface grinders can be classified as reciprocating table type and rotary table type. UNIT - VII 1. -------------- is the operation of running two mating parts or shapes together with an abrasive in between them [ ] (A) Equalising Lapping (B) Form Lapping (C) Both A & B (D) None of these 2. The material used for making a lap should soft so that the abrasive grains can be easily embedded into its surface. 3. Surface finishing operations are also called as micro finishing operations. 4. The term vehicle in lapping is used to denote the lubricant used to hold or retain the abrasive grains during the operation. 5. For cleaning laps, naphtha is commonly used. [TRUE/FALSE] 6. Honing is an abrading process mostly used for finishing internal cylindrical surfaces. 7. Honing is a wet process and it is necessary that a coolant be used in ample quantity during the operation. 8. Honing tool is a bonded abrasive stone made in the form of a stick. 9. In broaching, the sum of thicknesses of all layers taken together is called as feed per tooth. [TRUE/FALSE] 10. According to the method of cutting, broaching machines are classified as Push, Pull or Continuous. UNIT – VIII 1. ------------- is a device used to hold and locate the work piece, guide the cutting tool to work and is normally not fixed to the machine table [ ] (A) Jig (B) Fixture (C) Both A & B (D) None of these 2. The type of locating device and locating method to be used in a particular jig or a fixture is based on-------------------------------- [ ] (A) Shape and size of work piece (B) Type of operation (C) Degree of accuracy and surface finish (D) All of these 3. In all jigs or fixtures, the inserts or pads are made of soft material [TRUE/FALSE] 4. All locating and supporting surfaces of a jig or a fixture should be made of hardened material so that they are not quickly worn out. 5. Fixture is a device used to hold and locate the work piece, does not guide the tool and is fixed to the machine table. 6.Jigs & Fixtures offer high clamping rigidity [TRUE/FALSE] 7.Jigs & Fixtures enable quick setting and proper location of work [TRUE/FALSE] 8.According to the principle of six point location, a work piece can be completely restrained by providing three location points in one plane, two location points in second plane and one location point in third plane. 9.The following are the main elements of a jig or a fixture [ ] (A) Body (B) Locating elements (C) Clamping Elements (D) All of these 10. The following is an important factor to be considered while designing a jig or a fixture [ ] (A) Type and Capacity of the machine (B) Size, Shape and Weight of the Component (C) Method of loading & Un loading the component (D) All of these

JNTUA Question Papers

66

Code: 9A03503 1 III B. Tech I Semester (R09) Regular & Supplementary Examinations, November 2012 MACHINE TOOLS (Mechanical Engineering) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 Differentiate orthogonal cutting and oblique cutting with neat sketches. 2 Explain various work holding and tool holding device used on turret and capstan lathes. 3 ( How is the size of the shaper determined? (b) How are shapers classified? 4 Explain various operations performed on a drilling machine in detail. 5 Classify and explain briefly, various types of column and knee type milling machines. 6 ( What do you understand by a silicate bond? (b) What are the advantages and disadvantages of this bond? 7 ( Compare and contrast broaching and honing. (b) List the application of broaching. 8 Discuss the importance considerations in jig and fixture design. Code: 9A03503 2 III B. Tech I Semester (R09) Regular & Supplementary Examinations, November 2012 MACHINE TOOLS (Mechanical Engineering) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 With a neat sketch, explain the basic elements of any machining operation. 2 List various tools and attachments used on turret and capstan lathe. Explain some of them. 3 ( Explain the importance of slotting machine in a machine shop. (b Explain the operations performed on a slotting machine. 4 (

What do you mean by drilling, milling and boring?

(b How do they differ from each other? 5 Classify and explain various types of milling machine. 6 Explain various types of bond materials used in a grinding wheel. 7 With an example, explain how machining time can be calculated for a broaching machine. 8 Explain the main principles of design of jigs and fixtures.

67

Code: 9A03503 3 III B. Tech I Semester (R09) Regular & Supplementary Examinations, November 2012 MACHINE TOOLS (Mechanical Engineering) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 Discuss about various types of chips produced during machining of various metals

with neat figures. 2 (

Describe the different methods of feeding the tool in thread cutting.

(b) What is under cut? Why is it provided? 3 Classify and explain the basic operations that are done on a shaper. 4 (

How is drill size determined?

(b) What is the importance specification of a twist drill? 5 ( How is production milling machine different from fixed bed type milling machine? (b) Explain various types of production milling machine? 6 How are grinding machines classified? Explain various types. 7 ( Compare and contrast broaching and grinding. (b) List the application of broaching. 8 Discuss the important conditions that must be satisfied by a successfully designed jig. Code: 9A03503 4 III B. Tech I Semester (R09) Regular & Supplementary Examinations, November 2012 MACHINE TOOLS (Mechanical Engineering) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 Explain various methods and means of chip breaking. 2 Explain with a neat sketch, the working of an engine lathe. 3 Explain various quick return mechanisms used for shaper machine. 4 What is a twist drill? With a neat sketch explain the principal parts of a twist drill. 5 ( What is hand milling machine? Explain its uses. (b What are the planer type milling machines? Explain their features. 6 What is drilling? Explain the working principle involved in it. Describe the basic components

of a grinding machine. 7 Briefly the constructional features of lapping and broaching machines. 8 Discuss in detail the advantages of using jigs and fixtures in mass production.

68


B.Tech III-I Sem. (E.E.E) T P C

4 0 4

(9AHS401) MANAGERIAL ECONOMICS & FINANCIAL ANALYSIS

(Common to BOT, CE, ECM, EEE, ME)

UNIT I: INTRODUCTION TO MANAGERIAL ECONOMICS

Definition, nature and scope of managerial economics- relation with other disciplines- Demand Analysis: Demand Determinants, Law of Demand and its exceptions UNIT II: ELASTICITY OF DEMAND

Definition, Types, Measurement and Significance of Elasticity of Demand. Demand forecasting, factors governing demand forecasting, methods of demand forecasting (Survey methods, Statistical methods, Expert opinion method, Test marketing, Controlled experiments, Judgmental approach to Demand Forecasting) UNIT III: THEORY OF PRODUCTION AND COST ANALYSIS

Production Function – Isoquants and Isocosts, MRTS, least cost combination of inputs, Cobb-Douglas production function, laws of returns, internal and external economies of scale. Cost Analysis: Cost concepts, opportunity cost, fixed Vs variable costs, explicit costs Vs Implicit costs, out of pocket costs Vs Imputed costs. Break-Even Analysis (BEA) - Determination of Break Even Point (Simple Problems)- Managerial significance and limitations of BEA. UNIT IV: INTRODUCTION TO MARKETS AND PRICING POLICIES

Market structures: Types of competition, features of perfect competition, monopoly- monopolistic competition. Price-Output determination under perfect competition and monopoly - Methods of Pricing-cost plus pricing, marginal cost, limit pricing, skimming pricing, bundling pricing, sealed bid pricing and peak load pricing. UNIT V: BUSINESS ORGANISATIONS AND NEW ECONOMIC ENVIRONMENT

Characteristic features of business, features and evaluation of sole proprietorship, partnership, Joint Stock Company, public enterprises and their types, changing business environment in post-liberalization scenario. UNIT VI: CAPITAL AND CAPITAL BUDGETING

Capital and its significance, types of capital, estimation of fixed and working capital requirements, methods and sources of raising finance. Nature and scope of capital budgeting, features of capital budgeting proposal, methods of capital budgeting – payback method, accounting rate of return (ARR) and Net present value method (Simple problems). UNIT VII: INTRODUCTION TO FINANCIAL ACCOUNTING

Double-Entry Book Keeping, Journal, Ledger, Trial Balance- Final Accounts (Trading Account, Profit and Loss Account and Balance Sheet with simple adjustments). UNIT VIII: FINANCIAL ANALYSIS THROUGH RATIOS

Computation, Analysis and Interpretation of financial statements through Liquidity Ratios (Current and Quick ratio), Activity ratios (Inventory Turnover Ratio and Debtor Turnover Ratio), Capital Structure Ratios (Debt- Equity Ratio, Interest Coverage Ratio) and Profitability ratios (Gross Profit Ratio, Net Profit Ratio, Operating Ratio, P/E Ratios and EPS), Du Pont Chart. TEXT BOOKS:

1. Aryasri: Managerial Economics and Financial Analysis, 4/e, TMH, 2009. 2. Varshney & Maheswari: Managerial Economics, Sultan Chand, 2009. REFERENCES

1. Premchand Babu, Madan Mohan:Financial Accounting and Analysis,Himalaya, 2009 2. S.A. Siddiqui and A.S. Siddiqui: Managerial Economics and Financial Analysis, New Age International,. 2009. 3. Joseph G. Nellis and David Parker: Principles of Business Economics, Pearson, 2/e, New Delhi. 4. Domnick Salvatore: Managerial Economics in a Global Economy, Cengage, 2009. 5. H.L.Ahuja: Managerial Economics, S.Chand, 3/e, 2009

69

PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE

ACADEMIC YEAR: 2012-13 CLASS: III

Week

Dates

No.of periods in week

Topics to be covered

No.of periods required

Total Periods per unit

1

5

Unit-1 Introduction to Managerial Economics Definition, Nature and scope of managerial Economics Relation with Other Disciplines Demand Analysis :Demand Determinants Law of Demand and its Exceptions

1 1 1 1

5

2

4

Unit-2 Elasticity of Demand Definition,Types of Elasticity of Demand Measurement of Elasticity of Demand Significance of Elasticity of Demand ,demand forecasting

1 1 1 1

9

3

5

Factors Governing Demand Forecasting Methods of demand Forecasting (Survey Method,Statistical Method Expert Opinion Method, Test Marketing Controlled Experiments Judgemental approach to demand forecasting

1 1 1 1 1

4

5

UNIT-3 Theory of production and cost analysis Production function Isoquants and Isocosts MRTS Least cost combination of inputs Cobb-Douglars production function

1 1 1 1 1

13

5

5

Law of returns Internal and External Economics of sale Cost analysis Cost concepts : opportunity cost,fixed VS variable costs Explicit costs VS Implicit costs

1 1 1 1 1

6

3

Out of packet costs VS imputed costs Break –Even analysis(BEA) Determination of Break Even point (simple problem) Managerial significance and limitations of BEA

1 1 1

7

4

UNIT -4 Introduction to markets and pricing policies Market structures Types of competition, features of perfect

1 1 1

8

70

competitions Monopoly Monopolistic competition Price-output determination under perfect competition

1

8

4

Monopoly Methods of pricing –cost plus pricing Marginal cost,limit,pricing,skimming pricing Bundling pricing Sealed bid pricing and peak load pricing

1 1 1 1

9

5

UNIT-5 Business organizations and new Economics development Charecteristic features of business Features and Evaluation of sole proprietorship Joint stock company

1 1 1 1 1

7

10

2

Public enterprices and their types Changing business environment in post liberalization scenario

1 1

11

5

UNIT-6 Capital and capital budgeting Capital and it’s significance Types of capital Estimation of fixed and working capital requirements Methods and sources of raising finance

1 1 1 1 1

12

4

Nature and scope of capital budgeting Features of capital proposal Methods of capital budgeting –pay back method Acconting rate of return(ARR) and Net present value method (simple problems)

1 1 1 1

9

13

5

UNIT-7 Introduction to financial accounting Double –entry book keeping Jounal,Ledger,Trial balance Final accounts(trading accounts) Profit and loss account

1 1 1 1 1

9

14 4

Simple problems Balance sheet With simple adjustments Problems

1 1 1 1

15 5

UNIT-8 Financial analysis through ratios,Computation Analysis and interpretation of financial statements Through liquidity ratios(current and quick

1 1 1 1 1

10

71

Subject: MEFA FACULTY: G.KoteswaraRao

ratio) Activity ratio and Debtor turnover ratio

16 4

Capital structure ratios(Debt-Equity ratio, Interest coverage ratio)and Probability ratios(gross profit ratio Net profit ratio Operating ratio

1 1 1 1

17 1 p/E ratios and DU point chart revision

1

Total 70

72


III B.Tech(I-Sem) Branch: EEE Date: 09-2012

Time: 90min Sub: MEFA Max.marks:30

ANSWER ANY THREE OF THE FOLLOWING

1. Explain the scope and nature of managerial economics?

2. What are the factors influencing demand?

3. Explain the break even analysis.

4. Explain the price determination in perfect competition.

5. Explain the methods of measuring demand forecasting.


III B.Tech(I-Sem) Branch: EEE Date: 11-2012

Time: 90min Sub: MEFA Max.marks:30

ANSWER ANY THREE OF THE FOLLOWING

1. Explain the factors affecting the requirements of working capital?

2. Define company? Explain its features?

3. Define accounting and explain its functions

4. Explain features, advantages and disadvantages of sole trader?

5. What is meant by ratio analysis? Discuss its objectives and limitations?

VISVODAYA ENGINEERING COLLEGE, KAVALI SET-1 III. B.Tech I Sem: Civil (A&B) I Mid SUB: MEFA

73

TIME : 0.30Min Marks: 10 NAME____________________________________________ROLL NO____________________________ CHOOSE THE CORRECT ANSWER 1. Integration of Economic Theory with business practice is called [ ] A. Managerial Economics B. Economics C. Macro Economics D. Micro Economics 2. Managerial Economics as a subject gained popularly first in___________ [ ] A. India B. Germany C. U.S.A D. England 3.”Economics is the study of scarce resources and unlimited wants”, Who is said that? [ ] A. Paul A. Samuelson B. Prof. Lionel Robbins C. Adam smith D. Alfred Marshall 4. Which of the following pairs of goods is an example of substitutes ? [ ] A. Tea and sugar B. Car and petrol C. Tea and Coffee D. Shirt and Pant 5. Which of the following pairs of goods is example of complementary goods [ ] A. Car and Petrol B. Tea and Coffee C. Shirt and Pant D. Pen and Fan 6. In case of Giffen goods, the demand curve [ ] A. Slopes downwards B. Intersects supply curve C. Slopes upwards D. Meets cost curve 7. In case of unity elasticity, the elasticity is equal to [ ] A. One B. Greater than one C. Less than one D. Two 8. The elasticity between two separate points of demand curve is called_______ elasticity [ ] A. Point B. Arc C. Total outlay D. Zero 9. _________ describes the degree of association between two variables [ ] A. Correlation B. Relation C. Regression D. Precision 10. Which of the following results from the sporadic occurrence of strikes, riots and so on [ ] A. Trend B. Cyclic trend C. Seasonal trend D. Erratic trend 11. Conversion of inputs into output is called ___________ [ ] A. Production B. Expenditure C. Income D. Sales 12. Iso-quants are also called [ ] A. Iso cost curves B. Iso product curves C. AR curves D. MR curves 13. The cost of the next best alternative foregone is known as [ ] A. Implicit cost C. Sunk costs C. Opportunity cost D. Controllable cost 14. Which of the following is a technique for profit planning and control [ ] A. Cost control B. Sales control C. Break one point D. Break even Analysis 15. Contribution is defined as [ ] A. Total cost—variable cost B. Fixed cost+ profit C. Selling price+ variable cost D. Selling price—variable cost 16. ______________ is the example for perishable goods [ ] A. Pens B. Belts C. Vegetables D. Cloths 17. ______is a form of market organization in which there is only one seller of the commodity [ ] A. Oligopoly B. Monopoly C. Duopoly D. Perfect competition 18. The firm is said to be in equilibrium, when its marginal cost equals to [ ] a. Marginal revenue B. Total cost C. Total revenue D. Average cost 19. The price discrimination is also called as [ ] A. Standard pricing B. Differential pricing C. Preferential pricing D. Equal pricing 20. under which pricing method, price just equals Average cost [ ] A. Marginal cost pricing B. Cost plus pricing C. Full cost pricing D. Equal pricing VISVODAYA TECHNICAL ACADAMY, KAVALI III B. Tech(EEE & Mechanical & CIVIL) SUB: MEFA

QUESTION BANK

UNIT-1: INTRODUCTION TO MANAGERIAL ECONOMICS

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1. Define Managerial Economics? Explain its nature and Scope? 2. Elaborate the importance of Managerial Economics in decision-making. 3. Managerial Economics is multidimensional discipline. Explain. 4. Define Demand and explain the factors that influence the demand of product. 5. What is Demand? State and explain the Law of Demand. Are there any exceptions to the law?

UNIT-2 : ELASTICITY OF DEMAND

1. Define Elasticity of demand. Explain its Types and Significance. 2. Define Price Elasticity of demand. Explain different types of price Elasticity of demand. 3. Define Price Elasticity of demand. How do you measure it? 4. What is demand forecasting? Explain various factors governing demand forecasting. 5. What are the steps in Scientific approach to demand forecasting? 6. What do you understand by demand forecasting? What is the need for it?

UNIT-3 : THEORY OF PRODUCTION AND COST ANALYSIS

1. Draw Total Product, Average product and Marginal Product Curves on your answer book. Explain how output changes with Fixed Capital and Variable Labour inputs. 2. What are the economies of scale? Explain different types of Internal and External economies of scale. 3. Explain the following: A) Explicit and Implicit cost B)Fixed cost and Variable cost C)Opportunity cost 4. Define B.E.P. How do you determine it show graphical presentation of B.E.A? 5. Write short notes of the following: (A) Margin of safety (B) Contribution (C) Angle of incidence (D) P.V. Ratio 6. Explain the law of returns to scale. UNIT-4: INTRODUCTION TO MARKETS & PRICING STRATEGIES 1. Define Market. Explain how the Markets are classified? 2. Explain important features of Perfect Competition Market and how price is determined under perfect Market? 3. Define Monopoly. How is price determined under Monopoly? 4. Define Market. Distinguish between perfect and imperfect markets? 5. Explain price-output determination under Monopolistic Competition? 6. Define Market. Explain any four methods of pricing based on Strategy.

VISVODAYA TECHNICAL ACADEMY, KAVALI. Faculty: G. Koteswara Rao M.E.F.A III .B.Tech (EEE & ME &Civil-B)

75

UNIT-1: INTRODUCTION TO MANAGERIAL ECONOMICS 1. Managerial Economics as a subject gained popularly first in_____________ [ C ] a) India b) Germany c) U.S.A d) England 2. Integration of economic theory with business practice is called [ A ] a) managerial economics b)economics c) micro economics d) macro economics 3. `` Economics is the study of scarce resources and unlimited wants “. Who is said that [ B ] a) Paul. A.samuelson b) Prof. Iionel Robbins c) Adam smith d) Alfred Marshall 4. which of the following pairs of goods is an examples of substitutes ? [ B ] a) Rea and sugar b)Tea and coffee c) shirt and pant d) car and petrol 5. which of the following pairs of good is an example of complementary goods [ A ] a)car and petrol b) tea and coffee c) chair and table d) shirt and pant 6. In case of giffen goods, the demand curve [ B ] a) Slopes down wards b)slopes upwards c) intersects supply curve d) meets cost curve 7. The theory of firm also called as [ C ] a) Welfare Economics b) Industrial Economics c) Micro Economics d) Agricultural Economics 8. “Any activity aimed at earning or spending money” called _____________ activity [ C ] a) Service activity b) Accounting activity c) Economic activity d) Social activity 9. Who explained the “Law of Demand”? [ C ] a) Joel Dean b)Cobb-Douglas c) Marshall d) Adam Smith 10. Demand curve always _________________ sloping. [ D ] a) Positive b) Vertical c) Straight line d) Negative 11. Managerial Economics is close to Micro Economics. 12. The statements that contain the word ‘ought to’ are called normative 13. Adam Smith said that Economics is the study of nature and uses of national wealth. 14. Goods which are used for further processing are called produced goods 15. The relationship between one variable and its determinants with respect to the quantity demand is Called demand function UNIT-2: ELASTICITY OF DEMAND 1. In case of Unity elasticity, the elasticity is equal to [ B ] a) Greater than one b) One c) Less than one d) Two 2. When small change price leads great change in demand, we call it [ B] a) In elastic demand b) Negative demand c) Elastic demand d) Three 3. When a great change in price leads small change in demand, we call it [ C ] a) Elastic demand b) Positive demand c ) Inelastic demand d) Two 4. If the price of Colgate tooth paste decreases relative to the price of Close up, the demand for [ A ] a) Close up decreases b) Close up increases c) Demand for Close up is not affected c) Demand for Colgate increases 5. Demand for petrol is [ B } a) Elastic b) In elastic c) Perfectly elastic d) Perfectly inelastic 6. Forecasts in terms total sales can be viewed as__________ forecast [B } a) Specific b) General c) Determined d) Leading 7 .Which of the following results from the sporadic occurrence of strikes, riots and so on [ D ] a) Trend b) Cyclic trend c) Seasonal trend d) Erratic trend 8. Which of the following is also called the long term trend? [ C ] a) Cyclic trend b)Seasonal trend c) Trend d)Erratic trend 9. Under the __________ one set of data is used to predict another set [ B ] a) Exponential smoothing b) Barometric technique c) Moving average method d) Expert opinion method 10. _________ describes the degree of association between two variables [ A ]

76

a) Regression b) Relation c) Correlation d) Precision 11. The elasticity between two separate points of demand curve is called Arc elasticity. 12. Rate of responsiveness in demand of a commodity for a given change in price is called elasticity 13. Censes method is also called Total enumeration method. 14. When past data is arranged chronologically Total enumeration method. 15. One set of data is used to predict in a limited market to assess its acceptability among limited Number of customers is called Test marketing. UNIT-3: THEORY OF PRODUCTION AND COST ANALYSIS. 1. Conversion of inputs into output is called as ______________ [ C ] a). Sales b)Income c)Production d)Expenditure 2. Iso-quants are also called [ A] a) Iso product curves b) Iso cost curves c) Price indifference curves d)AR curves 3. The costs of the next best alternative fore gone is known as [ C ] a) Implicit cost b) Sunk costs c)Opportunity cost d) Controllable cost 4. Which of the following are fixed in the short run? [ D ] a) Variable cost b) Semi-variable cost c) Semi fixed costs d) Fixed costs 5. Which of the following varies with the volume of production? [ B ] a) Fixed costs b) Variable costs c) Semi fixed costs d) Semi variable cost 6. Explicit costs are called [ D ] a) In house costs b) Non cash costs c)In pocket costs d) Out of pocket costs 7. Implicit or imputed costs are also called [ C ] a) Future costs b) Controllable costs c) Book costs d) Joint costs 8. Which of the following is a technique for profit planning and control [ A ] a) Break even analysis b) Break one point c) Cost unit d) cost control 9. Contribution is defined as [ D] a) Total cost—variable cost b) Fixed cost+ Profit c) Selling price+ variable cost d) Selling price—Variable cost 10. Production is governed by certain laws of returns to scale, Which are known as [ B ] A ) Diseconomies of scale b) Economies of scale c) Nominal scale d) Ordinal scale 11. law of returns is also called Law of variable proportions 12. Tenders are based on sealed bid pricing. 13. Telephone bills is an example of Semi-fixed or semi-variable costs. 14.A firm is said to be attain the BEP where TR=TC 15. Contribution minus fixed cost is called profit UNIT—4: INTRODUCTION TO MARKETS & PRICING STRATEGIES.

1. Exchange value of a unit of good expressed in terms of money is called [ C } a) Cost b) Capital c) Price d) Expenditure 2. __________ is a place in which goods and services are bought and sold [ C ] a) Factory b) Work shop c) Market d) Warehouse 3. __________ is the example for Perishable goods. [ C ] a) Pens b) Belts c) Vegetables d) Cloths 4. In which period, the supply of commodity is fixed [C ] a) Short period b) long period c) Very short period d) very long period 5.The price at which demand and supply of a commodity equal is known as [ C ] a) High price b) Low price c) equilibrium price d) Marginal price 6. In which market single market price prevails for the commodity. [ D ] a) Monopoly market b) Duopoly market c) Oligopoly market d) Perfect competition 7._________ is a form of market organization in which there is only one seller of the commodity [ A ] a) Monopoly b) Perfect competition c) Duopoly d) Oligopoly

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8. The form is said to be in equilibrium, when its Marginal cost equals to [ B ] a) Total cost b) Marginal revenue c) Total revenue d) Average cost 9. Under which pricing method, price just equals Total cost [ C ] a) Marginal cost pricing b) Cost plus pricing c) Full cost pricing d) Going rate piecing 10. The price discrimination is also called as [ C ] a) Standard pricing b) Preferential pricing c) Differential pricing d) Equal pricing 11. Under Perfect competition, the price is equal to AR=MR 12. A Monopolist can either control the price or output but not both 13. The main feature of Monopolistic competition product differentiation 14. In Perfect competition market, seller is the price taker 15. Changing very low price in the beginning and increasing in gradually is called penetration pricing

78

JNTUA QUESTION PAPERS

Code: 9AHS401 1 IV B. Tech I Semester (R09) Regular Examinations, November 2012 MANAGERIAL ECONOMICS & FINANCIAL ANALYSIS (Common to CSE, IT & CSS) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 (a Define managerial economics. Explain its scope. (b) Distinguish between economics and managerial economics with suitable examples. 2 What do you understand by ‘Elasticity of Demand’? What are types of elasticity of demand? 3 Explain how do you determine breakeven point in volume and value? Explain graphically. 4 How does an individual firm behave under perfect completion? Also explain the firm and industry

equilibrium under perfect competition. 5 Discuss about the short-comings of the public sector enterprises in India and what is their future. 6 (a Define capital budgeting. Explain its importance. (b) How is useful of payback period method? Explain its features and limitations. 7 (a What is ‘Journal Entry’ and describes its importance in account books? (b) Explain the basic accounting concepts and convention, Give examples. 8 Discuss the importance of ratio analysis for inter firm and intra-firm comparison, including

circumstances responsible for its limitations, if any. Code: 9AHS401 IV B. Tech I Semester (R09) Regular Examinations, November 2012 MANAGERIAL ECONOMICS & FINANCIAL ANALYSIS (Common to CSE, IT & CSS) Time: 3 hours Max. Marks: 70 Answer any FIVE questions All questions carry equal marks 1 Elaborate the importance of managerial economics in decision making. 2 How do you measure elasticity of demand? Illustrate graphically. 3 What do you understand by cost output relationship? Explain how costs behave in the

short run. 4 Define market. Distinguish between perfect and imperfect markets. 5 ( Define partnership and explain its silent features and limitations. (b What are the qualities of a good partner? 6 ( What is capital? Explain the types and significance of capital. (b Explain the concept of working capital, its features & limitations. 7 Explain the following in briefly:-

(a) Double entry system. (b) Book – keeping. (c) Capital. (d) Income.

8 How ratios are classified for the purpose of financial analysis? With assumed data, illustrate any two types of ratios under each category.

79


B.Tech. III-I Sem (M.E) T P C

4 0 4

(9A03501) THERMAL ENGINEERING – II

UNIT – I

Basic Concepts: Rankine cycle - Schematic layout, Thermodynamic Analysis, Concept of Mean Temperature of Heat addition, Methods to improve cycle performance – Regeneration – reheating- combined- cycles. UNIT II

Boilers : Classification based on Working principles & Pressures of operation -L.P & H.P.Boilers – Mountings and Accessories – Boiler horse power, equivalent evaporation, efficiency and heat balance – Draught: classification – Height of chimney for given draught and discharge, condition for maximum discharge, efficiency of chimney – artificial draught, induced and forced draught. UNIT – III

Steam Nozzles: Function of nozzle – applications - types, Flow through nozzles, thermodynamic analysis – assumptions -velocity of nozzle at exit-Ideal and actual expansion in nozzle, velocity coefficient, condition for maximum discharge, critical pressure ratio. Criteria for design of nozzle shape: Super saturated flow, its effects, degree of super saturation and degree of under cooling - Wilson line –Shock at the exit. UNIT – IV

Impulse turbine; Mechanical details – Velocity diagram – effect of friction – power developed, axial thrust, blade or diagram efficiency – condition for maximum efficiency. De-Laval Turbine - its features. Methods to reduce rotor speed-Velocity compounding and pressure compounding, Velocity and Pressure variation along the flow – combined velocity diagram for a velocity compounded impulse turbine. Governing of impulse turbine. UNIT V

Reaction Turbine: Mechanical details – principle of operation, thermodynamic analysis of a stage, degree of reaction –velocity diagram – Parson’s reaction turbine – condition for maximum efficiency. Governing of reaction turbine. UNIT VI

Steam Condensers : Requirements of steam condensing plant, rare fraction – Classification of condensers – working principle of different types – vacuum efficiency and condenser efficiency – air leakage, sources and its effects, air pump- cooling water requirement. .UNIT – VII Gas Turbines : Simple gas turbine plant – Ideal cycle, essential components – parameters of performance – actual cycle – regeneration, inter cooling and reheating –Closed and Semi-closed cycles – merits and demerits, Brief concepts about compressors, combustion chambers and turbines of Gas Turbine Plant. UNIT – VIII

Jet Propulsion : Principle of Operation –Classification of jet propulsive engines – Working Principles with schematic diagrams and representation on T-S diagram - Thrust, Thrust Power and Propulsion Efficiency – Turbo jet engines –Turbo jet, Turbo prop, Pulse jet – Schematic Diagram, Thermodynamic Cycle, Performance Evaluation Thrust Augmentation – Methods. Introduction to Rocket propulsion.

TEXT BOOKS:

1. Thermal Engineering / R.K. Raj put / Lakshmi Publications

80

2. Basic and Applied Thermodynamics / P.K. Nag/TMH REFERENCES:

1. Gas Turbines – V.Ganesan /TMH 2. Thermodynamics and Heat Engines / R. Yadav / Central Book Depot 3. Gas Turbines and Propulsive Systems – P.Khajuria & S.P.Dubey - /Dhanpatrai 4. Thermal Engineering-R.S Khurmi/JS Gupta/S.Chand. 5. Thermal Engineering-M.L.Mathur & Mehta/Jain bros. 6. Thermal Engineering Data Book – B. S. Reddy and K. H. Reddy / I.K. International

Question Paper Pattern: 5 questions to be answered out of 8 questions

Each question should not have more than 3 bits

81


Department of Mechanical Engineering SUB: Thermal Engineering-II MID-I III-B.Tech. I-Semister Date: 03-09-2012 FN Max. Marks: 20,time: 90 min Answer any three questions

1. (a) Explain the Rankine cycle with neat schematic diagram and describe each process of the cycle and show them on P-v and T-s diagrams. (b) A simple Rankine cycle works between pressure of 30 bar and 0.04 bar, the initial condition of steam being dry saturated, calculate the cycle efficiency, work ratio and specific steam consumption. 2. (a) Draw the T-S and H-S diagrams of reheat cycle representing all the salient points. (b) In a regenerative cycle the inlet conditions are 40 bar and 4000 C. Steam is bled at 10 bar in regenerative heating. The exit pressure is 0.8 bar. Neglecting pump work, determine the efficiency of the cycle. 3. (a) How are the steam boilers classified? (b) In a boiler test 1250 kg of coal are consumed in 24 hours. The mass of water evaporated is 13000 kg and the mean effective pressure is 7 bar. The feed water temperature was 4000C, heating value of coal is 30000 kJ/kg. The enthalpy of 1 kg of steam at 7 bar is 2570.7 kJ. Determine: (i) Equivalent evaporation per kg of coal (ii) Efficiency of the boiler. 4. (a) Steam at pressure of 15 bar and dryness fraction of 0.97 is discharged through a convergent-divergent nozzle to a back pressure of 0.2 bar. The mass flow rate is 9 kg/kWh. If the power developed is 220 kW. Determine (i) Throat pressre (ii) No of nozzles required if each nozzle has a throat of rectangular cross-section of 4mmx8mm. (b) Dry saturated steam at a pressure of 10 bar expands to a pressure of 4 bar isentropically. If super saturated flow occurs, determine (i) The degree of super cooling (ii) Degree of super saturation (iii) Reduction in enthalpy drop due to super saturation. 5. Sketch the velocity diagram of a single stage impulse turbine and determine the expressions for the force, work done, diagram efficiency, stage efficiency and axial thrust.

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Department of Mechanical Engineering SUB: Thermal Engineering-II MID-I II-B.Tech. I-SEM Date: 03-09-2012 FN Quiz paper Max. Marks: 10, Time: 20 min Answer all questions

Name: ----------------------------- Roll No: ___________________

1. In Rankine cycle efficiency, all processes are [ ] (a) Reversible (b) Irreversible (c) Quasi static (d) a& c 2. A thermodynamic cycle used for steam power is [ ] (a) Carnot cycle (b) Rankine cycle (c) Brayton cycle (d) All 3. The flue gases flow through the tubes and water surrounds tubes in [ ] (a) Water tube boiler (b) Fire tube boiler (c) None 4. The draught in locomotive boilers is produced by [ ] (a) Chimney (b) Fan (c) steam jet (d) All 5. Water tube boilers are used for [ ] (a) High pressure and high output (b) High pressure and low output (c) High pressure only 6. Which of the following is not a water tube boiler [ ] (a) Locomotive (b) Stirling (c) Benson (d) Bobcock-Wilcox 7. The baffle plates are provided in Bobcock-Wilcox boiler to [ ] (a) Regulate water flow (b) regulate steam flow (c) change the direction of flue gases 8. High pressure boilers [ ] (a) Locomotive (b) Stirling (c) Benson (d) Bobcock-Wilcox (e) b,c 9. A super critical boiler has a pressure range of [ ] (a) 100- 150 bar (b) 150 – 180 bar (c) 150 – 220 bar (d) 225 – 250 bar 10. Which of the following device is used to remove the sludge from boiler? [ ] (a) SSV (b) Fusible plug (c) Super heater (d) Blow off cock 11. The evaporation of 15.653 kg of water per hour from and at 1000C is called [ ] (a) Boiler efficiency (b) Equivalent evaporation (c) Boiler hours power 12. La-Mont boiler is a ------------- pressure ------------ tube boiler ---------- working on --------------- circulation 13. The natural draught is produced by ------------------------ 14. The expansion of steam through nozzle is [ ] (a) Isothermal (b) Adiabatic (c) Throttling (d) Polytropic 15. . The following relation is valid for supersaturated flow in nozzle [ ] (a) pv1.135= C (b) pv1.35= C (c) pv1.3= C (d) pv1.4 = C 16. A steam nozzle is said to be choked [ ] (a) No flow through nozzle (b) Maintain constant discharge (b) Critical conditions and maximum discharge to be maintained (d) none 17. . When the nozzle designed for maximum discharge through convergent part is [ ] (a) Sonic (b) supersonic (c) sub-sonic (d) All 18. The effect of friction on flow of steam through a nozzle [ ] (a) Velocity increases (b) Velocity decreases (c) Dryness fraction increases (d) b & c 19. The steam enters the nozzle at ------------pressure and ------------- velocity. 20. In impulse steam turbine the expansion of steam takes place in [ ] (a) Blades only (b) Nozzles only (c) a & b (d) None

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QUESTION BANK

THERMAL ENGINEERING – II

UNIT – I

1. (a) Describe the different processes of Rankine cycle. Derive the expression for its efficiency and show them on P-v and T-s diagrams.. (b) A simple Rankine cycle works between pressure of 30 bar and 0.04 bar, the initial condition of steam being dry saturated, calculate the cycle efficiency, work ratio and specific steam consumption. 2. (a) Explain with the help of neat diagrams a Regenerative cycle. Derive also an expression for its thermal eficiency. (b) In a regenerative cycle the inlet conditions are 40 bar and 4000 C. Steam is bled at 10 bar in regenerative heating. The exit pressure is 0.8 bar. Neglecting pump work, determine the efficiency of the cycle. 3. A steam generator delivers steam at 100 bar, 5000 C. The feed water inlet temperature is 160oc The steam generation rate is 100,000 kg/hr and the steam generator efficiency is 88%. Determine: i. The fuel burning rate in kg/hr, if the calorific value of the fuel is 21 MJ/kg, ii. The percentage of total heat absorbed in the economizer, evaporator and super heater. Assume that only latent heat is absorbed in the evaporator and neglect any pressure drop. 4. (a) Draw the T-S and H-S diagrams of reheat cycle representing all the salient points. (b) In a steam power plant the condition of steam at inlet to the turbine is 20 bar, 3000 C and the condenser pressure is 0.1 bar. Two feed-water heaters operate at optimum temperatures of 1500 C and 1000 C. Determine the quality of steam at turbine exhaust, cycle efficiency and fraction of steam bleed into heaters. 5. Steam at a pressure of 15 bar and 3000 C is supplied to the throttle of an engine. The steam expands to 2 bar when release occurs. The exhaust takes place at 1.1 bar. A performance test gave the result of the specific steam consumption of 12.8kg/kWh and mechanical efficiency of 80%. Determine i) Ideal work on the modified rankine engine, ii) Ideal thermal efficiency, iii) Brake thermal efficiency. 6. (a) Explain the difference between Carnot cycle and Rankine cycle. Why do you think Carnot cycle is not suitable for steam power plants. (b) In a Rankine cycle, the steam at inlet to turbine is saturated at a pressure of 30 bar and the exhaust pressure is 0.25 bar, Determine. i. the pump work ii.Turbine work iii.Rankine cycle efficiency iv. Dryness fraction of steam at the end of expansion. Assuming the steam flow rate as 10 kg/sec. UNIT – II

1. (a) Explain the features of high pressure boilers and list the merits HP boilers. (b) What is the function of boiler mounting? Discuss with a neat sketch any one type of the mountings. 2. In a boiler trail of one hour duration the following observations were made: Steam generated = 5250 kg, coal burnt = 695 kg, calorific value of coal = 30200 kJ/kg, dryness fraction of steam = 0.94, rated pressure of the boiler = 12 bar, temperature of steam leaving the super heater = 240 0C, temperature of hot well = 470C. Calculate (a) Equivalent evaporation per kg of fuel without super heater (b) Equivalent evaporation per kg of fuel with super heater (c) thermal efficiency of the boiler without super heater (d) thermal efficiency of the boiler with super heater (e) heat supplied by the super heater per hour. Take Cp of steam as 2.184 kJ/kg K. 3. (a) Enumerate the various accessories and mountings normally used in a steam generating plant (b) A boiler with super heater generates 6000 kg/hr of steam at 15 bar and 0.8 dryness. The boiler exit temperature is 300 0C. The feed water temperature is 80 0C. The overall efficiency of the plant is 85%. Determine the consumption rate, assuming a calorific value of 30000kJ/kg Also find the equivalent evaporation from and at100 0C. What will be the area of super heater surface if the overall heat transfer coefficient is 4,50,000 kJ/m2-hr? 4. (a) How are the steam boilers classified? (b) Sketch and describe the working of Lancashire boiler. 5. (a) Discuss the function, construction and working principle of pressure reducing value.

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(b) What are various types of boiler drauqhts. Explain each of them. 6. (a) Discuss the construction and working of Cochran boiler. (b) Differentiate between artificialcial and natural draught. 7. (a) Discuss the construction and working principle of fusible plug, feed check value and blowof cock. (b) Estimate the draught, in mm of water column produced by a chimney of 30m height. The average temperature of hot gases is 498 K and the temperature of outside an is 293K. The quantity of air supplied is 18 kg per kg of fuel. 8. (a) Describe the construction and working principle of locomotive boiler. (b) Deduce a expression showing the relation between the draught, chimney height temperature of flue gas and mass of air. UNIT – III

1. (a) Explain the terms “over expanding” and “under expanding” as applied to a fluid flow through a nozzle. (b) Describe the changes which occur in a convergent divergent nozzle as the back pressure is slowly increased from the design pressure up to the pressure at entry 2. (a) Derive expression for mass of steam discharged through steam nozzle. (b) At one stage of a steam turbine, the nozzles expand 9 kg of steam per second from a pressure of 15 bar and 2500 C to 6 bar. The actual heat drop in the nozzle is 175 kJ. Calculate the number of nozzles required for a given outlet area for each nozzle approximately 3.5 sq.cm. and adjust the outlet dimensions to suit this number. 3. (a) Derive the expression for the critical pressure ratio to the index of expansion n a steam nozzle. (b) Find the maximum discharge and exit diameter of a convergent-divergent nozzle which receives dry and saturated steam at 15 bar and discharges to an impulse turbine at 0.3 bar. Neglect friction and take throat diameter equal to 8 mm. 4. (a) Steam is supplied to a nozzle at 13 bar, 0.9 dryness fraction and expands to 1.4 bar. The velocity at throat pressure of 8 bar is 3% less than the theoretical value and complete expansion takes place with an efficiency ratio of 0.9. If the throat section of each nozzle is to be about 1 sq.cm., determine suitable number of nozzles and specify the proper throat and outlet areas. The steam discharge through the nozzle is at the rate of 5kg/s. 5. (a) What do you mean by critical pressure ratio for the nozzle. (b) Dry saturated steam at a pressure of 8 bar enters a convergent-divergent nozzle and leaves it at a pressure of 1.5 Bar. If the flow is isentropic and corresponding find ratio of cross sectional area at exit and throat for maximum discharge. UNIT – IV 1. In a single row wheel impulse turbine the mean diameter of the blade is 1m. It runs at 3000 rpm. The steam issues from the nozzle at a velocity of 350 m/s and the nozzle angle is 200. The rotor blades are equiangular. The blade friction factor is 0.86. Determine the power developed if the axial thrust on the end bearing of a rotor is 118N. 2. What is compounding? Describe various ways of compounding impulse turbines and give their merits and demerits. 3. The rotational speed of an impulse steam turbine wheel is 3000 rpm. The nozzle is inclined at 200 to the plane of the wheel and its efficiency is 0.885. The isentropic heat drop for the stage is 160 kJ/kg. If the ratio of blade speed to steam speed is 0.4, the blade velocity coefficient is 0.82 and the blade efficiency is 0.76, find (a) the mean blade ring diameter (b) the residual energy of steam at outlet in kJ/kg of steam and (c) the power developed by the wheel when the steam flow is 15 kg/s. 4. (a) What are the various losses generally occur in a steam turbine? (b) The outlet area of a nozzle in a simple impulse turbine is 15 cm2 and steam leaves the nozzle at 1.4 bar, 0.9 dry and with a velocity 650 m/s. The nozzles are inclined at 200 to the plane of the wheel, the blade speed is 250 m/s, the blade exit angle is 300 and the blade velocity coefficient is 0.8. Estimate the power developed and steam consumption per kilowatt - hour. 5. In a Delaval turbine, the steam issues from the nozzles with a velocity of 850m/s. the nozzle angle is 200. Mean blade velocity is 350m/s.the blades are equiangular. The mass flow rate is 1000kg/min.friction factor is 0.8.determine: (a) Blade angles (b) Axial thrust on the end bearing (c) Power developed in kW (d) Blade efficiency (e) Stage efficiency, if nozzle efficiency is 93 6. The following particulars relate to a two row velocity compounded impulse turbine which forms the first stage

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of combination turbine. Steam velocity at nozzle output angle is 160. Outlet angle, first row of moving blades is 180. Outlet angle fixed blade is 220 outlet angle, second row of moving blades is 360. Steam flow rate is 2.5kg/sec. The ratio of the relative velocity of outlet to inlet is 0.84 for all blades. Determine for each row of moving blades the following: (a) the velocity of whirl (b)The tangential thrust on blades (c) axial thrust on blades (d) the power developed. 7. In a two-row velocity-compounded stage for an impulse turbine the initial speed of steam nozzle is 550 m/sec The speed of blades is 107 m/sec. The nozzle angle is 180 and the discharge angles of the three rows of blades in order are 21.50 ,280 and 450.Assuming loss due to friction at15% in each row of blades, find the work done by the steam per kg and the efficiency of the blading. Assuming constant volume rate of steam find the height required for each row of blades, taking the height of nozzles as 17.75 cm. UNIT –V

1. Derive the condition for maximum efficiency of reaction turbine. 2. In a Parson’s reaction turbine of 50% degree of reaction running at 25 r p s the available enthalpy drop for an expansion is 62.8 kJ/kg. If the mean diameter of the rotor is 1 m, find the number of rows of moving blades required. The outlet blade angle is 200 and speed ratio is 0.7. Assume that the stage efficiency is 80%. 3. (a) Explain the functionality of reaction steam turbine with suitable diagram. And how it is different from the impulse turbine? (b) What are different losses that are occurring in reaction turbine? Explain with preventive measures. 4. At a certain pair of a reaction turbine, the steam leaves the fixed blade at a pressure of 3 bar with a dryness fraction of 0.98 and a velocity of 130 m/s. The blades are 20 mm high and discharge angle for both the rings are 200. The ratio of axial velocity of flow to the blade velocity is 0.7 at inlet and 0.76 at the exit from the moving blade. If the turbine uses 4 kg of steam per second with 5% tip leakage, find the mean blade diameter and the power developed. 5. In a stage of impulse reaction turbine provided with single row wheel, the mean diameter of the blades is 1metre.it turns at 3000r.p.m.the steam issues from the nozzle at a velocity of 350m/sec and the nozzle angle is 200. The rotor blades are equiangular. The blade friction factor is 0.86.determine the power developed if the axial thrust on the end bearing of a rotor is 118N. UNIT –VI

1. (a) Derive the equations for the estimation of vacuum efficiency and condenser efficiency. (b) Find the weight of cooling water required in the surface condenser of 3000 kW, steam power plant with the following data Steam used = 10 kg/kWhr; Exhaust steam condition = 0.9 dry; pressure in the condenser = 0.1 bar; Hot well temperature = 32 0C; cooling water inlet temperature = 25 0C; cooling water outlet temperature = 32 0C; temperature of steam at entrance = 40 0C. And also calculate the vacuum efficiency. 2. (a) What are the functions of condensers in a steam power plant? Explain with a simple diagram. (b) A surface condenser is designed to handle 10,000 kg of steam per hr. The steam enters at 0.08 bar and 0.9 dry and the condensate leaves at the corresponding saturation temperature. The pressure is constant throughout the condenser. Estimate cooling water flow rate per hr, if the cooling water temperature rise is limited to 10 0C. 3. (a) Draw the schematic diagram of low level counter flow jet condenser and explain its working principle. (b) What are the advantages and limitations of surface condensers over jet condensers? 4. (a) Explain the working principle of counter flow jet condenser with neat sketch? and discuss the merits and demerits. (b) Determine the area at throat and at the exit, and also the velocity at the exit for the given mass flow rate of 0.2 kg/s. The inlet conditions are 10 bar pressure and 2750C temperature and the exit pressure is 2 bar. Assume that the expansion is isentropic and that the inlet velocity is negligible. 5. (a) Explain the working of a ejector condenser. (b) In a surface condenser the vacuum maintained is 700 mm of Hg. The Barometer reads 754 mm of Hg. If the temperature of condensate is 180C. Determine i. Mass of air per Kg of the steam. ii. vacuum efficiency. UNIT –VII

1. (a) What are different assumptions made in evaluation of thermal efficiency of Brayton cycle and derive thermal efficiency equation. (b) A gas turbine plant is supplied with air at a pressure of 1 bar and 300 K. The air is then compressed to a pressure of 5 bar and then heated to 8500C in the combustion chamber. Calculate the thermal efficiency of the cycle. 2. (a) What are different parameters influence the performance of gas turbine cycle .Explain.(b) In a gas turbine power cycle, the pressure ratio is 6 and the maximum cycle temperature is 650 0C. The air enters to the cylinder at 15 0C and the flow rate of air is 12 kg/s. Determine the power developed and thermal efficiency of cycle.

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3. A gas turbine cycle has a perfect heat exchanger in which air enters the compressor at a temperature and pressure of 300 K and 1 bar and discharges at 475 K and 5 bar. After passing through the heat exchanger the air temperature increases to 655 K. The temperature of air entering and leaving the turbine 870 0C and 450 0C. Assuming no pressure drop through the heat exchanger, the compute the output per kg of air, the efficiency of the cycle and the work output to drive the compressor. 4. (a) What are essential components required for the operation of gas turbine cycle and explain their functionality. 5. (a) The following data is refers to a closed cycle gas turbine plant Atmospheric Air temperature 270C, Maximum temperature of the cycle 8230C, Pressure at compressor inlet 1 bar, Pressure ratio 4, Compressor efficiency 80%, Turbine efficiency 85%, Heating value of fuel 41,800 kJ/Kg, Turbine efficiency 80%, Heater loss 10% of Heating value Find. i. Work ratio ii. Turbine work iii. Compressor work iv. Heat supplied Assume the working substance is Air ,regard as simple gas with Cp = 1 KJ/Kg 0K and = 1.4 (b) What is “regeneration ” in gas turbines. UNIT –VIII 1. A turbojet engine is traveling at 920 km/h at standard sea level conditions. The ram efficiency is 0.87 and compression ratio is 4.3, the compressor efficiency is 0.82 and the burner pressure loss is 2%. The air fuel ratio is 0.0119, the turbine inlet temperature is 950 K, the turbine efficiency is 0.83 and equivalent nozzle efficiency is 0.96. Calculate (a) the specific gross thrust and (b) the thrust specific fuel consumption. 2. (a) What is meant by jet propulsions? What are the basic differences between jet propulsion cycles and shaft power cycles. (b) Draw the typical layout of gas pressurization system and explain its working principle. Compare with the pump pressurization system. 3. (a) What is meant by thrust? Derive its equation of turboprop engine from the first principles. (b) Explain the advantages and disadvantages of bipropellants used in rocket engines over monopropellants. 4. A turbojet engine is being used to propel an aeroplane with the drag of 3900 N and the coefficient of drag is 0.01835. The wing area is 21.25 m2, the air consumption per second of the engine is 14.5 kg/s and thrust developed is 8900 N. Calculate the flight velocity and effective jet velocity and also specific thrust. 5. (a) Explain with a neat sketch a Turbo-jet Unit. (b) What are the fundamental differences between jet propulsion and rocket propulsion? 6. (a) Where is rocket propulsion is used? What are the kinds of rocket propellants? (b) Describe a liquid propellant rocket engine with a neat sketch.

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III- B.Tech, Semister-1 SUB: TE-II, Dept of Mechanical Engineering

Quiz Bank from Units of V, VI, VII and VIII for MID=II Examination

1. Which of the following is a pressure compounded turbine [ ] (a)Parsons (b) Curtis (c) Rateau (d) De-Laval 2. Which of the following is a 50% reaction turbine? [ ] (a)Parsons (b) Curtis (c) Rateau (d) De-Laval 3. Steam expands in reaction turbine over ------ blades [ ] (a) Moving (b) Fixed (c) a & b (d) None 4. The degree of reaction is ratio of ------------------ and ----------------------- 5. If the enthalpy drop in moving and fixed blades are 10 kj and 15 kj, the degree of reaction [ ] (a) 67% (b) 60% (c) 40% (d) 33% 6. In Parson’s reaction turbine the velocity diagram triangles at inlet and outlet are [ ] (a)Asymmetrical (b) isosceles (c) right angled (d) congruent 7. In Parson’s reaction turbine, the maximum blade efficiency is obtained when [ ] (a) P = cosα/2 (b) P = cosα (c) P = cos2α (d) 1+ cosα/2 8. The maximum work done in reaction turbine is--------- 9. The maximum efficiency of reaction turbine is -------------------- 10. In a 50% reaction turbine, the fixed blades will act as ---------------- 11. The following turbine has most efficient turbine [ ] a. De-Laval (b) Curtis (c) Rateau (d) Parson’s 12. Employing superheated steam in turbines leads to -------- erosion of blading [ ] a. Reduce (b) increase (c) no effect (d) None 13. The commonly used governing method in steam turbines is ---------- [ ] a. Throttle governing (b) Bypass governing (c) Nozzle governing (d) All 14. The vacuum efficiency of condenser is the ratio of ------------and --------------- 15. The vacuum in the condenser is 670 mm Hg and barometer reading is 750 mm, the absolute 16. Vacuum in the condenser is ------------------------- 17. The vacuum in the condenser is 670 mm Hg and barometer reading is 750 mm, the corrected vacuum in the condenser is ------------------------- 18. The vacuum in the condenser is 670 mm Hg and barometer reading is 750 mm, the vacuum efficiency in the condenser is ------------------------- 19. The cooling water outlet and inlet of condenser are 350C and 250C. The condenser efficiency for a given condenser vacuum of 70cm of Hg is --------------- 20. The maximum limit of vacuum in jet condenser is about --------------- (a) 55 mmof Hg (b) 60 mm of Hg (c) 65 mm of Hg (d) 70 mm of hg [ c ] 21. The effect of air leakage in to condenser leads (a) Increase in condenser efficiency (b) decrease in condenser efficiency [ ] © No effect in condenser efficiency (d) None 22. In----------------- condenser, steam and water do not mix [ ] (a)Jet condenser (b) surface condenser (c) Evaporative condenser (d) All 23. Wet pump in condenser is used to remove --------- and ----------------- 24. Dry pump in condenser is used to remove only ---------------------- 25. The function of cooling tower in steam condensing plant is ------------ [ ] (a)Cool the condenser water (b) Heat the condenser water (c) Cool the condensate (d) None 26. Gas turbines are useful in [ ] (a)Aviation (b) Marine propulsion (c) Oil & Gas fields (d) All 27. The use of gas turbine power plants is [ ] (a)To meet the base load (b) To meet the peak load (c) To start the plant (d) All 28. Gas turbines are working on ------------- cycle [ ] (a)Otto cycle (b) Joule cycle (c) Brayton cycle (d) b&c

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29. The processes of Brayton cycle are --------------- 30. While starting, a gas turbine is first motored to minimum speed called [ ] No load speed (b) motoring speed (c) coming in speed (d) All 31. The maximum temperature in gas turbine is limited to about [ ] (a)600 to 700K (b) 800 to 900K (c) 1000 to 1200K (d) 1250 to 1500K 32. What factors limits the maximum temperature in gas turbine [ ] (a)Quality of fuel (b) materials of blades (c) combustion chamber efficiency (d) All 33. Blade materials are---------------- [ ] (a)Alluminium (b) cost iron (c) cast steel (d) nickel steel 34. The air fuel ratio for gas turbine is about [ ] (a) 20:1 (b) 30:1 (c) 40:1 (d) 60:1 35. In gas turbine cycle, work output is 600 kj/kg, compressor work is 400 kj/kg and heat Supplied is 1000 kj/kg, the cycle efficiency is [ ] (a)20% (b) 40% (c) 60% (d) 80% 36. In gas turbine cycle, work output is 600 kj/kg, compressor work is 400 kj/kg, the work ratio Is ------------- - 37. The maximum temperature and minimum temperature of gas turbine cycle are 1000K and 300K. The optimum pressure ratio is --------------- 38. The maximum temperature and minimum temperature of gas turbine cycle are 1000K and 300K. The maximum cycle efficiency is --------------- 39. Work ratio is the ratio of ------------------ and -------------------- 40. A gas power plant produces 4000 kW power and work ratio is 40%, the compressor work is [ ] (a)2000 kW (b) 4000 kW (c) 6000 kW (d) 8000 kW 41. Effect of inter cooling in gas turbine cycle [ ] (a)Decrease in compressor and turbine work (b) Decrease in compressor and increase in net work (c) increase in both compressor and turbine work (d) All 42. In a gas turbine cycle, the regenerator is used to [ ] (a)Heat gases from combustion chamber (b) Heat air coming from compressor © cool the gases from turbine (d) None 43. In a gas turbine cycle with regeneration 44. Increase in pressure ratio (b) decrease in work out put (c) increase in cycle efficiency (d) All 45. A jet engine works on the principle of conservation of [ ] (a)Mass (b) discharge (c) energy (d) momentum 46. In ------ component of jet engine, the KE of air is converted to pressure energy 47. The reduction gearing is provided in [ ] (a)Turbo jet (b) turbo-propeller (c) ram jet (d) pulse jet 48. Propulsive efficiency is ratio of --------------- and --------------

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JNTUA Question papers

Code :R7320306 1

III B.Tech II Semester(R07) Regular & Supplementary Examinations, April/May 2011

THERMAL ENGINEERING-II

(Mechanical Engineering)

Time: 3 hours Max Marks: 70

Answer any FIVE questions

All questions carry equal marks

⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) Explain with the help of neat diagram a ‘Regenerative cycle’. Derive also an expression for its thermal efficiency. (b) A sample of fuel on analysis is found to contain carbon 85%, hydrogen 10%, sulphur 2% and ash 3%. Find the higher calorific value of the fuel. 2. (a) Derive an expression connecting the height of a chimney and the draught it produces in terms of atmospheric temperature and mean flue gas temperature. (b) To provide a natural draught a chimney of height 16 m is used. Calculate (i) the draught in mm of water when the temperature of chimney gases is such that the mass of the gases discharged is maximum, (ii) if the temperature of flue gases does not exceed 3500C, find air supplied per kg of fuel, when discharge is maximum. Take ambient temperature as 200C. 3. (a) Explain what is meant by critical pressure ratio of a nozzle. (b) Steam at a pressure of 10 bar and 0.9 dry discharges through a nozzle having throat area of 450 mm2. If the back pressure is 1 bar, find (i) final velocity of the steam and (ii) cross sectional area of the nozzle at exit for maximum discharge. 4. (a) What is the principle of operation of steam turbines? (b) The blade speed of a single ring impulse blading is 250 m/s and nozzle angle is 200. The heat drop is 550 kJ/kg and nozzle efficiency is 0.85. The blade discharge angle is 300 and the machine develops 30 kW, when consuming 360 kg of steam per hour. Draw the velocity diagram and calculate: (i) Axial thrust on the blading, and (ii) The heat equivalent per kg of steam friction of the blading. 5. A reaction turbine running at 360 R.P.M. Consumes 5 kg of steam per second. Tip leakage is 10%. Discharge blade tip angle for both moving and fixed blades is 200. Axial velocity of flow is 0.75 times blade velocity. The power developed by a certain pair is 4.8 KW where the pressure is 2 bar and dryness fraction is 0.95. Find the drum diameter and blades height. 6. (a) Explain: (i) Vaccum efficiency (ii) Condenser efficiency. (b) The pressure under the air baffle of a surface condenser is 52 mm of Hg. Temperature of the mixture learing the cooler suction is 250C. assuming available water at 15.50C, and external water might lower the temperature further to 200C. Explain the effect of this on the quantity of vapour accompanying the air to the air pump suction. 7. In a gas turbine plant, the air at 100C and 1 bar is compressed to 4 bar with compression efficiency of 80%. The air is heated in the regenerator and the combustion chamber till its temperature is raised to 7000C, and during the process the pressure falls by 0.14 bar. The air then expanded in the turbine and passes to the regenerator which has 75% effectiveness, and causes a pressure drop of 0.14 bar. If the isentropic efficiency of the turbine is 85%. Determine the thermal efficiency of the plant. 8. A turbo-jet engine consumes air at the rate of 60.2 kg/s when flying at a speed of 1000 km/hr. Calculate: (i) Exit velocity of; the jet when the enthalpy change for the nozzle is 230 kj/kg and velocity co efficient is 0.96 (ii) Fuel flow rate in kg/sec when air fuel ratio is 70:1 (iii) Thrust specific fuel consumption (iv) propulsive power (v) Propulsive efficiency (vi) overall efficiency.

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Code :R7320306 2 III B.Tech II Semester(R07) Regular & Supplementary Examinations, April/May 2011

THERMAL ENGINEERING-II (Mechanical Engineering)




⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) Give the advantages and disadvantages of regenerative cycle over simple Rankine cycle. (b) The following data were recorded during an experiment to find the calorific value of a sample of coal: Mass of coal burnt 1 gm, mass of water in the calorimeter 1020 gm, water equivalent of the calorimeter 170 gm, initial temperature of water 23.30C, final temperature of water 26.20C. Determine the calorific value of the sample of the coal. 2. (a) Describe, in brief, the construction of a Locomotive boiler. What is the main disadvantage of the Locomotive boiler? (b) In a boiler test 1250 kg of coal are consumed in 24 hours. The mass of water evaporated is 13000 kg and the mean effective pressure is 7 bar. The feed water temperature was 400C, heating value of coal is 30000 kJ/kg. The enthalpy of 1 kg of steam at 7 bar is 2570.7 kJ. Determine: (i) Equivalent evaporation per kg of coal (ii) Efficiency of the boiler. 3. (a) Derive an expression for maximum discharge through convergent-divergent nozzle for steam. (b) Dry air at a temperature of 270C and pressure of 20 bar enters a nozzle and leaves at a pressure of 4 bar. Find the mass of air discharged, if the area of the nozzle is 200 mm2. 4. (a) Which type of turbine is used in most of steam turbine power plants? Why? (b) In a certain stage of an impulse turbine, the nozzle angle is 200 with the plane of the wheel. The mean diameter of the blade ring is 2.8 meters. It develops 55 kW at 2400 r.p.m. Four nozzles, each of 10 mm diameter expand steam isentropically from 15 bar and 2500C to 0.5 bar. The axial thrust is 3.5 N. Calculate: (i) blade angles at entrance and exit and (ii) Power lost in blade friction. 5. Derive the condition for maximum efficiency in a parson’s reaction turbine. 6. (a) What are the various methods for obtaining maximum vaccum in condensers? (b) The air leakage into the condenser operating in conjunction with a steam turbine is estimated at 0.681 kg/min. The vaccum near the outlet to the air pump is 710mm when barometer reads 760 mm of Hg and temperature at this point is 180C. Find: (i) The minimum capacity of air pump in m3/min. (ii) Mass of vapour extracted with the air per minute. 7. In a gas turbine plant, the pressure ratio through which air at 150C is compressed is 6. The same air is then heated to a maximum permissible temperature of 7500C first in a heat exchanger which is 75% efficient, and then in the combustion chamber. The same air at 7500C is expanded in two stages such that expansion work is maximum. The air is reheated to 7500C after the first stage. Determine the cycle thermal efficiency, the work ratio and shaft work per kg of air. The machine efficiencies may be assumed to be 80% and 85% for the compressor and turbine respectively. 8. For a jet propulsion explain (i) thrust (ii) thrust power (iii) Propulsive efficiency (iv) Thermal efficiency. ⋆ ⋆ ⋆ ⋆ ⋆

Code :R7320306 3

91






⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) Explain the modified Rankine cycle with p-V and T-s diagrams. (b) A bomb calorimeter is used to determine the calorific value of a sample of coal and the following results are obtained: Mass of coal burnt 1 g, mass of water in the calorimeter 2.5 kg, water equivalent of the apparatus 0.75 kg, initial temperature of water 17.50C, maximum observed temperature of water 200C, cooling correction +0.0150C. If the fuel contains 4% of hydrogen, find the lower calorific value of the fuel. 2. (a) Give the function of the following accessories in a boiler plant (i) Economizer (ii) Air pre-heater (iii) Feed pump (iv) Injector (v) Super heater (b) Calculate the draught in mm of water column produced by a chimney 30 m high when the average temperature of hot gases is 2250 C and the temperature of outside air is 200 C. The quantity of air supplied is 18 kg / kg of fuel. 3. Draw the ‘discharge’ versus ‘ratio of pressures at outlet to inlet’ curve for a convergent steam nozzle. Discuss the physical significance of critical pressure ratio. 4. (a) What is the effect of blade friction on turbine performance? (b) Steam issuing from a nozzle at 600 m/s enters the first set of blades of a two row wheel impulse turbine. The tips of both the set of moving blades are inclined at 300 to the plane of motion. Find the speed of the blades, so that the steam is finally discharged axially. Neglect friction. Also find the power developed by the turbine, if the mass of steam supplied to the turbine is 3 kg/s. 5. The following data refer to a particular stage of a parson’s reaction turbine: Speed of the turbine = 1500 R.P.M. mean diameter of the rotor = 1 metre; stage efficiency: 80%; Blade outlet angle = 200, Speed ratio = 0.7. Determine the available isentropic enthalpy drop in the stage. 6. (a) Explain the working principle of an evaporative condenser with a neat sketch. (b) A steam jet turbo-generator develops 100 KW using 13.6 Kg of steam per kwhr. The exhaust steam pressure is 0.14 bar and 680.4 Kg of cooling water are passed through the condenser per minute. The inlet and outlet temperatures are 15.60C and 32.20C respectively. Estimate the dryness fraction of exhaust steam. Temperature of the hotwell is 350C. 7. A gas turbine set draws in atmospheric air at 1.013 bar and 15.60C, there are two pressure stages with inter cooler, and the total pressure ratio is 8:1. The maximum temperature of the cycle is 5930C and there is one turbine for expansion. A regenerator is used and recovers 80% of the available heat. Determine the efficiency of the plant and the ratio of useful work to turbine work (i.e., work ratio). The turbine and compressor efficiencies may be taken as 0.86 and 0.83 respectively. 8. Derive the equation for thermal efficiency of a jet nozzle with the help of Brayton cycle for turbo jet engine. ⋆ ⋆ ⋆ ⋆ ⋆

Code :R7320306 4

92






1. (a) State the comparison between Rankine cycle and Carnot cycle. (b) A fuel has the following composition by mass: carbon 86%, hydrogen 11.75%, oxygen 2.25%. Calculate the theoretical air supply per kg of fuel, and the mass of products of combustion per kg of fuel. 2. (a) Establish a condition for maximum discharge of flue gases through chimney. (b) Explain briefly about equivalent evaporation of a boiler, induced and forced draught for a boiler. 3. (a) Explain superheated or metastable flow of steam through a nozzle and the significance of Wilson’s line. (b) The dry and saturated steam at a pressure of 5 bar is expanded isentropically in a nozzle to a pressure of 0.2 bar. Find the velocity of steam leaving the nozzle. 4. Sketch the velocity diagram of a single stage impulse turbine and determine the expressions for the force, work done, diagram efficiency, gross stage efficiency and axial thrust. 5. In a reaction turbine, the fixed blades and moving blades are of the same shape but reversed in direction. The angles of receiving tips are 350 and of the discharging tips 200. Find the power developed per pair of blades for a steam consumption of 2.5 kg/sec. when the blade speed is 50 m/sec. If the heat drop per pair is 10.04 kj/kg, find the efficiency of the pair. 6. (a) Explain down flow type of surface condenser with a neat sketch. (b) The surface condenser is designed to handle 16000 kg of steam per hour The steam enters the condenser at 0.09 bar absolute pressure and 0.88 dryness fraction and the condensate leaves the condenser at the corresponding saturation temperature. Determine the rise in cooling water temperature if the cooling water flow rate is 8.96 x 105 Kg/hour. Assume that pressure is constant throughout the condenser. 7. The following data refer to a gas turbine using inter cooling, regeneration, reheating arrangement: Pressure ratio = 4, compressor inlet temperature = 260C, Turbine inlet temperature = 6000C, compressor & Turbine efficiency = 0.8, regenerator effectiveness = 0.85; Inlet pressure to compressor = 1 bar. Determine (i) cycle thermal efficiency (ii) Cycle work ratio (iii) cycle air rate. 8. With the help of a neat diagram, explain the description, advantages, disadvantages of a Turbo-jet engine. ⋆ ⋆ ⋆ ⋆ ⋆

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