(DME 211) - Anucde · All questions carry equal ... the diameters of certain bolts against the alternative hypothesis that ... 6. 8Synthesize a four bar linkage using Freudenstein's

(DME 211)

B.Tech. DEGREE EXAMINATION, DECEMBER 2008.

(Examination at the end of Second Year First Semester)

Mechanical Engineering

Paper I — ENGINEERING MATHEMATICS — III

Time : Three hours Maximum : 75 marks

Answer Question No. 1 compulsory and ONE question from each Unit.

All questions carry equal marks.

1. (a) Write the formulae for Fourier constants for )(xf in the interval ]2,0[ .

(b) Find nb in the expansion of 2x as a Fourier series in ],[ .

(c) Write the half-range sine series for 1 in ),0( .

(d) Find the period of )2cos2(sin xx .

(e) Given

xx

xxxf

0for10for1)(

Is the function even or odd?

(f) State convolution theorem for Fourier transforms.

(g) Write the finite Fourier sine transform of xxf )( in ),0( l .

(h) Define finite Fourier cosine transform of )(xf .

(i) State the Fourier integral theorem.

(j) Find the Fourier cosine transform of xe .

(k) What is meant by confidence limit?

(l) Write two applications of normal distribution.

(m) Is the function defined as follows a density function?

.000)(

xxexf

x

(n) Find the probability that a random variable having the standard normal distribution will take on a value greater than 0.85.

(o) Write two properties of t-distribution.

UNIT I 2. (a) (i) Prove that in lx 0 .

lx

lx

lxllx

5cos

513cos

31cos4

2 222 .

(ii) Obtain the half range cosine series for xx sin in ),0( and show that

4

275

153

131

1

.

Or (b) (i) Find Fourier series of 2x in ),( . Use Parseval’s identity, prove that

44

4

31

211

90

(ii) Analyse harmonically the data given below and express y in Fourier series upto the second harmonic.

x 0 /3 2 /3 4 /3 5 /3 2 y 1 1.4 1.9 1.7 1.5 1.2 1.0

UNIT II 3. (a) (i) Using Fourier integral, show that

x

xdx

00when2/sincos1

0

(ii) Find the Fourier sine transform of x

e ax

.

Or (b) (i) Solve the integral equation

.2,021,210,1

sin)(0 t

tt

dxtxxF

(ii) Find the Fourier cosine transform of 2xe . UNIT III

4. (a) (i) If two random variables have the joint density

elsewhere,0

10,10),(56

),(22 yxyxyxf

find the probability that 5.02.0 X and 6.04.0 Y . (ii) In a test on 2000 electric bulbs, it was found that the life of a particular make was normally distributed with an average life of 2040 hrs and standard deviation of 60 hrs. Estimate the number of bulbs likely to burn for (1) more than 2150 hrs (2) less than 1950 hrs (3) more than 1920 hrs and less than 2160 hrs.

Or (b) (i) If the probability density of a random variable is given by

elsewhere0

10)(3 xKxxf

Find the value K and the probability that the random variable takes on a value. (1) between 1/4 and 3/4

(2) greater than 2/3. (ii) A random sample of size 100 is taken from an infinite population having the mean

76 and the variance 2562 . What is the probability that X will be between 75 and 78?

UNIT IV

5. (a) (i) Ten bearings made by a certain process have a mean diameter of 0.5060 cm with a standard deviation of 0.0040 cm. Assuming that the data may be looked upon as a random sample from a normal population, construct a 95% confidence interval for the actual average diameter of bearings made by this process. (ii) The means of simple samples of sizes 1000 and 2000 are 67.5 and 68.0 cm respectively. Can the samples be regarded as drawn from the same population of standard deviation 2.5 cm.

Or (b) (i) Use the 0.01 level of significance to test the null hypothesis that 015.0 inch for the diameters of certain bolts against the alternative hypothesis that 015.0 inch, given that a random sample of size 15 yielded 00011.02 s .

(ii) Tests performed with a random sample of 40 diesel engines produced by a large manufacturer show that they have a mean thermal efficiency of 31.4% with a standard deviation of 1.6%. At the 0.01 level of significance, test the null hypothesis %3.32 against the alternative hypothesis %3.32 .

————————— (DME 212)




Paper II — MECHANICS OF MATERIALS



Answer Question No. 1 compulsory.

Answer ONE question from each Unit.

1. (a) Define elasticity and plasticity.

(b) What is Poison's ratio?

(c) What is factor of safety?

(d) Give an expression for the strain energy of axially loaded member of contact area of cross section subjected to static load.

(e) When do you call a structure statically indeterminate?

(f) Give the relationship between E and G.

(g) What is Mohr's circle?

(h) Define shear force and Bending moment.

(i) Give the flexural formula.

(j) What is shear centre?

(k) What are the stereo developed in thin cylindrical pressure vessel?

(l) State the principle of virtual work.

(m) Name the various types of beams.

(n) What is an unit load method?

UNIT I

2. (a) Draw the stress-strain diagram for a ductile specimen subjected to tensile test. (6)

(b) A strait bar is made up of two sections. First section is of 20 mm diameter and 500 mm long. Second section is of 10 mm diameter and 400 mm long. If the bar is subjected to an axial pull of 20 kN. Find the extension. Take E = 2 105 N/mm2. (9)

Or

3. A weight of 300 kN is supported by three short pillars as shown in Fig. 1. The central pillar is made of steel having cross sectional area 675 mm2. Two outer pillars are of copper, each having cross-sectional with 675 mm2. The pillars are so adjusted that at a temperature of 20C, the load is shared equally by all the pillars. The temperatures in raised to 120C. Determine the strain induced at 20C and 120C. (15)

Fig. 1

UNIT II

4. A shaft is transmitting 100 kW at 100 r.p.m. If the maximum torque is 25% greater than the mean torque, determine the diameter of the shaft. Take the permissible shear stress in the material as 40 MPa. If the modular of rigidity of the material is 80 109 N/m2, find the angular twist for a length of 2 m. (15)

Or

5. In a two dimensional state of stress at a part, plane AB carries a tensile star of 40 MPa and a positive shear stress of 25 MPa, while another plane BC carries a tensile stress of 40 MPa and a negative shear stress of 25 MPa. If the planar are inclined at 60 to each other, find (a) the principle

stress and (b) maximum shear stress. (15)

UNIT III

6. For a beam the rate of loading is given by the expression 22xxw . Where x is length, when 0x the S.F is 5 units and B.M. is 10 units. Find S.F and B.M at 10x units. (15)

Or

7. Draw the shear force and bending moment diagram for the beam shown in Fig. 2. (15)

AB = 1 m; BC = 1 m; CD = 2 m DB = 1 m and EF = 1 m

Fig. 2

UNIT IV

8. A beam of rectangular cross section 100 mm 50 mm is 3 m long and is simply supported at the ends. If the bending stress is limited to 120 N/mm2, find the maximum value of uniformly distributed load the beam can take. (15)

Or

9. Locate the shear center for the channel section shown in Fig. 3. (15)

Fig. 3

——————— (DME 213)




Paper III — KINEMATICS OF MACHINES



Answer question No. 1 is compulsory. (1 15 = 15)

Answer ONE question from each Unit. (4 15 = 60)

1. (a) What is a Rigid body?

(b) Differentiate between Kinematic Chain and Mechanism.

(c) What is velocity of rubbing?

(d) Give the notation for instantaneous rotation.

(e) Where is the location for the instantaneous center of slider?

(f) What is the direction of centripetal acceleration of a point?

(g) What is a precision point?

(h) Give a sketch of a cam and off set follower.

(i) What is number synthesis?

(j) What is a prime circle?

(k) State the law of gearing.

(l) What is an involute?

(m) Give a sketch of any bicycle gear train.

(n) What are the torques in Epicyclic gear trains?

UNIT I

2. (a) What is a machine? Differentiate between a machine and a structure.

(b) What do you mean by an equivalent mechanism? And explain by means of an example.

Or

3. For the mechanism shown in Fig. 1, the angular velocity of the Crank OA is 600 r.p.m. Determine the linear velocity of slides D, when the Crank is inclined at an angle of 75 to the vertical. The dimension of various links are : OA = 28 mm; B = 44 mm; BC = 49 mm; BD = 46 mm; OC = 65 mm. The path of travel of the slides is 11 mm below the fixed point C. The slides moves along a horizontal path and OC is vertical.

Fig. 1

UNIT II

4. Solve the problem-3 by the instantaneous cabt method.

Or

5. In the crank and slotted lever mechanism shown in Fig. 2, the crank rotates counter clockwise with uniform angular velocity. For the configuration shown if the velocity of the ram D is 2 m/s to the left, find the acceleration of ram D and the angular acceleration of slotted lever

Crank AB = 150 mm; Slotted arm OC = 700 mm and the link CD = 200 mm.

Fig. 2

UNIT III

6. Synthesize a four bar linkage using Freudenstein's equation to generate the function 8.1xy for the interval 51 x . The input crank is to start from 305 and is to have a range of 90. The output link is to start at 0s and is to have a range of 90. Take three accuracy point at

3,1x and 5 . Or

7. A cam drives a flat faced reciprocating follower in the following manner :

During first 120 of cam rotation, follower moves outwards through a distance of 20 mm with S.H.M. The follower dwells during next 30 of cam rotation. During next 1200 of cam rotation, the follower moves inwards with S.H.M. The follower dwells for the next 90 of cam rotation.

The minimum radius of the cam is 25 mm. Draw the profile of the cam.

UNIT IV

8. Two involute gear of 20 pressure angle are in mesh. The number of teeth on pinion is 20 and the gear ratio is 2. If the pitch expressed in module is 5 mm and the pitch line speed is 1.2 m/s, assuming addendum as standard and equal to one module, find :

(a) The angle turned through by pinion where one pair of teeth is the mesh; and

(b) The maximum velocity of sliding. Or

9. An epicyclic gear train consists of three gear A, B and C as shown in Fig. 3. The gear A has 72 interval teeth and gear C has 32 external teeth. The gear B meshes with both A and C and is carried on an arm EF which rotation about the centre of A at 18 r.p.m. If the gear A is fixed, determine the speed of gear B and C.

Fig. 3

———————— (DME 214)




Paper IV — FLUID MECHANICS


Answer Q. No. 1 compulsory and any FOUR questions.

1. (a) Two soap bubbles have diameters d and 2d. In which bubble, the internal pressure is higher? (2)

(b) When is a floating body said to be in stable equilibrium? (3)

(c) List the common features of stream and velocity potential functions. (2)

(d) Define Meta centre and Meta centric height. (2)

(e) What is laminar sub layer? (2)

(f) What do you mean by water hammer? (2)

(g) At critical pressure ratio, is the velocity at the throat of a nozzle, equal to the sonic speed or different? (2)

2. (a) What is a fluid? How are fluids classified? What are the various properties of fluids? What is the difference between an ideal and real fluid? (7)

(b) What do you mean by surface tension? If the pressure difference between the inside and outside of tile air bubble of diameter 0.01 mm is 29.2 kPa, what will be the surface tension at air - water interface? (8)

3. (a) What is Pascal’s law? How are manometers classified? Explain through a neat sketch a differential manometer. What are the advantages and limitations of the manometer? (7)

(b) A U-tube manometer is used to measure the pressure of oil of specific gravity 0.85 flowing in a pipe line. Its left end is connected to the pipe and the right limb open to the atmosphere. The centre of the pipe is 100 mm below the level of mercury (specific gravity = 13.6) in the right limb. If the difference of mercury level in the two limbs is 160 mm, determine the absolute pressure of the oil in the pipe. (8)

4. (a) Distinguish between path lines, stream lines and streak lines. (3)

(b) Derive the continuity equation in Cartesian coordinates. (5)

(c) Does the velocity potential axis for two dimensional incompressible flow prescribed by )4(;4 xyvyxu ? If so, determine its form as well as that of stream function.

(7)

5. (a) What are the deterrent energies of a fluid? Explain each of them. (3)

(b) Derive the Euler’s equation of motion. (5)

(c) A 200rnm X 100mm venture meter is provided in a vertical pipe carryingwater, flowing in the upward direction. A differential mercury manometer connected to the inlet and throat gives a reading of 220mm. Find the rate of flow. Assume Cd = 0.98. (7)

6. (a) What is an impulse-momentum equation? Derive the equation from the first principles. (7)

(b) Water is flowing through a pipe of diameter 300mm at a rate of flow of 250 liters/s. If the pipe is bent by 135º, find the magnitude and direction of the resultant force on the bend. The pressure of the water flowing is 40kN/m2. Take the sp.wt. of water as 981kN/m3. (8)

7. (a) Differentiate between a laminar flow and a turbulent flow. (3)

(b) Derive the Darcy Weisbach equation or head loss due to flow in a pipe in terms of friction factor ‘f’. (6)

(c) Derive an expression for the power transmission through the pipes. Find also the condition for maximum transmission of power and corresponding efficiency of transmission. (6)

8. (a) Explain the growth of boundary layer on a flat plate and discuss the salient features laminar and turbulent boundary layers. (7)

(b) The velocity distribution in a turbulent boundary layer is given by 7/1// yUu . Determine the displacement and momentum thickness of the boundary layer. (8)

9. (a) Define drag force and lift force of an object immersed in a fluid. (4)

(b) Distinguish between the friction drag and pressure drag. (4)

(c) What is Mach number? Prove that the velocity of sound wave in a compressible fluid is given by /KC , where K and p are the bulk modulus and density of Fluid respectively. (7)

——————— (DME 215)

B.Tech. DEGREE EXAMINATION, DECEMBER 2008. (Examination at the end of Second Year First Semester)

Mechanical Engineering Paper V — BASIC THERMODYNAMICS


Answer Q. No. 1 compulsorily. (1 15 = 15)



1. (a) What is meant by property?

(b) Explain the term path function.

(c) Define the term enthalpy.

(d) List out the specific heats for gas.

(e) What is reversible adiabatic process?

(f) Explain thermodynamic temperature scale.

(g) Define compression ratio in I.C. engine.

(h) Give an expression for pressure ratio as a function of limiting temperature ratio.

(i) What is thermodynamic equilibrium? (j) What is an Open system?

(k) What is the significance of using steam tables?

(l) What are T-ds relations?

(m) Why Carnot cycle is ideal cycle?

(n) Define the term dryness fraction.

(o) What is superheated steam?

UNIT I

2. (a) Derive the equation for work done during quasi static process.

(b) Fahrenheit and Centigrade thermometers are both immersed in fluid. Fahrenheit reading is numerically twice that of centigrade reading. What is temperature of the fluid expressed as ºR and K?

Or

3. (a) How are thermodynamic systems classified? Explain.

(b) The properties of a closed system charge following the relation between pressure and volume as PV = 3.0 where P is in bar, V is in m3. Calculate the workdone when the pressure increases from 1.5 bar to 7.5 bar.

UNIT II

4. (a) State First Law of Thermodynamics. Explain the concept of mechanical equivalent of heat.

(b) 0.45 kg of air at 179ºC expands adiabatically and reversibly to three times its original volume and during the process, there is a fall in temperature to 15.5ºC. The work done during the process is 53 kJ. Calculate CP and CV.

Or

5. (a) Applying the steady flow energy equation, derive the equation for velocity for a nozzle.

(b) A steam turbine receives steam at the rate of 22,700 kg/hr when it is delivering 500 kW power. The inlet and outlet velocities of steam are 75 m/s and 300 m/s respectively. The inlet pipe is 3m above the exhaust pipe. Neglecting the heat loss from the turbine, find the change in enthalpy per kg of steam.

UNIT III

6. (a) State and explain Kelvin-Plank statement of second law of thermodynamics.

(b) Derive the equation for change of entropy in isothermal process.

Or

7. (a) Discuss the availability in non-flow systems. Derive maximum work. (b) The overall volume expansion ratio of a Carnot cycle is 15. The cycle works between the temperature limit of 300ºC and 20ºC. Determine (i) the volume ratios of the isothermal and adiabatic process and (ii) the thermal efficiency of the cycle. The working fluid is air and 4.1(air) r

UNIT IV

8. (a) Derive air standard efficiency of a Diesel Cycle. (b) Describe the process involved in a Dual Cycle.

Or

9. (a) Explain the important terms relating to steam formation. (b) Steam enters an engine at a pressure of 12 bar with a 67ºC of superheat. It is exhausted at a pressure of 0.15 bar and 0.95 dry. Find the drop in enthalpy of steam.

————————— (DME 216)




Paper VI — MATERIAL SCIENCE AND METALLURGY


Answer question 1 compulsorily.


1. Write briefly on the following :

(a) Slip.

(b) Point defects.

(c) Screw dislocation.

(d) Miller indices.

(e) Normalizing.

(f) Toughness.

(g) Compacting.

(h) Piezo electricity.

(i) C-C composites.

(j) Sandwich structure.

(k) Hard magnetic meterials

(l) Self lubricated bearing

(m) BCC structure

(n) Planar density.

UNIT I 2. (a) What are various types of defects found in metals? Discuss planar defects. How these defects affect the properties of materials.

(b) Show in a diagram the (110) plane of a cubic lattice. Calculate their interplanar distance.

Or

3. (a) Describe the allotropic transformations in iron and explain their importance in practical applications.

(b) Explain ‘‘Zone refining’’.

UNIT II

4. (a) Explain briefly the process of steel making in an electric arc furnace and list out the advantages of electric process.

(b) Define Carburising. Describe the various carburising process.

Or

5. (a) Explain bainitic transformation.

(b) What is meant by hardenability? Describe how it is estimated experimentally.

UNIT III

6. (a) Explain viscoelastic behaviour of materials.

(b) How laminate composite are classified. Explain them.

Or

7. (a) Describe the following mechanisms.

(i) Solid solution strengthening

(ii) Dispersion strengthening.

(b) What do you mean by grain refinement?

UNIT IV

8. (a) Give approximate composition, properties and uses of the following :

(i) High speed tool steel

(ii) Gun metal.

(b) Enumerate advantages, disadvantages and limitations of powder metallurgy.

Or

9. (a) Write short notes on :

(i) magnetic susceptibility

(ii) dielectric constant.

(b) Explain :

(i) piezo electricity

(ii) ferroelectricity.

———————

(DME 217)




Paper VII — MACHINE DRAWING



Use first angle projection.

UNIT I

1. Fig. 1 shows a shaft support, for which draw the following :

(a) Sectional front view (in the direction of arrow).

(b) Half sectional view from the right.

(c) Top view.

Fig. 1 Shaft support

Or

2. (a) Sketch the following and mention the proportion dimensions :

(i) Hexagonal bolted joint

(ii) While's lock nut (b) Draw the following : (i) Schematic representation of Acme and Trapezoidal threads. (ii) Double start M 40 X 10 thread.

UNIT II 3. Draw the two views of protected flange coupling assembly.

Or 4. Sketch the required views showing all details of cotter joint for connecting 25 mm diameter shafts.

UNIT III 5. Assemble the parts of the Drill jig shown in Fig.2 and draw : (a) Sectional front view and (b) Top view.

Fig. 2 Drill Jig

Or

6. Draw at least two views of each component of a split sheave eccentric shown in Fig.3.

Fig. 3 Split sheave eccentric

——————— (DME 221)

B.Tech.> DEGREE EXAMINATION, DECEMBER 2008.

(Examination at the end of Second year Second Semester)


Paper I — ENGINEERING MATHEMATICS – IV


Answer Question No. 1 Compulsorily.

Parts List Part No. Name Material Qty. Part No. Name Material Qty. 1. Sheave piece CS 1 7. Strap Cl 1 2. Sheave piece CS 1 8 Shim Brass 2 3. Bolt M 30 135 MS 2 9 Bolt M 30 250 MS 2 4. Nut M 30 MS 6 10 Lock nut M 30 MS 2 5. Split pin 6 50 MS 6 11 Stud M 30 MS 2

6. Strap C1 1 12 Washer MS 2



1. (a) Write the two dimensional heal flow equation in steady state.

(b) Write the Laplace’s equation in polar co-ordinates.

(c) Write the necessary and sufficient conditions for the functions ivuzf to be analytic.

(d) Evaluate dzzz

c

352

, where 4: zc .

(e) Define radius of convergence.

(f) Define residue of zf at z = a.

(g) Define conformal mapping.

(h) State Residue theorem.

UNIT I

2. A tightly stretched string with fixed end points 0x and lx is initially is a position given by

lxyy sin0 . If it is released from rest from this position, find the displacement txy ,

Or

3. Solve 02

2

2

2

yu

xu which statistics the conditions 00,,,0 xuyluyu and

lnxaxu sin, .

UNIT II

4. (a) Determine the analytic functions zf such that 22 343Re yyxzf and 0 ilf .

(b) If zf is analytic, then show that

222

ffy

fx

.

Or

5. (a) Evaluate c

dtzf where

0,10,4

yyy

zfwhenwhen and c is the arc from iz 1 to iz 1

of the cubical curve 3xy .

(b) Evaluate dzzz

zz

c

24

23

442 , where c is the circle 42 z , clock wise.

UNIT III

6. Find all possible Laurent series of zz

zztf9

18973

2

about its singular points.

Or

7. Evaluate

dx

xa 222

1 .

UNIT IV

8. (a) Show that under the transformation z

w 1 , circle 0622 xyx is transformed into a

straight line in the w-plane.

(b) Find the graph of the Strip 21 x under the mapping z

w 1 .

Or

9. Discuss the bilinear transformation. Find the bilinear transformation which maps the points 1,,1 iiz onto the points iw , 0, –i¸ Hence find

(a) the einage of 111 z and

(b) the invariant points of this transformation.

——————— (DME 222)


(Examination at the end of Second Year Second Semester)


Paper II — ADVANCED MECHANICS OF MATERIALS


Answer Question No. 1 compulsorily. (1 15 = 15)


1. Write briefly on the following :

(a) Give the differential equation for the elastic curve of a beam.

(b) State the Mohr's First Moment – Area theorem.

(c) What is Macaulay's method ?

(d) Define Slenderness ratio.

(e) What is the equivalent length of one end fixed and other end hinged column?

(f) What is Rankine's formula?

(g) What are statically indeterminate beams?

(h) State the Clapeyron's theorem of three moments.

(i) Give the Lame's equations for thick cylinder.

(j) What is a compound cylinder?

(k) In general what is the cross-section of a crane hook.

(l) What is the nature of stress at the inside and outside of a crane hook?

(m) What is the hoop stress induced in a Rotating ring?

(n) What is the maximum hoop stress developed in a rotating disc with a small hole at its axis of rotation?

(o) Give the secant formula used for columns.

UNIT I

2. (a) Derive the differential equation of the deflection curve of a beam.

(b) A straight length a steel bar, 1.5 m long and 20 5 mm section is compressed longitudinally. Assuming Euler's formula to apply to this case, estimate the maximum central deflection before the steel passes the yield point at 320 MPa. Take GPa210E .

Or

3. (a) A tubular steel strut is 65 mm external diameter and 50 mm internal diameter. It is 2.5 m long and has hinged ends. The load is parallel to the axis but eccentric. Find the maximum eccentricity for a cripling load of 0.75 of the Euler value, the yield stress being 320 MPa and GPa210E .

(b) Find the deflection at the free end and mid length of a contilever beam carrying a concentrated load at the free end.

UNIT II

4. A beam AB of uniform section and 6 m span is built-in at the ends. A uniformly distributed load of 3 kN/m runs over the left half of the span, and there is in addition a concentrated load of 4 kN at 1.5 m from the right end.

Determine the fixing moments at the ends, and reaction. Sketch neatly the bending moment and shearing force diagrams marking salient values.

Or

5. A beam ABCD 9 m long is simply supported at A, B and C such that the span AB is 3 m, span BC is 4.5 m and the overhang CD is 1.5 m. It carries a uniformly distributed load of 1.5 kN/m in span AB and a point load or 1 kN at the free end D. The moment of inertia of the beam in span AB is I and that in the span BC is 2I. Find the reactions at the supports.

UNIT III

6. A steel tube 240 mm external diameter is to be shrunk on another steel tube of 80 mm internal diameter. After shrinking, the diameter at the junction is 160 mm. Before shrinking on, the difference of diameters at the junction was 0.08 mm.

Calculate the radial pressure at the junction and hoop stresses developed in the two tubes after shrinking on Take E as 200 kN/mm2.

Or

7. The section of a crane hook is a rectangle 60 mm 40 mm. The centre of curvature of the section is at a distance of 80 mm from the cartroid of the section. A load of 15 kN is acting through the centre of curvature. Determine the maximum and minimum bending stresses induced in the hook.

UNIT IV

8. (a) Derive the expression for the thickness of a rotating disc of uniform strength.

(b) A steam turbine rotor is 150 mm diameter below the blade ring and 20 mm thick. The turbine is running at 36000 rpm. The allowable stress is 150 MPa. What is the thickness of the rotor at a radius of 50 mm, and at the centre. Assume uniform strength and take density of material = 7800 kg/m3.

Or

9. (a) The thin rim of a wheel is 900 mm diameter neglecting the effect of spokes, how many revolutions per minute may it make with out the hoop stress exceeding 140 MPa. The density is 7800 kg/m3 and E = 200 GPa. Also find the cange in diameter.

(b) A disc of 500 mm diameter and uniform thickness is rotating at 2400 r.p.m. Determine the maximum stresses induced in the disc.

If a hole of 100 mm diameter is drilled at the centre of the disc determine the maximum intensities of radial and hoop stresses induced. Take 28.0 , density of the disc 7800 kg/m3.

——————— (DME 223)


(Examination at the end of Second Year Second Semester)


Paper III — ELECTRICAL TECHNOLOGY



Answer question No. 1 compulsorily. (1 15 = 15)


1. (a) Define ‘RMS-value’.

(b) What is difference between 3-phase, Balanced circuit and unbalanced circuit?

(c) Define ‘Armature reaction’ in d.c. generators.

(d) Write the expression for EMF generated in a d.c. generator.

(e) Write the expression for Torque developed in a d.c. motor.

(f) Name main components of a 3-point starter.

(g) Define ‘Regulation’ in a Transformer.

(h) To predict the Regulation of a Transformer, which test is to be conducted experimentally? Name the test.

(i) What is the function of a over load relay in a starter?

(j) What is ‘Slip Speed’ in an Induction rotor?

(k) What is ‘synchronous speed’?

(l) Name types of single-phase Induction motors.

(m) Name different methods of providing ‘Damping’. Torque in measuring Instruments.

(n) State the expression for ‘deflection torque’ in a marginal measuring instrument (permanent report type?

(o) Name the advantages of Induction heating.

UNIT I

2. (a) A circuit with a resistor and capacitor connected in series, is given with a 200 volts a.c. supply. When the frequency is 45 Hz, the current is 8 Amps. and when the frequency is 50 Hz, the current in the circuit is 10 Amps. Find the values of resistance and capacitance in the circuit.

(b) In a 220 volts compound generator, the resistances of the armature, shunt and series windings are 0.6 ohm, 250 ohms and 0.4 ohms respectively. The load consists of 200 Amps each rated 55 watts, 220 volts. Find the total electromotive force and armature current when the generator is connected (i) long shunt and (ii) short shunt. Ignore brush drop.

Or

3. (a) Three inductive coils each with a resistance of 15 ohms and an inductance of 0.03 Henry are connected in Delta and given with a 3-phase , 440 volts, 50 Hz supply. Calculate (i) phase currents, (ii) line currents and (iii) total power absorbed.

(b) The armature of a 6-pole D.C. shunt motor has a lap winding accommodated in 60 slots, each containing 40 conductors. If the useful flux per pole is 25 mlli webers. calculate the total torque developed Newton-meters, when the armature current is 60 Ampers.

UNIT II

4. (a) A 230 volts, D.C. shunt motor running on no load at normal speed, takes an armature current of 2.5 Amps. from 230 volts mains. The field circuit resistance is 230 ohms and armature resistance is 0.3 ohms. Calculate the motor output and the efficiency when the total current taken from the supply is 35 Amps.

(b) Explain the operation of single-phase transformer on no-load and load by means of phasor diagram.

Or

5. (a) A 400 volts, D.C. shunt motor takes 5 Amps. no- load input current. The armature and field resistances are 0.5 ohms and 200 ohms respectively. Find the efficiency of the motor when running on full-load and taking a current of 50 Amps.

(b) The O.C. and S.C tests on a 5 KVA, 230/110 volts, single-phase Transformer gave the following data :

O.C. Test (H.V. side) : 230 V, 0.6 A, 80 W.

S.C. Test (L.V. side) : 6 V, 15 A, 20 W.

Calculate the efficiency and regulation at full load and 0.8 p.f. lagging.

UNIT III

6. (a) Derive the expression for E.M.F. induced in a synchronous generator.

(b) An 8 pole, 50 Hz, 3-phase induction motor has a full load slip of 2 percent and a maximum torque of twice the full load torque. At what value of speed does maximum torque occurs?

Or

7. (a) Explain the working of shaded-pole type single-phase induction motor. Draw relevant sketches.

(b) R 3-phase induction motor with a star connected rotor has an induced emf of 100 volts between the slippings at stand still when the stator is fed from a supply of 400 volts. The resistance and stand still reactance of the rotor are 0.5 ohm and 2.5 ohm. per phase respectively. Calculate the current in each phase of the rotor circuit (i) When starting with an external resistance of 2 ohms per phase and (ii) When running with slip rings short circuited and with a slip of 2%.

UNIT IV

8. (a) Explain with relevant figures, construction and working of Moving Iron measuring instrument. Derive its expression for deflection torque.

(b) With neat figures, explain the construction and working of Core-Type Induction Furance.

Or

9. (a) Draw the relevant sketches and explain how a dynamometer type meter can be used as an ammeter, a volt meter and a wattmeter.

(b) A train has a schedule speed of 60 Km. per hour between the stops which are 6 Km. a part. Determine the crest speed over the run, assuming Km (i) duration of stops as 90 seconds, (ii) acceleration as 2 Km. per hr. per sec. and (iii) retardation as 4 Km. per hr. per sec. (iv) simplified trapezoidal speed - time curve.

———————— (DME 224)

B.Tech. DEGREE EXAMINATION, DECEMBER 2008. (Examination at the end of Second Year Second Semester)

Mechanical Engineering Paper IV — COMPUTER BASED NUMERICAL METHODS


Answer Question No. 1 compulsory. Answer ONE question from each Unit.

All questions carry equal marks. 1. (a) What are the various methods to reduce ‘‘round-off’’ and ‘‘truncation errors’’ in numerical calculations? (b) What is the geometrical significance of Newton-Raphson method? (c) Which formula is more useful for interpolation near the end of the tabular values? (d) What is inverse interpolation? (e) State the Trapezoidal rule. What is the error of approximation from this method? (f) How do you differentiate an initial value problem from a boundary value problem? Name some numerical methods of solve such problems. (g) What is an ill posed problem with reference to partial differential equations?

UNIT I

2. (a) Determine the two smallest roots of the equation 0cossin xxx by Newton-Raphson method.

Or

(b) Solve the following system of equations using Gauss-Seidel procedures :

.3

6323

zyxzyxzyx

UNIT II

3. (a) From the following table of values, determine )23.0(f and )27.0(f using Newton's forward and backward formulae.

x : 0.2 0.22 0.24 0.26 0.28 0.30 )(xf : 1.6596 1.6698 1.6804 1.6912 1.7024 1.7139

Or

(b) (i) Explain the problem of inverse interpolation and describe the connection between inverse interpolation and the solution of equations. (ii) If 19,12,4 431 yyy and 7xy , find x.

UNIT III

4. (a) Evaluate dxx13

1 by Simpson's rule with 8 strips. Determine the error by direct

integration.

Or (b) Calculate the first and second derivatives of the function (tabulated below) at the point

2.2x and also dxdy at 0.2x .

x : 1.0 1.2 1.4 1.6 1.8 2.0 2.2 y : 2.7183 3.3201 4.0552 4.9530 6.0496 7.3891 9.0250

UNIT IV

5. (a) (i) Explain Euler method with its error estimation.

(ii) Given xydxdy

1 and 0.1)0( y , obtain the Taylor series for )(xy and compute

)1.0(y correct to four decimal places.

Or

(b) Evaluate 1.0,1,0,2

3 00 hyxyxdxdy find )1(y , using Runge-Kutta fourth order

method.

——————— (DME 225)


Examination at the end of Second Year Second Semester


Paper V — APPLIED THERMODYNAMICS


1. Write short notes on the following :

(a) Regenerative cycle

(b) Diagram of safety valve

(c) Explain importance of inter cooler

(d) Need for refrigeration

(e) Why is excessive moisture in steam is not desirable in steam engines?

(f) What is mixed pressure turbine?

(g) Capacity of air extraction pump. (3)

UNIT I

2. (a) Discuss factors limiting thermal efficiency of a steam turbine.

(b) Draw a neat sketch and describe working of Cochvour boiler.

Or

3. (a) Describe with a neat sketch of a steam seperator.

(b) A steam turbine plant operates an Rankine cycle with steam entering turbine at 48 bar, 350 C and leaving at 0.05 bar. Steam leaving turbine condenses to saturated liquid inside condenser. Feed pump pumps saturated liquid into boiler. Determine the net work per kg of steam and cycle efficiency with an assumption that all cycles are ideal. Also determine pump work per kg of steam.

UNIT II

4. (a) Define volumetric efficiency of a compressor. Explain why it is less than unity. (b) A compressor compresses air from 1 bar to 7 bar. The clearance volume is 2.13 litres and compression and expansion are polytropic processes with n = 1.3. Find the volumetric efficiency

Or

5. (a) Enumerate the advantages and disadvantages of jet and surface condensers. (b) State briefly the sources and effect of air leakage into a condenser. Discuss the effect of vacuum on the performance of the steam condensers.

UNIT III

6. (a) Explain frictional effection on nozzle performance. (b) A convergent-divergent nozzle is to pass 400 kg per hour. Initially the steam is 0.97 dry at 21 ks ca and the back pressure is 0.7 ksca. Determine the required areas of throat and outlet. Assume the friction loss in the divergent portion to be 18% of total heat drop.

Or

7. (a) Discuss companding of steam turbines. (b) A single stage impulse turbine rotor has a diameter of 1.2 m running at 3000 rpm. The nozzle angle is 18. Blade speed ratio is 0.42. The ratio of relative velocity at outlet to relative velocity at inlet is 0.9. The outlet angle of the blade is 3 smaller than the inlet angle. The steam flow rate is 5 kg/s. Draw the velocity diagram and find out the following : (i) Velocity of whirl (ii) Axial thrust on the end bearing (iii) Blade angles and (iv) HP developed.

UNIT IV

8. (a) Explain Bell-Coleman cycle. Derive COP for the cycle. (b) Explain vapour compression refrigeration with a neat diagram.

Or

9. (a) Explain different psychometric processes. (b) Air flowing at 100 kg/min and a dry bulb temperature of 32 C and wet bulb temperature of 20 C mixes adiabatically with another stream of air flowing at 150 kg/min and at dry bulb temperature of 20 C and relative humidity of 50%. Determine with the help of charts, the humidity ratio and enthalpy of the two streams mixed together to form a third stream in a steady flow process.

————— (DME 226)


(Examination at the end of Second Year 2nd Semester)


Paper VI — CASTING, FORMING AND WELDING TECHNOLOGY


Answer Q. No. 1 compulsorily.



1. (a) Cores (b) Split patterns (c) Runner and Risers (d) Shell moulding (e) Testing methods for forging (f) Welding defects (g) Brazing operation (h) Honing (i) Coining

(j) Merits of electro-slap welding (k) High energy forming methods

(l) Battern allowances.

(m) Neat sketch of cupola

(n) CO2 process.

UNIT I

2. (a) Explain different testing methods of moulding sands.

(b) Briefly explain defects in castings due to improper moulding and explain remedial action. Or

3. (a) Explain different tools and equipment used in moulds.

(b) Explain different binders used in sand casting. Enumerate their relative merits.

UNIT II

4. (a) Explain gravity die casting with neat sketch. (b) What is meant by CO2 process? Discuss in detail.

Or

5. (a) What are the causes for casting defects? Give remedial measures to reduce them.

(b) What do you mean by fettling of castings? Explain.

UNIT III

6. (a) How is an electrode specified? What factors govern the selection of electrode?

(b) Describe the process of submerged arc welding stating its advantages and limitations.

Or

7. (a) Compare plasma arc welding and TIG welding.

(b) Enumerate various welding defects and explain how these can be avoided.

UNIT IV

8. (a) Explain the differences between punching, blanking and piercing.

(b) Using neat sketches, explain cold rolling and cold extrusion.

Or

9. (a) Discuss the methods used for production of pipes and tubes.

(b) Derive an expression of extrusion force of a ferrous material.

—————————

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