Hydraulic Machinery and Systems Jntu Model Paper Www Student Yogi Com 100113195214 Phpapp01

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Set No. 1Code No: R05310302

III B.Tech I Semester Regular Examinations, November 2007

HYDRAULIC MACHINERY AND SYSTEMS

( Common to Mechanical Engineering and Automobile Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

1. A jet of water coming out of nozzle at a velocity of 35m/sec strikes a series of vanes

without shock which are moving with a velocity of 10m/sec. The direction of jet is

200 to the motion of vanes. The relative velocity of jet at outlet is 0.9 times relative

velocity at inlet. The absolute velocity of jet at outlet is normal to the motion of vanes. Find

(a) the inlet and exit vane angles,

(b) work done

(c) E ciency of the system. [16]

2. A water tube has a velocity of 4m/sec at the entrance to the draft tube and a

velocity of 1.2m/sec at the exit. For Friction losses of 0.1m and a tail water 5m

below the entrance to the draft tube, nd the pressure head at the entrance. [16]

3. (a) What is meant by cavitation? What is Thomas cavitation factor and what isits signi cance for water turbines.

(b) Explain Iso-e ciency curves. [8+8]

4. (a) Why is the speed of a reciprocating pump lower than that of a centrifugal

pump? On what factors do es the speed of the recipro cating pump depend?

(b) Explain how the separation of ow is caused in reciprocating pumps. What

preventive measures are usually taken to reduce the same appreciably? [8+8]

5. (a) How will you obtain an expression for the minimum speed for starting a cen-

trifugal pump?(b) The internal and external diameter of the impeller of a centrifugal pump are

200 mm and 400 mm respectively. The pump is running at 1200 r.p.m. the

vane angles of the impeller at inlet and outlet are 20o and 30o respectively. The

water enters the impeller radially and velocity of ow is constant. Determine

the work done by the impeller per unit weight of water. [6+10]

6. (a) What do you understand by characteristic curves of a pump? What is the

signi cance of the characteristic curves.

(b) Find the number of pumps required to take water from a deep well under a

total head of 89 m. All the pumps are identical and are running at 800 r.p.m.

the speci c speed of each pump is given as 25 while the rated capacity of eachpump is 0.16 m3 . [8+8]





7. The diameter of ram of a jigger of the crane is 30 cm and velocity ratio of the crane

is 5 : 1. the length of supply pipe from accumulator = 150 m and its diameter is5 cm. the pressure in the accumulator = 54 bar. Friction on ram and pulley is

equivalent to a pressure of 4.9 bar. Take f = 0.01. Find the relation between the

load W (kN) lifted and speed of lifting V (m/s). Find V when W = 50 kN. [16]

8. (a) A pipe of diameter 300 mm and length 3500 m is used for the transmission of

power by water. The total head at the inlet of the pipe is 500 m. Find the

maximum power available at the outlet of the pipe, if the value of f=0.006.

(b) A nozzle is tted at the end of a pipe of length 300 m and of diameter

100 mm. For the maximum transmission of power through the nozzle, nd

the diameter of nozzle. Take f = 0.009.[8+8]











1. (a) Find an expression for the e ciency of a series of moving curved vanes when

a jet of water strikes the vanes at one of its tips.

(b) A jet of water of diameter 65 mm moving with a velo city of 30m/s, strikes a

curved xed plate tangentially at one end at an angle of 300 to the horizontal.

The jet leaves the plate at an angle of 180 to the horizontal. Find the force

exerted by the jet on the plate in the horizontal and vertical directions. [8+8]

2. An inward ow reaction turbine has outer and inner diameters of the wheel as 1 m

and 0.5 m respectively. The vanes are radial at inlet and the discharge is radial.

Water enters the vanes at an angle of 100. Assuming the velocity of ow as 3 m/s

and constant, nd the speed of the wheel and the vane angle at outlet. [16]

3. De ne cavitation. What factors a ect occurrence of cavitation in turbines. What

measures are to be taken to prevent it? If cavitation were to occur, at what locations

the cavitation damage is likely to take place. [16]

4. Derive expressions for the accelerations and friction head impressed on the water in

the suction and delivery pipes. Sketch indicator diagram and determine the work

done per stroke of the pump. [16]

5. (a) What do you mean by manometric e ciency, mechanical e ciency and overall

e ciency of a centrifugal pump.

(b) A centrifugal pump is to discharge 0.118 m3/s at a speed of 1450 r.p.m against

a head of 25 m. The impeller diameter is 250 mm, its width at outlet is 50

mm and manometric e ciency is 75%. Determine the vane angles at the outer

periphery of the impeller. [8+8]

6. (a) What is cavitation? State its e ect on the performance of water turbines and

also state how to prevent cavitation in water turbines.

(b) Find the rise in pressure in the impeller of a centrifugal pump through which

water is owing at the rate of 0.01 m3 . The internal and external diameterof the impeller are 15 cm and 30 cm respectively. The widths of the impeller

at inlet and outlet are 1.2 cm and 0.6 cm. The pump is running at 1500

r.p.m. The water enters the impeller radially at inlet and impeller vane angleat outlet is 45o. Neglect losses through the impeller. [6+10]

7. (a) A hydraulic lift is required to lift a load of 98.1kN through a height of 12 m,

once in every 100 seconds. The speed of the lift is 600 mm/s. Determine:





i. power required to drive the lift,

ii. working period of lift in seconds, and

iii. idle period of the lift in seconds.

(b) What is hydraulic intensi er? Explain its principle and working. [10+6]






the diameter of nozzle. Take f = 0.009. [8+8]











1. 5 cm diameter jet having a velocity of 20m/sec, strikes a at plate, the normal of

which is inclined at 250 to the axis of the jet. Calculate the normal force exerted

on the plate

(a) When the plate is stationary

(b) When the plate is moving with a velocity of 10m/sec in the direction of the

jet.

(c) When the plate is moving with a velocity of 7m/sec parallel to itself and in

the direction of the normal to its surface. [4+6+6]

2. Obtain an expression for the work done per second by water on the runner of a

Pelton wheel. Hence derive an expression for maximum e ciency of the Pelton

wheel giving the relationship between the jet speed and the bucket speed. [16]

3. (a) De ne Suction Speci c Speed. Explain the pro cedure for the selection of typeof turbine runner.

(b) List out di erent types of surge tanks and explain any two along with neat

sketches. [8+8]

4. A double acting reciprocating pump has a stroke of 250mm and plunger diameter

125 mm. The center of the pump is 4 m above the lower sump water level and 30

m below the delivery water. The lengths of suction and delivery pipes are 6 m and

35 m respectively. Both pipes are 60 mm in diameter. If the pump is to run at

30 rpm, nd the pressure head on the piston, at the beginning, middle and end of

the suction stroke. If mechanical e ciency is 75% and f=0.04, determine the power

required to drive the pump. [16]

5. The outer diameter of an impeller of a centrifugal pump is 400 mm and outlet

width 50 mm. The pump is running at 800 r.p.m and is working against a total

head of 15 m. The vanes angle at outlet is 40o and manometric e ciency is 75%.

Determine:

(a) velo city of ow at outlet

(b) velo city of water leaving the vane,

(c) angle made by the absolute velocity at outlet with the direction of motion at

outlet, and

(d) discharge. [16]





6. (a) Draw and discuss the operating charecteristcs of a centrifugal pump.

(b) Two geometrically similar pumps are running at the same speed of 1000 r.p.m.

One pump has an impeller diameter of 0.3 meter and lifts water at the rate

of 20 liters per second against a head of 15 meters. Determine the head and

impeller diameter of the other pump to deliver half the discharge. [6+10]

7. (a) How do es a torque convertor di er from a uid coupling? Explain the working

principle of any one of them.

(b) A hydraulic lift is required to lift a load of 8 kN through a height of 10 meters,

once in every 80 seconds. The speed of the lift is 0.5 m per second. Determine:

i. Power required to drive the lift,

ii. Working period of lift in seconds, and

iii. Idle period of the lift in seconds. [8+8]






the diameter of nozzle. Take f = 0.009. [8+8]











1. (a) Show that the force exerted by a jet of water on moving inclined plate in the

direction of jet is given by x = ( - )2 sin2 , where a=area of the jet,

=inclination of the plate with the jet, V=velocity of jet, u=velo city of plate

(b) A jet of water of diameter 100mm moving with a velocity of 25m/sec strikes

a curved xed symmetrical plate at the center. Find the force exerted by the

jet of water in the direction of the jet, if the jet is de ected through an angleof 1200 at the outlet of the curved plate. [8+8]

2. (a) Draw a neat diagram of a reaction turbine and explain its working. State the

equations for power produced and e ciency.

(b) Explain any two types of draft tubes with neat diagrams. [8+8]

3. What do you understand by characteristic curves of a turbine? Explain various

types of characteristic curves of a turbine along with neat sketches. [16]

4. (a) List out eight di erences between centrifugal pumps and recipro cating pumps.

(b) Di erentiate between

i. single acting and double acting reciprocating pump

ii. single cylinder and double cylinder recipro cating pump. [8+8]

5. (a) What do you mean by manometric e ciency, mechanical e ciency and overall

e ciency of a centrifugal pump.

(b) The diameters of an impeller of a centrifugal pump at inlet and outlet are

20 cm and 40 cm respectively. Determine the minimum speed for starting the

pump if it works against head of 25 m. [8+8]

6. A one- fth scale model of pump was tested in a laboratory at 1000 r.p.m. the head

developed and power input at the best e ciency point were found to be 8 m and

30 kW respectively. If the prototype pump has to work against a head of 25 m,

determine its working speed, the power required to drive it and the ratio of the

ow rates handled by the two pumps. [16]

7. (a) Water at a pressure of 8 bar is supplied to a crane for lifting a weight through

a height of 8 m. The diameter of the ram is 16 cm and velocity ratio 5.

Assuming the e ciency of the crane 70%, nd:

i. The weight lifted by the crane, and

ii. Volume of water su lied to the crane.





(b) Draw a neat diagram of a hydraulic press and explain its working. [8+8]

8. (a) A pipe line is 30 cm in diameter for rst 1000 m. length and 15 cm diameter for

next 1000 m. Find the discharge from the system for transmitting maximumpower. Total pressure at the intake 5.5 kN/m2. Take f = 0.008 for both pipes.

(b) Determine the maximum power available at the exit of the pipe of 30 cm

diameter and 3500 m long. The head at the inlet is 500m. Take f = 0.006.

[8+8]

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Hydraulic Machinery and Systems Jntu Model Paper Www Student Yogi Com 100113195214 Phpapp01