III Semester Diploma Mechanical Engineering preparatory Examination

FLUID MECHANICS AND MACHINERY

Time: 2 Hour (Max.Marks:50)

Instructions: 1) Section I is compulsory

2) Attempt any four questions from Section- II, III

3) Assume missing data, if any suitably.

SECTION –I (10)

1. (a) Fill in the blanks:

i) The of a liquid is its property, which enables it

to resist tensile stress.

ii) A flow , in which the volume of a fluid and its density changes

during the flow is called as

iii) is a pipe , which connects the turbine and tail race

or outlet channel

iv) Stokes is the unit of

v) Air vessels are required in pump

(b) Give any five differences between centrifugal pump and

reciprocating pump.

SECTION –II (20)

1. Derive an expression for the force of jet striking normally on a fixed

plate.

2. A centrifugal pump is to discharge 0.118 /s at a speed of 1450 r. p.m.

against a head of 25m.The impeller diameter is 250mm, its width of

outlet is 50mm and manometric efficiency is 75%.Determine the vane

angle at the outer periphery of the impeller.

3. Draw a neat sketch of parts of a pelton wheel and explain the functions

of nozzle, runner and buckets.

4. A jet of water 2.5cm diameter, moving with a velocity of 25m/s strikes

a fixed plate in such a way that the angle between the jet and plate is

.Find the force exerted by the jet on the plate in the direction of the

jet

5. A single acting reciprocating pump at 50 r.p.m., delivers 0.01 of

water. The diameter of the piston is 200mm and a length of the stroke

is 600mm. Determine

i) Theoretical discharge of the pump

ii) Discharge coefficient

6. Find the total head of water flowing with a velocity of 8 m/s under a

pressure of 80kPa, the centre of pipe is 5m above the datum line.

SECTION –III (20)

1. Write short notes on any two of the following

a) Draft tube

b) Water hammer in pipes

c) Syphon

d) Venturimeter

2. Explain the necessity of Air Vessels in Reciprocating pump.

3. Define the following terms of a turbine with formula

(a) Unit speed

(b) Unit discharge

(c) Unit power

(d) Specific speed

(e) Overall efficiency

4. An impulse turbine develops 1750 kW under a head of 100 metres

while running at 200r. p.m. and discharging 2500litres of water per

second. Find the unit speed , unit power and unit discharge of the

wheel

5. Differentiate between an impulse turbine and reaction turbine.

6. A pelton wheel develops 2000kW under a head of 100metres, and

with an overall efficiency of 85%.Find the diameter of the nozzle, if

the velocity coefficient 0.98 ( Use Q = V

)