D $2019 Pages: 3

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a) What is meant by cavitation in centrifugal pump? What are the effects of 5
cavitation? How it can be eliminated

b) Show that the saving in work done against friction in a double acting reciprocating
5 pump fitted with air vessel is 39.2%

7 a) Define minimum starting speed of a centrifugal pump. Write down the equation 4

for the same with notations.
b) With the help of necessary sketch, explain the working of a jet pump? Where are 6
they used?

8 a) What is meant by manometric head of a centrifugal pump? What are the different 4

ways of finding it?

b) The bore and stroke of a double acting reciprocating pump are 15cm and 30cm 6
respectively. The suction and delivery heads are 3m and 30m and the pump delivers
0.62m?/min when running at 60rpm. Find the percentage slip and power required to
run the pump if mechanical efficiency is 80%.

PART C Answer any four questions. Each question carries 10
marks.

9 a) Deduce an equation for the work done on a reciprocating compressor in terms of 5
pressure ratio using P-v diagram. Assume the process of compression fallows
polytropic according to pv" =a constant.

0) Asingle stage single acting reciprocating air compressor is used to compress 5 7x10"
3 m/min of air from a pressure of 1.013 bar to 14 bar. The index of polytropic
compression is 1.3 and mechanical efficiency is 82%. Determine the volumetric
efficiency and power required to drive the compressor if the clearance is 3% of the
swept volume.

10 a) Define the following with reference to reciprocating compressors 3

i) Isothermal efficiency ii) Adiabatic efficiency iii) Volumetric efficiency

b) Obtain the expressions for volumetric efficiency of an air Compressor in terms of 7
clearance ratio, index of compression and pressure ratio.

11 a) What are the advantages and disadvantages of multistage compression? 4 9) Prove
that for a multi stage compressor with perfect intercooling between stages, 6 the work
done is minimum when the intermediate pressure is the geometric mean of the suction

and delivery pressure between successive stages.

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