Skyline Institute of Engineering & Technology, Greater Noida

Assignment – 4

EME-011 FLUID MACHINERY B.Tech. (Sixth Semester) Mechanical Engineering 2010-11

1. Why is the suction height of a pump limited? On what factors does it depend?

2. Show that the work saved in overcoming friction in the pipelines by fitting air vessels is 84.8% for a single acting reciprocating pump.

3. In a reciprocating pump executing S.H.M. the velocity of water in the suction pipe varies between zero and Vmax during suction stroke. Show that mean friction head during the stroke is given by :

(hf )mean= 4 flVmax2/ 3 g.d, where l, d and f are the length,

diameter and friction coefficient respectively for the suction pipe.

4. A single acting reciprocating pump having plunger diameter of 115 mm

and stroke of 230 mm is placed with its centre line 3 m above the level of water in the sump. The suction pipe is 90 mm in diameter and 4.2 m long. If the separation occurs at 2.4 m of water, find the maximum speed of the pump to avoid separation at the beginning of suction stroke. Assume atm. Pressure as 10.3 m of water and S.H.M. of the plunger. What power is consumed in overcoming friction in suction pipe at this speed? Assume pipe friction coefficient as 0.01.

5. Describe with the help of a neat sketch the constructional features and

working of a gear pump. Discuss its performance characteristics. State its merits, limitations and applications.

6. Derive an expression for pressure head due to acceleration of the piston of a reciprocating pump. Show that the effect of acceleration on the indicator diagrams.

7. Compare the reciprocating pump and centrifugal pump.

8. Following data relate to a single acting reciprocating pump:- Bore = 25 cm, stroke = 40 cm, speed = 50 rpm, delivery pipe diameter = 10 cm, delivery pipe length = 75 m, coefficient of friction = 0.008 Compute the power saved in fitting an air vessel o the delivery side of the pump.

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