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ISRO 2008 Mechanical Engineering Questions, Answers and Explanation

               ISRO 2008 Mechanical Engineering Questions, Answers and Explanation

 38. In centrifugal pumps maximum efficiency is obtained when the blades are 
a) Straight
b) Bent forward
c) Bent backward
d) Radial

 Answer
c) Bent backward

 Explanation [Fluid Mechanics]
For fluids in in-compressible regime of operation such as water backward curved vanes are used for maximum efficiency.
For radial and forward bent vanes the power requirement increases monotonically as the discharge increases. But for backward curved the power requirement peaks at maximum efficiency. 

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