Fluid Mechanics

Impeller - of a pump throws water form the impeller center to the
periphery by the action of centrifugal force and go out through the small
opening provided in the casing . in this process inside the casing, a vacuum is
creating cause water to rise through the suction pipe to the impeller center.
Head flow depend upon the impeller diameter. fluid enter axially and leaves
radially. so impeller pump can suck water from negative suction also, provided
no leakage in the pump suction side (dpending upon the liquid). impeller take
minimum energy if we close the delivery valve of the pump, and increase with the
increase in flow.

Propeller - of a pump increase the head by throwing the fluid from
suction to delivery. in propeller pump suction and delivery are of same size.
T.D.H (total differential head) in the range of 5-5.5 m of water column.
propeller pump work only in positive suction head .propeller pump take more
energy in we throttle the delivery.

For the same flow rate of liquid propeller pump take less power than impeller
pump

eg for 100M3/hr propeller pump-30HP and impeller pump->55HP

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