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Fluid-mechanics Questions Set 74:

Quiz Mode

The unit speed of pump

N/H

Sqrt( H) / N

N/ sqrt(H)

Q/sqrt(H)

Solution:

Power need to drive the centrifugal pump is proportional to

N²

N³

N⁵

Solution:

Air vessels used in reciprocating pumps are initially filled with:

Water

Vacuum

Compressed air

None of the above

Solution:

Multistage centrifugal pumps are used for

Obtaining high head

Obtaining low discharge

Obtaining low head

High discharge requirements

Solution:

When the speed of a centrifugal pump is tripled, the power required to drive the pump will

Triple

Increase 9 times

Increase 27 times

Remain the same

Solution:

A centrifugal pump lift water through a height h and delivers it at a velocity vd. The loss of head through piping is hf . The gross lift is-

h + hf

hf+ v_d³ / 2g

h + hf+ v_d² / 2g

h+ v_d² / 2g

Solution:

If D is the diameter of impeller at inlet, w is the width of the impeller at inlet and Vf is the velocity of flow at inlet then discharge through a centrifugal pump is equal to:

πDVf

DVf w

πDVf w

πDw

Solution:

In axial flow pumps and compressors, the combined velocity diagram with a common base is used to determine changes in

absolute velocity (V2 – V1)

relative velocity ( Vr2- Vr1)

tangential velocity (U2 – U1)

whirl velocity ( Vu2 - Vu1)

Solution:

Two geometrically similar pumps are running at the same peed of 1000 RPM. One pump has an impeller diameter of 300 mm and lifts water at 0.02m3 /s against a head of 15 m. The head of the other pump delivers half the discharge.

9.15m

9.25m

9.35m

9.45m

Solution:

The mechanical efficiency of a centrifugal pump is the ratio of

manometric head to the energy supplied by the impeller per kN of water

energy supplied to the pump to the energy available at the impeller

actual work done by the pump to the energy supplied to the pump by the prime mover

energy available at the impeller to the energy supplied to the pump by the prime mover

Fluid-mechanics Questions Set 74:

The unit speed of pump

Solution:

Power need to drive the centrifugal pump is proportional to

Solution:

Air vessels used in reciprocating pumps are initially filled with:

Solution:

Multistage centrifugal pumps are used for

Solution:

When the speed of a centrifugal pump is tripled, the power required to drive the pump will

Solution:

A centrifugal pump lift water through a height h and delivers it at a velocity vd. The loss of head through piping is hf . The gross lift is-

Solution:

If D is the diameter of impeller at inlet, w is the width of the impeller at inlet and Vf is the velocity of flow at inlet then discharge through a centrifugal pump is equal to:

Solution:

In axial flow pumps and compressors, the combined velocity diagram with a common base is used to determine changes in

Solution:

Two geometrically similar pumps are running at the same peed of 1000 RPM. One pump has an impeller diameter of 300 mm and lifts water at 0.02m3 /s against a head of 15 m. The head of the other pump delivers half the discharge.

Solution:

The mechanical efficiency of a centrifugal pump is the ratio of

Solution:

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