Hydraulic Machines

21. Head developed by a centrifugal pump depends on

  1. impeller diameter
  2. speed
  3. fluid density
  4. type of casing
  5. (a) and (b) above.

Correct answer: (E)
(a) and (b) above.

22. High specific speed of a pump implies it is

  1. centrifugal pump
  2. mixed flow pump
  3. axial flow pump
  4. any one of the above
  5. none of the above.

Correct answer: (C)
axial flow pump

23. High specific speed of turbine implies it is

  1. propeller turbine
  2. Francis turbine
  3. impulse turbine
  4. any one of the above
  5. none of the above.

Correct answer: (A)
propeller turbine

24. Hydraulic accumulator is used for

  1. accumulating oil
  2. supplying large quantities of oil for very short duration
  3. generally high pressures to operate hydraulic machines
  4. supplying energy when main supply fails
  5. accumulating hydraulic energy.

Correct answer: (D)
supplying energy when main supply fails

25. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water would discharge

  1. same quantity of liquid
  2. 0.75 Q
  3. Q/0.75
  4. 1.5 Q
  5. none of the above.

Correct answer: (A)
same quantity of liquid

26. Impulse turbine is generally fitted

  1. at the level of tail race
  2. little above the tail race
  3. slightly below the tail race
  4. about 2.5 m above the tail race to avoid cavitation
  5. about 2.5 m below the tail race to avoid cavitation.

Correct answer: (B)
little above the tail race

27. In a centrifugal pump casing, the flow of water leaving the

  1. radial
  2. radial
  3. centrifugal
  4. rectilinear
  5. vortex.

Correct answer: (E)
vortex.

28. In a centrifugal pump casing, the flow of water leaving the impeller, is

  1. rectilinear flow
  2. radial flow
  3. free vortex motion
  4. forced vortex
  5. none of the above.

Correct answer: (C)
free vortex motion

29. In a centrifugal pump, the liquid enters the pump

  1. at the top
  2. at the bottom
  3. at the center
  4. from sides
  5. none of the above.

Correct answer: (C)
at the center

30. In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by

  1. designing new impeller
  2. trimming the impeller size to the required size by machining
  3. not possible
  4. some other alterations in the impeller
  5. none of the above.

Correct answer: (B)
trimming the impeller size to the required size by machining

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