Hydraulic Machines

51. The angle of taper on draft tube is

  1. greater than 15°
  2. greater than 8°
  3. greater than 5°
  4. less than 8°
  5. less than 3°.

Correct answer: (D)
less than 8°

52. The discharge through a reaction turbine with increase in unit speed

  1. increases
  2. decreases
  3. remains unaffected
  4. first increases and then decreases
  5. first decreases and then increases.

Correct answer: (B)
decreases

53. The efficiency of a centrifugal pump is maximum when its blades are

  1. straight
  2. bent forward
  3. bent backward
  4. bent forward first and then backward
  5. bent backward first and then forward.

Correct answer: (C)
bent backward

54. The flow rate in gear pump

  1. increases with increase in pressure
  2. decreases with increase in pressure
  3. more or less remains constant with in-crease in pressure
  4. unpredictable
  5. none of the above.

Correct answer: (C)
more or less remains constant with in-crease in pressure

55. The horse power required in above case will be

  1. same
  2. 0.75 B.H.P.
  3. B.H.P./0.75
  4. 1.5 B.H.P.
  5. none of the above.

Correct answer: (B)
0.75 B.H.P.

56. The maximum number of jets generally employed in impulse turbine without jet interference is

  1. 4
  2. 6
  3. 8
  4. 12
  5. 16

Correct answer: (B)
6

57. The optimum value of vane exit angle for a centrifugal pump impeller is

  1. 10-15°
  2. 20-25°
  3. 30-40°
  4. 50-60°
  5. 80-90°.

Correct answer: (B)
20-25°

58. The specific speed of turbine is defined as the speed of a unit

  1. of such a size that it delivers unit dis-charge at unit head
  2. of such a size that it delivers unit dis-charge at unit power
  3. of such a size that it requires unit power per unit head
  4. of such a size that it produces unit horse power with unit head
  5. none of the above.

Correct answer: (D)
of such a size that it produces unit horse power with unit head

59. When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be

  1. horizontal
  2. nearly horizontal
  3. steep
  4. first rise and then fall
  5. none of the above.

Correct answer: (B)
nearly horizontal

60. When a piping system is made up primarily of vertical lift and very little pipe friction, the pump characteristics should be

  1. horizontal
  2. nearly horizontal
  3. steep
  4. first rise and then fall
  5. none of the above.

Correct answer: (C)
steep

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