Hydraulic Turbines and Jets MCQ

61. A turbine is called impulse if at the inlet of the turbine

  1. Total energy is only kinetic energy
  2. Total energy is only pressure energy
  3. Total energy is the sum of kinetic energy and pressure energy
  4. None of the above
Answer
Answer. a

62. For high head, the suitable turbine is

  1. Pelton
  2. Francis
  3. Kaplan
  4. None of the above
Answer
Answer. a

63. Muschel curves belong to the category of

  1. main characteristic curves of a turbine
  2. operating characteristic curves of a turbine
  3. constant efficiency curves of a turbine
  4. operating characteristics of a pump
Answer
Answer. c

64. Which of the following statements is correct?

  1. Pelton wheel is reaction turbine
  2. Pelton wheel is a radial flow turbine
  3. Pelton wheel is an impulse turbine
  4. None of the above
Answer
Answer. c

65. If the energy present in a jet of water of 20 cm diameter and having a velocity of 25 m/s could be extracted by a device with 90% efficiency, the power extracted would be nearly

(taking 1/2g = 0.051 sec2/m)

  1. 180 kW
  2. 225 kW
  3. 260 kW
  4. 300 kW
Answer
Answer. b

66. The work done by a kN of water jet moving with a velocity of 60 m/sec when it impinges on a series of vanes moving in the same direction with a velocity of 9 m/sec is

  1. 55.6 kNm
  2. 45.0 kNm
  3. 60.2 kNm
  4. 46.8 kNm
Answer
Answer. d

67. Consider the following data from a test on Pelton wheel:

Head at the base of the nozzle = 32 m
Discharge of the nozzle = 0.18 m3/s
Area of the jet = 7500 mm2
Power available at the shaft = 44 kW
Mechanical efficiency = 94%

The power lost in the nozzle will be nearly

  1. 4.7 kW
  2. 3.9 kW
  3. 2.3 kW
  4. 3.5 kW
Answer
Answer. a

68. A jet of water coming out of a nozzle with velocity 50 m/s is having cross sectional area of 20 cm2. The jet is directed against a fixed flat plate held normal to the jet. Find the force exerted on the plate.

  1. 5000 N
  2. 2000 N
  3. 5000 kN
  4. 200 N
Answer
Answer. a

69. If ‘v1‘is the velocity of jet at inlet and ‘u’ is the tangential velocity of vane, for maximum efficiency of Pelton Wheel the condition is

  1. u = v1/4
  2. u = v1/2
  3. u = v1
  4. 2u= v1
Answer
Answer. b

70. In the Pelton wheel turbine, the formula to find the number of buckets (Z) on a runner is (where D = pitch diameter of the pelton wheel, d = diameter of the jet):

  1. Z = 15 + D/2d
  2. Z = 20 + D/d
  3. Z = 15 + D/3d
  4. Z = 15 + D/d
Answer
Answer. a
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