Hydraulic Turbines and Jets MCQ

21. A turbine is a device that converts

  1. Hydraulic energy into mechanical energy
  2. Mechanical energy into hydraulic energy
  3. Kinetic energy into mechanical energy
  4. Electrical energy into mechanical energy
Answer
Answer. a

22. The operating characteristic curves of a turbine are

  1. Varying speed curves
  2. Constant efficiency curves
  3. Constant head curves
  4. Constant speed curves
Answer
Answer. d

23. If the overall efficiency of a Pelton Turbine is 63% and its Mechanical efficiency is 80%, then its Hydraulic efficiency would be?

  1. 81.25%
  2. 55.25%
  3. 75.25%
  4. 85.25%
Answer
Answer. a

24. A Jet of water has a diameter of 0.3 cm. The absolute surface tension of water is 0.072 N/m and atmospheric pressure is 101.2 kN/m2. The absolute pressure within the jet of water will be

  1. 101.104 kN/m2
  2. 101.152 kN/m2
  3. 101.248 kN/m2
  4. 101.296 kN/m2
Answer
Answer. c

25. Cavitation in turbines affects turbines in the following ways except

  1. irregular collapse of vapour cavities
  2. vibration of turbine parts
  3. loss of turbine material
  4. reduction in efficiency of turbine
  5. excessive heating of water
Answer
Answer. e

26. Hydraulic efficiency of Francis turbine is

  1. directly proportional to velocity of whirl at inlet and inversely proportional to net head on turbine
  2. directly proportional to velocity of whirl at inlet and net head on turbine
  3. inversely proportional to velocity of whirl at inlet and net head on turbine
  4. inversely proportional to velocity of whirl at inlet and directly proportional to net head on turbine
Answer
Answer. a

27. A turbine develops 7225 kW power under a head of 25 m at 135 rpm. The specific speed of the turbine will be nearly

  1. 245
  2. 225
  3. 205
  4. 185
Answer
Answer. c

28. Which of the following statement is wrong?

  1. A Francis turbine is an impulse turbine
  2. The impulse turbine is generally fitted slightly above tail race
  3. The angle of taper on draft tube is less than 8°
  4. The reaction turbines are used for low head and high discharge.
Answer
Answer. a

29. A turbine develops 500 kW power under a head of 100 m at 252 r.p.m. What would be its normal speed under a head of 80m.

  1. 670 r.p.m.
  2. 250 r.p.m.
  3. 225 r.p.m.
  4. 550 r.p.m.
Answer
Answer. c

30. In Sardar Sarovar dam, around 80% of the total power is generated using

  1. Francis Turbine
  2. Kaplan Turbine
  3. Pelton Turbine
  4. Gravity Turbine
Answer
Answer. a
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