Hydraulic Turbines and Jets MCQ

31. Consider the following statements regarding turbine:

1. Specific speed plays an important role in the selection of the type of turbine.
2. An increase in specific speed of the turbine is accompanied by higher maximum efficiency.
3. The runner of too high specific speed with high available head increases the cost of the turbine on account of the high mechanical strength required.

Which of the above statements are correct?

1. i, ii and iii
2. i and ii only
3. ii and iii only
4. i and iii only

32. Consider the following statements in connection with hydraulic turbines:

1. The Kaplan turbine is a radial flow turbine in which the guide vane angles as well as the runner vane angles are adjustable.
2. Francis and Kaplan turbines are provided with draft tubes which carry water from exit of runner to tailwater to increase the gross head across the turbine.
3. The parts of turbines susceptible to cavitaiton are the guide vanes and runner vanes-drastically reducing the turbine efficiency.
4. The specific speed of a 4-jet Pelton turbine will be 28 if the specific speed of a single-jet Pelton turbine is 14.

Which of the above statements are correct?

1. ii and iii only
2. i and iii only
3. i and iv only
4. ii and iv only

33. Consider the following statements regarding turbines:

1. The main function of a governor is to maintain a constant speed even as the load on the turbine fluctuates
2. In the case of Pelton turbines, the governor closes or opens the wicket gates
3. In the case of Francis turbines, the governor opens or closes the needle valve
4. In the case of a Kaplan turbine, the governor swings the runner blades appropriately in addition to further closing or further opening of the wicket gates

Which of the above statements are correct?

1. ii and iv only
2. i and iii only
3. i and iv only
4. ii and iii only

34. A hydraulic turbine develops 5000 kW under a head of 30 m when running at 100 rpm. This turbine belongs to the category of

1. Francis Turbine
2. Pelton wheel
3. Propeller Turbine
4. Kaplan Turbine

35. In a pelton turbine, the degree of reaction is

1. one
2. zero
3. in the range 0 to 0.5
4. In the range 0.5 to 1

36. The overall efficiency of a turbine is the ratio of the

1. power developed by the runner of a turbine to the power supplied by the water at the inlet of the turbine
2. power at the shaft of the turbine to the power developed by the runner
3. volume of water actually striking the runner to the volume of water supplied to the turbine
4. power available at the shaft of the turbine to the power supplied by the water at the inlet of the turbine

37. Water is to be pumped out of a deep well under a total head of 95 m. A number of identical pumps of design speed 1000 rpm and specific speed 900 rpm with a rated capacity of 150 l/s are available. The number of pumps required will be

1. 7
2. 3
3. 1
4. 5

38. __________ are those which are capable of working under heads less than 30 m.

1. Low head turbine
2. Medium head turbine
3. High head turbine
4. None of above

39. Which of the following turbine is preferred for 0 to 25 m head of water?

1. Kaplan turbine
2. Pelton wheel
3. Francis turbine
4. None of these

40. Which of the following are component parts for an oil pressure governor in modern turbines?

1. Servomotor, known as relay cylinder
2. Oil sump
3. Oil pump which is driven by belt connected to turbine main shaft
4. Draft tube

1. i, ii and iv only
2. i, ii and iii only
3. ii, iii and iv only
4. i, iii and iv only