Hydraulic Machines Multiple Choice Questions and Answers

51. According to fan laws, for the fans having constant wheel diameters, the power demand varies

1. directly as fan speed
2. square of fan speed
3. cube of fan speed
4. square root of fan speed

52. 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

53. For starting an axial flow pump, its delivery valve should be

1. closed
2. open
3. depends on starting condition and flow desired
4. could be either open or closed

54. Low 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

55. Medium 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

56. 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

57. For small discharge at high pressure, following pump is preferred

1. centrifugal
2. axial flow
3. reciprocating.
4. propeller

58. For very high discharge at low pressure such as for flood control and irrigation applications, following type of pump is preferred

1. centrifugal
2. axial flow
3. reciprocating
4. mixed flow

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

1. at the top
2. at the bottom
3. at the center
4. from sides

60. 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