Hydraulic Machines MCQs Quiz Multiple Choice Questions & Answers

1. Maximum impulse will be developed in hydraulic ram when

1. waste valve closes suddenly
2. supply pipe is long
3. supply pipe is short
4. ram chamber is large

2. A hydraulic accumulator normally consists of

1. two cylinders, two rams and a storage device
2. a cylinder and a ram
3. two co-axial rams and two cylinders
4. a cylinder, a piston, storage tank and control valve

3. A hydraulic intensifier normally consists of

1. two cylinders, two rams and a storage device
2. a cylinder and a ram
3. two co-axial rams and two cylinders
4. a cylinder, a piston, storage tank and control valve

4. In reaction turbine, draft tube is used

1. to transport water downstream without eddies
2. to convert the kinetic energy to flow energy by a gradual expansion of the flow cross-section
3. for safety of turbine
4. to increase flow rate

5. 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

6. In centrifugal pumps, maximum efficiency is obtained when the blades are

1. straight
2. bent forward
3. bent backward
4. radial

7. Motion of a liquid in a volute casing of a centrifugal pump is an example of

1. spiral vortex flow.
2. radial
3. forced spiral vortex flow
4. forced cylindrical vortex flow

8. Air vessels in reciprocating pump are used to

1. smoothen flow
2. reduce acceleration to minimum
3. increase pump efficiency
4. save pump from cavitation

9. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water would discharge

1. same quantity of liquid
2. 0.75 Q
3. Q/0.75
4. 1.5 Q

10. 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.

11. In a reciprocating pump, air vessels are used to

1. Reduce the flow
2. Increase the delivery head
3. Smoothen the flow
4. Reduce the acceleration head

12. In a centrifugal pump casing, the flow of water leaving the impeller, is

1. rectilinear flow
2. radial flow
3. free vortex motion
4. forced vortex

13. Pressure intensifier increases the pressure in proportion to

1. ratio of diameters
2. square of ratio of diameters
3. inverse ratio of diameters
4. square of inverse ratio of diameters

14. In axial flow fans and turbines, fluid enters and leaves as follows

1. radially, axially
2. axially, radially
3. axially, axially
4. radially, radially

15. In a centrifugal pump casing, the flow of water leaving the

1. radial
2. radial
3. centrifugal
4. vortex

16. Low specific speed of turbine implies it is

1. propeller turbine
2. Francis turbine
3. impulse turbine
4. any one of the above

17. Medium specific speea of turbine implies it is

1. propeller turbine
2. Francis turbine
3. impulse turbine
4. any one of the above

18. High specific speed of turbine implies it is

1. propeller turbine
2. Francis turbine
3. impulse turbine
4. any one of the above

19. 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

20. Any change in load is adjusted by adjusting following parameter on turbine

1. net head
2. absolute velocity
3. blade velocity
4. flow

21. Francis turbine is best suited for

1. medium head application from 24 to 180 m
2. low head installation up to 30 m
3. high head installation above 180 m
4. all types of heads

22. An impulse turbine is used for

1. Low head of water
2. High head of water
3. Medium head of water
4. High discharge

23. Reaction turbines are used for

1. low head
2. high head
3. high head and low discharge
4. low head and high discharge

24. Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between

1. lift and resultant force
2. drag and resultant force
3. lift and tangential force
4. lift and drag

25. A turbine is a device which converts

1. Kinetic energy in to mechanical energy
2. Mechanical energy in to hydraulic energy
3. Hydraulic energy into mechanical energy
4. None of the above.

26. Centrifugal pump is started with its delivery valve

1. kept fully closed
2. kept fully open
3. irrespective of any position
4. kept 50% open

27. Axial flow pump is started with its delivery valve

1. kept fully closed
2. kept fully open
3. irrespective of any position
4. kept 50% open

28. A centrifugal pump is superior to a reciprocating pump because

1. It is a high speed pump
2. It is more economical
3. It gives smooth flow
4. All the above

29. Which place in hydraulic turbine is most susceptible for cavitation

1. inlet of draft rube
2. blade inlet
3. guide blade
4. penstock

30. 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

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

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

32. Francis, Kaplan and propeller turbines fall under the category of

1. Impulse turbines
2. Reaction turbines
3. Axial flow turbines
4. Mixed flow turbines

33. Head developed by a centrifugal pump depends on

1. impeller diameter
2. speed
3. fluid density
4. a and b above

34. 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

35. 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

36. Reciprocating pumps are no more to be seen in industrial applications (in comparison to centrifugal pumps) because of

1. high initial and maintenance cost
2. lower discharge
3. lower speed of operation
4. necessity of air vessel

37. Multistage centrifugal pumps are used to obtain

1. high discharge
2. high head
3. pumping of viscous fluids
4. high head and high discharge

38. The angle of taper on draft tube is

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

39. Multi stage centrifugal pumps are used to

1. Give high discharge
2. Produce high heads
3. Pump viscous fluids
4. All the above

40. Runaway speed of a hydraulic turbine is

1. full load speed
2. the speed at which turbine runner will be damaged
3. the speed if the turbine runner is allowed to revolve freely without load and with the wicket gates wide open
4. the speed corresponding to maximum overload permissible

41. Casting of a centrifugal pump is designed so as to minimize

1. friction loss
2. cavitation
3. static head
4. loss of kinetic energy

42. A draft tube is not required for a

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

43. Indicator diagram of a reciprocating pump is a graph between

1. flow vs swept volume
2. pressure in cylinder vs swept volume
3. flow vs speed
4. pressure vs speed

44. Overall efficiency of a centrifugal pump is the ratio of

1. Energy available at the impeller to the energy supplied to the pump by the prime mover
2. Actual work done by the pump to the energy supplied to the pump by the prime mover
3. Energy supplied to the pump to the energy available at the impeller
4. Manometric head to the energy supplied by the impeller per Newton of water

45. Puck up the wrong statement about centrifugal pump

1. discharge a diameter
2. head a speed2
3. head a diameter
4. Power a speed

46. According to fan laws, at constant speed and capacity, the pressure and power vary

1. directly as the air or gas density
2. inversely as square root of density
3. inversely as density
4. as square of density

47. According to fan laws, at constant pressure, the speed capacity and power vary

1. directly as the air or gas density
2. inversely as square root of density
3. inversely as density
4. as square of density

48. According to fan laws, at constant weight of air or gas, the speed, capacity and pressure vary

1. directly as the air or gas density
2. inversely as square root of density
3. inversely as density
4. as square of density

49. According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies

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

50. According to fan laws, for fans having constant wheel diameter, the pressure varies

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