1000+ Hydraulics & Fluid Machineries MCQ for XAT [Solved]

1. The discharge of a double acting reciprocating pump is (where L = Length of stroke, A = Cross-sectional area of piston, and N = Speed of crank in r.p.m.)
A. L.A.N
B. 2 L.A.N
C. (L.A.N)/60
D. (2 L.A.N)/60
Answer : D

2. The force exerted by a jet of water (in a direction normal to flow) impinging on a fixed plate inclined at an angle ? with the jet is
A. waV/2g × sin?
B. waV/g × sin?
C. waV²/2g × sin2?
D. waV²/g × sin?
Answer : C

3. The Fourneyron turbine is _________ reaction turbine.
A. An axial flow
B. An inward flow
C. An outward flow
D. A mixed flow
Answer : C

4. In axial flow fans and turbines, fluid enters and leaves as follows
A. Radially, axially
B. Axially, radially
C. Axially, axially
D. Radially, radially
Answer : C

5. Runaway speed of a hydraulic turbine is
A. Full load speed
B. The speed at which turbine runner will be damaged
C. The speed if the turbine runner is allowed to revolve freely without load and with the wicket gates wide open
D. The speed corresponding to maximum overload permissible
Answer : C

6. In a centrifugal pump, the liquid enters the pump
A. At the top
B. At the bottom
C. At the canter
D. From sides
Answer : C

7. A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the
A. Kinetic head
B. Velocity head
C. Manometric head
D. Static head
Answer : C

8. When a piping system is made up primarily of vertical lift and very little pipe friction, the pump characteristics should be
A. Horizontal
B. Nearly horizontal
C. Steep
D. First rise and then fall
Answer : C

9. Overall efficiency of a centrifugal pump is the ratio of
A. Energy available at the impeller to the energy supplied to the pump by the prime mover
B. Actual workdone by the pump to the energy supplied to the pump by the prime mover
C. Energy supplied to the pump to the energy available at the impeller
D. Manometric head to the energy supplied by the impeller per kN of water
Answer : B

10. Which of the following statement is wrong?
A. The reaction turbines are used for low head and high discharge.
B. The angle of taper on draft tube is less than 8°.
C. An impulse turbine is generally fitted slightly above the tail race.
D. A Francis turbine is an impulse turbine.
Answer : D

11. A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is
A. 0.25 kW
B. 0.75 kW
C. 1.75 kW
D. 3.75 kW
Answer : C

12. A hydraulic coupling belongs to the category of
A. Power absorbing machines
B. Power developing machines
C. Energy transfer machines
D. Energy generating machines
Answer : C

13. A turbine is required to develop 1500 kW at 300 r.p.m. under a head of 150 m. Which of the following turbine should be used?
A. Pelton wheel with one nozzle
B. Pelton wheel with two or more nozzles
C. Kaplan turbine
D. Francis turbine
Answer : A

14. Reciprocating pumps are no more to be seen in industrial applications (in comparison to centrifugal pumps) because of
A. High initial and maintenance cost
B. Lower discharge
C. Lower speed of operation
D. Necessity of air vessel
Answer : A

15. In an inward flow reaction turbine
A. The water flows parallel to the axis of the wheel
B. The water enters at the centre of the wheel and then flows towards the outer periphery of the wheel
C. The water enters the wheel at the outer periphery and then flows towards the centre of the wheel
D. The flow of water is partly radial and partly axial
Answer : C

16. A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit speed of the wheel is
A. 10 r.p.m.
B. 20 r.p.m.
C. 40 r.p.m.
D. 80 r.p.m.
Answer : B

17. The number of buckets on the periphery of a Pelton wheel is given by
A. (D/2d) + 5
B. (D/2d) + 10
C. (D/2d) + 15
D. (D/2d) + 20
Answer : C

18. According to fan laws, for the fans having constant wheel diameters, the power demand varies
A. Directly as fan speed
B. Square of fan speed
C. Cube of fan speed
D. Square root of fan speed
Answer : C

19. Francis, Kaplan and propeller turbines fall under the category of
A. Impulse turbines
B. Reaction turbines
C. Axial flow turbines
D. Mixed flow turbines
Answer : B

20. Geometric similarity is said to exist between the model and the prototype, if both of them
A. Have identical velocities
B. Are equal in size and shape
C. Are identical in shape, but differ only in size
D. Have identical forces
Answer : C

21. In order to avoid cavitation in centrifugal pumps
A. The suction pressure should be high
B. The delivery pressure should be high
C. The suction pressure should be low
D. The delivery pressure should be low
Answer : A

22. The hydraulic efficiency of an impulse turbine is the
A. Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine
B. Ratio of the actual work available at the turbine to the energy imparted to the wheel
C. Ratio of the work done on the wheel to the energy of the jet
D. None of the above
Answer : C

23. The flow ratio in case of Francis turbine varies from
A. 0.15 to 0.3
B. 0.4 to 0.5
C. 0.6 to 0.9
D. 1 to 1.5
Answer : A

24. The depth of the bucket for a Pelton wheel is generally ________ the diameter of jet.
A. Equal to
B. 1.2 times
C. 1.8 times
D. Double
Answer : B

25. The runaway speed of a hydraulic turbine is the speed
A. At full load
B. At which there will be no damage to the runner
C. Corresponding to maximum overload permissible
D. At which the turbine will run freely without load
Answer : D

26. Head developed by a centrifugal pump depends on
A. Impeller diameter
B. Speed
C. Fluid density
D. Both (A) and (B) above
Answer : D

27. Kinematic similarity is said to exist between the model and the prototype, if both of them
A. Have identical velocities
B. Are equal in size and shape
C. Are identical in shape, but differ only in size
D. Have identical forces
Answer : A

28. Pressure intensifier increases the pressure in proportion to
A. Ratio of diameters
B. Square of ratio of diameters
C. Inverse ratio of diameters
D. Square of inverse ratio of diameters
Answer : B

29. The efficiency of a Pelton wheel working under constant head ________ with the increase in power.
A. Remain same
B. Increases
C. Decreases
D. None of these
Answer : B

30. Which of the following pump is successfully used for lifting water from deep wells?
A. Centrifugal pump
B. Reciprocating pump
C. Jet pump
D. Air lift pump
Answer : D

31. Medium specific speed of a pump implies it is
A. Centrifugal pump
B. Mixed flow pump
C. Axial flow pump
D. Any one of the above
Answer : B

32. Slip of a reciprocating pump is negative, when
A. Suction pipe is short and pump is running at low speeds
B. Delivery pipe is long and pump is running at high speeds
C. Suction pipe is short and delivery pipe is long and the pump is running at low speeds
D. Suction pipe is long and delivery pipe is short and the pump is running at high speeds
Answer : D

33. According to fan laws, for fans having constant wheel diameter, the pressure varies
A. Directly as fan speed
B. Square of fan speed
C. Cube of fan speed
D. Square root of fan speed
Answer : B

34. Delivery head of a centrifugal pump is
A. Directly proportional to N
B. Inversely proportional to N
C. Directly proportional to N²
D. Inversely proportional to N²
Answer : C

35. The force exerted by a jet of water impinging normally on a plate which due to the impact of jet, moves in the direction of jet with a velocity v is
A. [wa (V - v)]/2g
B. [wa (V - v)]/g
C. [wa (V - v)²]/2g
D. [wa (V - v²)]/g
Answer : D

36. The unit speed of the turbine runner is
A. N/?H
B. N/H
C. N/H^3/2
D. N/H²
Answer : A

37. The power developed by a turbine is (where H = Head of water under which the turbine is working)
A. Directly proportional to H^1/2
B. Inversely proportional to H^1/2
C. Directly proportional to H^3/2
D. Inversely proportional to H^3/2
Answer : C

38. The efficiency of a hydraulic press is given by (where W = Weight lifted by ram, P = Force applied on plunger, A = Area of ram, and a = Area of plunger)
A. (W/p) × (A/a)
B. (p/W) × (a/A)
C. (W/p) × (a/A)
D. (p/W) × (A/a)
Answer : C

39. Manometric head, in case of a centrifugal pump, is equal to
A. Suction lift + Loss of head in suction pipe due to friction + Delivery lift + Loss of head in delivery pipe due to friction + Velocity head in the delivery pipe
B. Workdone per kN of water Losses within the impeller
C. Energy per kN at outlet of impeller Energy per kN at inlet of impeller
D. All of the above
Answer : D

40. Low specific speed of turbine implies it is
A. Propeller turbine
B. Francis turbine
C. Impulse turbine
D. Any one of the above
Answer : C

41. The discharge through a turbine is
A. Directly proportional to H^1/2
B. Inversely proportional to H^1/2
C. Directly proportional to H^3/2
D. Inversely proportional to H^3/2
Answer : A

42. High specific speed of a pump implies it is
A. Centrifugal pump
B. Mixed flow pump
C. Axial flow pump
D. Any one of the above
Answer : C

43. A hydraulic press is a device used
A. To store pressure energy which may be supplied to a machine later on
B. To increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure
C. To lift larger load by the application of a comparatively much smaller force
D. All of the above
Answer : C

44. Multistage centrifugal pumps are used to
A. Give high discharge
B. Produce high heads
C. Pump viscous fluids
D. All of these
Answer : B

45. 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, the horse power required will be
A. Same
B. 0.75 B.H.P.
C. B.H.P./0.75
D. 1.5 B.H.P.
Answer : B

46. The discharge through a reaction turbine with increase in unit speed
A. Increases
B. Decreases
C. Remain unaffected
D. First increases and then decreases
Answer : B

47. When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be
A. Horizontal
B. Nearly horizontal
C. Steep
D. First rise and then fall
Answer : B

48. Head developed by a centrifugal pump is
A. Proportional to diameter of impeller
B. Proportional to speed of impeller
C. Proportional to diameter and speed of impeller
D. None of the above
Answer : C

49. Dynamic similarity is said to exist between the model and the prototype, if both of them
A. Have identical velocities
B. Are equal in size and shape
C. Are identical in shape, but differ only in size
D. None of the above
Answer : D

50. A hydraulic ram is a device used to
A. Store the energy of water
B. Increase the pressure of water
C. To lift water from deep wells
D. To lift small quantity of water to a greater height when a large quantity of water is available at a smaller height
Answer : D