Hydraulics & Fluid Machineries MCQ Solved Paper for NMAT

1. 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

2. According to fan laws, at constant pressure, the speed capacity and power vary
A. Directly as the air or gas density
B. Inversely as square root of density
C. Inversely as density
D. As square of density
Answer : B

3. The specific speed of turbine is defined as the speed of a unit
A. Of such a size that it delivers unit discharge at unit head
B. Of such a size that it delivers unit discharge at unit power
C. Of such a size that it requires unit power per unit head
D. Of such a size that it produces unit horse power with unit head
Answer : D

4. The hydraulic efficiency of a reaction turbine, is the ratio of
A. Power produced by the turbine to the energy actually supplied by the turbine
B. Actual work available at the turbine to energy imparted to the wheel
C. Workdone on the wheel to the energy (or head of water) actually supplied to the turbine
D. None of the above
Answer : C

5. The specific speed of a hydraulic turbine depends upon
A. Speed and power developed
B. Discharge and power developed
C. Speed and head of water
D. Speed, power developed and head of water
Answer : D

6. 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

7. Saving of work done and power by fitting an air vessel to double acting reciprocating pump is of the order of
A. 39.2 %
B. 49.2 %
C. 68.8 %
D. 84.8 %
Answer : A

8. 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

9. The flow ratio of Francis turbine is defined as the ratio of the
A. Velocity of flow at inlet to the theoretical jet velocity
B. Theoretical velocity of jet to the velocity of flow at inlet
C. Velocity of runner at inlet to the velocity of flow at inlet
D. None of the above
Answer : A

10. Power required to drive a centrifugal pump is directly proportional to ________ of its impeller.
A. Diameter
B. Square of diameter
C. Cube of diameter
D. Fourth power of diameter
Answer : D

11. 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

12. 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

13. The width of the bucket for a Pelton wheel is generally ________ the diameter of jet.
A. Double
B. Three times
C. Four times
D. Five times
Answer : D

14. 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

15. In a centrifugal pump, the regulating valve is provided on the
A. Casing
B. Delivery pipe
C. Suction pipe
D. Impeller
Answer : B

16. For small discharge at high pressure, following pump is preferred
A. Centrifugal
B. Axial flow
C. Mixed flow
D. Reciprocating
Answer : D

17. Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between
A. Lift and resultant force
B. Drag and resultant force
C. Lift and tangential force
D. Lift and drag
Answer : A

18. 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

19. Low specific speed of a pump implies it is
A. Centrifugal pump
B. Mixed flow pump
C. Axial flow pump
D. None of the above
Answer : A

20. The overall efficiency of a reaction turbine is the ratio of
A. Power produced by the turbine to the energy actually supplied by the turbine
B. Actual work available at the turbine to the energy imparted to the wheel
C. Workdone on the wheel to the energy (or head of water) actually supplied to the turbine
D. None of the above
Answer : A

21. 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

22. Which of the following pump is successfully used for lifting water to the boilers?
A. Centrifugal pump
B. Reciprocating pump
C. Jet pump
D. Airlift pump
Answer : C

23. The specific speed (Ns) of a centrifugal pump is given by
A. (N?Q)/H^2/3
B. (N?Q)/H^3/4
C. (N?Q)/H
D. (N?Q)/H^5/4
Answer : B

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

25. The flow rate in gear pump
A. Increases with increase in pressure
B. Decreases with increase in pressure
C. More or less remains constant with increase in pressure
D. Unpredictable
Answer : C

26. A Pelton wheel is
A. Tangential flow impulse turbine
B. Inward flow impulse turbine
C. Outward flow impulse turbine
D. Inward flow reaction turbine
Answer : A

27. 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

28. 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

29. The type of centrifugal pump preferred for a specific speed of 20 r.p.m. is
A. Slow speed pump with radial flow at outlet
B. Medium speed pump with radial flow at outlet
C. High speed pump with radial flow at outlet
D. High speed pump with axial flow at outlet
Answer : A

30. Which of the following is not an impulse turbine?
A. Girad turbine
B. Turgo turbine
C. Pelton wheel
D. Kaplan turbine
Answer : D

31. The specific speed of a centrifugal pump, delivering 750 litres of water per second against a head of 15 metres at 725 r.p.m., is
A. 24.8 r.p.m.
B. 48.2 r.p.m
C. 82.4 r.p.m.
D. 248 r.p.m
Answer : C

32. 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

33. 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

34. The static head of a centrifugal pump is equal to the ________ of suction head and delivery head.
A. Product
B. Difference
C. Sum
D. None of these
Answer : C

35. Which of the following statement is correct?
A. The centrifugal pump is suitable for large discharge and smaller heads.
B. The centrifugal pump requires less floor area and simple foundation as compared to reciprocating pump.
C. The efficiency of centrifugal pump is less as compared to reciprocating pump.
D. All of the above
Answer : D

36. The water in a jet propelled boat is drawn through the openings facing the direction of motion of the boat. The efficiency of propulsion is given by
A. 2V/(v_r - v)
B. 2V/(v_r + v)
C. V/(v_r - v)
D. V/(v_r + v)
Answer : B

37. 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

38. If the ratios of all the corresponding linear dimensions are equal, then the model and the prototype are said to have
A. Geometric similarity
B. Kinematic similarity
C. Dynamic similarity
D. None of these
Answer : A

39. A double overhung Pelton wheel has
A. Two jets
B. Two runners
C. Four jets
D. Four runners
Answer : B

40. Multistage centrifugal pumps are used to obtain
A. High discharge
B. High head
C. Pumping of viscous fluids
D. High head and high discharge
Answer : B

41. Indicator diagram of a reciprocating pump is a graph between
A. Flow vs. swept volume
B. Pressure in cylinder vs. swept volume
C. Flow vs. speed
D. Pressure vs. speed
Answer : B

42. 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

43. Which of the following statement is correct?
A. In an impulse turbine, the water impinges on the buckets with pressure energy.
B. In a reaction turbine, the water glides over the moving vanes with kinetic energy.
C. In an impulse turbine, the pressure of the flowing water remains unchanged and is equal to atmospheric pressure.
D. In a reaction turbine, the pressure of the flowing water increases after gliding over the vanes.
Answer : C

44. Air vessels in reciprocating pump are used to
A. Smoothen flow
B. Reduce acceleration to minimum
C. Increase pump efficiency
D. Save pump from cavitations
Answer : B

45. The unit discharge through the turbine is
A. Q/?H
B. Q/H
C. Q/H^3/2
D. Q/H²
Answer : A

46. One horsepower is equal to
A. 102 watts
B. 75 watts
C. 550 watts
D. 735 watts
Answer : D

47. Discharge of a centrifugal pump is
A. Directly proportional to diameter of its impeller
B. Inversely proportional to diameter of its impeller
C. Directly proportional to (diameter)² of its impeller
D. Inversely proportional to (diameter)² of its impeller
Answer : D

48. Axial flow pump is started with its delivery valve
A. Kept fully closed
B. Kept fully open
C. Irrespective of any position
D. Kept 50% open
Answer : B

49. The mechanical efficiency of an impulse turbine is
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 : B

50. 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 discharge of wheel is
A. 0.25 m³/s
B. 0.5 m³/s
C. 1.5 m³/s
D. 2.5 m³/s
Answer : A