Hydraulics & Fluid Machineries 1000+ MCQ with answer for SSC MTS

1. In an outward 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 : B

2. In a Kaplan turbine runner, the numbers of blades are generally between
A. 2 to 4
B. 4 to 8
C. 8 to 16
D. 16 to 24
Answer : B

3. Which of the following pump is successfully used for lifting water to the turbines?
A. Centrifugal pump
B. Reciprocating pump
C. Jet pump
D. Air lift pump
Answer : C

4. The working of which of the following hydraulic units is based on Pascal's law?
A. Air lift pump
B. Jet pump
C. Hydraulic coupling
D. Hydraulic press
Answer : D

5. Casting of a centrifugal pump is designed so as to minimize
A. Friction loss
B. Cavitations
C. Static head
D. Loss of kinetic energy
Answer : D

6. The ratio of actual work available at the turbine to the energy imparted to the wheel is known as ________ efficiency.
A. Hydraulic
B. Mechanical
C. Overall
D. None of these
Answer : B

7. The optimum value of vane exit angle for a centrifugal pump impeller is
A. 10-15°
B. 20-25°
C. 30-40°
D. 50-60°
Answer : B

8. The unit power developed by a turbine is (where P = Power developed by the turbine under a head of water (H).
A. P/ ?H
B. P/ H
C. P/ H^3/2
D. P/ H²
Answer : C

9. 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

10. By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. The saving in case of a double acting reciprocating pump is
A. 39.2 %
B. 48.8 %
C. 84.8 %
D. 88.4 %
Answer : A

11. 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

12. 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

13. 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

14. 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

15. In centrifugal pumps, maximum efficiency is obtained when the blades are
A. Straight
B. Bent forward
C. Bent backward
D. Radial
Answer : C

16. Which of the following pump is suitable for small discharge and high heads?
A. Centrifugal pump
B. Axial flow pump
C. Mixed flow pump
D. Reciprocating pump
Answer : D

17. Specific speed for reaction turbines ranges from
A. 0 to 4.5
B. 10 to 100
C. 80 to 200
D. 250 to 300
Answer : B

18. 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

19. The force exerted (in Newton) by a jet of water impinging normally on a fixed plate is (where w = Specific weight of water in N/m3, a = Crosssectional area of jet in m², and V = Velocity of jet in m/s)
A. waV / 2g
B. waV / g
C. waV² / 2g
D. waV² / g
Answer : D

20. In a reaction turbine, the draft tube is used
A. To run the turbine full
B. To prevent air to enter the turbine
C. To increase the head of water by an amount equal to the height of the runner outlet above the tail race
D. To transport water to downstream
Answer : C

21. 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

22. 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

23. A ship with jet propulsion draws water through inlet orifices at right angles to the direction of its motion. The propelling force of the jet is (where a = Area of the jet, Vr = Relative velocity of the jet and ship = V + v, v = Velocity of the ship, and V = Velocity of the jet issuing from the ship)
A. waVr /g × (Vr + v)
B. waVr /g × (Vr - v)
C. waVr /g × (Vr + v)²
D. waVr /g × (Vr - v)²
Answer : B

24. The cavitation in reaction turbines is avoided, to a great extent by
A. Installing the turbine below the tail race level
B. Using stainless steel runner of the turbine
C. Providing highly polished blades to the runner
D. All of the above
Answer : D

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

26. 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

27. In impulse Turbine, energy available at the inlet is in the form of
A. Potential Energy
B. Strain Energy
C. Kinetic energy
D. None of these
Answer : C

28. Reaction turbines are used for
A. Low head
B. High head
C. High head and low discharge
D. Low head and high discharge
Answer : D

29. A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ________ of the jet velocity
A. One-half
B. One-third
C. Two-third
D. Three-fourth
Answer : B

30. The function of guide vanes in a reaction turbine is to
A. Allow the water to enter the runner without shock
B. Allow the water to flow over them, without forming eddies
C. Allow the required quantity of water to enter the turbine
D. All of the above
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. Which of the following hydraulic unit is used for transmitting increased or decreased torque to the driven shaft?
A. Hydraulic ram
B. Hydraulic intensifier
C. Hydraulic torque converter
D. Hydraulic accumulator
Answer : C

33. The overall efficiency for a Pelton wheel lies between
A. 0.50 to 0.65
B. 0.65 to 0.75
C. 0.75 to 0.85
D. 0.85 to 0.90
Answer : D

34. 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

35. Which of the following turbine is preferred for 0 to 25 m head of water?
A. Pelton wheel
B. Kaplan turbine
C. Francis turbine
D. None of these
Answer : B

36. In a centrifugal pump casing, the flow of water leaving the impeller, is
A. Rectilinear flow
B. Radial flow
C. Free vortex motion
D. Forced vortex
Answer : C

37. 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

38. In reaction turbine, draft tube is used
A. To transport water downstream without eddies
B. To convert the kinetic energy to flow energy by a gradual expansion of the flow cross-section
C. For safety of turbine
D. To increase flow rate
Answer : B

39. 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
A. Same quantity of liquid
B. 0.75 Q
C. Q/0.75
D. 1.5 Q
Answer : A

40. 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

41. 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

42. If the net positive suction head (NPSH) requirement for the pump is not satisfied, then
A. No flow will take place
B. Cavitation will be formed
C. Efficiency will be low
D. Excessive power will be consumed
Answer : B

43. 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

44. In a centrifugal pump casing, the flow of water leaving the
A. Radial
B. Axial
C. Centrifugal
D. Vortex
Answer : D

45. 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

46. 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

47. 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

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

49. 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

50. A hydraulic accumulator normally consists of
A. Two cylinders, two rams and a storage device
B. A cylinder and a ram
C. Two coaxial rams and two cylinders
D. A cylinder, a piston, storage tank and control valve
Answer : B