Hydraulics & Fluid Machineries 1000+ MCQ with answer for FCI Recruitment

1. 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

2. The efficiency of jet propulsion for a ship with inlet orifices at right angles to the direction of motion of ship is given by
A. [2(V_r - v) v]/ V_r²
B. 2(V_r + v) v]/ V_r²
C. [(V_r - v) v]/ V_r
D. [(V_r + v) v]/ V_r
Answer : A

3. Any change in load is adjusted by adjusting following parameter on turbine
A. Net head
B. Absolute velocity
C. Blade velocity
D. Flow
Answer : D

4. Discharge of a centrifugal pump is (where N = Speed of the pump impeller)
A. Directly proportional to N
B. Inversely proportional to N
C. Directly proportional to N²
D. Inversely proportional to N²
Answer : A

5. Which place in hydraulic turbine is most susceptible for cavitations?
A. Inlet of draft rube
B. Blade inlet
C. Guide blade
D. Penstock
Answer : A

6. 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

7. For very high discharge at low pressure such as for flood control and irrigation applications, following type of pump is preferred
A. Centrifugal
B. Axial flow
C. Reciprocating
D. Mixed flow
Answer : B

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

9. 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

10. 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

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 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

12. 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

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

14. 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

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

16. 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

17. The gross or total head of the turbine is the ________ of the water levels at the head race and tail race.
A. Sum
B. Difference
C. Product
D. None of these
Answer : B

18. 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

19. 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

20. Which type of the pump is different from others in the same group?
A. Screw pump
B. Gear pump
C. Cam and piston pump
D. Plunger pump
Answer : D

21. 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

22. 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

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

24. Power required (in watts) to drive a centrifugal pump is (where H_m = Manometric head in metres, w = Specific weight in N/m³, Q = Discharge of the pump in m³/s, and ?_o = Overall efficiency of the pump)
A. (w H_m) / (Q × ?_o)
B. (w H_m Q) / ?_o
C. (w Q) / (H_m × ?_o)
D. (w Q ?_o) / H_m
Answer : B

25. The maximum efficiency of jet propulsion of a ship with inlet orifices at right angles to the direction of motion of ship, is
A. 40 %
B. 50 %
C. 60 %
D. 80 %
Answer : B

26. 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

27. The speed of an imaginary turbine, identical with the given turbine, which will develop a unit power under a unit head, is known as
A. Normal speed
B. Unit speed
C. Specific speed
D. None of these
Answer : C

28. 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

29. The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is
A. Slow speed with radial flow at outlet
B. Medium speed with radial flow at outlet
C. High speed with radial flow at outlet
D. High speed with axial flow at outlet
Answer : D

30. 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

31. 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

32. 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

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

34. The speed of a turbine runner 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

35. A hydraulic intensifier 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 : C

36. 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

37. The maximum number of jets generally employed in impulse turbine without jet interference is
A. 4
B. 6
C. 8
D. 12
Answer : B

38. 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

39. 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

40. 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

41. 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

42. 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

43. In a Francis 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 : D

44. 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

45. 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

46. 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

47. The specific speed of a turbine is given by the equation
A. N?P / H^3/2
B. N?P / H²
C. N?P / H^5/4
D. N?P / H³
Answer : C

48. Slip of a reciprocating pump is defined as the
A. Ratio of actual discharge to the theoretical discharge
B. Sum of actual discharge and the theoretical discharge
C. Difference of theoretical discharge and the actual discharge
D. Product of theoretical discharge and the actual discharge
Answer : C

49. A hydraulic accumulator is a device used to store ________ energy which may be supplied to a machine later on.
A. Strain
B. Pressure
C. Kinetic
D. None of these
Answer : B

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