Hydraulic Machines-Fluid Machineries - Set 06 - ObjectiveBooks

# Practice Test: Question Set - 06

1. The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. 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 mixed flow at outlet

2. Reaction turbines are used for
(C) High head and low discharge
(D) Low head and high discharge

3. 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

4. A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the

5. 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

6. 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) Work-done on the wheel to the energy (or head of water) actually supplied to the turbine
(D) None of the above

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

8. Casting of a centrifugal pump is designed so as to minimize
(A) Friction loss
(B) Cavitations
(D) Loss of kinetic energy

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

10. According to fan laws, at constant speed and capacity, the pressure 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

11. The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as
(A) Manometric efficiency
(B) Mechanical efficiency
(C) Overall efficiency
(D) Volumetric efficiency

12. Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet, and Vf = Velocity of flow at inlet)
(A) Q = π.D.Vf
(B) Q = π.b.Vf
(C) Q = π.D.bf.V
(D) Q = D.b.Vf

13. Multistage centrifugal pumps are used to obtain
(A) High discharge
(C) Pumping of viscous fluids
(D) High head and high discharge

14. 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

15. 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

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