  # Turbo Machines MCQ's with answers - part 1

## SET 1 of Turbo Machines MCQs

Q.no 1. The relative velocity is obtained by the equation_________, if V is the Velocity of Jet and U is the velocity of the Plate.
A : V-U
B : VxU
C : V/U
D : U/V

Q.no 2. 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 : Tangential flow impulse turbine

Q.no 3. Specific speed of a turbo-machine
A : relates the shape rather than the size of the machine
B : remains unchanged under different conditions of operation
C : has the dimensions of rotational speed
D : is the speed of a machine having unit dimensions.

Answer:-A : relates the shape rather than the size of the machine

Q.no 4. The undershot water wheels are those in which
A : The wheel runs entirely by the weight of water
B : The wheel runs entirely by the impulse of water
C : The wheel runs partly by the weight of water and partly by the impulse of water
D : None of these

Answer:-B : The wheel runs entirely by the impulse of water

Q.no 5. The runner passages of a reaction turbine are
A : partially filled with water
B : always completely filled with water
C : never filled with water
D : None of these.

Answer:-B : always completely filled with water

Q.no 6. Which of the following turbines is suitable for specific speed ranging from 300 to 1000 and heads below 30 m:
A : Kaplan turbine
B : Propeller
C : Francis turbine
D : Pelton wheel

Q.no 7. In a velocity triangle absolute velocity at inlet V1 has two components, Vf1 and ________
A : Vf2
B : Vw1
C : Vw2
D : Vri

Q.no 8. Francis turbine is
A : A reaction radial flow turbine
B : An axial flow turbine
C : A radial flow turbine
D : An impulse turbine

Q.no 9. Mass of 1 litre of water is equivalent to
A : 10 Kg
B : 100 Kg
C : 1000 Kg
D : 1000 gm

Q.no 10. In a francis turbine the gross head on the turbine is 170 m. net head is 110 m. Determine head lost due friction.
A : 60 m
B : 16.2 m
C : 23.4 m
D : 135.6 m

## SET 1 of Turbo Machines MCQs

Q.no 11. 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

Q.no 12. In a velocity triangle at outlet, if angle β is 90 degrees , then Vf2= _________
A : U2
B : Vw2
C : V2
D : None

Q.no 13. 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

Q.no 14. Centrifugal pump is
A : power producing device
B : power absorbing device
C : Both power producing and power absorbing machine
D : none

Q.no 15. An impulse turbine is used for
A : Low head of water
B : High head of water
C : Medium head of water
D : High discharge

Q.no 16. The width of the bucket for a Pelton wheel is generally …………… the diameter of jet.
A : Double
B : Three time
C : Four times
D : Five times

Q.no 17. The equation F. dt = d (mv) is called as
A : Impulse momentum equation
B : Impulse reaction principle
C : Newton’s second law of motion.
D : None of these

Q.no 18. The value of speed ratio (Ku) in case of a Francis turbine ranges from
A : 0.2 to 0.3
B : 0.4 to 0.5
C : 0.6 to 0.9
D : None of these

Q.no 19. Which of the following serious problems arise from cavitation?
A : Noise and vibration.
B : Damage to blade surface.
C : Fall in efficiency.
D : All of the above.

Answer:-D : All of the above.

Q.no 20. For 450 m head of water, _________ shall be used.
A : Pelton wheel
B : Kaplan turbine
C : Francis turbine
D : None of these