# Turbo Machines MCQs with answers - Part 2

This sets of MCQ's contains objective on turbo machines with answers for preparation of your exams in part 2....

## SET 1 of turbo machines mcqs

Q.no 1. Governing mechanism used in case of Pelton wheel turbine is ________
A : Guide vane
B : Nozzle & Spear
C : Control valve
D : Dam gates

Q.no 2. 1 Newton force is Equivalent to
A : 10 dyne
B : 100 dyne
C : 1000 dyne
D : None of these

Q.no 3. Cavitation damage in turbine runner occurs near
the
A : inlet on the convex side of blades
B : outlet on the convex side of blades
C : inlet on the concave side of blades
D : outlet on the concave side of blades.

Q.no 4. The ratio of power developed by the runner to the power supplied at entrance of the turbine is known as
A : hydraulic efficiency
B : mechanical efficiency
C : volumetric efficiency
D : overall efficiency

Q.no 5. Which of the following statement is correct?
A :  In an impulse turbine, the water impinges on the bucket 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 : In an impulse turbine, the pressure of the flowing water remains unchanged and is equal to atmospheric pressure

Q.no 6. A turbo-machine becomes more susceptible to
cavitation if
A : velocity attains a high value
B : pressure become very high
C : temperature rises above the critical value
D : pressure falls below the vapour pressure.

Answer:-D : pressure falls below the vapour pressure.

Q.no 7. The mechanical efficiency of an impulse turbine is
A : ratio of the actual power developed 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 these

Answer:-B : ratio of the actual work available at the turbine to the energy imparted to the wheel

Q.no 8. The pressure of water is atmospheric and remains constant while
passing over the runner in
A : Impulse turbine
B : Reaction turbine
C : both in impulse and reaction turbines
D : None of these

Q.no 9. In a reaction turbine the function of a draft tube
is to
A : provide safety to turbine
B : prevent air from entering
C : reconvert the kinetic energy to flow energy
D : increase the rate of flow.

Answer:-C : reconvert the kinetic energy to flow energy

Q.no 10. In a velocity triangle at outlet, if angle β is 90 degrees , then Vw2=
_________
A : zero
B : more than zero
C : less than zero
D : none

## SET 1 of turbo machines mcqs

Q.no 11. Component of velocity in direction of jet is given by VCosθ. What does ‘θ’ indicate?
A : Angle made by jet
B : Angle made by jet and outlet tip
C : Angle made by jet and inlet tip
D : Tangent angle

Q.no 12. Mass of water striking per second , for a series of flat plates mounted on
drum is _______
A : ρaV
B : ρa(V-u)
C : ρa( V-u)/2
D : ρaV/2

Q.no 13. The ratio of the normal force of jet of water on a plate inclined at an
angle θ= 30 degrees as compared to that when the plate is normal to the jet, is
A : 0.707
B : 0.5
C : 2
D : 1.41

Q.no 14.  What is the formula to calculate specific speed (Ns) of a turbine rotating
at a speed of 'N' rpm that develops the power of 'P' kW at the heat of 'H' m?
A :  (Ns) = (√N x P) x (H)(5/4)
B :  (Ns) = (2 √N x P) x (H)(5/4)
C : (Ns) = (N √P) / (H)(5/4)
D : (Ns) = (2N √P) x (H)(5/4)

Answer:-C : (Ns) = (N √P) / (H)(5/4)

Q.no 15. when a jet of water strikes a vertical hinged plate, the angle of swing
about the hinge is given by ______________. Where, V=Velocity of the jet of water and
W= weight of the hinged plate
A : Sinθ= ρAV2/W
B : Cosθ= ρAV2/W
C : Tanθ= ρAV2/W
D : None of these

Q.no 16. A reaction turbine works under a head of 60 m. Assuming speed ratio as 0.6, find tangential vlocity of blade.
A : 42.18 m/s
B : 20.58 m/s
C : 6.79 m/s
D : 6.58 m/s

Q.no 17. The maximum number of jets, generally, employed in an impulse turbine without jet interference are
A : Two
B : Four
C : Six
D : Eight

Q.no 18. The jet ratio of a pelton wheel lies between
A : 3 to 5
B : 6 to 10
C : 11 to 14
D : 20 to 25

Q.no 19. The force exerted (in Newton) by a jet of water impinging normally on a fixed plate is
A : ρav
B : ρav2
C : ρav/2
D : 2ρav

Q.no 20. The speed factor (speed ratio) of a pelton turbine for its efficient operation lies in the range
A : 0.43 -0.47
B : 0.8 -0.9
C : 0.96 -0.98
D : 1.2-1.4