  # Turbo Machines MCQs with answers - Part 5

This sets of MCQ's contains objective on turbo machines with answers for preparation of your exams in part 5....

Q.no 1. In a velocity triangle absolute velocity at inlet V2 has two components, Vf2 and Vw2, Vf2 is called as __________
A : Velocity of whirl at inlet
B : Velocity of flow at exit
C : Velocity of vane at inlet
D : Velocity of Whirl at at exit

Answer:-B : Velocity of flow at exit

Q.no 2. The force analysis on a curved vane is understood using______
A : Velocity triangles
B : Angle of the plate
C : Vane angles
D : Plate dimensions

Q.no 3. In a velocity triangle absolute velocity at inlet V1 has two components,
Vf1 and Vw1. Vw1 is called as __________
A : Velocity of whirl at inlet
B : Velocity of flow at inlet
C : Velocity of vane at inlet
D : Velocity of flow at exit

Answer:-A : Velocity of whirl at inlet

Q.no 4. In force exerted by jet on seroes of radial curves vanes, angle β is called_________
A : guide vane angle at inlet
B : moving vane angle at inlet
C : angle made absolute velocity at exit
D : moving vane angle at exit

Q.no 5. Critical value of cavitation factor (σc) is givenby:
A : ((Ha+Hv)-Hs)/H
B : ((Ha- Hv)+Hs)/H
C : ((Ha- Hv)-Hs)/H
D : ((Ha + Hv) + Hs)/H

Q.no 6. The force exerted by a jet impinging normally on a stationary fixed plate is
A : (ρAV)/4
B : (ρAV)
C : (ρAV2)/4
D : (ρAV2)

Q.no 7. The force exerted by a jet in the direction of jet impinging on a stationary fixed plate inclined at an angle θ with the jet is
A : ρAVsinθ
B : ρAVsin2θ
C : ρAV2sin2θ
D : ρAV2sinθ

Q.no 8. The value of flow ratio (Kf) in case of a Francis turbine varies from:
A : 0.1 to 0.14
B : 0.15 to 0.30
C : 0.35 to 0.5
D : 0.6 to 0.9

Q.no 9. What is runaway speed of the runner of Pelton wheel?
A : Maximum unsafe speed of the runner due to sudden increase in load on turbine
B : Minimum safe speed of the runner due to sudden increase in load on turbine
C : Maximum unsafe speed of the runner due to sudden decrease in load on turbine
D : Minimum safe speed of the runner due to sudden decrease in load on turbine

Answer:-C : Maximum unsafe speed of the runner due to sudden decrease in load on turbine

Q.no 10. Which of the following is an example of impulse turbine?
A : Propeller turbine
B : Francis turbine
C : Kaplan turbine
D : Pelton wheel

Q.no 11. A reaction turbine with overall efficiency 92 % developes power 405 kW. Find the power supplied to the turbine.
A : 140.86 kW
B : 959.67 kW
C : 440.21 kW
D : 180.48 kW

Q.no 12. A Francis turbine supplied through a 6 m diameter penstock has the following particulars : Discharge = 117 m3/s, Mean diameter of turbine at inlet = 4 m, Mean blade width at entry = 1 m . Determine Velocity of flow at inlet.
A : 4.46 m/s
B : 2.79 m/s
C : 12.84 m/s
D : 9.31 m/s

Q.no 13. A turbine develops 10000 kW under a head of 25 metres at 135 r.p.m. Its specific speed is
A : 175.4 rpm
B : 215.5 rpm
C : 241.5 rpm
D : 275.4 rpm

Q.no 14. In force exerted by jet on seroes of radial curves vanes, angle ϴ is called_________
A : guide vane angle at inlet
B : moving vane angle at inlet
C : angle made absolute velocity at exit
D : moving vane angle at exit

Answer:-B : moving vane angle at inlet

Q.no 15. Depth of Pelton wheel bucket lies between____ Where d is diameter of jet
A : 0.6 to 1.0 d
B : 0.8 d to 1.2 d
C : 1.0 d to 1.2 d
D : 1.5 d to 2. 0 d

Answer:-B : 0.8 d to 1.2 d

Q.no 16. Turbo Machines are
A : power producing devices
B : power absorbing devices
C : Both power producing and power absorbing devices
D : none

Answer:-C : Both power producing and power absorbing devices

Q.no 17. The overall efficiency for the 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 18. The runaway speed of a hydraulic turbine is the speed
B : At which there will be no damage to the runner
C : Corresponding to maximum overload permissible
D : At which the turbine will run freely without load

Q.no 19. Which component of fluid velocity is responsible for transmission of power through rotodynamic machine.
B : Axial
C : Tangential
D : None of these

Q.no 20. Gross head is the difference between __________.
A : head race and tail race
C : head race and friction losses
D : net head and friction losses

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