Steam and Gas Turbines Multiple Choice Questions on “Nozzle Losses and Shock Waves”.
1. Coefficient of velocity of nozzle is _______________
a) theoretical velocity/Actual velocity
b) actual velocity/Theoretical velocity
c) it is an experimental value
d) none of the mentioned
Answer: b
Clarification: Coefficient of velocity is the ratio of actual velocity to theoretical velocity.
2. Coefficient of discharge of Nozzle is _______
a) Cd = Cc/Cv
b) Cd = Cc*Cv
c) Cd = Cv/Cc
d) None of the mentioned
Answer: b
Clarification: Coefficient of discharge is the product of coefficient of velocity and coefficient of contraction.
3. Coefficient of contraction is the__________
a) ratio of Actual cross sectional area to geometric cross sectional area
b) ratio of geometric cross sectional area to actual cross sectional area
c) ratio of pressure exerted to cross sectional area
d) none of the mentioned
Answer: a
Clarification: Coefficient of contraction is the factor with which the fluid contracts inside the nozzle.
4. Viscous losses takes place in nozzle.
a) False
b) True
Answer: b
Clarification: Velocity coefficient is included because of viscous losses in nozzle.
5. Momentum loss takes place in Nozzle.
a) True
b) False
Answer: a
Clarification: When fluid is transferring from convergent to divergent or reverse then its momentum might be lost.
6. Pressure loss occurs in nozzle due to __________
a) due to viscous force
b) when fluid flows from convergent to divergent
c) frictional forces
d) none of the mentioned
Answer: c
Clarification: Pressure losses occurs when fluid flows from convergent to divergent.
7. Head loss in nozzles occurs due to __________
a) pipes head loss
b) pressure loss
c) friction loss
d) none of the mentioned
Answer: a
Clarification: Head losses in nozzles are due to pipelines.
8. Minimum jet area that can be visible downstream is called vena contracta.
a) False
b) True
Answer: b
Clarification: Vena contrata is the minimum jet area visible down stream.
9. Viscous effect of fuel is measured in terms of __________
a) Nusselt’s number
b) Prandtl number
c) Reynold’s number
d) None of the mentioned
Answer: c
Clarification: Reynold’s number is the measure of viscous force.
10. At vena contracta the velocity is _________ and pressure is ___________
a) lowest, highest
b) highest, highest
c) highest, lowest
d) none of the mentioned
Answer: c
Clarification: At vena contracta the velocity will be highest and its pressure will be lowest.
11. When flow converts from supersonic to subsonic then __________ is produced.
a) shock wave
b) pressure drop
c) shock wave & pressure drop
d) none of the mentioned
Answer: a
Clarification: Shock waves are produced when flow changes suddenly from supersonic to subsonic.
12. Shock wave causes instantaneous _________ to the subsonic speed.
a) increase
b) decrease
c) remains constant
d) none of the mentioned
Answer: b
Clarification: Shock waves are produced due to more back pressures which indirectly reduces the subsonic speeds.
13. Region of supersonic acceleration is ________ by shock wave.
a) terminated
b) increased
c) decreased
d) none of the mentioned
Answer: a
Clarification: Due to shock waves subsonic speeds are decreased hence terminating the supersonic region.