250+ TOP MCQs on Steam Turbines Basics – II and Answers

Power Plant Questions and Answers for Entrance exams on “Steam Turbines Basics – II”.

1. The ratio of the work done on the blades to the energy supplied to the blades is called ____________
a) gross or stage efficiency
b) blading efficiency
c) nozzle efficiency
d) mechanical efficiency
Answer: b
Clarification: Blading Efficiency is the ratio of work done on the blades to the energy supplied to the blades of a turbine.

2. A nozzle is said to be a convergent nozzle when?
a) the cross-section of the nozzle increases continuously from entrance to exit
b) the cross-section of the nozzle decreases continuously from entrance to exit
c) the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
d) none of the mentioned
Answer: b
Clarification: In case of a convergent nozzle, the cross-section of the nozzle decreases continuously from entrance to exit.

3. Multi-stage steam turbines are of the ___________
a) reaction type
b) velocity compounded type
c) pressure compounded type
d) all of the mentioned
Answer: d
Clarification: There are various types of multi-stage steam turbines which are, reaction; velocity compounded; & pressure compounded, respectively.

4. The impulse reaction turbine has its driving force ___________
a) partly as an impulsive force and partly as a reaction force
b) as an impulsive force
c) as a reaction force
d) none of the mentioned
Answer: a
Clarification: The impulse reaction turbine has its driving force partly as an impulsive force & partly as a reaction force as the components add to the resultant.

5. In a nozzle, whole frictional loss is assumed to occur between ___________
a) inlet and throat
b) throat and exit
c) inlet and outlet
d) none of the mentioned
Answer: b
Clarification: In a nozzle, whole frictional loss is assumed to occur between the throat & exit of the nozzle.

6. The ratio of total useful heat drop to the total isentropic heat drop is called?
a) Rankine efficiency
b) Stage efficiency
c) Internal efficiency
d) None of the mentioned
Answer: c
Clarification: The ratio of total useful heat drop to the total isentropic heat drop is called internal efficiency.

7. What is the action of steam in a steam turbine?
a) neither static nor dynamic
b) dynamic
c) static
d) both dynamic & static
Answer: b
Clarification: Steam action in a steam turbine is Dynamic.

8. The critical pressure gives the velocity of steam at the throat ___________
a) equal to the velocity of sound
b) more than velocity of sound
c) less than the velocity of light
d) none of the mentioned
Answer: a
Clarification: The critical pressure gives the velocity of steam at the throat which is equal to the velocity of sound.

9. The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be ___________
a) 0.67
b) 0.4
c) 0.5
d) 0.56
Answer: a
Clarification: The required degree of reaction will be 0.67.

10. The flow through a nozzle is regarded as ___________
a) isothermal flow
b) isobaric flow
c) isochoric flow
d) isentropic flow
Answer: d
Clarification: The flow through a nozzle is regarded as isentropic flow.

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