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compressors gas turbines and jet engines MCQs

Practise focused compressors gas turbines and jet engines questions with marked answers for exam preparation and subject revision.

compressors gas turbines and jet engines Mcqs
1. Compression efficiency is compared against_____________________?
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A. isothermal compression

B. adiabatic compression

C. isentropic compression

D. botii isothermal and adiabatic compression

E. ideal compression

2. During peak load periods, the best method of controlling compressors is___________________?
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A. constant speed unloader

B. relief valve

C. start-stop motor

D. variable speed

E. none of the above

3. Out of the following, from where you will prefer to take intake for air compressor_________________?
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A. from any one of the above locations

B. from coal yard side

C. from outside atmosphere at 1C

D. from an air conditioned room maintained at 20C

E. from a side where cooling tower is located nearby
4. The vloumetric efficiency of compressor with increase in compression ratio will ___________________?
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A. may increase/decrease depending on clearance volume

B. increase

C. remain same

D. decrease

E. none of the above

5. Clearance volume in actual reciprocating compressors is essential __________________?
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A. to attain high volumetric efficiency

B. to provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

C. to avoid mechanical bang of piston with cylinder head

D. to provide cushioning effect

E. to accommedate Valves in the cylinder head

6. There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would__________________?
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A. remain same

B. decrease

C. unpredictable

D. none of the above

E. increase
7. Surging is the phenomenon of___________________?
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A. air stream blocking the passage

B. unsteady, periodic and reversed flow

C. air stream not able to follow the blade contour

D. production of no air pressure

E. motion of air at sonic velocity

8. In turbo fan engine, the jet velocity as compared to turbo-jet engine is_________________?
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A. may be less or more depening upon speed

B. less

C. same

D. none of the above

E. more

9. A closed gas turbine in which fuel is burnt directly in the air is not possible because of__________________?
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A. high friction losses

B. paucity of 02

C. high pressure ratio

D. high specific volume

E. increasing gas temperature

10. The ideal efficiency of simple gas turbine cycle depends on________________?
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A. minimum cycle temperature

B. maximum cycle temperature

C. none of the above

D. all of the above

E. pressure ratio
11. The thrust on the rotor in a centrifugal compressor is produced by________________?
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A. resultant component

B. tangential component

C. axial component

D. radial component

12. Axial flow compressor resembles____________________ ?
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A. none of the above

B. turbine

C. centrifugal pump

D. reciprocating pump

E. sliding vane compressor

13. Producer gas is produced by_____________________?
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A. passing steam over incandescent coke

B. passing air and a large amount of steam over waste coal at about 65C

C. carbonisation of coal

D. same way as the natural gas

E. partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
14. A gas turbine used in air craft should have______________________?
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A. high h.p. and low weight

B. high speed and high h.p.

C. small frontal area and high h.p.

D. all of the above

E. low weight and small frontal area
15. Reheating in multistage expansion gas turbine results in____________________?
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A. decrease of heat loss in exhaust

B. none of the above

C. maximum work output

D. high thermal efficiency

E. reduction in compressor work

16. High air-fuel ratio is used in gas turbines______________________?
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A. to save fuel

B. to reduce the exit temperature

C. to increase the efficiency

D. to increase the output

E. none of the above

17. The efficiency and work ratio of a gas turbine plant can be increased by _____________________?
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A. all of the above

B. using mulit-stage compressor with mfercooler

C. adding heat exchanger

D. reheating the air after partial expansion in the turbine

E. injecting water in/around combustion chamber

18. Ram compression in turbojet involves____________________?
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A. lost work

B. increasing speed of incoming air

C. compression of inlet air

D. leakage losses

E. reduction of speed of incoming air and conversion of part of it into pressure energy
19. A compressor at high altitude will draw________________?
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A. less power

B. none of the above

C. more/less power depending on other factors

D. same power

E. more power

20. For slow-speed large capacity compressor, following type of valve will be best suited________________?
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A. none of the above

B. disc or feather type

C. poppet valve

D. mechanical valve of the corliss, sleeve, rotary or semirotary type

E. any of the above