SECTION -3 
COMPRESSORS, GAS TURBINES AND JET ENGINES MCQ

 

 
Q11. The volumetric efficiency of a compressor, for the same compression ratio, will increase if the index of compression (n) is

(a) increased 
(b) decreased 
(c) constant 
(d) none of the above. 

Ans:(d) none of the above.

 

Q12. For the least work to be done on a compressor, the compression should be

(a) adiabatic 
(b) isothermal 
(c) polytropic 
(d) none of the above.

Ans:(b) isothermal

 

Q13. For a two-stage compressor, for maximum efficiency the condition is that the intermediate pressure should be

(a) average of the initial and final pressure 
(b) geometric mean of initial and final pressure 
(c) product of two pressures 
(d) the ratio of two pressures. 

Ans:(b) geometric mean of initial and final pressure

 

Q14. For a two-stage compressor, the ratio of diameters of L.P. cylinder to H.P. cylinder is equal to

(a) square of the ratio of final pressure to initial pressure 
(b) the ratio of final pressure to initial pressure 
(c) the square root of the ratio of final pressure to initial pressure 
(d) cube root of the ratio of final pressure to initial pressure. 

Ans:(c) the square root of the ratio of final pressure to initial pressure

 

Q15. For a three-stage compressor for maximum efficiency, the compression ratio is equal to

(a) square of the ratio of final pressure to initial pressure 
(b) the ratio of final pressure to initial pressure 
(c) square root of the ratio of final pressure to initial pressure 
(d) cube root of the ratio of final pressure to initial pressure.

Ans:(d) cube root of the ratio of final pressure to initial pressure.

 

Q16. The phenomenon of unsteady, periodic and reversed flow is known as

(a) choking 
(b) surging 
(c) stalling 
(d) none of the above. 

Ans:(b) surging

 

Q17. The phenomenon of fixed mass flow rate in compressor regardless of pressure ratio is known as

(a) choking 
(b) surging 
(c) stalling 
(d) none of the above. 

Ans:(a) choking

 

Q18. The phenomenon of air steam not able to follow the blade contour of an axial compressor is known as

(a) choking 
(b) surging 
(c) stalling 
(d) none of the above.

Ans:(c) stalling

 

Q19. In multi-stage compressors, the air after compression in the first stage is cooled in an intercooler at constant pressure before passing into the second stage. The cooling is said to be perfect if

(a) air is cooled to a temperature more than its original temperature 
(b) air is cooled to a temperature less than its original temperature 
(c) air is cooled to its original temperature 
(d) none of the above. 

Ans:(c) air is cooled to its original temperature

 

Q20. The assumptions made for calculating the work done in multi-stage compressor are

(a) the index of compression is same in each stage 
(b) intercooling in each stage is at constant pressure 
(c) suction and delivery pressures remain constant during each stage 
(d) all of the above

Ans:(d) all of the above

 

 

 

 

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Compressors, Gas turbines and Jet Engines – Section-1
 
Compressors, Gas turbines and Jet Engines – Section-2
 
Compressors, Gas turbines and Jet Engines – Section-3
 


 

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