compressors gas turbines and jet engines MCQs – Page 3

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

41. Pick up the correct statement?
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A. thrust in turbo-jet is produced by nozzle exit gases

B. gas turbine uses same working fluid over and over again

C. closed cycle gas turbine is an I.C engine

D. ideal efficiency of closed cycle gas turbine plant is more than carnot cycle efficiency

E. air-fuel ratio in a gas turbine is 100 : 1

42. The ratio of isentropic work to Euler work is known as_____________________?
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A. work coefficient

B. compressor efficiency

C. pressure coefficient

D. polytropic reaction

E. slip factor

43. The compressor performance at higher altitude compared to sea level will be _______________?
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A. same

B. none of the above

C. dependent on other factors

D. lower

E. higher

44. The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio_____________________?
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A. increases

B. decreases

C. remains same

D. first decreases and then increases

E. first increases and then decreases

45. In the axial flow gas turbine, the work ratio is the ratio of____________________?
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A. compressor work and turbine work

B. actual compressor work and theoretical comprssor work

C. actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet

D. output and input

E. none of the above

46. Reciprocating air compressor is best suited for___________________?
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A. large quantity of air at low pressure

B. small quantity of air at low pressure

C. small quantity of air at high pressure

D. any one of the above

E. large quantity of air at high pressure

47. Separators in compressor installations are located_____________________?
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A. after receiver

B. before suction

C. before intercooler

D. after intercooler

E. between after-cooler and air receiver

48. The indicated work per unit mass of air delivered is___________________?
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A. inversely proportional to clearance volume

B. directly proportional to clearance volume

C. not affected by clearance volume

D. greatly affected by clearance volume

49. The ratio of work doen per cycle to the swept volume in case of compressor is called ______________?
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A. mean effective pressure

B. compressor effectiveness

C. compression index

D. compressor efficiency

E. compression ratio

50. Maximum work is done in compressing air when the compression is_________________?
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A. adiabatic

B. any one of the above

C. isothermal

D. polytropic

E. none of the above

51. The criterion of the thermodynamic efficiency for rotary compressor is_________________?
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A. polytropic compression

B. isentropic compression

C. isothermal compression

D. any one of the above

E. none of the above

52. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is____________________?
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A. bled gas from turbine is heated and readmitted for complete expansion

B. compressed air before entering the combustion chamber is heated

C. exhaust gases drive the compressor

D. heated

E. part of exhaust gases are heated and mixed up with atmospheric air to utilise exhaust heat

53. The fuel consumption in gas turbines is accounted for by___________________?
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A. higher heating value

B. heating value

C. highest calorific value

D. low.er heating value

E. higher calorific value

54. What will be the volume of air at 327C if its volume at 27C is 1.5 m3/mt ?
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A. 3 m3/mt

B. 18 m3/mt

C. 0.75 m3/mt

D. 1.5 m3/mt

E. 6 m3/mt

55. Which is false statement about advantages of multistage compressor in comparison to single stage compressor_________________?
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A. less power requirement

B. less loss of air due to leakage past the cylinder

C. better mechanical balance

D. more effective lubrication

E. lower volumetric efficiency

56. For minimum work in multistage compression, assuming same index of compression in all stages_________________?
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A. work done in first stage should be more

B. work done in subsequent stages should decrease

C. work done in any stage is no criterion for minimum work but depends on other factors

D. work done in all stages should be equal

E. work done in subsequent stages should increase

57. A rocket works with maximum overall efficiency when air craft velocity is equal to the_________________?
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A. no such co-relationship with jet velocity exists

B. jet velocity

C. average of the jet velocity

D. twice the jet velocity

E. half the jet velocity

58. Isothermal compression though most efficient, but is not -practicable because_________________?
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A. it does not increase pressure much

B. it requires cylinder to be placed in water

C. it is impossible in practice

D. ityrequires very big cylinder

E. compressor has to run at very slow speed to achieve it

59. Pick up the wrong statement ?
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A. ramjet-engine has no turbine

B. bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

C. pulsojet requires no ambient air for propulsion

D. propeller is an indirect reaction device

E. turbine drives compressor in a burbojet

60. Intercooling in gas turbine results in ____________________ ?
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A. increase in net output but decrease in thermal efficiency

B. increase in thermal efficiency but decrease in net output

C. increase in both thermal efficiency and net output

D. decrease in both thermal efficiency and net output

E. none of the above

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