compressors gas turbines and jet engines MCQs – Page 5

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
81. The following property is most important for material used for gas turbine blade___________________?
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A. bulk modulus

B. toughness

C. fatigue

D. corrosion resistance

E. creep
82. Propulsive efficiency is defined as ratio of___________________?
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A. thrust power and fuel energy

B. thrust power and propulsive power

C. propulsive power and fuel input

D. none of the above

E. engine output and propulsive power

83. After-cooler is used to__________________?
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A. increase pressure

B. decrease the delivery temperature for ease in handling

C. cool the air

D. cause moisture and oil vapour to drop out

E. reduce volume

84. In multistage compressor, the isothermal compression is achieved by_________________?
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A. by running compressor at very slow speed

B. employing intercooler

C. by constantly cooling the cylinder

D. none of the above

E. by insulating the cylinder

85. Air-fuel ratio in a jet engine will be of the order of__________________?
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A. 20:01

B. 100:00:00

C. 60 : 1

D. 15:01

E. 10:01

86. The pressure ratio of an ideal vaned compressor with increase in mass flow rate_________________?
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A. remains constant

B. first decreases and then increases

C. unpredictable

D. decreases

E. increases

87. Which is false statement about multistage compression ?
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A. Outlet temperature is reduced

B. It is best suited for compression ratios around 7:1

C. Power consumption per unit of air delivered is low

D. Volumetric efficiency is high

E. The moisture in air is condensed in the intercooler

88. The power available for take off and climb in case of turbojet engine as compared to reciprocating engine is ___________________?
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A. more

B. less

C. same

D. unpredictable

E. may be less or more depending on ambient conditons

89. Which of the following fuels can be used in turbojet engines _____________________?
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A. liquid hydrogne

B. high speed diesel oil

C. kerosene

D. demethylated spirit

E. methyl alcohol

90. The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called__________________?
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A. pressure coefficient

B. degree of reaction

C. slip factor

D. pressure ratio

E. stage factor

91. The thermal efficiency of a gas turbine as compared to a diesel plant is__________________?
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A. less

B. depends on other factors

C. same

D. unpredictably

E. more

92. The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will___________________?
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A. none of the above

B. first increase, reach maximum and then decrease

C. increase first at slow rate and then fast

D. increase first at fast rate and then slow

E. decrease continuously

93. Turbofan engine employs ____________________ ?
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A. two or more air streams

B. rocket principle for its operation

C. one air stream

D. solid fuel firing

E. no air stream

94. As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio_____________________?
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A. first increases and then decreases

B. remains same

C. decreases

D. first decreases and then increases

E. increases
95. The effective power of gas turbines is increased by adding the following in compressor__________________?
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A. hydrogen

B. ammonia and water vapour

C. none of the above

D. nitrogen

E. carbon dioxide

96. In gas turbines^ high thermal efficiency is obtained in_________________?
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A. closed cycle

B. open cycle

C. both of the above

D. closed/open depending on other con-siderations

E. unpredictable

97. The main purpose of reheating in gas turbine is to__________________?
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A. increase pressure ratio

B. increase power output

C. reduce turbine size

D. increase speed

E. increase temperature

98. Mining industry usually employs following motive power___________________?
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A. diesel engine

B. D.C. electric motor

C. compressed air

D. A.C. electric motor

E. petrol engine

99. The net work input required for compressor with increase in clearance volume_____________________?
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A. unpredictable

B. remains same

C. increases

D. increases/decreases depending on com-pressor capacity

E. decreases

100. Ram-jet engine__________________?
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A. is self-operating at zero flight speed

B. is not self-operating at zero^flight speed

C. none of the above

D. requires no air for its operation

E. produces a jet consisting of plasma