compressors gas turbines and jet engines MCQs – Page 4

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

61. Volumetric efficiency is_____________________?
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A. the ratio of stroke volume to clearance volume

B. reciprocal of compression ratio

C. proportional to compression ratio

D. the ratio of the air actually delivered to the amount of piston displacement

E. index of compressor performance

62. Choose the correct statement ________________?
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A. gas turbine requires lot of cooling water

B. gas turbines can be used to generate power only

C. gas turbines have high standby losses and require lot of maintenance

D. gas turbines have flat efficiency at part loads

E. gas turbine is capable of rapid start up and loading

63. Standard air is the air at_____________________?
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A. 25C, 1 kg/cm2 and RH of 60%.

B. 15C and 1 kg/cm2

C. 20C and 1 kg/cm2 and relative humidity 36%

D. 0C and standard atmospheric conditions

E. atmospheric conditions at any specific location

64. If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix i and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity______________?
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A. Vi=V0B

B. U,<V0

C. Vri=Vm

D. Vt>V0

E. V,= U0

65. For speed above 3000 km/hour, it is more advantageous to use____________________?
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A. rockets

B. turbo-jet engine

C. hydraulic jet propulsion

D. propellers

E. ram-jet engine

66. The ratio of specific weighf/h.p. of gas turbin and I.C engines may be typically of the order of_______________________?
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A. 4:01

B. 2:01

C. 1:01

D. 1 : 6

E. 1:02

67. Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is_________________?
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A. cant be compared

B. unpredictable

C. equal

D. higher

E. lower

68. Losses in a centrifugal compressor are due to__________________?
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A. diffuser losses

B. all of the above

C. inlet losses

D. none of the above

E. impeller channel losses

69. Pick up the wrong statement ?
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A. axial flow compressors have instability region of operation

B. axial flow compressors are more stable than centrifugal type compressors but not as efficient

C. axial flow compressors have high capacity and efficiency

D. large gas turbines employ axial flow compressors

E. centrifugal compressors are used mainly on low flow pressure ratio gas turbines

70. The hottest point in a gas turbine is______________________?
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A. uniformly heated

B. at the base

C. at the tip

D. between ~ to i of the blade height

E. in the center

71. As the value of index is decreased, the volumetric efficiency will___________________?
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A. may increase/decrease depending on compressor clearance

B. decrease

C. remain unaffected

D. increase

E. none of the above

72. Water gas is produced by ___________________ ?
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A. same way as the natural gas

B. partial combustion of caol, eke, anthractie coal or charcoal in a mixed air steam blast

C. passing steam over incandescent coke

D. carbonisation of coal

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

73. A rocket engine for the combustion of its fuel_____________________?
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A. does not require oxygen

B. uses surrounding air

C. depends on electrical energy supplied by solar cells

D. carries its own oxygen

E. uses compressed atmospheric air

74. The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is_______________?
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A. low/high depending on make and type

B. low

C. unpredictable

D. high

E. same

75. For a two stage compressor* if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will___________________?
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A. increase

B. decrease

C. unpredictable

D. remain unaffected

E. other factors control it

76. Actual compression curve is___________________?
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A. in between isothermal and adiabatic

B. better than isothermal and adiabatic

C. none of the above

D. same as adiabatic

E. same as isothermal

77. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to ____________________?
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A. intake temperature and pressure conditions

B. N.T.P. conditions

C. none of the above

D. 20C and 1 kg/cm2

E. 0C and 1 kg/cm2

78. Pick up the wrong statement about advantages of multistage compression____________________?
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A. mechanical balance is better

B. better lubrication is possible advantages of multistage

C. more loss of air due to leakage past the cylinder

D. more uniform torque, light cylinder and saving in work

E. air can be cooled perfectly in between

79. Which of the following plants is smallest and lightest for genrating a given amount of power__________________?
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A. steam power plant

B. gas turbine plant

C. solar plant

D. diesel engine

E. petrol engine

80. 1 m of air at atmospheric condition weighs approximately__________________?
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A. 0.5 kg

B. 1.0 kg

C. 2.2 kg

D. 1.3 kg

E. 3.2 kg

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