compressors gas turbines and jet engines Mcqs
101. Gas turbine works on_______________?
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A. Erricsson cycle

B. Brayton or Atkinson cycle

C. Rankine cycle

D. Joule cycle

E. Carnot cycle

102. Gas turbine works on______________?
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A. Brayton or Atkinson cycle

B. Joule cycle

C. Carnot cycle

D. Erricsson cycle

E. Rankine cycle

103. Diffuser in a compressor is used to _____________________?
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A. increase degree of reaction

B. increase velocity

C. convert kinetic energy into pressure energy

D. make the flow stream-line

E. convert pressure energy into kinetic energy

104. Turbo propeller has the following additional feature over the turbojet __________________?
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A. intercooler

B. peopeller

C. diffuser

D. starting engine

E. turbine and combustion chamber

105. To avoid moisture troubles, the branch connections from compressed air lines should be taken from_________________?
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A. any location

B. bottom side of main

C. top side of main

D. left side of main

E. right side of main

106. Volumetric efficiency of a compressor with clearance volume ________________?
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A. decreases with increase in compression ratio

B. may increase/decrease depending on compressor capacity

C. in not dependent upon compression ratio

D. increases with increase in compression ratio

E. unpredictable

107. Gas turbine cycle with Regenerator __________________?
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A. permits high moisture content fuel to be used

B. decreases heat loss is exhaust

C. allows operation at very high altitudes

D. increases thermal efficiency

E. allows high compression ratio

109. The capacity of a compressor is 5 m /mih. 5 m /min refers to_______________?
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A. free air

B. air sucked

C. standard air

D. compressed air at delivery pressure

E. compressed air

110. Pressure ratio in gas turbines is the ratio of ____________________?
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A. inlet pressure to exhaust pressure

B. compressor pressure ratio

C. pressures across the turbine

D. highest pressure to exhaust pressure

E. none of the above

111. Ratio of indicated H.P. and brake H.P. is known as_________________?
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A. mechanical efficiency

B. relative efficiency

C. adiabatic efficiency

D. isothermal efficiency

E. volumetric efficiency

112. The closed cycle in gas turbines_________________?
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A. in never used

B. is used when gas is to be burnt

C. provides greater flexibility

D. provides lesser flexibility

E. none of the above

113. Volumetric efficiency of a compressor without clearance volume________________?
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A. may increase/decrease depending on compressor capacity

B. is not dependent upon compressin ratio

C. unpredictable

D. decreases with increase in compression ratio

E. increases with increase in compression ratio

115. In which case the air-fuel ratio is likely to be maximum _________________?
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A. 2-stroke engine

B. gas turbine

C. 4-stroke diesef engine

D. multi-cylinder engine

E. 4-stroke petrol engine

116. Axial flow compressor has the following advantage over centrifugal compressor__________________?
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A. none of the above

B. aerofoil blades are used

C. higher average velocities

D. larger air handling ability per unit frontal area

E. higher pressure ratio per stage

117. In jet propulsion power unit, the inlet duct of diverging shape is used in order to _______________ ?
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A. provide robust structure

B. collect more air

C. beautify the shape

D. convert kinetic energy of air into pres-sure energy

E. none of the above

118. Gas turbines for power generaion are normally used___________________?
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A. when other sources of power fail

B. in emergency

C. to enable start thermal power plant

D. to supply peak load requirements

E. to supply base load requirements

119. Pick up the correct statement ?
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A. gas turbine uses low air-fuel ratio to develop the high thrust required

B. gas turhine uses high air-fuel ratio to reduce outgoing temperature

C. gas turbine uses low air-fuel ratio to economise on fuel

D. none of the above

E. all of the above

120. Isothermal compression effeicency can be attained by running the compressor__________________?
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A. at very high speed

B. at zero speed

C. at average speed

D. isothermally

E. at very slow speed
121. Ratio of compression is the ratio of__________________?
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A. pressures at discharge and suction cor-responding to same temperature

B. none of the above

C. absolute discharge pressure to the ab-solute intake pressure

D. gauge discharge pressure to the gauge intake pressure

E. stroke volume and clearance volume

122. The compressor efficiecny is the__________________?
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A. isothermal H.P/indicated H.R

B. total output/air input

C. none Of the above

D. compression work/motor input

E. isothermal H.P./shaft H.R

124. In the cross compounding of the gas turbine plant__________________?
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A. h.p. compressor L connected to h.p. turbine and l.p. compressor ot l.p. tur-bine

B. h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine

C. both the arrangements can be employed

D. all are connected in series

E. none of the above

125. Cylinder clearance in a compressor should be _________________?
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A. as small as possible

B. as large as possible

C. about 100% of swept volume

D. about 50% of swept volume

E. none of the above

127. A jet engine works on the principle of conservation of____________________?
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A. mass

B. energy

C. angular momentum

D. linear momentum

E. flow

128. To aviod moisture troubles, the compressed air main line should __________________?
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A. none of the above

B. be laid vertically

C. drop gradually towards the point of use

D. rise gradually towards the point of use

E. be laid exactly horizontally

129. The efficiency of jet engine is__________________?
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A. lower at low speed

B. higher at high speed

C. higher at ground

D. higher at high altitudes

E. same at all altitudes

130. An air compressor may be controlled by____________________?
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A. none of the above

B. any one of the above

C. blow-off control

D. throttle control B. clearance control

131. Aeroplanes employ following type of compressor_______________?
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A. centrifugal

B. radial flow

C. none of the above

D. axial flow

E. combination of above

132. In jet engines the products of combustion after passing through the gas lurbine are discharged into_______________?
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A. none of the above

B. atmosphere

C. vacuum

D. back to the compressor

E. discharge nozzle
134. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on___________________?
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A. pressure ratio alone

B. maximum cycle temperature alone

C. minimum cycle temperature alone

D. both pressure ratio and maximum cycle temperature

E. none of the above

135. Rotary compressors are suitable for ____________________?
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A. low discharge at low pressure

B. large discharge at low pressure

C. large discharge at high pressure

D. low discharge at high pressure

E. there is no such limitation

136. A simple turbo-jet engine is basically_________________?
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A. ram-jet enigne

B. a propeller system

C. chemical rocket regine

D. gas-turbine engine equipped with a propulsive nozzle and diffuse*

E. none of the above

137. Which is false statement about air receivers ___________________?
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A. These are used to dampen pulsations ,

B. These increase compressor efficiency

C. These knock out some oil and moisture

D. These act as reservoir to- take care of sudden demands

E. These reduce frequent on/off operation of compressors

138. Work ratio of a gas turbine may be improved by f____________________?
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A. decreasing the compression work

B. decreasing the turbine work

C. increasing the turbine work

D. A. and C. above

E. increasing the compression work

139. Eulers equation is applicable for__________________?
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A. none of the above

B. pumps

C. all of the above

D. centrifugal compressor

E. axial compressor

140. In air breathing jet engine, the jet is formed by expanding__________________?
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A. highly heated atmospheric air

B. solids

C. plasma

D. liquid

E. gases

142. The working fluid in ai turbine is___________________?
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A. in three phases

B. in a single phase

C. in the form of air and water mixture

D. in two phases

E. gas and no air

143. The work ratio of a gas turbine plant is defined as the ratio of__________________?
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A. net work output and isentropic heat drop

B. net work output and heat supplied (6) net work output and work done by turbine

C. isentropic increase/drop in temperature and actual increase/ drop in temperature

D. actual heat drop and isentropic heat drop

145. An ideal air compressor cycle without clearance on p-v diagram can be represented by following processes________________?
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A. two isobaric, two adiabatic and one constant volume

B. one adiabatic, two isobaric, and one constant volume

C. two adiabatic, one isobaric and one constant volume

D. two adiabatic and two isobaric

E. one adiabatic, one isobaric and two constant volume

147. A centrifugal compressor works on the principle of__________________?
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A. combination of A. and D.

B. generating pressure directly

C. conversion of pressure energy into kinetic energy

D. conversion of kinetic energy into pressure energy

E. centripetal action