compressors gas turbines and jet engines MCQs – Page 8

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

141. The weight per horse power ratio for gas. turbine as compared to I.C. engine and steam turbine is________________?
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A. lower

B. higher

C. same

D. uncomparable

E. unpredictable

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

144. The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation___________________?
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A. 1.0%

B. 0.50%

C. 0.10%

D. 10%.

E. 5%

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

146. The pressure ratio in gas turbines is of the order of__________________?
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A. 12:01

B. 2:l

C. 9:01

D. 4:01

E. 61: 1

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

148. The work done per unit mass of air in compression willbe least when n is equal to______________?
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A. 1.3

B. 1

C. 1.5

D. 1.4

E. 1.2 ,

149. More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than____________________?
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A. none of the above

B. 2 kg/cm2

C. 6 kg/cm2

D. 14.7 kg/cm2

E. 10 kg/cm2

150. In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of__________________?
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A. liquid hydrogen

B. vacuum

C. compressed air

D. oxygen alone

E. atmospheric air

151. The compressor capacity with decrease in suction temperature_________________?
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A. remains unaffected

B. increases

C. increases upto certain limit and then decreases

D. decreases

E. may increase or decrease depending on compressor capacity

152. For supplying intermittent small quantity of air at high pressure, following compressor is best suited__________________?
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A. reciprocating

B. axial

C. screw

D. centrifugal

E. turbo jet

153. The volumetirc efficiency of a compressor is calculated on the basis of __________________?
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A. volume of air inhaled at N.T.P. conditions

B. volume of air inhaled at working conditions

C. none of the above

D. volume at 0C and 1 kg/cm2

E. volume at 20C and 1 kg/cm2

154. The compression ratio in a gas turbine is of the roder of____________________?
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A. 5:01

B. 3.5 : 1

C. 12:01

D. 8 : 1

E. 20:01

155. In the aircraft propellers __________________?
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A. all of the above

B. its functioning does not depend on presence of air

C. none of the above

D. propulsive matter is ejected from within the propelled body

E. the propulsive matter is caused to flow around the propelled body

156. For a compressor, least work will be done if the compression is________________ ?
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A. none of the above

B. somewhere in between isentropic and isothermal

C. isentropic

D. polytropic

E. isothermal

157. Fighter bombers use following type of engine __________________?
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A. ram-jet ,

B. turbo-propeller

C. pulsojet

D. turbo-jet

E. rocket

158. The advantage of multistage compression over single stage compression is ________________?
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A. all of the above

B. moisture free air

C. lower power consumption per unit of air delivered

D. decreased discharge temperature

E. higher volumetric efficiency

159. Volumetric efficiency of air compressors is of the order of________________?
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A. 20-30%

B. 70-90%

C. 40-50%

D. 90-100%

E. 60-70%

160. During base load operation, the best method of controlling compressor is ___________________?
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A. variable speed

B. relief valve

C. none of the above

D. start-stop motor

E. constant speed unloader

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