Compressors

61. In the axial flow gas turbine, the work ratio is the ratio of

  1. compressor work and turbine work
  2. output and input
  3. actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet
  4. actual compressor work and theoretical comprssor work
  5. none of the above.

Correct answer: (C)
actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet

62. In the cross compounding of the gas turbine plant

  1. h.p. compressor L connected to h.p. turbine and l.p. compressor ot l.p. tur-bine
  2. h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine
  3. both the arrangements can be employed
  4. all are connected in series
  5. none of the above.

Correct answer: (B)
h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine

63. In turbo fan engine, the jet velocity as compared to turbo-jet engine is

  1. less
  2. more
  3. same
  4. may be less or more depening upon speed
  5. none of the above.

Correct answer: (A)
less

64. In which case the air-fuel ratio is likely to be maximum

  1. 2-stroke engine
  2. 4-stroke petrol engine
  3. 4-stroke diesef engine
  4. multi-cylinder engine
  5. gas turbine.

Correct answer: (E)
gas turbine.

65. Inter cooling in compressors

  1. cools the delivered air
  2. results in saving of power in compressing a given volume to given pressure
  3. is the standard practice for big compressors
  4. enables compression in two stages
  5. prevents compressor jacket running very hot.

Correct answer: (B)
results in saving of power in compressing a given volume to given pressure

66. Isothermal compression effeicency can be attained by running the compressor

  1. at very high speed
  2. at very slow speed
  3. at average speed
  4. at zero speed
  5. isothermally.

Correct answer: (B)
at very slow speed

67. Isothermal compression efficiency, even when running at high speed, can be approached by using

  1. multi-stage compression
  2. cold water spray
  3. both (a) and (b) above
  4. fully insulating the cylinder
  5. high stroke.

Correct answer: (C)
both (a) and (b) above

68. Isothermal compression though most efficient, but is not -practicable because

  1. ityrequires very big cylinder
  2. it does not increase pressure much
  3. it is impossible in practice
  4. compressor has to run at very slow speed to achieve it
  5. it requires cylinder to be placed in water.

Correct answer: (D)
compressor has to run at very slow speed to achieve it

69. It is not possible to use closed gas turbine cycle in aeronautical engines because

  1. it is inefficient
  2. it is bulky
  3. it requires cooling water for its operation
  4. None of above
  5. all of above

Correct answer: (C)
it requires cooling water for its operation

70. Losses in a centrifugal compressor are due to

  1. inlet losses
  2. impeller channel losses
  3. diffuser losses
  4. all of the above
  5. none of the above

Correct answer: (D)
all of the above

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