Compressors

131. The jnaximum combustion pressure in gas turbine as compared to I.C. engine is

  1. more
  2. less
  3. same
  4. depends on other factors
  5. unpredictable.

Correct answer: (B)
less

132. The main purpose of reheating in gas turbine is to

  1. increase temperature
  2. reduce turbine size
  3. increase power output
  4. increase speed
  5. increase pressure ratio.

Correct answer: (C)
increase power output

133. The material commonly used for air craft gas turbine is

  1. stainless steel
  2. high alloy’ steel
  3. duralumin
  4. Timken, Haste and Inconel allpys
  5. titanium.

Correct answer: (D)
Timken, Haste and Inconel allpys

134. The maximum compression ratio in an actual single stage axial flow comperssor is of the order of

  1. 01:01.2
  2. 01:02
  3. 01:05
  4. 01:10
  5. 01:01

Correct answer: (A)
01:01.2

135. The maximum propulsion efficiency of a turbojet is attained at around following speed –

  1. 550 km/hr
  2. 1050km/hr
  3. 1700 km/hr
  4. 2400km /hr
  5. 4000 km/hr.

Correct answer: (D)
2400km /hr

136. The- most efficient method of compressing air is to compress it

  1. isothermally
  2. adiabatically
  3. isentropically
  4. isochronically
  5. as per law pV

Correct answer: (A)
isothermally

137. The net work input required for compressor with increase in clearance volume

  1. increases
  2. decreases
  3. remains same
  4. increases/decreases depending on com-pressor capacity
  5. unpredictable.

Correct answer: (C)
remains same

138. The overall isothermal eiffciency of compressor is defined as the ratio of

  1. isothermal h.p. to the BHP of motor
  2. isothermal h.p. to adiabatic h.p.
  3. power to drive compressor to isothermal h.p.
  4. work to compress air isothermally to work for actual compression
  5. isothermal work to ideal work.

Correct answer: (A)
isothermal h.p. to the BHP of motor

139. The power available for take off and climb in case of turbojet engine as compared to reciprocating engine is

  1. less
  2. more
  3. same
  4. may be less or more depending on ambient conditons
  5. unpredictable.

Correct answer: (A)
less

140. The pressure and temperature conditions of air at the suction of compressor are

  1. atmospheric
  2. slightly more than atmospheric
  3. slightly less than atmospheric
  4. pressure slightly more than atmospheric and temperature slightly less than atmospheric
  5. pressure sightly less than atmospheric and temperature slightly more than atmospheric.

Correct answer: (E)
pressure sightly less than atmospheric and temperature slightly more than atmospheric.

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