compressors gas turbines and jet engines MCQs – Page 2

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

21. Pick up the correct statement ?
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A. large gas turbines use radial inflow turbines

B. gas turbines have their blades similar to steam turbine

C. gas .turbines blade will appear as impulse section at the hub and as a reaction section at tip

D. gas turbines use both air and liquid cooling

E. all of the above are correct.

22. The air-fuel ratio in gas turbines is of the order of ______________________?
0

A. 30:01:00

B. 15:01

C. 7:01

D. 40:01:00

E. 50: 1

23. Free air is the air at________________?
0

A. 25C, 1 kg/cm2 and relative humidity of 50%.

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

C. 15C and 1 kg/cm2

D. atmospheric conditions at any specific location

E. 0C and standard atmospheric conditions

24. Pick up the false statement ?
0

A. gas turbine can be easily started and stopped and thus is best suited for peaking demands

B. exhaust losses in gas turbine are high due to large mass flow rate

C. gas turbine is a self-starting unit

D. gas turbine does not require huge quantity of water like steam plant

E. overall efficiency of gas turbine plant is lower than that of a reciprocating engine

25. The clearance volume of the air compressor is kept minimum because____________________?
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A. none of the above

B. it permits isothermal compression

C. it greatly affects volumetric efficiency

D. it allows maximum compression to be achieved

E. it results in minimum work

26. The volumetric efficiency of a compressor falls roughly as follows for every 5C increase in atmospheric temperature__________________?
0

A. 10%.

B. 0.50%

C. 5%

D. 1%

E. 0.10%

27. The blades of gas turbine are made of_________________?
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A. high alloy seel

B. mild steel

C. carbon steel

D. high nicket alloy (neimonic)

E. stainless steel

28. The maximum compression ratio in an actual single stage axial flow comperssor is of the order of________________?
0

A. 1 : 1.2

B. 1:01

C. 1:05

D. 1:10

E. 1:02

29. Reheating in gas turbine results in___________________?
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A. increase of work ratio

B. decrease of thermal efficiency

C. decrease of work ratio

D. both A. and B. above

E. both B. and C. above

30. The material commonly used for air craft gas turbine is__________________?
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A. stainless steel

B. titanium

C. Timken, Haste and Inconel allpys

D. duralumin

E. high alloy steel

31. In jet engines the compression ratio__________________?
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A. varies as square root of the speed

B. Varies linearly to the speed

C. varies as square of the speed

D. varies as cube of the speed

E. is constant irrespective of variation in speed

32. Maximum delivery pressure is a rotary air compressor is of the order of__________________?
0

A. 16 kg/cm2

B. 25 kg/cm2

C. 10 kg/cm2

D. 40 kg/cm2

E. 6 kg/cm2

33. The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the_____________________?
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A. total temperature drop

B. total adiabaitc temperature drop

C. adiabatic temperature drop in the stage

D. difference of maximum and minimum temperature in the cycle

E. total temperature drop in the stage

34. Rotary compressor is best suited for_____________________?
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A. large quantity of air at high pressure

B. any one of the above

C. small quantity of air at low pressure

D. large quantity of air at low pressure

E. small quantity of air at high pressure

35. The capacity of compressor will be highest when its intake temperature is___________________?
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A. highest

B. none of the above

C. anything.

D. atmospheric

E. lowest

36. Gas turbine blades are given a rake___________________?
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A. equal to zero

B. in the direction of motion of blades

C. opposite to the direction of motion of blades

D. depending on the velocity

E. none of the above

37. Adiabatic compression is one in which___________________?
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A. work done is maximum

B. entropy decreases

C. no heat leaves or enters the compressor cylinder during cornpression

D. temperature rise follows a linear relationship

E. temperature during compression remains constant

38. The- most efficient method of compressing air is to compress it_________________?
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A. isochronically

B. adiabatically

C. as per law pV

D. isothermally

E. isentropically

39. The overall isothermal eiffciency of compressor is defined as the ratio of_______________?
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A. isothermal work to ideal work

B. work to compress air isothermally to work for actual compression

C. power to drive compressor to isothermal h.p.

D. isothermal h.p. to the BHP of motor

E. isothermal h.p. to adiabatic h.p.

40. Work ratio of a gas turbine plant is ratio of______________________?
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A. net work output and heat supplied

B. actual/heat drop and isentropic heat drop

C. work done by turbine and net work output

D. work done by turbine and heat supplied

E. net work output and work done by turbine

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