1000+ Compressors, Gas Turbines & Jet Engines MCQ for IBPS Clerk [Solved]

1. The efficiency and work ratio of a gas turbine plant can be increased by
A. Adding heat exchanger
B. Injecting water in/around combustion chamber
C. Reheating the air after partial expansion in the turbine
D. All of the above
Answer : D

2. The absolute pressure of air at the outlet of a compressor is called
A. Back pressure
B. Critical pressure
C. Discharge pressure
D. None of these
Answer : C

3. The intercooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p? = Intake pressure of air, p? = Intercooler pressure, and p? = Delivery pressure of air)
A. p? = p? × p?
B. p? = p?/p?
C. p? = p? × p?
D. p? = p?/p?
Answer : C

4. Which of the following statement is correct?
A. The reciprocating compressors are best suited for high pressure and low volume capacity
B. The effect of clearance volume on power consumption is negligible for the same volume of discharge
C. Both (A) and (B)
D. None of these
Answer : C

5. To avoid moisture troubles, the branch connections from compressed air lines should be taken from
A. Top side of main
B. Bottom side of main
C. Left side of main
D. Right side of main
Answer : A

6. In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during
A. Isothermal compression
B. Isentropic compression
C. Polytropic compression
D. None of these
Answer : A

7. Producer gas is produced by
A. Carbonisation of coal
B. Passing steam over incandescent coke
C. Passing air and a large amount of steam over waste coal at about 65°C
D. Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
Answer : D

8. The stagnation pressure rise in a centrifugal compressor takes place
A. In the diffuser only
B. In the impeller only
C. In the diffuser and impeller
D. In the inlet guide vanes only
Answer : C

9. A rotary compressor is driven by an
A. Electric motor
B. Engine
C. Either (A) or (B)
D. None of these
Answer : C

10. In jet engines the products of combustion after passing through the gas turbine are discharged into
A. Atmosphere
B. Back to the compressor
C. Discharge nozzle
D. Vacuum
Answer : C

11. The compressor capacity is defined as the
A. Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions
B. Volume of air delivered by the compressor
C. Volume of air sucked by the compressor during its suction stroke
D. None of the above
Answer : B

12. The efficiency of jet engine is
A. Lower at low speed
B. Higher at high altitudes
C. Same at all altitudes
D. Higher at high speed
Answer : B

13. The thrust on the rotor in a centrifugal compressor is produced by
A. Radial component
B. Axial component
C. Tangential component
D. None of the above
Answer : B

14. The volume of air delivered in a medium capacity air compressor per unit time is
A. 0.1 to 1.2 m³/s
B. 0.15 to 5 m³/s
C. Above 5 m³/s
D. None of these
Answer : B

15. Which of the following plants is smallest and lightest for generating a given amount of power?
A. Gas turbine plant
B. Petrol engine
C. Diesel engine
D. Solar plant
Answer : A

16. The working fluid in a turbine is
A. In two phases
B. In three phases
C. In a single phase
D. In the form of air and water mixture
Answer : C

17. In an axial flow compressor, the ratio of pressure in the rotor blades to the pressure rise in the compressor in one stage is known as
A. Work factor
B. Slip factor
C. Degree of reaction
D. Pressure coefficient
Answer : C

18. The inlet pressure is always ________ the discharge pressure.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B

19. A closed cycle gas turbine works on
A. Carnot cycle
B. Rankine cycle
C. Ericsson cycle
D. Joule cycle
Answer : D

20. Clearance volume in actual reciprocating compressors is essential
A. To accommodate Valves in the cylinder head
B. To provide cushioning effect
C. To attain high volumetric efficiency
D. To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head
Answer : D

21. Volumetric efficiency of a compressor with clearance volume
A. Increases with increase in compression ratio
B. Decreases with increase in compression ratio
C. In not dependent upon compression ratio
D. May increase/decrease depending on compressor capacity
Answer : B

22. The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : C

23. In axial flow compressor, exit flow angle deviation from the blade angle is a function of
A. Blade camber
B. Blade camber and incidence angle
C. Spacechord ratio
D. Blade camber and spacechord ratio
Answer : B

24. In a closed cycle gas turbine, the air is compressed
A. Isothermally
B. Polytropically
C. Isentropically
D. None of these
Answer : C

25. High air-fuel ratio is used in gas turbines
A. To increase the output
B. To increase the efficiency
C. To save fuel
D. To reduce the exit temperature
Answer : D

26. In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at
A. Diffuser inlet radius
B. Diffuser outlet radius
C. Impeller inlet radius
D. Impeller outlet radius
Answer : B

27. Gas turbine as compared to internal combustion engine
A. Can be driven at a very high speed
B. Produces uniform torque
C. Has more efficiency
D. All of these
Answer : D

28. The pressure and temperature conditions of air at the suction of compressor are
A. Atmospheric
B. Slightly more than atmospheric
C. Slightly less than atmospheric
D. Pressure slightly less than atmospheric and temperature slightly more than atmospheric
Answer : D

29. The indicated work per unit mass of air delivered is
A. Directly proportional to clearance volume
B. Greatly affected by clearance volume
C. Not affected by clearance volume
D. Inversely proportional to clearance volume
Answer : C

30. Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on
A. Mass flow rate
B. Pressure ratio
C. Change in load
D. Stagnation pressure at the outlet
Answer : D

31. In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into
A. Atmosphere
B. Vacuum
C. Discharge nozzle
D. Back to the compressor
Answer : C

32. The mean effective pressure of the compressor is the
A. Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions
B. Volume of air delivered by the compressor
C. Volume of air sucked by the compressor during its suction stroke
D. None of the above
Answer : D

33. The most efficient method of compressing air is to compress it
A. Isothermally
B. Adiabatically
C. Isentropically
D. Isochronically
Answer : A

34. Out of the following, from where you will prefer to take intake for air compressor
A. From an air conditioned room maintained at 20°C
B. From outside atmosphere at 1°C
C. From coal yard side
D. From a side where cooling tower is located nearby
Answer : D

35. Diffuser in a compressor is used to
A. Increase velocity
B. Make the flow streamline
C. Convert pressure energy into kinetic energy
D. Convert kinetic energy into pressure energy
Answer : D

36. If the flow of air through the compressor is perpendicular to its axis, then it is a
A. Reciprocating compressor
B. Centrifugal compressor
C. Axial flow compressor
D. Turbo compressor
Answer : B

37. The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
A. Pressure drop across the valves
B. Superheating in compressor
C. Clearance volume and leakages
D. All of these
Answer : D

38. Surging is the phenomenon of
A. Air stream blocking the passage
B. Motion of air at sonic velocity
C. Unsteady, periodic and reversed flow
D. Air stream not able to follow the blade contour
Answer : C

39. In jet engines, paraffin is usually used as the fuel because of its
A. High calorific value
B. Ease of atomisation
C. Low freezing point
D. Both (A) and (C) above
Answer : D

40. A centrifugal compressor works on the principle of
A. Conversion of pressure energy into kinetic energy
B. Conversion of kinetic energy into pressure energy
C. Centripetal action
D. Generating pressure directly
Answer : B

41. An ideal air compressor cycle with clearance on PV diagram can be represented by following processes
A. One adiabatic, two isobaric, and one constant volume
B. Two adiabatic and two isobaric
C. Two adiabatic, one isobaric and one constant volume
D. One adiabatic, one isobaric and two constant volumes
Answer : B

42. The capacity of a compressor is 5 m /min refers to
A. Standard air
B. Free air
C. Compressed air
D. Compressed air at delivery pressure
Answer : B

43. In the aircraft propellers
A. The propulsive matter is caused to flow around the propelled body
B. Propulsive matter is ejected from within the propelled body
C. Its functioning does not depend on presence of air
D. All of the above
Answer : D

44. The air-fuel ratio in gas turbines is of the order of
A. 7 : 1
B. 15 : 1
C. 30 : 1
D. 50 : 1.
Answer : D

45. In jet propulsion power unit, the inlet duct of diverging shape is used in order to
A. Collect more air
B. Convert kinetic energy of air into pressure energy
C. Provide robust structure
D. Beautify the shape
Answer : B

46. Water gas is produced by
A. Carbonisation of coal
B. Passing steam over incandescent coke
C. Passing air and a large amount of steam over waste coal at about 65°C
D. Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast
Answer : B

47. The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called
A. Slip factor
B. Velocity factor
C. Velocity coefficient
D. None of the above
Answer : A

48. In a jet engine, the air-fuel ratio is
A. 30 : 1
B. 40 : 1
C. 50 : 1
D. 60 : 1
Answer : D

49. The propulsive power of the rocket is (where v? = Jet velocity, and v? = Aircraft velocity)
A. (v?² -v?²)/2g
B. (v? - v?)²/2g
C. (v?² -v?²)/g
D. (v? - v?)²/g
Answer : A

50. Axial flow compressor has the following advantage over centrifugal compressor
A. Larger air handling ability per unit frontal area
B. Higher pressure ratio per stage
C. Aerofoil blades are used
D. Higher average velocities
Answer : A