CEED - Compressors, Gas Turbines & Jet Engines 1000+ MCQ [Solved] PDF Download

1. The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is
A. Less
B. More
C. Same
D. More/less depending on compressor capacity
Answer : B

2. 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

3. A turboprop is preferred to turbojet because
A. It has high propulsive efficiency at high speeds
B. It can fly at supersonic speeds
C. It can fly at high elevations
D. It has high power for take off
Answer : D

4. The performance of air compressor at high altitudes will be ________ as compared to that at sea level.
A. Same
B. Lower
C. Higher
D. None of these
Answer : B

5. Which of the following fuels can be used in turbojet engines?
A. Liquid hydrogen
B. High speed diesel oil
C. Kerosene
D. Methyl alcohol
Answer : C

6. Adiabatic compression is one in which
A. Temperature during compression remains constant
B. No heat leaves or enters the compressor cylinder during compression
C. Temperature rise follows a linear relationship
D. Work done is maximum
Answer : B

7. The ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called
A. Compressor efficiency
B. Volumetric efficiency
C. Isothermal efficiency
D. Mechanical efficiency
Answer : D

8. For slow speed large capacity compressor, following type of valve will be best suited
A. Poppet valve
B. Mechanical valve of the Corliss, sleeve, rotary or semi rotary type
C. Disc or feather type
D. Any of the above
Answer : C

9. The velocity of air entering in a rocket is ________ as compared to an aircraft.
A. Zero
B. Less
C. More
D. Same
Answer : A

10. For supplying intermittent small quantity of air at high pressure, following compressor is best suited
A. Centrifugal
B. Reciprocating
C. Axial
D. Screw
Answer : B

11. The compressor capacity with decrease in suction temperature
A. Increases
B. Decreases
C. Remain unaffected
D. May increase or decrease depending on compressor capacity
Answer : A

12. 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

13. If infinite number of heaters be used in a gas turbine, then expansion process in turbine approaches
A. Isothermal
B. Isentropic
C. Adiabatic
D. Isochoric
Answer : A

14. A large clearance volume in a reciprocating compressor results in
A. Reduced volume flow rate
B. Increased volume flow rate
C. Lower suction pressure
D. Lower delivery pressure
Answer : A

15. A simple turbojet engine is basically
A. A propeller system
B. Gas turbine engine equipped with a propulsive nozzle and diffuse
C. Chemical rocket engine
D. Ramjet engine
Answer : B

16. In air compressors, free air delivery means 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 : A

17. The work done per unit mass of air in compression will be least when n is equal to
A. 1
B. 1.2
C. 1.3
D. 1.4
Answer : A

18. The maximum temperature in a gas turbine is
A. 200°C
B. 500°C
C. 700°C
D. 1000°C
Answer : C

19. A closed gas turbine in which fuel is burnt directly in the air is not possible because of
A. Paucity of O2
B. Increasing gas temperature
C. High specific volume
D. High friction losses
Answer : A

20. The main purpose of reheating in gas turbine is to
A. Increase temperature
B. Reduce turbine size
C. Increase power output
D. Increase speed
Answer : C

21. In multistage compressor, the isothermal compression is achieved by
A. Employing intercooler
B. By constantly cooling the cylinder
C. By running compressor at very slow speed
D. By insulating the cylinder
Answer : C

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

23. Mining industry usually employs following motive power
A. A.C. electric motor
B. Compressed air
C. Petrol engine
D. Diesel engine
Answer : B

24. 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

25. Maximum temperature in a gas turbine is of the order of
A. 700°C
B. 2000°C
C. 1500°C
D. 1000°C
Answer : A

26. Volumetric efficiency of air compressors is of the order of
A. 20 - 30 %
B. 40 - 50 %
C. 60 - 70 %
D. 70 - 90 %
Answer : D

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

28. For a two stage compressor, if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will
A. Increase
B. Decrease
C. Remain unaffected
D. Other factors control it
Answer : A

29. Work ratio of a gas turbine plant is ratio of
A. Net work output and work done by turbine
B. Net work output and heat supplied
C. Work done by turbine and heat supplied
D. Work done by turbine and net work output
Answer : A

30. Volumetric efficiency of a compressor without clearance volume
A. Increases with increase in compression ratio
B. Decreases with increase in compression ratio
C. Is not dependent upon compression ratio
D. May increase/decrease depending on compressor capacity
Answer : C

31. The air is delivered ________ in one revolution in case of a three lobbed rotor.
A. Two times
B. Three times
C. Four times
D. Six times
Answer : D

32. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is
A. Heated
B. Compressed air before entering the combustion chamber is heated
C. Bled gas from turbine is heated and readmitted for complete expansion
D. Exhaust gases drive the compressor
Answer : B

33. The overall efficiency of the compressed air system is the
A. Ratio of shaft output of the air motor to the shaft input to the compressor
B. Ratio of shaft input to the compressor to the shaft output of air motor
C. Product of shaft output of air motor and shaft input to the compressor
D. None of the above
Answer : A

34. When air is to be compressed at a high pressure, then it is advantageous to use
A. Single stage compression
B. Multistage compression without intercooling
C. Multistage compression with intercooling
D. None of these
Answer : C

35. Choose the correct statement
A. Gas turbine requires lot of cooling water
B. Gas turbine is capable of rapid start up and loading
C. Gas turbines has flat efficiency at part loads
D. Gas turbines have high standby losses and require lot of maintenance
Answer : B

36. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on
A. Pressure ratio alone
B. Maximum cycle temperature alone
C. Minimum cycle temperature alone
D. Both pressure ratio and maximum cycle temperature
Answer : D

37. The ratio of isentropic work to Eulers work is known as
A. Compressor efficiency
B. Isentropic efficiency
C. Euler's efficiency
D. Pressure coefficient
Answer : D

38. The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature
A. 0.1 %
B. 0.5 %
C. 1 %
D. 5 %
Answer : C

39. For speed above 3000 km/hour, it is more advantageous to use
A. Turbojet engine
B. Ramjet engine
C. Propellers
D. Rockets
Answer : B

40. The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is
A. Same
B. Higher
C. Lower
D. None of these
Answer : C

41. For minimum work required to compress and deliver a quantity of air by multistage compression
A. The compression ratio in each stage should be same
B. The intercooling should be perfect
C. The workdone in each stage should be same
D. All of the above
Answer : D

42. In a high pressure compressor, the delivery pressure is
A. 1 to 5 bar
B. 5 to 8 bar
C. 8 to 10 bar
D. 10 to 15 bar
Answer : C

43. Propulsion efficiency of the following order is obtained in practice
A. 34 %
B. 50 %
C. 60 %
D. 72 %
Answer : C