Compressors, Gas Turbines and Jet Engines - Set 03

Practice Test: Question Set - 03

1. Separators in compressor installations are located
    (A) Before inter-cooler
    (B) After inter-cooler
    (C) After receiver
    (D) Between after-cooler and air receiver

2. Pick up the wrong statement
    (A) Pulse-jet requires no ambient air for propulsion
    (B) Ramjet engine has no turbine
    (C) Turbine drives compressor in a Turbojet
    (D) Bypass turbojet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

3. The overall isothermal efficiency of the compressor is defined as the ratio of
    (A) Work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio
    (B) Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor
    (C) Volume of free air delivery per stroke to the swept volume of the piston
    (D) Isentropic power to the power required to drive the compressor

4. Reciprocating air compressor is best suited for
    (A) Large quantity of air at high pressure
    (B) Small quantity of air at high pressure
    (C) Small quantity of air at low pressure
    (D) Large quantity of air at low pressure

5. In a double acting compressor, the air is compressed
    (A) In one cylinder
    (B) In two cylinders
    (C) In a single cylinder on both sides of the piston
    (D) In two cylinders on both sides of the piston

6. After-cooler is used to
    (A) Cool the air
    (B) Decrease the delivery temperature for ease in handling
    (C) Cause moisture and oil vapour to drop out
    (D) Reduce volume

7. 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

8. Mining industry usually employs following motive power
    (A) A.C. electric motor
    (B) Compressed air
    (C) Petrol engine
    (D) Diesel engine

9. 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

10. 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

11. 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

12. 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

13. An ideal air compressor cycle without clearance on P-V 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

14. The thrust of a jet propulsion power unit can be increased by
    (A) Injecting water into the compressor
    (B) Burning fuel after gas turbine
    (C) Injecting ammonia into the combustion chamber
    (D) All of the above

15. Maximum work is done in compressing air when the compression is
    (A) Isothermal
    (B) Adiabatic
    (C) Polytropic
    (D) None of the above

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