# Compressors, Gas Turbines and Jet Engines – Set 12

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## Q1. 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

## Q2. In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in __ of the piston.

(A) One stroke
(B) Two strokes
(C) Three strokes
(D) Four strokes

## Q3. Inter-cooling in multistage compressors is done

(A) To cool the air during compression
(B) To cool the air at delivery
(C) To enable compression in two stages
(D) To minimize the work of compression

## Q4. The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called

(A) Pressure ratio
(B) Pressure coefficient
(C) Degree of reaction
(D) Slip factor

## Q5. Open cycle gas turbine works on

(A) Brayton or Atkinson cycle
(B) Rankine cycle
(C) Carnot cycle
(D) Ericsson cycle

(A) 7: 1
(B) 15: 1
(C) 30: 1
(D) 50: 1.

## Q7. 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

## Q8. Which of the following statement is wrong?

(A) In a two stage reciprocating air compressor with complete intercooling, maximum work is saved
(B) The minimum work required for a two stage reciprocating air compressor is double the work required for each stage
(C) The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency
(D) None of the above

## Q9. 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

## Q10. Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on

(A) Mass flow rate
(B) Pressure ratio
(D) Stagnation pressure at the outlet

## Q11. The fuel consumption in gas turbines is accounted for by

(A) Lower heating value
(B) Higher heating value
(C) Heating value
(D) Higher calorific value

## Q12. The thermal efficiency of a gas turbine as compared to a diesel plant is

(A) Same
(B) More
(C) Less
(D) Depends on other factors

## Q13. With the decrease in compression ratio, the volumetric efficiency

(A) Does not change
(B) Increases
(C) Decreases
(D) First decrease and then increase

## Q14. The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the

(A) Rotor to static enthalpy rise in the stator
(B) Stator to static enthalpy rise in the rotor
(C) Rotor to static enthalpy rise in the stage
(D) Stator to static enthalpy rise in the stage

## Q15. Which of the following statement is correct relating to rocket engines?

(A) The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel
(B) The stagnation conditions exist at the combustion chamber
(C) The exit velocities of exhaust gases are much higher than those in jet engine
(D) All of the above

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