# Compressors, Gas Turbines and Jet Engines MCQ Practice Test – Set 8 :: Mechanical Engineering

Are you guys looking for Mechanical Engineering MCQ Questions with Answers PDF Free Download as per Mechanical Engineering new exam pattern? You came to the right page. This may assist you to understand and check your knowledge about the Subjects. Students also can take a free test of the Multiple Choice Questions of Mechanical Engineering. Each question has four options followed by the right answer. These Mechanical Engineering MCQ Questions are selected supported by the newest exam pattern.

## Q1. Reheating in a multistage expansion gas turbine __ compressor work.

(A) Has no effect on
(B) Decreases
(C) Increases
(D) None of these

## Q2. Maximum work is done in compressing air when the compression is

(A) Isothermal
(C) Polytropic
(D) None of the above

## Q3. 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) To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

## Q4. 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

## Q5. 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) Decreases with increase in compression ratio

(A) 10 bar
(B) 20 bar
(C) 30 bar
(D) 50 bar

## Q7. Which of the following statement is correct?

(A) The ratio of the discharge pressure to the inlet pressure of air is called compressor efficiency
(B) The compression ratio for the compressor is always greater than unity
(C) The compressor capacity is the ratio of work-done per cycle to the stroke volume
(D) During isothermal compression of air, the work-done in a compressor is maximum

Answer: (B) The compression ratio for the compressor is always greater than unity

## Q8. The assumption made in two stage compression with inter-cooler is that

(A) There is no pressure drop in the inter-cooler
(B) The compression in both the cylinders is polytropic
(C) The suction and delivery of air takes place at constant pressure
(D) All of the above

Answer: (D) All of the above

## Q9. If the flow of air through the compressor is parallel to its axis, then the compressor is

(A) Reciprocating compressor
(B) Centrifugal compressor
(C) Axial flow compressor
(D) Turbo compressor

## Q10. A compressor at high altitudes will require __ power.

(A) Same
(B) Less
(C) More
(D) None of these

## Q11. 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

## Q12. A jet engine has

(A) No propeller
(B) Propeller in front
(C) Propeller at back
(D) Propeller on the top

## Q13. Pick up the wrong statement

(A) Large gas turbines employ axial flow compressors
(B) Axial flow compressors are more stable than centrifugal type compressors but not as efficient
(C) Axial flow compressors have high capacity and efficiency
(D) Axial flow compressors have instability region of operation

Answer: (B) Axial flow compressors are more stable than centrifugal type compressors but not as efficient

## Q14. The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turbine and fixed higher and lower temperature) with increase in pressure ratio will

(A) Increase first at fast rate and then slow
(B) Increase first at slow rate and then fast
(C) Decrease continuously
(D) First increase, reach maximum and then decrease

Answer: (D) First increase, reach maximum and then decrease

## Q15. The compressor performance at higher altitude compared to sea level will be

(A) Same
(B) Higher
(C) Lower
(D) Dependent on other factors

## Q16. Isothermal compression efficiency, even when running at high speed, can be approached by using

(A) Multistage compression
(B) Cold water spray
(C) Both (A) and (B) above
(D) Fully insulating the cylinder

Answer: (C) Both (A) and (B) above

## Q17. Which is false statement about advantages of multistage compressor in comparison to single stage compressor?

(A) Less power requirement
(B) Better mechanical balance
(C) Less loss of air due to leakage past the cylinder
(D) Lower volumetric efficiency

## Q18. Gas turbines for power generation are normally used

(A) To supply base load requirements
(B) To supply peak load requirements
(C) To enable start thermal power plant
(D) In emergency

## Q19. Fighter bombers use following type of engine

(A) Turbojet
(B) Turbo-propeller
(C) Rocket
(D) Ramjet