# Compressors, Gas Turbines and Jet Engines MCQ Practice Test – Set 2 :: 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. The gas in cooling chamber of a closed cycle gas turbine is cooled at

(A) Constant volume
(B) Constant temperature
(C) Constant pressure
(D) None of these

## Q2. To avoid moisture troubles, the compressed air main line should

(A) Rise gradually towards the point of use
(B) Drop gradually towards the point of use
(C) Be laid vertically
(D) Be laid exactly horizontally

## Q3. 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

Answer:(B) Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor

## Q4. Gas turbine as compared to steam turbine

(A) Requires less space for installation
(B) Has compressor and combustion chamber
(C) Has less efficiency
(D) All of these

## Q5. 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) Ratio of shaft output of the air motor to the shaft input to the compressor

## Q6. Cylinder clearance in a compressor should be

(A) As large as possible
(B) As small as possible
(C) About 50% of swept volume
(D) About 100% of swept volume

Answer: (B) As small as possible

## Q7. The compressor efficiency is the

(A) Isothermal H.P/indicated H.R
(B) Isothermal H.P./shaft H.R
(C) Total output/air input
(D) Compression work/motor input

## Q8. Only rocket engines can be propelled to space because

(A) They can generate very high thrust
(B) They have high propulsion efficiency
(C) These engines can work on several fuels
(D) They are not air breathing engines

Answer: (D) They are not air breathing engines

## Q9. 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

## Q10. 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) Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions

## Q11. The maximum combustion pressure in gas turbine as compared to I.C. engine is

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

## Q12. The volumetric efficiency of a compressor

(A) Increases with decrease in compression ratio
(B) Decreases with decrease in compression ratio
(C) Increases with increase in compression ratio
(D) Decreases with increase in compression ratio

Answer:(D) Decreases with increase in compression ratio

## Q13. 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

Answer: (A) Large quantity of air at high pressure

## Q14. The following property is most important for material used for gas turbine blade

(A) Toughness
(B) Fatigue
(C) Creep
(D) Corrosion resistance

## Q15. 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) No heat leaves or enters the compressor cylinder during compression

## Q16. The ratio of work-done per cycle to the stroke volume of the compressor is known as

(A) Compressor capacity
(B) Compression ratio
(C) Compressor efficiency
(D) Mean effective pressure

## Q17. The ratio of the net work obtained from the gas turbine plant to the turbine work is known as

(A) Compression ratio
(B) Work ratio
(C) Pressure ratio
(D) None of these

## Q18. The advantage of multistage compression over single stage compression is

(A) Lower power consumption per unit of air delivered
(B) Higher volumetric efficiency
(C) Decreased discharge temperature
(D) All of the above

Answer: (D) All of the above

## Q19. For minimum work in multistage compression, assuming same index of compression in all stages

(A) Work done in first stage should be more
(B) Work done in subsequent stages should increase
(C) Work done in subsequent stages should decrease
(D) Work done in all stages should be equal

Answer: (D) Work done in all stages should be equal

## Q20. 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