# Compressors, Gas Turbines and Jet Engines MCQ Practice Test – Set 7 :: 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 compressor capacity is defined as 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: (B) Volume of air delivered by the compressor

## Q2. 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

Answer: (A) One adiabatic, two isobaric, and one constant volume

## Q3. Ratio of indicated H.P. and brake H.P. is known as

(A) Mechanical efficiency
(B) Volumetric efficiency
(C) Isothermal efficiency

Answer: (A) Mechanical efficiency

## Q4. Which of the following statement is correct as regard to centrifugal compressors?

(A) The flow of air is parallel to the axis of the compressor
(B) The static pressure of air in the impeller increases in order to provide centripetal force on the air
(C) The impeller rotates at high speeds
(D) The maximum efficiency is higher than multistage axial flow compressors

Answer: (B) The static pressure of air in the impeller increases in order to provide centripetal force on the air

## Q5. Volumetric efficiency of air compressors is of the order of

(A) 20 – 30%
(B) 40 – 50%
(C) 60 – 70%
(D) 70 – 90%

Answer: (D) 70 – 90%

## Q6. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to

(A) N.T.P. conditions
(B) Intake temperature and pressure conditions
(C) 0°C and 1 kg/cm²
(D) 20°C and 1 kg/cm²

Answer: (B) Intake temperature and pressure conditions

(A) 0.1%
(B) 0.5%
(C) 1%
(D) 5%

## Q8. The type of rotary compressor used in aeroplanes, is of

(A) Centrifugal type
(B) Axial flow type
(C) Radial flow type
(D) None of these

Answer: (B) Axial flow type

## Q9. For maximum work, the reheating should be done to an intermediate pressure of(Where p₁ = Maximum pressure, and p₂ = Minimum pressure)

(A) (p₁ – p₂)/2
(B) (p₁ + p₂)/2
(C) p₁/p₂
(D) p₁ p₂

Answer: (D) p₁ p₂

## Q10. In the aircraft propellers

(A) The propulsive matter is caused to flow around the propelled body
(B) Propulsive matter is ejected from within the propelled body
(C) Its functioning does not depend on presence of air
(D) All of the above

Answer: (D) All of the above

## Q11. 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

## Q12. 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

Answer:(D) All of the above

## Q13. The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as

(A) Compressor efficiency
(B) Volumetric efficiency
(C) Isothermal efficiency
(D) Mechanical efficiency

## Q14. Isothermal compression efficiency can be attained by running the compressor

(A) At very high speed
(B) At very slow speed
(C) At average speed
(D) At zero speed

Answer: (B) At very slow speed

(A) Zero
(B) Less
(C) More
(D) Same

## Q16. The blades of gas turbine are made of

(A) High nickel alloy
(B) Stainless steel
(C) Carbon steel
(D) High alloy steel

Answer: (A) High nickel alloy

## Q17. The indicated work per unit mass of air delivered is

(A) Directly proportional to clearance volume
(B) Greatly affected by clearance volume
(C) Not affected by clearance volume
(D) Inversely proportional to clearance volume

Answer:(C) Not affected by clearance volume

## Q18. Phenomenon of choking in compressor means

(A) No flow of air
(B) Fixed mass flow rate regardless of pressure ratio
(C) Reducing mass flow rate with increase in pressure ratio
(D) Increased inclination of chord with air steam

Answer: (B) Fixed mass flow rate regardless of pressure ratio

## Q19. The pressure ratio of an ideal vaned compressor with increase in mass flow rate

(A) Increases
(B) Decreases
(C) Remain constant
(D) First decreases and then increases

Answer: (C) Remain constant

## Q20. In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into

(A) Atmosphere
(B) Vacuum
(C) Discharge nozzle
(D) Back to the compressor

Answer: (C) Discharge nozzle

We hope the given Mechanical Engineering MCQ Questions with Answers will definitely yield fruitful results. Hope you got enough ideas on the MCQs on Mechanical Engineering. If you have any queries related to Mechanical Engineering MCQs Multiple Choice Questions with Answers, drop your questions below and will get back to you in no time.