Compressors, Gas Turbines And Jet Engines MCQ Questions & Answers

21

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

Discuss

Answer & Solution

Answer: Option C

Solution:

Isothermal compression efficiency, even when running at high speed, can be approached by using Multistage compression and Cold water spray

22

A rotary compressor is driven by an

A) Electric motor B) Engine C) Either (A) or (B) D) None of these

Discuss

Answer & Solution

Answer: Option C

Solution:

A rotary compressor is driven by an Electric motor and Engine

23

The capacity of a compressor is expressed in

A) kg/m² B) kg/m³ C) m³/min D) m³/kg

Discuss

Answer & Solution

Answer: Option C

Solution:

The capacity of a compressor is expressed in m³/min.

24

Ramjet engine

A) Is self operating at zero flight speed B) Is not self operating at zero flight speed C) Requires no air for its operation D) Produces a jet consisting of plasma

Discuss

Answer & Solution

Answer: Option B

Solution:

Ramjet engine Is not self operating at zero flight speed A ramjet uses this high pressure in front of the engine to force air through the tube, where it is heated by combusting some of it with fuel. It is then passed through a nozzle to accelerate it to supersonic speeds.

25

The blades of gas turbine are made of

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

Discuss

Answer & Solution

Answer: Option A

Solution:

The blades of gas turbine are made of High nickel alloy

26

The axial flow compressor is preferred in aircraft gas turbines because of

A) Low frontal area B) Higher thrust C) High pressure rise D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

The axial flow compressor is preferred in aircraft gas turbines because of Low frontal area

27

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

Discuss

Answer & Solution

Answer: Option D

Solution:

In the aircraft propellers - The propulsive matter is caused to flow around the propelled body -Propulsive matter is ejected from within the propelled body -Its functioning does not depend on presence of air

28

For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is p_a, then the intermediate pressure p₂ is given by

A) $${{\text{p}}_2} = \frac{{{{\text{p}}_1} + {{\text{p}}_3}}}{2}$$ B) $${{\text{p}}_2} = \sqrt {{{\text{p}}_1}{{\text{p}}_3}} $$ C) $${{\text{p}}_2} = {{\text{p}}_{\text{a}}} \times \frac{{{{\text{p}}_3}}}{{{{\text{p}}_1}}}$$ D) $${{\text{p}}_2} = {{\text{p}}_{\text{a}}}\sqrt {\frac{{{{\text{p}}_3}}}{{{{\text{p}}_1}}}} $$

Discuss

Answer & Solution

Answer: Option B

Solution:

For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is p_a, then the intermediate pressure p₂ is given by $${{\text{p}}_2} = \sqrt {{{\text{p}}_1}{{\text{p}}_3}} $$

29

If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix ‘I’ and ‘o’ stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity

A) Vi = Vo B) Vt > Vo C) U < Vo D) V = Uo

Discuss

Answer & Solution

Answer: Option A

Solution:

If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix ‘I’ and ‘o’ stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity Vi = Vo

30

The air is delivered ________ in one revolution in case of a three lobbed rotor.

A) Two times B) Three times C) Four times D) Six times

Discuss

Answer & Solution

Answer: Option D

Solution:

The air is delivered six times in one revolution in case of a three lobbed rotor.

Compressors, Gas Turbines And Jet Engines MCQ Questions & Answers | Mechanical Engineering