Compressors, Gas Turbines and Jet Engines MCQs

Question 1

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

Accepted Answer

Low frontal area

Answer

Higher thrust

Answer

High pressure rise

Answer

None of these

Question 2

In the aircraft propellers

Accepted Answer

All of the above

Answer

The propulsive matter is caused to flow around the propelled body

Answer

Propulsive matter is ejected from within the propelled body

Answer

Its functioning does not depend on presence of air

Question 3

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 pa, then the intermediate pressure p2 is given by

Accepted Answer

$${{	ext{p}}_2} = \sqrt {{{	ext{p}}_1}{{	ext{p}}_3}} $$

Answer

$${{	ext{p}}_2} = \frac{{{{	ext{p}}_1} + {{	ext{p}}_3}}}{2}$$

Answer

$${{	ext{p}}_2} = {{	ext{p}}_{	ext{a}}} 	imes \frac{{{{	ext{p}}_3}}}{{{{	ext{p}}_1}}}$$

Answer

$${{	ext{p}}_2} = {{	ext{p}}_{	ext{a}}}\sqrt {\frac{{{{	ext{p}}_3}}}{{{{	ext{p}}_1}}}} $$

Question 4

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

Accepted Answer

Vi = Vo

Answer

Vt > Vo

Answer

U < Vo

Answer

V = Uo

Question 5

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

Accepted Answer

Six times

Answer

Two times

Answer

Three times

Answer

Four times

Question 6

Losses in a centrifugal compressor are due to

Accepted Answer

All of the above

Answer

Inlet losses

Answer

Impeller channel losses

Answer

Diffuser losses

Question 7

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

Accepted Answer

Stagnation pressure at the outlet

Answer

Mass flow rate

Answer

Pressure ratio

Answer

Change in load

Question 8

Diffuser in a compressor is used to

Accepted Answer

Convert kinetic energy into pressure energy

Answer

Increase velocity

Answer

Make the flow streamline

Answer

Convert pressure energy into kinetic energy

Question 9

A large clearance volume in a reciprocating compressor results in

Accepted Answer

Reduced volume flow rate

Answer

Increased volume flow rate

Answer

Lower suction pressure

Answer

Lower delivery pressure