Compressors, Gas Turbines and Jet Engines MCQs

Question 1

If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by

Accepted Answer

$$1 + {	ext{K}} - {	ext{K}}{\left( {\frac{{{{	ext{p}}_2}}}{{{{	ext{p}}_1}}}} ight)^{\frac{1}{{	ext{n}}}}}$$

Answer

$$1 - {	ext{K}} + {	ext{K}}{\left( {\frac{{{{	ext{p}}_1}}}{{{{	ext{p}}_2}}}} ight)^{\frac{1}{{	ext{n}}}}}$$

Answer

$$1 - {	ext{K}} + {	ext{K}}{\left( {\frac{{{{	ext{p}}_1}}}{{{{	ext{p}}_2}}}} ight)^{\frac{{{	ext{n}} - 1}}{{	ext{n}}}}}$$

Answer

$$1 + {	ext{K}} - {	ext{K}}{\left( {\frac{{{{	ext{p}}_2}}}{{{{	ext{p}}_1}}}} ight)^{\frac{{{	ext{n}} - 1}}{{	ext{n}}}}}$$

Question 2

Axial flow compressor has the following advantage over centrifugal compressor

Accepted Answer

Larger air handling ability per unit frontal area

Answer

Higher pressure ratio per stage

Answer

Aerofoil blades are used

Answer

Higher average velocities

Question 3

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

Accepted Answer

Remain constant

Answer

Increases

Answer

Decreases

Answer

First decreases and then increases

Question 4

The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio

Accepted Answer

Increases

Answer

Decreases

Answer

First increases and then decreases

Answer

First decreases and then increases

Question 5

A closed cycle gas turbine consists of a

Accepted Answer

All of these

Answer

Compressor

Answer

Heating chamber

Answer

Cooling chamber

Question 6

During base load operation, the best method of controlling compressor is

Accepted Answer

Start-stop motor

Answer

Constant speed unloader

Answer

Relief valve

Answer

Variable speed

Question 7

The effective power of gas turbines is increased by adding the following in compressor

Accepted Answer

Ammonia and water vapour

Answer

Carbon dioxide

Answer

Nitrogen

Answer

Hydrogen

Question 8

For an irreversible gas turbine cycle, the efficiency and work ratio both depend on

Accepted Answer

Both pressure ratio and maximum cycle temperature

Answer

Pressure ratio alone

Answer

Maximum cycle temperature alone

Answer

Minimum cycle temperature alone

Question 9

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

Accepted Answer

Work done in all stages should be equal

Answer

Work done in first stage should be more

Answer

Work done in subsequent stages should increase

Answer

Work done in subsequent stages should decrease