Compressors, Gas Turbines And Jet Engines MCQ Questions & Answers

11

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

Discuss

Answer & Solution

Answer: Option C

Solution:

The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called degree of reaction

12

Pick up the wrong statement

A) Pulse-jet requires no ambient air for propulsion B) Ramjet engine has no turbine C) Turbine drives compressor in a Turbojet D) Bypass turbojet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

Discuss

Answer & Solution

Answer: Option A

Solution:

- A pulse jet is a type of jet engine in which combustion occurs in pulses.
- A pulsejet engine can be made with few or no moving parts and is capable of running statically, it does not need to have air forced into its inlet typically by forward motion.

13

Pick up the wrong statement

A) Centrifugal compressors deliver practically constant pressure over a considerable range of capacities B) Axial flow compressors have a substantially constant delivery at variable pressures C) Centrifugal compressors have a wider stable operating range than axial flow compressors D) Axial flow compressors are bigger in diameter compared to centrifugal type

Discuss

Answer & Solution

Answer: Option D

Solution:

-Centrifugal compressors deliver practically constant pressure over a considerable range of capacities -Axial flow compressors have a substantially constant delivery at variable pressures -Centrifugal compressors have a wider stable operating range than axial flow compressors

14

Pick up the wrong statement

A) Large gas turbines employ axial flow compressors B) Axial flow compressors are more stable than centrifugal type compressors but not as efficient C) Axial flow compressors have high capacity and efficiency D) Axial flow compressors have instability region of operation

Discuss

Answer & Solution

Answer: Option B

Solution:

-Large gas turbines employ axial flow compressors -Axial flow compressors have high capacity and efficiency -Axial flow compressors have instability region of operation

15

The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation

A) 0.1% B) 0.5% C) 1.0% D) 5%

Discuss

Answer & Solution

Answer: Option C

Solution:

The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation 1.0%

16

Rotary compressors are used for delivering

A) Small quantities of air at high pressures B) Large quantities of air at high pressures C) Small quantities of air at low pressures D) Large quantities of air at low pressures

Discuss

Answer & Solution

Answer: Option D

Solution:

Rotary compressors are used for delivering Large quantities of air at low pressures

17

The air entry velocity m a rocket as compared to aircraft is

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

Discuss

Answer & Solution

Answer: Option D

Solution:

The air entry velocity m a rocket as compared to aircraft is zero

18

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

Discuss

Answer & Solution

Answer: Option A

Solution:

The compressor efficiency is the Isothermal H.P/indicated H.R The mechanical efﬁciency varies with compressor size and type, but 95% is a useful planning number. When calculating the compressor head and discharge temperature the efﬁciency used will be isentropic or polytropic

19

In jet engines, paraffin is usually used as the fuel because of its

A) High calorific value B) Ease of atomisation C) Low freezing point D) Both (A) and (C) above

Discuss

Answer & Solution

Answer: Option D

Solution:

In jet engines, paraffin is usually used as the fuel because of its hogh calorific value and low freezing point

20

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

Discuss

Answer & Solution

Answer: Option A

Solution:

In air compressors, free air delivery means the Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions

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