Questions and answers for exam Preparation

MCQs

Total Questions : 164 | Page 7 of 17 pages

Question 61. Which of the following statement is correct as regard to centrifugal compressors?

The flow of air is parallel to the axis of the compressor.
The static pressure of air in the impeller increases in order to provide centripetal force on the air.
The impeller rotates at high speeds.
The maximum efficiency is higher than multi-stage axial flow compressors.

Discuss Question

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

Question 62. Maximum work is saved in a two stage reciprocating air compressor with incomplete intercooling.

Agree
Disagree
Can't say
None of these

Discuss Question

Answer: Option B. -> Disagree
Answer: (b).Disagree

Question 63. In jet propulsion power unit, the inlet duct of diverging shape is used for converting kinetic energy of air into pressure energy.

True
False
Can't say
None of these

Discuss Question

Answer: Option A. -> True
Answer: (a).True

Question 64. The process, which causes the air to enter the impeller blades of a centrifugal compressor at __________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

reduced
increased
Can't say
None of these

Discuss Question

Answer: Option A. -> reduced
Answer: (a).reduced

Question 65. The ratio of the net work obtained from the gas turbine plant to the turbine work is known as

compression ratio
work ratio
pressure ratio
none of these

Discuss Question

Answer: Option B. -> work ratio
Answer: (b).work ratio

Question 66. The mass of gas turbine per kW developed is about __________ as that of an I.C. engine.

same
one-half
one-fourth
one-sixth

Discuss Question

Answer: Option D. -> one-sixth
Answer: (d).one-sixth

Question 67. In a centrifugal compressor, the ratio of the __________ to the blade velocity is called slip factor.

inlet whirl velocity
outlet whirl velocity
inlet velocity of flow
outlet velocity of flow

Discuss Question

Answer: Option D. -> outlet velocity of flow
Answer: (d).outlet velocity of flow

Question 68. The temperature of air at the beginning of the compression stroke is __________ the atmospheric temperature.

equal to
less than
more than
None of these

Discuss Question

Answer: Option C. -> more than
Answer: (c).more than

Question 69. The air is delivered __________ in one revolution in case of a three-lobbed rotor.

two times
three times
four times
six times

Discuss Question

Answer: Option D. -> six times
Answer: (d).six times

Question 70. In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in

exit nozzle, which is a constant volume process
exit nozzle, which is essentially an isentropic process
turbine blades, which is a constant volume process
turbine blades, which is essentially an isentropic process

Discuss Question

Answer: Option D. -> turbine blades, which is essentially an isentropic process
Answer: (d).turbine blades, which is essentially an isentropic process