61. The velocity of air entering in a rocket is __________ as compared to an aircraft.
zero
less
more
same
✅ The correct answer is option A.
Compressors, Gas Dynamics and Gas Turbines MCQs
62. The performance of air compressor at high altitudes will be __________ as compared to that at sea level.
same
lower
higher
✅ The correct answer is option B.
63. The air power of the compressor is also known as
indicated power
brake power
frictional power
none of these
✅ The correct answer is option A.
64. 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
✅ The correct answer is option B.
65. The overall efficiency of the compressed air system is the
ratio of shaft output of the air motor to the shaft input to the compressor
ratio of shaft input to the compressor to the shaft output of air motor
product of shaft output of air motor and shaft input to the compressor
none of the above
✅ The correct answer is option A.
66. In a jet engine, the compression varies as the square of the speed.
Correct
Incorrect
✅ The correct answer is option A.
67. A regenerator in a gas turbine improves thermal efficiency.
Correct
Incorrect
✅ The correct answer is option A.
68. The absolute pressure of air at the outlet of a compressor is called
back pressure
critical pressure
discharge pressure
none of these
✅ The correct answer is option C.
69. 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
✅ The correct answer is option A.
70. The workdone on a compressor will be minimum if air is taken from
the atmosphere
a source at 0° C
a source of low temperature air
a source of high tempe
✅ The correct answer is option C.