# Centrifugal Compressors - Mechanical Engineering (MCQ) questions and answers

1)   The mass flow rate of air compressed in axial flow compressor is _____________centrifugal compressor.

a. lower than
b. higher than
c. same as
d. unpredictable
 Answer  Explanation ANSWER: higher than Explanation: No explanation is available for this question!

2)   Which of the following is NOT a type of rotary compressor?

a. Positive displacement type of compressor
c. Both a. and b.
d. None of the above
 Answer  Explanation ANSWER: None of the above Explanation: No explanation is available for this question!

3)   Which compressors are suitable for large volume flow rates of above 1200 m3/min

a. Centrifugal compressors
b. Axial flow compressors
c. Both a. and b.
d. None of the above
 Answer  Explanation ANSWER: Axial flow compressors Explanation: No explanation is available for this question!

4)   The function of _________ is to convert high kinetic energy of gases into pressure energy.

a. impeller
b. diffuser
c. casing
d. None of the above
 Answer  Explanation ANSWER: diffuser Explanation: No explanation is available for this question!

5)   How is the variation of air velocity while passing through impeller followed by diffuser in centrifugal compressor?

a. Air velocity goes no increasing in impeller followed by diffuser
b. Air velocity goes no decreasing in impeller followed by diffuser
c. Air velocity increases in impeller and then decreases in diffuser
d. Air velocity decreases in impeller and then increases in diffuser
 Answer  Explanation ANSWER: Air velocity increases in impeller and then decreases in diffuser Explanation: No explanation is available for this question!

6)   Angular momentum of gas in the free vortex of vaneless diffuser ___________.

a. increases
b. decreases
c. remains constant
d. becomes unpredictable
 Answer  Explanation ANSWER: remains constant Explanation: No explanation is available for this question!

7)   Vaneless diffusers are suitable for ___________.

a. only low pressure rise
b. only high pressure rise
c. both low as well as high pressure rise

 Answer  Explanation ANSWER: only low pressure rise Explanation: No explanation is available for this question!

8)   The diffuser blades are kept ______ the number of impeller blades .

a. 1/10 th of
b. 1/3 rd of
c. 10 times
d. 3 times
 Answer  Explanation ANSWER: 1/3 rd of Explanation: No explanation is available for this question!

9)   The ratio of actual whirl velocity to the ideal whirl velocity in the centrifugal compressor is called as _________.

a. velocity factor
b. slip factor
c. work factor
d. none of the above
 Answer  Explanation ANSWER: slip factor Explanation: No explanation is available for this question!

10)   What is the ratio of isentropic work to Euler work in an centrifugal compressor called?

a. Work coefficient
b. Velocity coefficient
c. Pressure coefficient
d. Flow coefficient
 Answer  Explanation ANSWER: Pressure coefficient Explanation: No explanation is available for this question!