Applied Thermodynamics (3161910) MCQs

MCQs of Part-II Centrifugal Compressors

Showing 11 to 20 out of 24 Questions
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11.

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

(a)

inlet whirl velocity
(b)

outlet whirl velocity
(c)

inlet velocity of flow
(d)

outlet velocity of flow
Answer:

Option (b)

12.

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:

Option (c)

13.

When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be

(a)

forward curved
(b)

backward curved
(c)

radial
(d)

none of these
Answer:

Option (a)

14.

In a centrifugal compressor, an increase in speed at a given pressure ratio causes

(a)

increase in flow
(b)

decrease in flow
(c)

increase in efficiency
(d)

increase in flow and decrease in efficiency
Answer:

Option (d)

15.

Which one of the following is the effect of blade shape on the performance of a centrifugal compressor?

(a)

Backward curved blades has poor efficiency
(b)

Backward curved blades lead to stable performance
(c)

Forward curved blades has higher efficiency
(d)

Forward curved blades produce lower pressure ratio
Answer:

Option (d)

16.

The thrust on the rotor in a centrifugal compressor is produced by

(a)

Radial component
(b)

Axial component
(c)

Tangential component
(d)

None of the above
Answer:

Option (b)

17.

Pick up the wrong statement. The surging phenomenon in centrifugal compressor depends on

(a)

mass flow rate
(b)

pressure ratio
(c)

change in load
(d)

stagnation pressure at the outlet
Answer:

Option (d)

18.

Surging is the phenomenon of

(a)

unsteady, periodic and reversed flow
(b)

airstream blocking the passage
(c)

motion of air at sonic velocity
(d)

air stream not able to follow the blade contour
Answer:

Option (a)

19.

The phenomenon of choking in compressor means

(a)

no flow of air
(b)

fixed mass flow rate regardless of pressure ratio
(c)

reducing mass flow rate with increase in pressure ratio
(d)

increased inclination of chord with air steam
Answer:

Option (b)

20.

Losses in a centrifugal compressor are due to

(a)

inlet losses
(b)

impeller channel losses
(c)

diffuser losses
(d)

all of the above
Answer:

Option (d)

Showing 11 to 20 out of 24 Questions
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