D $2019 Pages: 3

12 a) Define slip factor and pressure coefficient in centrifugal compressors 4
b) An axial flow compressor draws in air at 20°C and delivers it at 50°C. Assuming 6

50% degree of reaction, calculate the velocity of flow and number of stages if blade
velocity is 100m/s, work factor as 0.85. Assume the blades are symmetrical and air

inlet and exit angle ‏و‎ = 10°, 3 = 40°
13 A centrifugal compressor has a compression ratio of 4:1 with an isentropic 10 efficiency
88% when running at 14000 rpm and including air at 25°C. Curved vanes at inlet gives
the air a pre -whirl of 18° to axial direction at all radii and the mean diameter of eye is
245mm. Absolute air velocity at inlet is 120m/s. Impeller tip diameter is 580mm.

Calculate the slip factor.

14 a) Explain the working of axial flow compressor and obtain the expression for the 5
work done.
b) Explain surging and choking in centrifugal compressors. 5
KKK

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