Discuss the effect of pre-whirl on the performance of centrifugal compressors.
A single sided centrifugal air compressor delivers 1800 kg of air per minute. The air enters the eye of the impeller axially at total pressure of 100 kPa and total temperature of 290 K. The overall diameter of the impeller is 700 mm and it rotates at 1600 RPM. The slip factor is 0.9 and work input factor is 1.1. Isentropic efficiency is 85%. Calculate (i) power required by the compressor, (ii) pressure coefficient and (iii) total pressure at delivery.