Effect of Partial Shrouds on the Performance and Flow Field of a Low Speed Centrifugal Compressor

The performance of a centrifugal compressor without and with partial shroud (PS) attached to the rotor blade tip at three values of tip clearance, viz. =2.2 %, 6.1 % and 7.9 % of rotor blade height at the exit. The rotor exit flow is measured using a precalibrated five hole probe at three flow coefficients, namely, =0.18 (below design flow coefficient), =0.28 (design flow coefficient) and =0.34 (above design flow coefficient). The axial distribution of total pressure coefficient at rotor exit for the three flow coefficients clearly indicate increase in total pressure in the rotor tip region for the configuration with PS compared to that for the basic configuration. Similar increase is observed in the static pressure distribution at the rotor exit for the higher values of clearance. The mass averaged total and static pressures at the rotor exit for both configurations at the three values of tip clearances clearly show that partial shrouds are beneficial in improving the pressure rise of the compressor. This benefit is found to be more at the higher value of tip clearance tested.