Slip Factor for Jet-Wake Flow in a Centrifugal Impeller

The centrifugal impeller outlet relative flow exhibits two regions, across blade to blade pitch. A region of low relative velocity towards the suction surface called wake flow and a region of high relative velocity towards the pressure surface called jetflow are known to exist. This leads to a high absolute velocity in the wake flow and a low absolute velocity in the jet flow with a large difference in absolute flow angles in these two regions. The slip facrors for these two flows were experimentally evaluated through hot-wire anemometry measurement at different flow coefficients and they were compared with the values obtained from various correlations available in literature. The measurements indicate that the slip factor for the wake flows are different. The measured slip factor for the jet flow is lower than the values suggested by the correlations which is attributed due to viscous effects. The slip factor for the wake flow largely deviates from the value suggested by the jet-wake model. New slip correlations are being suggested for jet and wake flow based on the measurements. The slip factor has been found to depend on flow coefficient and its value increases with decrease inflow coefficient.\u