Flow behaviour in centrifugal impellers

Detailed investigations through hot-wire anemometry at the outlet of a centrifugal compressor impeller reveal a complex nature of flow behavior both spatially across the blade to blade pitch and with respect to time. The relative flow angle and velocity do not fit into the conventional steady state jet-wake model nor the one-dimensional slip theory. A hypothesis that periodic vortices shed from the suction surface well inside the impeller sweeping across the impeller passage is put forward to explain the large variations in flow angle observed