Abstract
The flow field in a centrifugal compressor is highly three-dimensional and complicated by the strong secondary flows. In order to improve the performance and operating range, it is indispensable to elucidate the three-dimensional flow phenomena. In this paper, the flow fields in a centrifugal compressor impeller with vaneless diffuser have been investigated by numerical flow analysis. Three-dimensional separated and vortical flow fields were analyzed by Reynolds-averaged Navier-Stokes simulations (RANS) using an unfactored implicit upwind relaxation scheme. As the turbulence model k-ω two-equation model was employed. To elucidate the complicated flow fields, vortex structures were identified by the critical point theory. From numerical analysis results , it was found that the tip leakage vortex breakdown occurred and the leakage vortex of the full-blade interacts with the splitter-blade leading edge at the operating point of maximum pressure rise. This phenomenon causes the large loss and significant impact on the total performance characteristics.
