NUMERICAL ANALYSIS OF FLOW IN ULTRA MICRO CENTRIFUGAL COMPRESSOR INFLUENCE OF IMPELLER OUTLET BLADE ANGLE

For an ultra micro centrifugal compressor, the applicability of two-dimensional (2D) blade has been investigated with the consideration of productivity in the downsizing of impeller. On the other hand, the improvement of the pressure recovery ratio in the diffuser is also required to increase the overall pressure ratio of a centrifugal compressor system. In this study, the flows in three types of centrifugal compressor impeller with the 2D blade which are different in the impeller outlet blade angle were analyzed numerically because the outlet blade angle is the most important design parameter to specify the shape of such impeller. The computed results clarified that the increase of impeller outlet blade angle reduces the tip leakage flow and the reversed flow at the impeller outlet, but increases the wall friction loss due to the increase of the cascade passage length