Flow Separation and Performance of Decelerating Channels for Centrifugal Turbomachines

Fundamental studies on diffusers were performed in order to get a better knowledge of flow in centrifugal turbomachines and to improve their performance. First, the flow inside channels with logarithmic spiral walls was investigated. Boundary layer development and its effect on the diffuser performance (pressure-rise and its efficiency) were analyzed. Effects of diffuser configurations in circular cascades were also made clear. Further, separation in impellers with logarithmic spiral blades was computed and discussed.