Influences of cavity leakage on the design of low flow coefficient centrifugal impeller

The low flow coefficient centrifugal impeller (LFCCI) gives a relatively low efficiency and a special treatment is required for the design of this kind of impeller. This paper investigates the influences of cavity leakage on the performance prediction and design of LFCCI based on Computational Fluid Dynamics (CFD) techniques. The results show that, the reduction in the efficiency of impeller due to the introduction of cavity leakage varies with the blade shape of impeller in a wide range since there is a strong and complex interaction of main flow and leakage flow in the LFCCI. To get a credible optimization result, the backside and foreside cavities should be considered in the CFD-based design of LFCCI.