Inception of Inlet Reverse Flow in Centrifugal Pump Impeller.

Abstract

In the previous reports, effects of an impeller blade tip clearance and the blade number on the inlet reverse flow starting point were clarified for three and five blades open-type and closed-type impellers with good suction performences. Then, in this paper, for the close-type and open-type impellers with the blade inlet angle decided by conventional design method, the same experiment was carried out to know effects of the blade inlet angle on the inlet flow condition at low flow rates and the inlet reverse flow starting point, and the results were compared with the previous ones. Furthermore, the inlet reverse flow occurrence mechanism of the centrifugal pump impeller was examined based on the experimental results. It was particularly shown that the inlet reverse flow inception point can be predicted by investigating the relative flow along the impeller shroud surface.