Study on improvement of hump characteristic of an axial flow axial pump by grooving inlet wall

Abstract

When operating at part load conditions, flow separations may occur in the impeller of an axial flow pump due to the increase of the incidence angle at the impeller leading edge, probably resulting in instability in head curve. In this paper, the hump characteristic in head curve of an axial flow pump has been examined by CFD method with the help of ANSYS CFX 16.0. The results show that the head of the axial flow pump in the hump area decreased by 40% at 61% of the design flow rate, caused by stalls in the pump impeller. Furthermore, the improvement of head curve has been conducted by applying axial grooves at the wall of the pump inlet section. It is found that under the condition of small flow rates, the axial groove can effectively reduce the inlet circulation and the attack angle at the leading edge of the impeller. As a result, the back flow on the suction side of the impeller has been reduced. Consequently, the hump phenomenon in the head curve of the axial flow pump has been effectively eliminated.