Stall Inception Control by Setting Groove Based on Its Formation Mechanism in Centrifugal Impeller

Abstract

Stall, a complex flow phenomenon in centrifugal pump, plays a crucial role in pump safety and stability under part-load conditions. In this paper, a verified numerical simulation method is employed to analyze the three-dimensional flow field under the stall inception conditions. The results reveal the initial stall vortex occurs near the Q=0.7Qd condition in the prototype impeller. Based on stall formation mechanism, the high-velocity fluid near the blade pressure side is sucked into suction side of next impeller channel by setting a groove near the blade leading edge. This jet flow can prevent the narrow vortices near the impeller shroud from moving towards the blade suction side, thereby suppressing the formation of stall vortex. By comparing the effects of different groove locations, directions, and sizes on stall vortex control, the optimal groove width is determined to be approximately 1mm. Compared with the prototype impeller, the grooved impeller can completely eliminate the stall vortex and significantly reduce pressure pulsation under part-load conditions. Moreover, the head of grooved impeller is increased by nearly 15% under Q=0.6Qd condition, and the potential suppression mechanism is also explained. Based on the stall formation mechanism, this paper puts forward an effective stall control method, which delays the stall inception significantly.

Keywords

• numerical simulation
• impeller
• groove
• narrow vortex
• stall control