PIV experimental study on dynamic and static interference flow field of multi-operating centrifugal pump under the influence of impeller wake

In order to study the influence law of the impeller wake on dynamic and static interference flow field of the centrifugal pump, this paper obtains the dynamic and static interference flow field of the centrifugal pump under different flow conditions (15 m³/h, 50 m³/h, 70 m³/h) based on PIV technology, and analyzes the influence mechanism of the impeller wake change on dynamic and static interference flow field. The results show that rotating stall occurs in the centrifugal pump under low flow condition, but it has little effect on the head loss in the centrifugal pump. In the dynamic and static interference flow field, under the condition of the low flow rate, the impeller wake collides with the baffle tongue, resulting in serious velocity fluctuation, and then there will be the secondary collision with the volute wall, which will eventually cause the wake to dissipate, and the change process of the wake shows the periodic characteristic. In the design condition and the large flow condition, the spacer tongue will have the cutting effect on the wake, and the high-speed accumulation phenomenon will occur in the volute flow path near the spacer tongue. In the side flow path of the volute, under the condition of the low flow, the impeller wake is mainly located at the exit of the impeller, and the end of the impeller wake is easy to fall off and gradually break up under the impact of the main stream. Under the design condition, the flow stability is good, and the wake vortex is close to the trailing edge of the blade, and there is no obvious shedding phenomenon. Under the condition of the large flow rate, the velocity fluctuates sharply, and many large-scale vortex structures appear on the cross section of the flow channel due to the cutting of the wake near the diaphragm tongue. In the impeller passage, the movement and distribution of the wake are significantly affected by changes in flow conditions. The research results provide a basis for optimizing volute channel.