Flow numerical analysis within auxiliary-impellers of centrifugal pumps

For pumps with auxiliary impeller dynamic seals can meet the requirements of high efficiency, long life and high reliability, they are used more and more by industries to meet environmental protection and energy saving. However, the researches have yet been carried out little on the internal flow mechanism of the auxiliary impeller dynamic seals and their design optimization based on energy saving. In order to understand the detailed internal flow within the centrifugal pump with and an auxiliary impeller dynamic seal, a lot of numerical simulations were carried out by FLUENT, based on the S-A turbulent model and the time-averaged Reynolds equation. The steady simulation was designed to analyze the sealing mechanism and internal flow within an auxiliary impeller dynamic seal, and to research the effects of the auxiliary impeller dynamic seal on pump performance. The results show that an auxiliary impeller dynamic seal has influence to flow within main impeller and volute, but the influence is slight. Compared to the pump without the auxiliary impeller, the head of the centrifugal pump with an auxiliary impeller is higher while its efficiency is lower, and the difference of the head become larger while that of the efficiency becomes smaller as its flow rate increases.