Numerical Analysis of Three-Dimensional Unsteady Turbulent Flow in Circular Casing of a High Power Centrifugal Diffuser Pump

摘要

For high power centrifugal pump which is usually used in high risk applications, circular casing structure has been adopted to increase the reliability of the pump. This special casing structure can make the flow more complex and cause huge hydraulic losses. In this paper, the periodically unsteady turbulent flow in the circular casing of a high power centrifugal diffuser pump has been investigated numerically by CFD calculation. The velocity distributions in different positions were analyzed, and the pressure fluctuation results in time and frequency domains were considered. Finally, the pressure fluctuation intensity coefficient (PFIC) and peak pressure coefficient (PPC) based on statistical thinking were defined on each grid node and the results were analyzed quantitatively to check the time accumulation effect of the unsteady flow phenomenon. The results show that strong flow unsteadiness can be found near diffuser outlet positions of the circular channel and in discharge tube. In addition, the PPC and PFIC results can supply a new angle of view to evaluate the pressure variation, and it is a good supplement to the traditional unsteady pressure analysis method in time and frequency domains.