Computational Fluid Dynamical Analysis Of Complex Internal Flows In Centrifugal Pumps

Abstract

A commercial computational fluid dynamics (CFD) computer code was employed to compute the flow field from 105 percent down to 21 percent of the 4525 gpm BEP flowrate of a 1785 rpm, 1500 specific speed impeller of 14,000 suction specific speed. Suction and discharge recirculation were both computed, and the results agreed in all details that have also been observed experimentally. The insights gained from these computations led to the design and construction of a new impeller aimed at smoother minimum flow operation. The same code was then applied to the computation of the highly three-dimensional flowfield of the diffusing crossover of a 325 gpm, 3580 rpm, 900 to 1000 specific speed multistage volute pump. Flow distortions produced by this crossover were computed at the outlet to the impeller of the succeeding stage, and the effects on performance were estimated. Candidate improvements to the crossover were evaluated with the same code, illustrating the utility of CFD as a design and improvement tool. This tool can be used to improve pump performance and reliability in many different areas.