Numerical Optimization of a Centrifugal Pump Impeller with Splitter Blades Running in Reverse Mode

Abstract

In this paper the numerical modeling and optimization of a centrifugal pump impeller running in reverse operation is presented. The turbine operating point was determined using empirical correlations, which were also validated by the numerical performance curves obtained from multiple operating point simulations. This information is used to validate the numerical approach and assumptions in order to be used in the optimization of the impeller in turbine operation. Subsequently, a parametric study is performed comparing the relative effect in performance of various design modifications, such as the inlet edge shape, the meridional channel width, the number of vanes, and the effect of splitter blades. Using the previous results as guidelines, the numerical optimization of the runner is performed using two optimization algorithms. In the first, only the blade shape was allowed to change while the meridional contour of the runner was maintained constant in order to accommodate the available spiral casing dimensions. In the second optimization, the runner diameter was also included. From the results of the optimization, an overall increase in turbine efficiency of approximately 2.7% could be achieved.