Dissecting a complex system; a computational study of flow behavior in a single-blade pump

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.In this paper a computational, time-accurate analysis of a single-blade pump, whose flow system is characterized by highly oscillatory behavior, is presented. The study lays bare the immanent challenges present in applying CFD to such complex flow systems. Four time-accurate simulations with different modeling choices are completed in order to reveal the computational flow system's sensitivities to such decisions and obtain reliable performance predictions for experimental comparison. The time-accurate simulations consistently overpredicted the hydrodynamic performance according to expectations, but demonstrated strong dependency on particular CFD aspects: The strictness of the numerical convergence and the changes in the inflow and outflow configurations have a considerable effect on the system's flow behavior. Elevated levels of uncertainty also accompany the transient simulations.