A Reduced Order CFD Method for Preliminary Design Analysis of Pumps

Abstract

The need for fast and reliable analysis of preliminary pump designs exists. Traditionally this analysis has been performed with streamline-curvature throughflow methods or similar inviscid methods. In this paper a newly developed Reynolds-Averaged Navier-Stokes (RANS) CFD solver for preliminary pump design analysis is described. The solver will serve as a reduced order method, although of a higher order than the streamline-curvature throughflow method, still being fast and reliable and without having to revert to the full 3-D viscous CFD analysis at the early stage of the design process. The new quasi 3D code has two general solver modes, the throughflow (r-z plane) and blade to blade (m’-theta plane), respectively. With the new solver the well known limitation, not allowing for reversal flows, of the traditionally used streamline-curvature throughflow method does not exist due to its formulation. This allows for more realistic off design flow predictions. The RANS solver uses the artificial compressibility method to drive the solution to the incompressible limit and being an implicit unstructured solver allows for fast turnaround time and handles additional compartments, seal cavities and impeller sidewall gaps etc., connected to the blade passage with ease. Both solver modes handle multiple components (rotor and stator). In the blade to blade mode unsteady rotor stator interaction can be performed with the aid of dual-time stepping, moving mesh and non-conformal sliding interfaces. Strengths and shortcomings of the solver are discussed together with validation examples taken from many pump types. These examples show that the solver is an attractive tool for preliminary design analysis.