Numerical investigation of two-phase air-water flow in a centrifugal pump with closed or semi-open impeller

Abstract

3D CFD-simulations of a centrifugal research pump in single- and two-phase flow conditions with closed and semi-open impeller are performed. In single-phase flow, a satisfactory agreement to experimental data in terms of head prediction is obtained. For two-phase flows, an Eulerian-Eulerian monodisperse model in combination with a statistical turbulence model is used. A grid dependency is unavoidable for large bubbles since a bubble diameter exceeding the grid scale limits a further refinement of finite volume grid cells. The air bubble diameter is a key parameter for pump performance calculation, which can be shown by a bubble size variation, in which the experimental pump head is captured qualitatively well. Further studies will focus on the improvement of the two-phase model to allow simulations of dense disperse phase and bubble sizes larger than the grid scale. Enabling polydispersity and bubble interaction are assumed to be essential for quantitative pump head prediction.