Evaluation of near-wall solution approaches for large-eddy simulations of flow in a centrifugal pump impeller

• Published in: Engineering applications of computational fluid mechanics 2016-01, Vol.10 (1), p.452-465
• Main Authors: Yao, Zhi-Feng, Yang, Zheng-Jun, Wang, Fu-Jun
• Format: Article
• Language: English
• Subjects: Boundary layer flow; centrifugal pump impeller; Centrifugal pumps; Computational fluid dynamics; Computer simulation; evaluation; Flow simulation; Fluid flow; Impellers; Large eddy simulation; Laser doppler velocimeters; near-wall solution; Predictions; Product design; Pump impellers; Simulation; Steady flow; Turbulent flow; Velocimetry; Vortices
• ISSN: 1994-2060; 1997-003X
• DOI: 10.1080/19942060.2016.1189362

The turbulent flow in a centrifugal pump impeller is bounded by complex surfaces, including blades, a hub and a shroud. The primary challenge of the flow simulation arises from the generation of a boundary layer between the surface of the impeller and the moving fluid. The principal objective is to evaluate the near-wall solution approaches that are typically used to deal with the flow in the boundary layer for the large-eddy simulation (LES) of a centrifugal pump impeller. Three near-wall solution approaches -the wall-function approach, the wall-resolved approach and the hybrid Reynolds averaged Navier-Stoke (RANS) and LES approach - are tested. The simulation results are compared with experimental results conducted through particle imaging velocimetry (PIV) and laser Doppler velocimetry (LDV). It is found that the wall-function approach is more sparing of computational resources, while the other two approaches have the important advantage of providing highly accurate boundary layer flow prediction. The hybrid RANS/LES approach is suitable for predicting steady-flow features, such as time-averaged velocities and hydraulic losses. Despite the fact that the wall-resolved approach is expensive in terms of computing resources, it exhibits a strong ability to capture a small-scale vortex and predict instantaneous velocity in the near-wall region in the impeller. The wall-resolved approach is thus recommended for the transient simulation of flows in centrifugal pump impellers.