Application of a new DES model based on Wray-Agarwal turbulence model in flow simulation of a mixed-flow pump

• Published in: Proceedings of the Institution of Mechanical Engineers. Part A, Journal of power and energy Journal of power and energy, 2024-08, Vol.238 (5), p.847-867
• Main Authors: Ji, Leilei, Li, Haoming, Li, Wei, Shi, Weidong, Li, Shuo, Yang, Yang, Zhao, Chensong, Agarwal, Ramesh K
• Format: Article
• Language: English
• Subjects: Accuracy; Detached eddy simulation; Eddy viscosity; Flow characteristics; Flow separation; Flow simulation; Flow velocity; Fluid dynamics; Fluid flow; Guide vanes; Performance prediction; Rotor stator interactions; Rotors; Shear stress; Simulation; Stators; Stress transfer; Three dimensional flow; Turbulence models; Turbulent flow; Velocity distribution; Viscosity; Vortices
• ISSN: 0957-6509; 2041-2967
• DOI: 10.1177/09576509241236533

In recent years, it has been demonstrated for many two- and three-dimensional external and internal turbulent flows that the one-equation Wray-Agarwal turbulence model can compute the complex turbulent flow fields with high computational accuracy, excellent computational convergence and efficiency. In this paper, Wray-Agarwal (WA) turbulence model is employed as part of a detached eddy simulation (DES) method to predict the performance of a mixed-flow pump. By comparing the computations with the experimental results, the differences and similarities between the WA-DES model and the Shear Stress Transfer (SST) k-ω model in predicting the internal and external flow characteristics of the pump are analyzed. The results show that both the SST k-ω model and the WA-DES model can reasonably predict the performance of the pump between 0.6Q and 1.2Q, where Q is the design flow rate; however, they have their own merits and deficiencies in predicting head and efficiency of the pump at low and high flow rates. For the velocity field in the rotor-stator interaction region, the WA-DES model shows better prediction accuracy since it can accurately predict the large-scale recirculating vortex structure at the inlet of the guide vane. The SST k-ω model over-predicts the separated flow region, which leads to the emergence of a small vortex structure before the backflow region of the pump. Although the turbulent eddy viscosity predicted by the WA-DES model is higher than that of the SST k-ω model and there is small difference in the results for the scale of the tip leakage vortex (TLV) between the two models, the overall simulation results of the WA-DES model for the high turbulent viscosity region and the pressure increase in the impeller are consistent with the SST k-ω model results. The results of this paper demonstrate the potential of WA-DES model for prediction of flows in pumps.