Application of scale-resolving simulation to a hydraulic coupling, a hydraulic retarder, and a hydraulic torque converter

Abstract

The paper describes the qualification and validation of large eddy simulation (LES) and hybrid Reynolds-averaged Navier–Stokes (RANS)/LES, the so-called scale-resolving simulation (SRS) approaches, which are currently employed in transient simulations of internal flow for fluid machineries. Firstly, the application of various turbulence models in ANSYS FLUENT is briefly introduced to acquire the external performance of three hydrokinetic devices and to compare it with experimental data. It was found that a remarkable improvement in external performance was achieved. The best results could be as low as 4% for the absolute error in hydraulic coupling, 2%–5% for the error for the hydraulic retarder, and 2%–4% for the hydraulic torque converter. Basically, all models had better error levels than that of around 10%–15% obtained by RANS. Then four typical SRS simulations were applied to conduct numerical simulations of the internal flow fields for hydraulic coupling, the hydraulic retarder, and the hydraulic torque converter. The results provided two indisputable facts, firstly, that SRS models are more accurate in certain flow situations than RANS models and, secondly, that SRS models can give additional information compared with RANS simulations. Finally, the BSL SBES DSL model, a dynamic hybrid RANS/LES (DHRL) turbulence model, was applied to simulate and analyze the flow mechanism of the hydraulic coupling to deepen our understanding of it. The detailed flow structure in hydraulic coupling was determined and was used to understand the flow mechanism.