尺度解析模拟在液力偶合器、液力缓速器和液力变矩器中的应用（英文）

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

目的:针对流体机械数值模拟过程中雷诺时均应力(RANS)方法占据主导地位但预测精度较低且缺乏对流场信息准确描述的现状,提出应用尺度解析模拟(SRS)方法来改进性能的预测精度以及加深对流动结构的理解。创新点:1.利用SRS方法,降低RANS湍流模型的选择困难,实现性能精准预测;2.建立全流道网格计算模型,充分展现单流道间瞬时流动信息的差异。方法:1.通过较少的网格划分及周期计算,对具有简单循环圆和平面叶片的液力偶合器进行计算,并与试验数据进行对比,初步筛选出较为适合的湍流模型(图6),进而在模型更为复杂、流动更加多变的液力缓速器和液力变矩器性能预测中进行验证(图15和21);2.通过对复杂的瞬态流动现象的清晰捕捉,深入展示3种液力元件的内部流动机理(图9、10、16、17、22和23),并评估SRS方法相较RANS方法在流动结构描述方面的先进性(图7和8)。结论:1.在液力偶合器、液力缓速器和液力变矩器等液力流体机械的计算流体动力学(CFD)模拟中,SRS方法可以提高性能预测精度并提供更为细致的流场信息;2. SRS方法中的混合RANS/LES(大涡模拟)模型在液力元件流场计算中的预测准确度、流场结构描述及计算成本等方面表现出色,尤其是BSLSBESDSL模型值得重点关注和发展;3.为了进一步验证SRS方法的实用性,可以在模拟中考虑工作介质物理属性的影响,细化网格并对气液两相流动及边界层流动进行详细计算。

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 tran- sient 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 re- tarder,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.