液力变矩器热流动尺度解析模拟与特性精确预测

Scale-resolving Simulation of Thermal Flow and Accurate Performance Prediction in Hydrodynamic Torque Converter

针对液力变矩器数值模拟中雷诺时均方法(RANS)占据主导地位,但预测精度较低且缺乏对流场结构准确描述的现状,利用尺度解析模拟(Scale-resolving simulation,SRS)方法实现其原始特性及内流场的模拟分析。结果表明,在典型工况下,SRS方法能够更好地捕捉到流动信息,具有较高的原始特性预测精度。尤其是SBES(Stress-blended eddy simulation)方法中的动态混合模型(Dynamic hybrid RANS-LES,DHRL)得到原始特性预测结果的最大误差仅为3.24%。此外提出了变黏度SRS热流场计算方法,发现在考虑工作介质黏度随温度变化后,相对恒黏度数值模拟结果,原始特性预测精度有明显改善,其最大误差小于3%。尺度解析模拟方法在液力变矩器性能预测方面的应用,有助于实现产品的低成本与短周期设计。

For the current situation that RANS method has always played a dominant role in numerical simulation of hydrodynamic torque converter, but it has low prediction accuracy and lacks accurate description of flow field structures, the SRS(scale-resolving simulation) method is employed to simulate the performance and internal flow field. The results show that SRS method can accurately capture the flow information and efficiently predict the original characteristics with high accuracy in the typical working conditions. Especially, the DHRL(dynamic Hybrid RANS-LES) model of SBES(stress-blended eddy simulation) method has shown the best prediction with the maximum error 3.24%. In addition, a method based on SRS model for calculating the thermal flow field with variable viscosity of transmission oil is also considered. It can be found that the performance prediction accuracy is obviously improved and the maximum error is less than 3% when the variable viscosity with temperature is considered. Applications of SRS analysis in the performance prediction of torque converter contributes to achieve low cost and short cycle design of the products.