油相-气相两相流对湿式离合器带排转矩影响的数值分析

Numerical Analysis of Effect of Liquid-gas Two-phase Flow on the Drag Torque Characteristics of Wet Clutch

为减小怠速工况下湿式离合器因油液剪切产生的带排转矩,考虑油相-气相两相混合的影响,对摩擦副油路进行数值求解。基于k-ε两层湍流模型和欧拉方法中流体体积模型,采用流场计算STAR-CCM+软件建立含径向槽的摩擦副内流域模型,进行稳态计算。研究入口流量和相对转速对带排转矩的影响,并与试验结果进行对比,结果趋势相似,平均数值误差7.54%.改变槽角结构,研究油相-气相两相流动同带排转矩的相关性。结果表明:入口流量越大,带排转矩越大,当流量为7 L/min时,带排转矩最大值为4.63 N·m;当流量由7 L/min分别降低至5 L/min、3 L/min时,带排转矩值分别下降20.95%、33.69%;槽角有利于减小带排转矩,负向槽角的优势更为明显;单相流转速区,正向槽角越大,油液流通性越好,带排转矩越大;两相流转速区,槽角越大,油液连续性越差,油液占比越小,带排转矩越小。

For the purpose of reducing the torque caused by oil shear in disengaged clutch discs,a fluid dynamic simulation about the flow field inside two discs is made in considering the influence of oil-gas mixing process.A 3D CFD simulation model including the information about radial groove is built by STAR-CCM+,which calculates the steady state based on Euler two-phase model and k-εtwo-layer turbulence model.The calculated results are used to investigate the effects of the flow rate and relative rotating speed on drag torque,which agree with the experimental results with average error of 7.54%.The correlation between oil-gas distribution and drag torque characteristics is observed by changing the structure of groove angle.The research results show that the drag torquel increases with the flow rate.The maximum torque is 4.63 N·m when the flow rate is 7 L/min,and the values of drag torque are reduced by about 20.95%and 33.69%,respectively,when the flow rate is reduced from 7 L/min to 5 L/min and 3 L/min.The groove angle can reduce the drag torque,and the negative groove angle has a better effect in reducing the drag torque.In the single-phase flow velocity zone,the bigger the positive groove angle is,the better the oil liquidity is,and the bigger the drag torque is.In the two-phase flow velocity zone,the continuity of the oil flow is worse,the proportion of oil is smaller and the the drag torque is smaller with increase in groove angle.