汽车外流场数值仿真k-ε模型适用性研究

A Study on the Applicability of k-ε Model for Numerical Simulation of Automobile External Flow Field

由于目前的湍流模型并非针对汽车空气动力学进行数值仿真,因而造成潜在的计算误差。因此,为探寻适合的数值计算模型,以MIRA阶梯背汽车1/3比例模型为研究对象,对常用的Standard k-ε、RNG k-ε和Realizablek-ε3种k-ε涡黏湍流模型进行数值仿真,以计算所得的气动力系数、尾部流场及表面压力系数为适用性评价指标,并与HD-2风洞试验数据对标。研究结果表明:3种模型中,Standard k-ε模型收敛速度和效率最优,但气动阻力的计算精准度最差;RNG k-ε模型的表现一般,而Realizable k-ε模型能获得最高的气动阻力计算精度,与风洞试验结果对比,误差在5%以内,但收敛速度和效率相对较差;同时,3种湍流模型对气动升力的计算结果与风洞试验对比存在较大误差。

Due to the fact that the current turbulence model is not intended for the numerical simulation of aerodynamic especially,there will be some potential calculation errors in this process.In order to find the suitable numerical model,taking the 1/3 proportion Mira ladder model as the research object,a numerical simulation test has thus been carried out of three normal vortex viscous turbulence models,i.e.Standard k-ε,RNG k-ε and Realizable k-ε,with the obtained statistics of the aerodynamic drag coefficient,the tail flow field and the surface pressure coefficient as the applicability evaluation indices,which are then compared with HD-2 wind tunnel test data.The results show that the convergence speed and efficiency of the Standard k-ε model are the best among three models,while with the least accuracy in its aerodynamic drag.The performance of RNG k-ε model is general.The realizable k-ε model has the highest aerodynamic drag calculation precision,with its error less than 5% compared with the wind tunnel test results.However,the convergence rate and efficiency are relatively poor.Meanwhile,the results of the three turbulence models are quite different from those of the wind tunnel experimental data.