分离涡流场数值仿真的参数影响研究

分离涡流场普遍存在于工业现场,数值仿真和试验研究在分离涡研究中相辅相成。数值仿真控制方程存在多个参数,某些参数变化对仿真结果有很大影响。以二维后向台阶流场、圆管后向台阶流场和圆管楔形流场为例,借助粒子图像测速技术和数值仿真方法,对参数变化影响进行研究。使用切应力运输(Shear stress transport,SST)k-ω湍流模型对分离涡流场进行数值仿真,理论推导得到SST k-ω湍流模型参数a_1变化对三种具有分离涡的流场数值仿真结果的影响。研究结果认为参数a_1越大,回流区长度越小。通过数值仿真验证理论推导结论。并通过比较模型参数变化对数值仿真结果的影响,认为圆管楔形流场与二维后向台阶流场、圆管后向台阶流场具有相似流场特性。根据粒子图像测速技术观测结果,优化模型参数a_1的设置。

Research on the Effects of Numerical Simulation Parameters of Separation Vortex Flow Field

Separation vortex flow field widely exists in the industrial field. Numerical simulation and experimental study of separation vortex complement each other. Numerical simulation equations include a number of parameters. Some of them have a great impact on the simulation results. Based on 2D backward facing step flow field, pipe backward facing step flow field and pipe wedge flow field, using particle image velocimetry(PIV) and numerical simulation, the effects of parameters variation are obtained. Numerical simulation of separation vortex is carried out by shear stress transport(SST) k-ωmodel. The effect of the variation of SST k-ωmodel parameter a1 on three kinds of flow field numerical simulation results with separation vortex is obtained by theoretical derivation. It shows that the recirculation zone length increases with the increase of a1. Theoretical derivation result is verified by numerical simulation. By comparing the effects of variation of model parameters on the simulation results, it shows that the characteristics of 2D backward facing step flow field and the pipe backward facing step flow field is similar with pipe wedge flow field. According to the results of PIV, the setting of model parameter a1 is optimized.