应用各向异性湍流模型对气膜冷却的数值研究

Numerical investigation of film cooling with anisotropic turbulence model

应用引入各向异性系数的k-w湍流模型和标准k-ε模型,对平板气膜冷却经典实验进行了数值研究,分析了各向异性系数的引入对气膜孔下游流场与温度场的影响机理,探讨了该系数的适用性问题.研究表明:①展向各向异性系数的引入,增加了流体在展向的湍流脉动,强化了气膜冷气沿展向的扩散;②各向异性模型的计算结果在低吹风比(M=0.5)的工况下与实验值符合得较好;③各向异性系数在气膜脱离壁面与主流掺混的区域适用性较差.

An in-house three-dimensional Navier-Stokes code was developed to evaluate numerically the advantages of the anisotropic turbulence model over the classical isotropic k-ε model in a typical film cooling experiment.The anisotropic turbulence model was the k-w turbulence model incorporated with anisotropic coefficient.The effects of the anisotropic turbulent transport coefficient on the flow and temperature filed were analyzed in detail.The applicability of this model was also discussed.Comparison result reveals that the introduction of the anisotropic turbulent transport coefficient intensified the turbulent mixing of cooling jet with the main stream in lateral direction,and subsequently enhanced the lateral spreading of cooling air.The cooling effectiveness in centerline predicted by the anisotropic model was much closer to experimental data than that by the standard k-ε model.The anisotropic model was in good agreement with the experimental results at low-mass flux ratio condition（M=0.5）.However,with the increase of mass flux ratio,the jets tend to be detached and then reattached to the wall,the discrepancy upstream the reattachment increased due to the limitation of the anisotropic coefficient,and downstream the reattachment these two agreed well consistently.