气膜冷却恢复区的湍流模型
A TURBULENCE MODEL FOR FILM COOLING RECOVERY REGION
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摘要: 在 Lam- Bremhorst低雷诺数 k-ε模型的基础上, 发展了气膜冷却恢复区的湍流模型。原模型中的常数 cμ 和 c1代之以沿 x、y方向变化的参数, 低雷诺数函数 fμ、f1和 f2 沿 x方向有所变化。修正后的模型可以在 0 .4~ 1.0的吹风比范围内, 较好地描写恢复区内时均速度、湍动能和湍应力分布, 并能正确模拟向不吹风情况过渡的恢复过程。Abstract: It is observed that the normal k-ε turbulence model,which is very popular in computational fluid dynamics,is inapplicable to predicting the film cooling recovery region flow successfully.The reason might be the fact that the profiles of flow parameters are significantly different from those in normal boundary layer due to the blowing and the distance needed for flow returning to the normal boundary layer is too large.A new turbulence model based on Lam-Bremhorst low Reynolds number k-ε turbulence model has been proposed for prediction of the film cooling recovery region.It was found that the constant c μ and c 1 in the original model should be modified to be functions of coordinates x and y,and the low Reynolds number functions f μ,f 1 and f 2 should be varied with x and y too.The modified expressions feature that they should be approaching to nonblowing boundary layer when the distance from initial section becomes large enough.Three numerical examples demonstrate the advantages of this new model over the original one for the blowing ratio ranging from 0 4 to 1 0.
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