燃气轮机旋转状态下的动叶气膜冷却效果数值模拟研究

采用数值模拟的方法研究了旋转对叶片气膜冷却效果的影响，详细对比了不同吹风比下叶片在旋转和静止状态下的气膜冷却特性，并用平均气膜冷却效率和不均匀系数评估了气膜冷却效果。结果表明：在叶片压力面，叶片的旋转使得射流气体从气膜孔流出后法向动量增大，与主流掺混作用加强，从而使得叶片压力面气膜冷却效率值低于静止状态；在叶片吸力面，叶片旋转使得冷却气体流出后法向动量减小，能够更好地贴附在叶片表面向下游流动，使得旋转时叶片吸力面气膜冷却效率要优于静止状态，并且叶片后沿的平均气膜冷却效率较静止状态有显著提高；旋转状态下叶片表面的不均匀度系数要略大于静止时叶片表面不均匀度系数。

Numerical Simulation Study of Film Cooling Effectiveness on the Rotating Gas-Turbine Blade

In this paper, the film cooling effectiveness of rotating gas turbine blade is investigated through numerical simulations. The cooling characteristics under different blowing ratios in rotating state as well as static state are compared in details. The average film cooling efficiency and cooling non-uniformity coefficient are used to evaluate the film cooling effect. The results show that on the pressure surface of the blade, due to the blade rotation the momentum of the jet cooling air in the normal direction will increase after the airflow passes through the film hole and then intensify with the mix of mainstream, such that the film cooling efficiency on pressure surface is lower than that of the static state. While on suction surface the rotation will result in the decrease of the normal momentum of jet air through the film hole, which will make it remain well attached to the surface and move downstream. Therefore the film cooling efficiency on suction surface is higher than that of the static state, and the average film cooling efficiency on the trailing edge is significantly boosted in comparison with the static state. The cooling non-uniformity coefficient on rotating blade is slightly greater than that of the static blade.