非设计攻角下气膜冷却掺混损失模化研究

Modeling of Film Cooling Mixing Loss at Off-design Incidence Angle

气膜冷却能够对涡轮叶片表面起到良好的保护作用,但是在非设计状态下,边界层、冷气与主流的相互作用对涡轮气动性能产生不利影响。采用数值模拟的方法,研究了不同来流攻角下冷气的气动参数对掺混损失的影响规律。根据冷气与主流的动能比将主流与冷气的掺混过程分为低吹风比和高吹风比两种典型的模式。当动能比大于1时,掺混损失与动能比存在着线性关系;当动能比小于1时,掺混损失与吹风比存在着线性关系。基于主流与冷气不同的掺混模式并考虑攻角的影响,发展了一种预测非设计攻角下掺混损失的模型进行了初步验证。结果表明,大部分工况下掺混损失的预测结果与数值模拟结果的偏差在10%之内。

The turbine blade surface can be protected by film cooling.However,the interaction of boundary layer,cooling flow and main flow has adverse effects on the turbine aerodynamic performance for off-design condition.The effect of cooling flow aerodynamic parameters on the mixing loss at off-design incidence angle was investigated numerically.According to the kinetic energy ratio of cooling flow and main flow,the mixing between the main flow and the cooling flow can be divided into two typical modes:low blowing ratio mode and high blowing ratio mode.When the kinetic energy ratio is greater than 1,there is a linear relationship between the mixing loss and the kinetic energy ratio.When the kinetic energy ratio is less than 1,there is a linear relationship between the mixing loss and the blowing ratio.Based on the different modes and taken the effect of incidence angle into consideration,a model for predicting the mixing loss at off-design condition was developed and the preliminary verification was carried out.The results showed that the deviation between the predictions and the numerical results is within 10%for most conditions.