Abstract Large eddy simulations (LES) of jet in crossflow (JICF) by modifying the upstream obstacles for enhancing the film cooling performance are performed in this study. Three types of upstream obstacles are considered, i.e. no obstacle, step and ramp placed upstream of the film cooling orifice. The numerical methods and mesh resolution are carefully validated with the experimental data. The predicted results show that the designed upstream obstacle leads to the changes of the flow structure and has a great improvement on the adiabatic cooling efficiency. The obstacle affects the development of the boundary layer upstream of cooling jet orifice and the recirculation zones are formed between the upstream obstacle and cooling jet orifice. The formation of horseshoe vortex structures are suppressed by the formed recirculation zones, which indicates that the existence of the recirculation zone enables some cooling gas to enter the recirculation zone and increases the air film cooling effects in the near field, which is conducive to the improvement of adiabatic cooling efficiency. The case with ramp has the best overall film cooling performance among the configurations considered in this work, especially on the wall surface away from the central plane. Besides, the cooling efficiency and characteristics with different upstream obstacles have also been addressed.

中文翻译：

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不同上游障碍物的气膜冷却大涡模拟

摘要 本研究通过修改上游障碍以提高薄膜冷却性能，对横流（JICF）中的射流进行大涡模拟（LES）。考虑了三种类型的上游障碍物，即无障碍物、台阶和斜坡放置在薄膜冷却孔口的上游。数值方法和网格分辨率都经过实验数据的仔细验证。预测结果表明，设计的上游障碍物导致流动结构的变化，对绝热冷却效率有很大的提高。障碍物影响冷却射流孔口上游边界层的发育，上游障碍物与冷却射流孔口之间形成回流区。马蹄形涡结构的形成被形成的回流区抑制，说明回流区的存在使部分冷却气体进入回流区，增加了近场气膜冷却效果，有利于提高绝热冷却效率。在这项工作中考虑的配置中，带斜坡的情况具有最佳的整体薄膜冷却性能，尤其是在远离中心平面的壁面上。此外，还解决了具有不同上游障碍的冷却效率和特性。在这项工作中考虑的配置中，带斜坡的情况具有最佳的整体薄膜冷却性能，尤其是在远离中心平面的壁面上。此外，还解决了具有不同上游障碍的冷却效率和特性。在这项工作中考虑的配置中，带斜坡的情况具有最佳的整体薄膜冷却性能，尤其是在远离中心平面的壁面上。此外，还解决了具有不同上游障碍的冷却效率和特性。