Film cooling is an important cooling method to protect the hot components in aero-engines and it is a classical research topic for decades. However, accurate simulation of the film cooling is still challenging. The present study aims to study film cooling with a newly developed Very-Large Eddy Simulation (VLES) method. State-of-the-art turbulence modelling methods are also included for comprehensive comparisons of film cooling simulations, i.e., VLES and DES (Detached Eddy Simulation) of hybrid RANS-LES method and the classical LES (Large Eddy Simulation) method are applied. Numerical simulations are performed for a single row film cooling benchmark test case (Sinha et al., 1991), in which the turbulence intensity of the freestream flow is about 0.2%, at two density ratios and two blowing ratios, corresponding to four momentum flux ratios. The results predicted by different turbulence methods are compared in detail, including the film cooling effectiveness, the velocity flow fields, as well as the relevant turbulent flow structures. The predicted results are also compared with available experimental data. It is found that for the three cases with low momentum flux ratios (smaller than 0.3), the three turbulence methods produce quite different results, while for the case with higher momentum flux ratio of 0.5, the differences between the results of three turbulence methods become less significant. Overall, the present VLES method performs best among the three selected methods, and its predictions agree well with the experimental data. While for the DES method, it severely delays the Kelvin-Helmholtz instability of the turbulence mixing process in film cooling and thus fails to accurately predict the cooling effectiveness at low momentum flux ratio. The study demonstrates the potentials of the newly developed VLES method for accurate prediction of complex film cooling problems.

气膜冷却是保护航空发动机热部件的重要冷却方法，是几十年来的经典研究课题。然而，薄膜冷却的精确模拟仍然具有挑战性。本研究旨在使用新开发的甚大涡模拟 (VLES) 方法研究气膜冷却。还包括最先进的湍流建模方法，用于薄膜冷却模拟的综合比较，即应用混合 RANS-LES 方法和经典 LES（大涡流模拟）方法的 VLES 和 DES（分离涡流模拟）。对单排薄膜冷却基准测试案例（Sinha 等，1991）进行了数值模拟，其中自由流的湍流强度约为 0.2%，在两个密度比和两个鼓风比下，对应于四个动量通量比率。详细比较了不同湍流方法预测的结果，包括气膜冷却效果、速度流场以及相关的湍流结构。预测结果也与可用的实验数据进行了比较。发现对于低动量通量比（小于0.3）的三种情况，三种湍流方法产生的结果差异较大，而对于较高动量通量比为0.5的情况，三种湍流方法的结果差异为不太重要。总体而言，目前的 VLES 方法在所选的三种方法中表现最好，其预测与实验数据非常吻合。而对于 DES 方法，它严重延迟了薄膜冷却中湍流混合过程的 Kelvin-Helmholtz 不稳定性，因此无法准确预测低动量通量比下的冷却效果。该研究证明了新开发的 VLES 方法在准确预测复杂薄膜冷却问题方面的潜力。