A large eddy simulation (LES) was performed for film cooling in the gas turbine blade involving spanwise injection angles (orientation angles). For a streamwise coolant injection angle (inclination angle) of 35°, the effects of the orientation angle were compared considering a simple angle of 0° and 30°. Two ratios of the coolant to main flow mass flux (blowing ratio) of 0.5 and 1.0 were considered and the experimental conditions of Jung and Lee (2000) were adopted for the geometry and flow conditions. Moreover, a Reynolds averaged Navier–Stokes simulation (RANS) was performed to understand the characteristics of the turbulence models compared to those in the LES and experiments. In the RANS, three turbulence models were compared, namely, the realizable k-ε, k-ω shear stress transport, and Reynolds stress models. The temperature field and flow fields predicted through the RANS were similar to those obtained through the experiment and LES. Nevertheless, at a simple angle, the point at which the counter-rotating vortex pair (CRVP) collided on the wall and rose was different from that in the experiment and LES. Under the compound angle, the point at which the CRVP changed to a single vortex was different from that in the LES. The adiabatic film cooling effectiveness could not be accurately determined through the RANS but was well reflected by the LES, even under the compound angle. The reattachment of the injectant at a blowing ratio of 1.0 was better predicted by the RANS at the compound angle than at the simple angle. The temperature fluctuation was predicted to decrease slightly when the injectant was supplied at a compound angle.

中文翻译：

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带有复合角孔的薄膜冷却的大涡模拟：LES和RANS的比较研究

针对涉及翼展方向喷射角（取向角）的燃气轮机叶片中的薄膜冷却，进行了大涡模拟（LES）。对于35°的纵向冷却剂喷射角（倾斜角），考虑了0°和30°的简单角度，比较了定向角的影响。考虑冷却剂与主流质量通量的两个比率（吹塑比）为0.5和1.0，并采用Jung和Lee（2000）的实验条件作为几何形状和流动条件。此外，进行了雷诺平均Navier-Stokes模拟（RANS），以了解与LES和实验中相比，湍流模型的特征。在RANS中，比较了三种湍流模型，即可实现的k - ε，k- ω剪切应力传输和雷诺应力模型。通过RANS预测的温度场和流场类似于通过实验和LES获得的温度场和流场。然而，在一个简单的角度上，反向旋转涡流对（CRVP）在壁上碰撞并上升的点与实验和LES中的点不同。在复合角下，CRVP变为单个涡旋的点与LES中的不同。绝热膜的冷却效率无法通过RANS准确确定，但即使在复角度下，LES也能很好地反映出来。用RANS在复合角度下比在简单角度下更好地预测了喷射比为1.0时的喷射器重新连接。