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使用气热耦合数值计算方法对带有“淋浴喷头”式前缘气膜冷却的C3X燃气轮机叶片进行数值模拟。通过对使用不同湍流模型的计算结果与实验测量值进行对比,使用转捩模型能够比较准确的模拟带有气膜冷却射流的边界层内的流动和传热过程。气膜冷却射流在叶片吸力面上游层流边界层区域内表现出比较明显的三维湍流特性,但在吸力面下游边界层转捩为湍流以后,湍流使得气膜冷却射流与主流燃气掺混过程加速而使其三维流动特性迅速消失;在吸力面由于边界层流动始终为层流状态,冷却射流与主流掺混较缓慢而使其仍能保持较强的三维湍流特性。边界层内由高温燃气与被冷却叶片之间温度差形成的温度梯度有益于增强边界层流动的稳定性。
The numerical simulation of the C3X gas turbine blade with “shower head” air film cooling was carried out using the numerical calculation method of air-heat coupling. By comparing the calculated results with experimental data using different turbulence models, the transition model can be used to simulate the flow and heat transfer in the boundary layer with film-cooled jet more accurately. The film cooling jets show obvious three-dimensional turbulent characteristics in the laminar boundary layer upstream of the suction side of the blade. However, turbulence accelerates the mixing process of the film cooling jets and the mainstream gas after the transition of the downstream boundary layer of the suction surface is turbulent And the three-dimensional flow characteristics disappear rapidly. Because the boundary layer flow is always laminar at the suction side, the cooling jet can still maintain a strong three-dimensional turbulent flow even when mixed with the mainstream. The temperature gradient formed by the temperature difference between the hot gas and the cooled blade in the boundary layer is beneficial for enhancing the stability of the boundary layer flow.