涡轮叶片尾缘凹坑/凸起结构气膜冷却特性研究

为探究吸力面凹坑和凸起结构对涡轮叶片尾缘气膜冷却特性的影响,在吹风比M=1.1时(雷诺数Re=2.5×10~5),采用数值模拟方法,通过在叶片尾缘吸力面上加入凹坑或凸起,对涡轮叶片尾缘的冷却性能和流动机理进行了详细分析。结果表明:与原始结构相比,叶片尾缘凹坑和凸起结构提高了劈缝出口下游远距离端X/H6 (H为劈缝宽度,为4.8mm)区域气膜冷却效率,对下游的X/H6区域气膜冷却效率影响较小;三种叶片尾缘结构,沿着流向方向会产生由二维展向涡到发卡涡,再到流向涡的变化过程,凹坑和凸起结构通过抑制流体的扰动,改变流体流动情况,提高了劈缝出口下游远距离端气膜冷却效率。

Film Cooling Characteristic on Trailing Edge Cutback of Gas Turbine Airfoils with Dimple/Protrusion Structure

In order to further clarify the effects of dimple and protrusion structure on suction side film cooling effectiveness on trailing edge cutback of gas turbine airfoils, numerical simulations were conducted with the blow ratio is 1.1. Dimple and protrusion were located at the suction side of blade to study the influences of dimple and protrusion on performance film cooling and flow mechanism of a gas turbine airfoils. The results show that compared with the original structure, the dimple and protrusion structure of the blade improves the film cooling efficiency at the downstream X/H>6 region of the split outlet, but has little effect at the downstream X/H<6 region of the split outlet. The vortex change from the two-dimensional vortex expansion to the hairpin vortex, and then to the flow vortices along the direction flow. The dimple and protrusion structure of the blade trailing edge restrains the fluid disturbance and changing fluid flow, for the purpose of improving the film cooling efficiency at the far downstream of the split outlet.