涡轮叶片尾缘凹坑 /凸起结构气膜冷却特性研究

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

关键词:  涡轮  叶片  气膜冷却  吹风比  数值模拟  凹坑-凸起结构

Key words:  Turbine  Blade  Film cooling  Blowing ratio  Numerical simulation  Dimple-protrusion structure

摘要:

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/H>6（ H为劈缝宽度，为4.8mm）区域气膜冷却效率，对下游的 X/H<6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。

Abstract:

In order to investigate the effects of the dimple and protrusion structures of suction surface on film cooling characteristics of turbine blade trailing edge, the cooling performance and flow mechanism of turbine blade trailing edge were analyzed in detail by numerical simulation method when the blowing ratio M=1.1 ( Re=2.5×10 ⁵). The results show that，compared with the original one， the dimple and protrusion structure on trailing edge can improve the film cooling efficiency in the region of X/ H > 6 （the split width of H is 4.8mm）downstream of the split outlet , while have little effect on the film cooling efficiency in the region of X/H< 6 downstream. Along the direction of flow, these three kinds of trailing edge structures will produce a process from two-dimensional spread vortices to hairpin vortices, then to flow vortices. By restraining fluid disturbance and changing the fluid flow, the dimple and protrusion structures can improve the film cooling efficiency at the far downstream of the split outlet.