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污染物沉积到有热障涂层的涡轮叶片上之后,会导致叶片表面状况的改变,进而影响气膜冷却效率。为分析影响规律,利用三维数值计算研究了3种典型情况下的气膜冷却特性:污染物沉积、热障涂层脱落及气膜孔堵塞,并得到了吹风比的影响规律。研究结果表明,平板气膜冷却吹风比为0.5时,冷却效果最佳;在发生沉积和堵塞后,气膜孔附近产生的反旋涡对会削弱沉积和堵塞后的气膜冷却效率,沉积高度增加会强化这种削弱效果;由于在沉积情况下高吹风比会诱导出正向旋涡使得气膜贴近壁面,因此随着吹风比增大,气膜冷却效果增强;因涂层脱落而在孔下游产生的裂纹在低吹风比时会降低冷却效率,高吹风比时改进冷却效果,使得最佳吹风比由0.5上升到0.7左右;气膜孔堵塞会降低冷却效率,使得气膜更易脱离壁面。
The deposition of contaminants on a thermally barrier coated turbine blade results in a change in the surface condition of the blade, which in turn affects the cooling efficiency of the film. In order to analyze the influence law, three typical numerical examples were used to study the film cooling characteristics: pollutant deposition, thermal barrier coating shedding and gas film pore plugging, and the influence law of blowing ratio was obtained. The results show that the cooling effect is the best when the film cooling cooling ratio is 0.5. The anti-vortex vortex generated near the film hole will weaken the film cooling efficiency after deposition and plugging, and the deposition height increases after deposition and plugging Will strengthen the weakened effect; due to the deposition in the case of high hair will induce a positive whirlwind so that the film close to the wall, so as the blowing ratio increases, the film cooling effect is enhanced; Of the cracks in the low blow ratio will reduce the cooling efficiency, high blow ratio to improve the cooling effect, making the best hair blowing ratio from 0.5 to 0.7 or so; film hole plugging will reduce the cooling efficiency, making the film more easily from the wall.