燃气轮机火焰筒双耳孔冷却特性的分析

为进一步提高燃烧室火焰筒的冷却性能，提出一种具有更高冷却性能的双耳孔型气膜冷却结构。采用数值模拟方法对比分析吹风比在0.67～2.01时，传统圆柱孔、扩散孔、收敛孔、双耳孔的流动传热和冷却特性。计算结果表明：与其他3种孔型相比，冷却壁面长径比在0～40时，双耳孔出口冷却气流在高温主流作用下形成的肾形涡对尺寸较小，强度较弱，对涡中心的间距较大，且冷却气流横向分布更广，壁面换热系数比更低，提高了气膜冷却性能。在吹风比为2.01时，与圆柱孔相比，扩散孔的流量系数提高了13.7%,展向换热系数比降低了1.5%;收敛孔的流量系数没有变化，展向换热系数比降低了2.7%;但双耳孔的流量系数却降低3.1%,展向换热系数比降低了11.25%。在吹风比为1.33时，与扩散孔和收敛孔相比，双耳孔的流量系数更低，在长径比小于40时，双耳孔的换热系数比最低，冷却效果最好。

Analysis of cooling characteristics of gas turbine flame tube with binaural hole

To further improve the cooling performance of the combustor flame tube, a binaural hole film cooling structure with higher cooling performance is proposed. The flow, heat transfer and cooling characteristics of traditional cylindrical hole, diffuser hole, convergent hole and binaural hole with blowing ratio from 0.67 to 2.01 were analyzed by numerical simulation. The results show that, compared with the other three film hole shapes, the aspect ratio of the cooling wall is in the range from 0 to 40, the kidney-shaped vortices formed by the cooling air flow at outlet of the binaural hole under the action of high temperature main flow are smaller in size, weaker in strength, larger in distance between the centers of the vortices, wider in transverse distribution of the cooling air flow, and lower in heat transfer coefficient on the wall, the film cooling performance is improved. When the blowing ratio is 2.01, compared with cylindrical hole, the flow coefficient of diffuser hole is increased by 13.7% , the wall heat transfer coefficient ratio is decreased by 1.5% , the flow coefficient of the convergent hole is unchanged, the heat transfer coefficient ratio is decreased by 2.7%. However, the flow coefficient of the binaural aperture decreased by 3.1% and that in the aspect of heat transfer coefficient ratio decreased by 11.25%. When the blowing ratio is 1.33, compared with diffusion hole and convergent hole, the flow coefficient of binaural hole is lower. When the slenderness ratio less than 40, the heat transfer coefficient ratio of binaural hole is the lowest and the cooling effect is the best.