棘轮型超紧凑燃烧室全覆盖气膜冷却性能

Performance of full-coverage film cooling on ratchet ultra-compact combustor

摘要:

针对新一代棘轮型超紧凑燃烧室壁面的高温问题,对全覆盖气膜冷却的方式进行了研究。在对KJ-66微型涡喷发动机实验与模拟的基础上,将原燃烧室替换为缩放优化后的棘轮型超紧凑燃烧室。在实际燃烧工况下,对突扩段斜坡和二次补燃区内环上的高温壁面进行全覆盖冷却研究,比较了不同排布方式、孔倾角和扩张型气膜孔对气膜冷却效果的影响。结果表明:突扩段斜坡上圆柱型气膜孔的气膜覆盖性不理想,综合气膜冷却效果欠佳,并且不同排布方式与孔倾角对气膜冷却效果的影响不大；扩张型气膜孔对斜坡的气膜贴壁性和冷却效果都有很大的改善,在45°孔倾角,出口直径0.6 mm的扩张孔模型中,由吹离高温火焰面与气膜叠加覆盖产生的综合冷却效果达到最优；在主流高离心力场的影响下,吹风比较大时二次补燃区下游也能获得较好的气膜贴壁效果；排布方式对二次补燃区气膜冷却效果的影响比孔倾角更明显。在实际燃烧工况下全覆盖气膜冷却对棘轮型超紧凑燃烧室壁面有很好的冷却作用,扩张型气膜孔能有效改善气膜冷却效果。

Abstract:

To solve the high temperature problem of new ratchet ultra-compact combustor, a full-coverage film cooling method was adopted. Based on the experiment and simulation of KJ-66 micro gas turbine, the original combustor was replaced with a ratchet ultra-compact combustor after scaling optimization. Then, according to the high temperature wall of the slope of the sudden expansion section and the inner ring in the secondary combustion zone, the influences of different arrangement modes, hole inclination angles and expansion film holes on the film cooling effect under actual combustion conditions were compared. The results showed that the film coverage of the cylindrical film holes on the slope of the sudden expansion section was not ideal, the comprehensive film cooling effect was not good, and different arrangements and hole inclination angles had little influence on the film cooling effect. The air film adhesion and cooling effects of the slope were greatly improved by expansion film holes. In the expansion film holes with 45° hole inclination angle and 0.6 mm outlet diameter, the comprehensive cooling effect produced by blowing off the high temperature flame surface and overlaying the air film was the best. Under the influence of the mainstream high centrifugal force field, the downstream of the secondary combustion zone could also obtain better adhesion effects of film when the blowing ratio was larger. The influence of the arrangements on the film cooling effects in the secondary combustion zone was more obvious than that of the hole inclination angles. On the whole, the full-coverage film cooling has good cooling effects on the wall of the ratchet ultra-compact combustor under actual combustion conditions. Expansion film holes can effectively improve the film cooling effects.