航空发动机进口支板外部热气膜对水滴撞击特性的影响

Influence of exterior hot-film on droplet impingement characteristics over aero-engine inlet strut

设计了4种不同气膜缝角度的防护结构,发展并验证了基于欧拉法框架的水滴撞击算法,针对直径为20μm的过冷小水滴,定量分析了气膜缝角度和吹风比对支板壁面水滴撞击特性的影响规律.研究结果表明,外部热气膜射流对水滴有明显吹袭作用,导致壁面平均局部水收集系数和撞击极限减小,而且气膜缝开孔位置越靠近支板前缘,吹袭水滴效果越明显.4种结构的平均局部水收集系数与无气膜缝结构相比分别下降了82%,8%,1%和0.5%.此外,吹风比增大会导致前缘最大局部水收集系数和撞击极限的减小变明显,尤其是气膜缝角度为5°结构的水滴撞击特性受吹风比影响最显著.前缘区域局部水收集系数呈现了相似的分布规律;支板后部区域,当吹风比增大到一定程度时,水滴被完全吹除.

Four ice-protection structures with different film-slot angles were designed, an Eulerian-framework based droplet impingement computation method was developed and verified to study the influences of film-slot angle and blowing ratio on droplet impingement characteristics for 20μm diameter. The results indicated that the exterior hot-film can blow the droplet away to decrease local collection efficiency and impingement limitation significant- ly, and the influence was more evident when the position of film-slot was closer to strut lead- ing edge, the average local collection efficiencies of four structures declined 82%, 8%, 1% and 0.5%, respectively, compared with no-film situation. Besides, the maximum local collection efficiency and impingement limitation decreased with the increasing blowing ratio. The impingement characteristics of film-slot angle 5° was most sensitive to blowing ratio. Similar local collection efficiency distribution features were presented at leading edge. For rear area, when blowing ratio was big enough, no droplet impinged on the surface.