带球窝结构的尾缘开缝壁面气膜冷却特性研究  

Research on Film Cooling Characteristics of Trailing Edge Cutback with Dimples

作　　者：何坤[1] 王茜 晏鑫[1] HE Kun;WANG Xi;YAN Xin(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《西安交通大学学报》2024年第12期22-33,共12页Journal of Xi'an Jiaotong University

基　　金：陕西省自然科学基金资助项目(2023-JC-YB-340);国家自然科学基金资助项目(52076165)。

摘　　要：为提升燃气透平叶片尾缘开缝区域的气膜冷却性能,将多排球窝结构应用于尾缘冷却通道下游开缝壁面,以增加近壁面区域的冷气覆盖。采用非定常延迟-分离涡模拟方法,研究了有、无球窝结构下尾缘开缝壁面的气膜冷却性能,获得了4种吹风比、3种球窝高径比以及2种球窝结构(球形球窝和泪滴形球窝)条件下尾缘开缝壁面的气膜冷却性能和流量系数,并利用已有实验数据考核了数值方法的有效性,阐明了球窝结构减小冷热气流掺混、改善尾缘开缝区域气膜冷却性能的作用机制。结果表明:球窝结构有利于冷气向壁面附近聚集,使得冷气不易被主流卷起,减小了冷热气流掺混,有效增加了开缝壁面沿流向的气膜覆盖面积;相对于光滑尾缘开缝模型(无球窝结构),带球形球窝结构的尾缘开缝模型流量系数增大了4.8%~6%,平均气膜冷却效率提高了4.6%~19%;吹风比越大,球窝结构对冷气的吸附作用越显著,带球窝结构的尾缘开缝壁面平均气膜冷却效率越高;球窝高径比越大,尾缘开缝壁面的气膜冷却效率越高且分布越均匀。泪滴形球窝可有效解决球形球窝内壁前缘冷却不足问题,相对于带球形球窝结构的尾缘开缝,带泪滴形球窝结构的尾缘开缝壁面的冷却效率提高了8.2%,流量系数提高了1.1%。To enhance the film cooling performance of the trailing edge cutback region in a gas turbine blade,multiple arrays of dimples are applied to the downstream cutback of the cooling slot to improve the coolant coverage near the wall.Using the delayed-detached eddy simulation method,the film cooling performance of the trailing edge cutback with/without dimples is investigated.The film cooling performance and flow coefficient of the trailing edge cutback are obtained under four blowing ratios,three dimple height-to-diameter ratios,and two dimple structures(spherical dimples and teardrop-shaped dimples).The effectiveness of the numerical method is verified using existing experimental data,elucidating the mechanism by which the dimple structure reduces the mixing of hot and cold airflows and improves the film cooling performance in the trailing edge cutback region.The results indicate that the dimple structure promotes the accumulation of cool air near the wall surface,preventing it from being easily entrained by the mainstream flow,thereby reducing the mixing of hot and cold airflows and effectively increasing the film coverage area along the cutback in the downstream direction.Compared to the smooth trailing edge cutback model(without dimple structure),the flow coefficient of the trailing edge cutback model with spherical dimples increases by 4.8%to 6%,and the average film cooling efficiency increases by 4.6%to 19%.With increasing blowing ratio,the adsorption effect of the dimple structure on cool air becomes more significant,leading to higher average film cooling efficiency on the trailing edge cutback with a dimple structure.A higher dimple height-to-diameter ratio results in increased and more uniform film cooling efficiency on the trailing edge cutback.The teardrop-shaped dimples effectively address the issue of insufficient cooling at the leading edge of the spherical dimples:compared to the trailing edge cutback model with spherical dimples,the cooling efficiency of the trailing edge cutback with teardrop-shaped

关 键 词：航空发动机 尾缘开缝 球窝 气膜冷却 流量系数 延迟-分离涡模拟 

分 类 号：TK47[动力工程及工程热物理—动力机械及工程]