跨/超声速间隙流动与传热特性的影响机理研究  

Investigations on the Influence Mechanism of Flow and Heat Transfer Characteristics in Transonic/Supersonic Gap

作　　者：李磊[1] 邹建军[1] 王成龙 LI Lei;ZOU Jian-jun;WANG Cheng-long(College of Aerospace Science,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学空天科学学院,长沙410073

出　　处：《科学技术与工程》2023年第16期7120-7128,共9页Science Technology and Engineering

基　　金：国家自然科学基金(12002374)。

摘　　要：随着涡轮性能不断提升,叶片顶部与机匣间隙两侧压差不断提高。在此作用下不可避免地产生跨/超声速间隙流动,造成流体做工的能量损失,并且对涡轮叶片顶部产生严重加热与烧蚀。针对不同间隙构型及冷却射流对间隙流场及换热的影响进行研究,结果表明:在常规平顶构型的跨/超声速间隙流动中,下壁面热流在距分离泡尾部再附点后约0.5 mm处达到最大,间隙内激波边界层干扰为典型的层流入流边界层干扰。间隙采用压力侧凹腔构型能有效降低下壁面热流,使得热流峰值相比平顶构型降低23.3%;间隙前缘的小钝化半径对热流影响较小,但会造成较大泄漏增量,这说明叶片在高温工况下自然钝化并不能有效降低热流。随着前缘钝化半径逐渐增加,存在临界半径使得分离泡恰好消失,整体热流峰值骤降。考虑叶顶射流主动冷却作用,分离泡内射流对流场的影响取决于射流压力的大小,存在合理范围使得冷却流体在分离泡后部产生较好的冷却效果,同时对前部热流影响较小。With the continuous improvement of turbine performance,the pressure difference on the two sides of the gap between the top of the blade and the casing is increasing.Under the action of the pressure difference,transonic/supersonic clearance flow is inevitable,resulting in energy loss of fluid,as well as serious heating and ablation on the top of the turbine blade.The effects of different gap configuration and cooling jets on the flow field and heat transfer in the gap were studied.The results show that in the transonic/supersonic gap flow with conventional flat top configuration,the heat flux on the lower wall reaches the maximum at about 0.5 mm after the reattachment point at the tail of the separation bubble,and the shock wave boundary layer interference in the gap is a typical layer inflow boundary layer interference.The pressure side concave cavity configuration of the gap can effectively reduce the heat flux on the lower wall,so that the peak heat flux is reduced by 23.3%compared with the flat top configuration.The small passivation radius of the leading edge of the gap has little effect on the heat flux,but it will cause a larger leakage increment.This shows that the natural passivation of the blade under high temperature conditions can􀆳t effectively reduce the heat flux.With the gradual increase of the leading edge passivation radius,there is a critical radius so that the separation bubble just disappears and the peak value of the overall heat flux drops sharply.Considering the active cooling effect of the tip jet,the influence of the jet in the separation bubble on the flow field depends on the jet pressure.There is a reasonable range so that the cooling fluid has a better cooling effect at the back of the separation bubble and has little effect on the front heat flux.

关 键 词：跨/超声速间隙流动 激波边界层干扰 间隙构型 前缘钝化 冷却射流 

分 类 号：V211.6[航空宇航科学与技术—航空宇航推进理论与工程]