斜向冲击强化换热特性试验

针对某型发动机主动间隙控制系统中典型冷却结构——45°斜向射流冲击,利用热膜法和红外热像仪测试技术,开展了局部强化冷却特性试验研究,分析了冲击雷诺数Re(33297～83242)、斜向冲击间距比H/d (2～6)等参数对冲击靶板表面局部换热特性参数Nu及Nu的影响.试验中发现位于驻点处和下游附驻点区出现了两个Nu峰值,当冲击Re较大、斜向冲击间距比H/d较小时,该现象尤为突出.试验结果表明:随着冲击Re的增大,靶板局部强化换热效果显著提升,Nu和Nu均显著增强;随着H/d的减小,驻点区域局部强化换热效果逐步提升,但增加幅度微弱;而在远离驻点区域,特别是在第二个峰值位置,冲击间距减小使得冲击强化换热效果明显增强. 

Experiment on heat transfer characteristics with inclined impingement

Experiments were conducted to investigate the heat transfer characteristics of a typical cooling structure of blade tip clearance active control system with 45 degree inclined impingement.In experiments,jet Reynolds number Re(33297～83242) and the ratio of jet impingement distance to the diameter of the jet hole H/d(2～6) were changed.Heated foil and infrared thermal imaging technology were used to investigate the local Nu(Nusselt number) and Nu(average Nusselt number) by varying those parameters.It was found that there existed two peaks of heat transfer coefficient along the jet line,located at the main and secondary stagnation points respectively.The two peaks were more evident in larger Re and smaller H/d cases.The experimental results show that the flow characteristics are significantly strengthened with the increase of Re increasing,which results in much larger Nu and Nu.With H/d decrease,the local heat transfer at the main stagnation point increases faintly,meanwhile,the local heat transfer at the secondary stagnation point is enhanced greatly.