圆角凹坑气膜孔的气膜冷却流动特性研究

Study on film cooling flow characteristics of film holes in rounded corner crater

为了挖掘凹坑气膜孔的气膜冷却潜力,数值模拟研究了等截面凹坑孔、同心椭圆凹坑孔以及在这2种孔型基础上提出的2种圆角凹坑气膜孔的气膜冷却特性,对4种凹坑气膜孔在吹风比为0.5、1.0和1.5时的冷却效率曲线进行分析。结果表明:凹坑气膜孔与带圆角凹坑气膜孔的凹坑展向宽度增加,有利于冷却气膜的展向覆盖;在3个吹风比条件下,凹坑气膜孔进行圆角处理之后,附壁效应强化了冷却射流贴附壁面的能力,近孔区域的气膜冷却效率明显提高;随着吹风比增加,对于等截面凹坑孔,圆角处理之后的面平均气膜冷却效率分别提高了76%、139%、155%;圆角同心椭圆凹坑孔相比同心椭圆凹坑孔,面平均气膜冷却效率分别提升18%、27%、29%。

In order to explore the film cooling potential of crater holes,numerical simulations are performed to investigate the film cooling characteristics of equal-section crater hole,concentric elliptical crater hole,and two types of rounded corner crater holes proposed on the basis of these two types of crater holes.Cooling efficiency curves are analyzed for four types of crater holes at blowing ratios of 0.5,1.0 and 1.5.The results show that,the crater spreading width of crater holes and crater film holes with rounded corners increases,which is beneficial to spreading coverage of the cooling film.After the crater holes are rounded at three blowing ratios,the Coanda effect strengthenes the ability of the cooling jet to adhere to the wall,and the film cooling efficiency in the near-hole region improves significantly.As the blowing ratio increases,the area-averaged film cooling efficiency after the rounded corner treatment increases by 76%,139%and 155%,respectively,for the equal-section crater hole.The area-averaged film cooling efficiency improves by 18%,27%,and 29%,respectively,for the concentric-elliptical crater hole with rounded corner compared with that of the concentric-elliptical crater hole.