利用上游沙丘形斜坡增强气膜冷却

在平板上开设单排气膜孔,并通过红外测温法,实验研究了四个典型吹风比(0.5、1.0、1.5和2.0)下圆柱形气膜孔(CH)安置上游沙丘形斜坡(SDR)的绝热气膜冷却效率,并与平直楔形斜坡(SWR)进行了对比,同时结合数值模拟对不同形状的上游斜坡作用机制进行了剖析。研究结果表明：相比SWR,SDR可以诱导出特有的反肾形涡对,因而其在强化气膜冷却方面更具优势。在小吹风比下(吹风比为0.5),SWR和SDR可以分别提高特定区域(孔下游15倍孔径范围内)的面积平均气膜冷却效率达26%和75%左右,在高吹风比下(吹风比为1.5),两者的相对提高幅度分别高达100%和150%左右。

Film cooling enhancement by using upstream sand-dune-shaped ramp

Single-row film holes were drilled on flat plates, and experimental tests were performed to investigate the cylindrical-hole (CH) film cooling in the presence of upstream sand-dune-shaped ramp (SDR) under four typical blowing ratios of 0.5, 1.0, 1.5 and 2.0 using infrared thermometry method. A straight-wedge-shaped ramp (SWR) was adopted for the comparison. At the same time, numerical simulations were also performed to illustrate different roles of respective upstream ramps on the film cooling enhancement. Results showed that the presence of the upstream sand-dune-shaped ramp helped to generate an additional pair of anti-kidney vortices. As a consequence, the SDR provided a more favorable film cooling enhancement than the SWR. Under a small blowing ratio of 0.5, the area-averaged adiabatic film cooling effectiveness in a specific zone (within 15 times of the hole diameter downstream of the film hole) increased about 26% by SWR and 75% by SDR, with respect to the baseline cylindrical-hole situation. Under a high blowing ratio of 1.5, the area-averaged adiabatic film cooling effectiveness could be increased up to 100% and 150%, respectively, by using SWR and SDR.