“月牙形凸台+等离子体激励器”结构改善气膜冷却效果的数值研究

利用等离子体激励器作为改善气膜冷却效果的方法在近年来得到了初步研究,但现阶段改善程度依然有限.提出“月牙形凸台十等离子体激励器”新型气膜冷却结构,通过CFD计算方法分析常规圆形孑、带月牙形凸台和带等离子体气动激励等不同气膜冷却结构的流场特性、温度场特性和冷却效率.结果表明:在圆形孔气膜冷却结构中,流场中形成了肾形涡对,由于肾形涡对使得冷流抬离壁面以及卷吸热流的作用,壁面的冷却效果最差;冷流经过等离子体激励器或月牙形凸台后,流场产生了反肾形涡对,抑制了肾形涡对的结构尺寸和强度,与圆形孔气膜冷却结构相比,气膜冷却效果在展向和流向上得到较大改善;在“月牙形凸台十等离子体激励器”气膜冷却结构中,冷热流掺混后形成的反肾形涡对强度最大,并且显著提高了孔间区域的冷却效率,在各吹风比下气膜冷却效果最佳.

Numerical simulation on improving film cooling effectiveness with crescent-shaped block plasma actuator

Numerical simulation was carried out to investigate the film cooling mechanism of the crescent-shaped block & plasma actuator structure. With CFD method, flow field characteristics, temperature characteristics and cooling effectiveness were analyzed for different film cooling structures: the common circle-hole, crescent-shaped block and plasma actuator film cooling structure. The results show that in circle-hole film cooling structure, counter-rotating vortex pair(CRVP), which lifted the cooling flow and entrain the hot flow, was formed, therefore the cooling effectiveness was the lowest. In the plasma actuator structures and crescent-shaped block structures, anti-CRVP, which restrained the scale and strength of CRVP, was formed. Compared to that with common circle-hole cooling structure, the film cooling effectiveness is improved a lot both in lateral and streamwise. In the crescent-shaped block & plasma actuator structure, the anti-CRVP reached its maximum, therefore significantly improving cooling effectiveness in the area between the holes and generating the best cooling performance.