激波发生器几何结构对激波-气膜干涉影响的数值仿真

Influence of Shock-Wave Generator Geometric Structure on Shock Wave-Film Cooling Interaction

为探究激波-气膜干涉流动机理,采用带激波发生器的平板模拟跨声速叶栅内的流场。以激波发生器模拟入射激波,采用数值计算的方法研究当来流马赫数为1.45、吹风比为0.25、0.50和0.75时,楔形激波发生器角度和长度对超声速下平板气膜冷却流场的影响规律。结果表明:激波发生器角度影响激波强度,激波-气膜干涉会引起附面层流动分离产生分离泡,且分离泡尺度随激波强度的增强而增大;由于分离泡形成的鼓包使气流转折角增大,在5°和7°激波发生器下会形成局部正激波;激波发生器长度影响入射激波和膨胀波系之间的距离,随着激波发生器长度的增加,入射激波受膨胀波系影响减小。通过对比发现,合适的激波发生器可有效减弱流场内干扰波系的影响,从而突出激波对气膜冷却的干涉作用。

In order to investigate the mechanism of shock wave-film interaction,a flat plate with a shock-wave generator was used to simulate the flow field inside a transonic cascade.The incident shock wave was simulated by the shock-wave generator,and the effects of the angle and length of the wedge-shaped shock-wave generator on the flow field of flat plate film cooling were studied by numerical calculations under supersonic conditions of an approaching Mach number of 1.45 and blowing ratios of 0.25,0.50 and 0.75.The results show that the angle of the generator affects shock wave intensity and the shock wave-film cooling interaction causes the boundary layer flow separation and the formation of separation bubbles.Moreover,the size of the separation bubble increases with the increase of the shock wave intensity;Due to the bulge formed by the separation bubble,the turning angle of the airflow increases,leading to the generation of a local normal shock wave when the shock wave generator angle is 5°or 7°;the length of the generator affects the distance between the incident shock wave and the expansion waves,as the generator length increases,the effect of the expansion waves on the incident shock wave decreases.Comparative analysis reveals that an appropriate shock generator can effectively mitigate the influence of disturbing waves within the flow field,thereby highlighting the interaction effects of shock waves on film cooling.