高马赫数来流条件下斜激波与流向涡对相互作用

Oblique Shock Wave/Streamwise-Vortex-Pair Interaction at a High Mach Number

关键词:  斜激波  涡流发生器  流向涡对  涡破碎  激波风洞

Key words:  Oblique shock wave  Vortex generator  Streamwise vortex pair  Vortex breakdown  Shock tunnel

摘要:

针对斜激波入射流向涡对形成的复杂流动干扰现象，在来流马赫数6条件下，利用双支架支撑的后掠斜坡式涡流发生器生成流向涡对，采用数值模拟结合激波风洞实验，研究了斜激波与流向涡对相互作用引起的激波变形和旋涡演变。结果表明，斜激波与流向涡对相互作用的剧烈程度大致分为强、中、弱三种。在强相互作用下，激波面向上游凸起的程度最剧烈，呈现类“T”字型特征，其对称面处接近于一道正激波，波后出现回流区和局部流动滞止，使得流向涡对发生破碎；在中等相互作用下，对称面处存在局部正激波，但没有出现回流区；在弱相互作用下，不再出现局部正激波。进一步地分析发现，斜激波与流向涡对相互作用产生的流向涡对破碎现象，不符合经典的激波作用下单个流向涡破碎理论的预测。采用流向涡对对称面处的气流参数，对经典的流向涡破碎理论进行修正后，能够预测本文流向涡对在斜激波作用下是否发生破碎。

Abstract:

The shock deformation and vortex evolution induced by oblique shock wave/streamwise-vortex-pair interaction were investigated to better understand the flow physics of this complex phenomenon. Numerical simulations and shock tunnel experiments were conducted at a freestream Mach number of 6 using a swept-ramp vortex generator supported by two trestles to produce the streamwise-vortex-pair. The results show that the intensity of the oblique shock wave/streamwise-vortex-pair interaction can be classified into strong， moderate， and weak types. The strong interaction is characterized by a highly bulged-forward shock front that looks like a T-shaped structure in a three-dimensional view. The bulged-forward shock approximates a normal shock wave in the symmetry plane. Downstream of the bulged-forward shock， subsonic reverse-flow and a saddle point of flow stagnation are formed， which indicates the breakdown of the streamwise-vortex-pair. For the moderate interaction， reverse flow is not observed， although a localized normal shock wave is presented in the symmetry plane. Neither a localized normal shock wave nor reverse flow are shown in the weak interaction. It is demonstrated that the streamwise-vortex-pair breakdown induced by an oblique shock wave cannot be predicted by the classic theories for predicting the onset of a streamwise vortex breakdown. Thus， a modified theory is proposed by using the flow parameters in the symmetry plane， which shows a good agreement with the present oblique shock wave/streamwise-vortex-pair interactions. This study provides an important model for understanding the mechanisms of streamwise-vortex-pair breakdown induced by an oblique shock wave.