基于N-S方程,针对超声速气体绕0°迎角钝锥流动采用三阶WENO(Weighed Essentially Non Oscillatory)格式进行数值模拟,研究了熵层的基本流特性.研究给出了边界层及熵层外缘的确定方法,并分析了其适用性与局限性.数值计算结果显示基本流剖面存在“双广义拐点”现象,N-S方程与Euler方程数值结果对比发现,熵层区出现的广义拐点是由熵层区有旋运动引起的,而边界层的广义拐点由粘性作用导致.这是进行流动稳定性分析的基础.文章还分析了球头半径与马赫数对熵层特性的影响.结果表明,马赫数越大,熵层区的涡量越大,熵层影响的范围越大;雷诺数对无粘流的特征影响很小,熵层大小随球头半径几乎呈线性关系.%Based on the N-S equation,the third-order Weighed Essentially Non-Oscillatory (WENO) scheme is used to simulate the hypersonic flow around a blunt cone at zero angle of attack,and the basic properties of the entropy layer are studied.The method is proposed to determine the outer edge of boundary layer and entropy layer,and its applicability and limitation are analyzed.The numerical results show that there exists a "double generalized inflection point" phenomenon in the basic flow profile.The comparison between the results of the N-S equation and the Euler equation shows that the generalized inflection point in the entropy layer region is caused by the rotational flow in the entropy layer region,while the general inflection point in the boundary layer is caused by the viscous effect.This behaviour is the basis for the flow stability analysis.The influence of nose radius and Mach number is also analyzed on entropy layer characteristics.The results show that with the increase of Mach number,the flow in the entropy layer is increasingly rotational,and entropy layer has an enhanced influence on the downstream flow.The Reynolds number has slight influence on the entropy layer characteristics,and the size of the entropy layer is almost proportional to the nose radius.
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