万兵兵, 罗纪生. 超声速绕钝板熵层不稳定性的研究[J]. 空气动力学学报, 2018, 36(2): 247-253. DOI: 10.7638/kqdlxxb-2018.0029
引用本文: 万兵兵, 罗纪生. 超声速绕钝板熵层不稳定性的研究[J]. 空气动力学学报, 2018, 36(2): 247-253. DOI: 10.7638/kqdlxxb-2018.0029
WAN Bingbing, LUO Jisheng. Entropy-layer instability over a blunt plate in supersonic flow[J]. ACTA AERODYNAMICA SINICA, 2018, 36(2): 247-253. DOI: 10.7638/kqdlxxb-2018.0029
Citation: WAN Bingbing, LUO Jisheng. Entropy-layer instability over a blunt plate in supersonic flow[J]. ACTA AERODYNAMICA SINICA, 2018, 36(2): 247-253. DOI: 10.7638/kqdlxxb-2018.0029

超声速绕钝板熵层不稳定性的研究

Entropy-layer instability over a blunt plate in supersonic flow

  • 摘要: 为了研究熵层的不稳定性,首先选择马赫数为4.5、前缘为圆头的0°钝板模型,利用直接数值模拟得到基本流场,然后在此基础上进行线性稳定性分析,同时通过经验方法确定熵层和边界层区域。研究发现,对于某一流向站位的基本流剖面,存在两个广义拐点,分别位于边界层和熵层。针对熵层的广义拐点,进行稳定性分析研究了熵层中不稳定模态特性,得出该模态的不稳定区域集中在前缘附近,且扰动增长率很小。通过直接数值模拟熵层扰动的演化,发现在前缘附近扰动幅值也是缓慢上升,之后缓慢下降。另外,距离前缘较远处的数值模拟得到的扰动幅值与LST结果比较,二者吻合得很好,说明熵层在下游具有很好的平行性。

     

    Abstract: In this paper, the instability of the entropy layer over a blunt plate at a Mach number 4.5 is investigated. Direct numerical simulation (DNS) is used to compute basic flow for linear stability theory (LST). Two empirical formulas are introduced to identify the entropy-layer region and boundary-layer region. It is found that there are two generalized inflection points at a certain streamwise location in the boundary layer and entropy layer respectively. For the generalized inflection point in the entropy layer, the entropy-layer mode instabilities are studied by using the LST. The unstable region of entropy-layer disturbances is close to the leading edge, and the disturbances growth rate is very low. The evolution of entropy-layer disturbance is computed by using a DNS. The amplitude of the entropy-layer disturbance increases slowly near the leading edge, and then decreases slowly downstream. In addition, the amplitude obtained by the LST at a long distance from the leading edge is in good agreement with that of the DNS, indicating that the flow in the entropy layer has good parallelism.

     

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