二维有限长度柔性壁面上T-S波演化的数值研究

受自然界鸟类羽毛的柔性特征启发，利用数值模拟的方式开展了柔性壁面对亚声速边界层中T-S波演化的影响研究。刚性壁面上的数值结果与线性理论吻合得很好，验证了数值方法的可靠性。在此基础上，将部分刚性壁面替换为柔性壁面，结果表明，柔性壁面可以抑制T-S波在空间上的增长，从而推迟边界层流动转捩。壁面的变形不只跟随T-S波的波形，还因为柔性段与刚性段相接的前缘和后缘引起与扰动源频率相同的更大尺度的壁面波动，壁面的实际变形由这几种波叠加而成。开展的参数研究结果表明，增大表面的质量密度对于柔性壁面衰减扰动的效果几乎没有影响；增大表面张力和增加底部支撑的弹性系数可以增加壁面的刚性，减小壁面变形的幅度；增加阻尼可以抑制柔性段前后缘产生的大尺度壁面波动的传播，而对跟随T-S波的变形影响不大。总体上，柔性壁面的变形程度越大，其扰动的抑制效果越强。 

Numerical investigation on evolution of T-S wave on a two-dimensional compliant wall with finite length

Inspired by the flexible characteristics of bird feathers, numerical simulations are used to study the influence of the compliant wall on the evolution of T-S wave in the subsonic boundary layer flow. First, the numerical results on the rigid wall are in good agreement with the linear stability theory, which verifies the reliability of the adopted numerical methods. On this basis, part of the rigid wall is replaced with a compliant wall, and the results show that the compliant wall can suppress the spatial growth of T-S wave, thus delaying the flow transition. Furthermore, the deformation of the compliant wall not only follows the waveform of T-S wave, but also includes larger-scale vibrations with the same frequency as the disturbance source, which are caused by the leading edge and trailing edge of the compliant section. The actual deformation of the compliant wall is a superposition of these waves. Later parameter study shows that increasing the surface mass density has almost no effect on the compliant wall in terms of attenuating disturbance. Increasing the surface tension or increasing the elastic coefficient of the foundation can increase the stiffness of the compliant wall and thus reduce the amplitude of wall deformation. Increasing the damping can suppress the propagation of large-scale wall vibrations generated at the leading edge and trailing edge of the compliant section, while having little effect on the deformation directly corresponding to T-S wave. The overall trend is that when the amplitude of wall deformation decreases, the attenuation effect of the compliant wall on T-S wave decreases.