This paper investigates the effects of a porous wall on the development of Tollmien–Schlichting (TS) waves propagating inside a boundary layer. An experimental study performed in a low-speed wind tunnel showed that microperforated panels over hollow chambers could promote laminar–turbulent transition. First, measurements of the streamwise evolution of the TS instabilities reveal that greater amplification occurs over perforated panels compared to a solid wall. This effect was attributed to a wall impedance condition imposed by the perforated panels over the chambers. This setup is somewhat analogous to an acoustic liner for which the wall response is represented by a complex impedance. The impedance of the experimental setup was thus measured in situ. These experimental impedance values were then used as wall boundary conditions of a linear local stability calculation to quantify the influence of the wall impedance condition on TS wave growth. The ${\mathrm{e}}^N$ approach was applied to predict the corresponding transition positions. Comparison between experimental and numerical results shows that the use of impedance boundary conditions is a promising approach to predict transition location, particularly in the case of the panel with the lowest resistance.

本文研究了多孔壁对在边界层内传播的 Tollmien-Schlichting (TS) 波发展的影响。在低速风洞中进行的一项实验研究表明，空心室上方的微穿孔板可以促进层流-湍流转变。首先，对 TS 不稳定性的流向演变的测量表明，与实心墙相比，穿孔板上发生了更大的放大。这种效应归因于腔室上方的穿孔板所施加的壁阻抗条件。这种设置有点类似于声学衬垫，其壁响应由复阻抗表示。因此，在原位测量了实验装置的阻抗。然后将这些实验阻抗值用作线性局部稳定性计算的壁边界条件，以量化壁阻抗条件对 TS 波增长的影响。这${\mathrm{电子}}^N$应用方法来预测相应的过渡位置。实验和数值结果之间的比较表明，使用阻抗边界条件是预测过渡位置的一种很有前途的方法，特别是在具有最低电阻的面板的情况下。