Experimental study of a Tollmien–Schlichting wave interacting with a shallow 3D roughness element
Experimental study of a Tollmien–Schlichting wave interacting with a shallow 3D roughness element
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Tollmien-Schlichting 波与浅 3D 粗糙度元素相互作用的实验研究
DOI：
10.1080/14685240701790706
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发表时间：
2008
影响因子：
1.9
通讯作者：
M. Medeiros
中科院分区：
文献类型：
--
作者：
I. B. de Paula;W. Wurz;M. Medeiros
本文致力于实验研究浅 3D 粗糙度元素对 Blasius 边界层中 2D Tollmien-Schlichting 波演化的影响。实验是在受控扰动条件下在翼型截面上进行的，该翼型截面可以提供零压力梯度流的长期运行。使用气动驱动的狭缝源将 Tollmien-Schilichting 波引入中性稳定性曲线下分支的上游。在下游几个波长处，T-S 波与圆柱形粗糙度元件相互作用。粗糙度的高度随时间缓慢振荡，这使得可以连续测量粗糙度下游的 T-S 波响应。振荡频率大约比所研究的 Tollmien-Schlichting 波的频率低 1500 倍，因此相对于 T-S 波表现为稳定的粗糙度。热线风速测量用于测量壁法线轮廓和接近 T-S 波本征函数最大值的展向扫描。粗糙度的振荡和所有设备的同步允许使用整体平均技术。研究了具有无量纲频率 F120E-06 的两种不同振幅的 T-S 波。它们显示出在较小的展向波数范围内扰动的强烈放大。对壁法向 T-S 剖面的分析表明倾斜模式的增长。
The paper is devoted to an experimental study of the effect of a shallow 3D roughness element on the evolution of a 2D Tollmien–Schlichting wave in a Blasius boundary layer. The experiments were carried out under controlled disturbance conditions on an airfoil section which could provide a long run with zero pressure gradient flow. A pneumatically driven slit source was used to introduce the Tollmien–Schilichting wave upstream of the lower branch of the neutral stability curve. A few wavelengths downstream, the T–S wave interacts with a cylindrical roughness element. The height of the roughness was slowly oscillating in time, which allows a continuous measurement of the T–S wave response downstream the roughness. The oscillation frequency was approximately 1500 times lower than the frequency of the studied Tollmien–Schlichting wave and therefore, behaved as a steady roughness with respect to the T–S wave. Hot wire anemometry was used to measure wall normal profiles and spanwise scans close to the maximum of the eigenfunction of the T–S wave. The oscillation of the roughness and the synchronization of all-equipments permitted the use of ensemble average techniques. Two different amplitudes of T–S waves with a non-dimensional frequency of F120E-06 were studied. They show a strong amplification of the disturbances in a small spanwise wave number range. The analysis of the wall normal T–S profiles suggests the growth of oblique modes.