发表机构
Faculty of Mechanical Engineering, Technion - Israel Institute of Technology（以色列理工学院机械工程学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
实验研究梯形突起后表面倾角与长度对湍流产生的影响，发现流动拓扑由长度主导，而局部湍流产生取决于尾缘流动状态与剪切层位置。
AI 中文摘要
后表面倾角对安装在表面上的突起周围湍流的影响取决于接近其尾缘的分离流动。本研究通过立体粒子图像测速技术，对十二个具有上表面长高比 $L/h=1,2,3,4$ 和后表面倾角分别为 $30^\circ$、$45^\circ$ 和 $90^\circ$ 的梯形突起进行了实验研究。测量在基于高度的大约 $5\times10^4$ 的雷诺数下进行，来流边界层厚度与突起高度相当。对于 $L/h=1$ 和 2，一个连接的反向流动区域从上表面延伸到尾流中。对于 $L/h=3$ 和 4，上表面的再附着将这两个区域分开。长度决定了这一拓扑变化以及常见空间位置处湍流水平的变化，而后表面倾角的影响在靠近表面处最强。从 $L/h=2$ 开始，较缓的斜面具有更高的近表面湍动能，而垂直面具有较低的能量但更大的展向比例。对平面内偏斜产生的分解将雷诺应力和平均应变幅值的影响与其相对主轴方向的影响区分开来。在斜面处，这一贡献在 $L/h=1$ 和 2 之间从负变为正，然后发生上表面再附着。其随后随长度的增加主要由张量幅值的增大驱动，在 $L/h=4$ 和 $30^\circ$ 时贡献最大，此时强产生仍靠近后表面。这些结果表明，局部湍流产生同时取决于接近尾缘的流动状态以及高能剪切层相对于后表面的位置。
英文摘要
The influence of rear-face inclination on turbulence around a surface-mounted protrusion depends on the separated flow approaching its trailing edge. This dependence is examined experimentally using stereoscopic particle image velocimetry over twelve trapezoidal protrusions with upper-surface length-to-height ratios $L/h=1,2,3,4$ and rear-face angles of $30^\circ$, $45^\circ$, and $90^\circ$. Measurements were conducted at a height-based Reynolds number of approximately $5\times10^4$, with an incoming boundary-layer thickness comparable to the protrusion height. For $L/h=1$ and 2, a connected reverse-flow region extends over the upper surface into the wake. For $L/h=3$ and 4, upper-surface reattachment separates the two regions. Length governs this change in topology and the variation in turbulence levels at common spatial locations, whereas rear-face inclination has its strongest influence close to the surface. From $L/h=2$ onward, shallower faces have higher near-face turbulent kinetic energy, while vertical faces have lower energy but a larger spanwise fraction. A decomposition of the in-plane deviatoric production separates the effects of Reynolds-stress and mean-strain magnitudes from those of their relative principal-axis orientation. At the inclined faces, this contribution changes from negative to positive between $L/h=1$ and 2, before upper-surface reattachment occurs. Its subsequent increase with length is driven mainly by increasing tensor magnitudes, with the largest contribution at $L/h=4$ and $30^\circ$, where strong production remains close to the rear face. These results show that local turbulence production depends jointly on the flow state approaching the trailing edge and the position of the energetic shear layer relative to the rear surface.
Comments17 pages, 11 figures
