Particle-Image Velocimetry Measurements of Separation and Re-attachment of Airflow over Two-Dimensional Hills with Various Slope Angles and Approach-Flow Characteristics
Particle-Image Velocimetry Measurements of Separation and Re-attachment of Airflow over Two-Dimensional Hills with Various Slope Angles and Approach-Flow Characteristics
复制标题
具有不同坡度和接近流特性的二维山上气流分离和重新附着的粒子图像测速测量
DOI：
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发表时间：
2013
影响因子：
4.3
通讯作者：
S. Wakamatsu
中科院分区：
文献类型：
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作者：
I. Kanda;Yukio Yamao;K. Uehara;S. Wakamatsu
利用粒子图像测速技术在风洞中对二维山丘上方的气流进行了研究。我们重点关注气流分离行为。在大多数实验中使用了梯形山丘形状，但气流分离的临界坡度角与光滑山丘形状所确定的临界坡度角大致相同。随着坡度角\(\theta\)的增加，分离气流的再附着点离山丘越来越远，当\(\theta\gtrsim60^{\circ}\)时，达到约为山丘高度7倍的饱和值。研究发现，增加上风面的粗糙长度会抑制气流分离。这种趋势与之前平板上湍流边界层的实验结果类似。边界层厚度因测试段入口处是否存在库尼汉型尖塔而有所不同，而齿形栅栏对气流分离的影响可忽略不计。
Airflow over two-dimensional hills was investigated in a wind tunnel using particle image velocimetry. We focus on the flow separation behaviour. A trapezoidal hill shape was used in most of the experimental runs, but the critical slope angle for flow separation was approximately the same as that established for smooth hill shapes. The re-attachment point of the separated flow became farther from the hill as the slope angle $$ heta $$ increased, reaching a saturation of about seven times the hill height for $$ heta gtrsim 60^circ $$. Increasing the upwind surface roughness length was found to suppress flow separation. This tendency is analogous to the previous experimental results for turbulent boundary layers on flat plates. The boundary-layer thickness varied by the presence or absence of Counihan-type spires and a castellated fence at the test-section entrance had negligible effect on the flow separation.