Smoke Observation on Boundary Layer Transition Caused by a Spherical Roughness Element
Smoke Observation on Boundary Layer Transition Caused by a Spherical Roughness Element
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球面粗糙度元引起的边界层转变的烟雾观察
DOI：
10.1143/jpsj.16.995
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发表时间：
1961
影响因子：
1.7
通讯作者：
M. Mochizuki
中科院分区：
文献类型：
--
作者：
M. Mochizuki
在风洞中沿沿着边界层进行了观测。一个不同直径的球体被放置在板上作为一个孤立的粗糙元素和由此产生的流型进行了检查的烟雾从不同的高度和位置相对于球。为了弄清流场随雷诺数变化的机理，分别从流场的上侧面和侧面对流场进行了立体摄影。在低速时，会形成特殊的涡丝。随着速度的增加，它们开始周期性地变形，并形成一排特征性的拱形涡。随着速度的进一步增加，楔形湍流区出现在下游，并逐渐接近球体，侵占层流部分。平行于主流方向的涡丝以恒定的间距出现，其头部沿着楔形体的两侧。这些观察结果与测量结果进行了比较。
Observations were made in the boundary layer along a flat plate in a wind tunnel. A sphere of various diameters was placed on the plate as an isolated roughness element and the resulting flow patterns were examined by the smoke emitted from various heights and positions relative to the sphere. The patterns were stereographically photographed from upper and lateral sides, in order to make clear the mechanism of the change of patterns with varying velocities, namely Reynolds numbers. At low velocities, peculiar vortex filaments are formed. With increasing velocity, they begin to be deformed periodically and a characteristic row of arch-shaped vortices is formed. As the velocity is further increased, the wedge-shaped turbulent region appears downstream and gradually approaches the sphere, encroaching upon the laminer part. Vortex filaments parallel to the direction of the main stream appear with a constant spacing with their heads along the sides of the wedge. These observations were compared with measuremen...