On a turbulent wall jet flowing over a circular cylinder
On a turbulent wall jet flowing over a circular cylinder
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DOI：
10.1017/s0022112098003668
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发表时间：
1999-02-25
影响因子：
3.7
通讯作者：
Wygnanski, I
中科院分区：
文献类型：
--
作者：
Neuendorf, R;Wygnanski, I
实验研究了表面曲率对二维壁面射流发展的影响。对沿圆柱体流动的壁面射流与沿圆柱体流动的平面射流进行了比较。曲线壁射流的速度测量和表面压力测量表明存在两个主要的感兴趣区域。第一个区域，从潜在核心的末端到θ = 120°的近似角位置，具有恒定的表面压力和平均流量的自相似性。第二个区域的标志是一个不利的压力梯度，导致约θ = 230度的分离。这种流动的扩散速度，即使在初始区域，也比在平面壁面射流中要高得多，湍流和雷诺应力的水平也是如此。在这个流动中，主要的长度尺度是曲率半径R，主要的速度尺度是运动射流动量除以曲率半径的平方根。环境流体的夹带导致射流粘附在曲面上，这也是射流分离的主要原因，而射流的快速扩散导致边界层近似失效。
The effect of surface curvature on the development of a two-dimensional wall jet was investigated experimentally. A comparison was made between a wall jet flowing around a circular cylinder and its plane equivalent. Velocity surveys and surface pressure measurements in the curved wall jet suggest the existence of two primary regions of interest. The first region, ranging from the end of the potential core to an approximate angular position of theta = 120 degrees, is characterized by a constant surface pressure and a self similarity of the mean flow. The second region is marked by an adverse pressure gradient leading to separation around theta = 230 degrees. The rate of spread of this flow, even in the initial region, is much higher than in the plane wall jet and so are the levels of turbulence and Reynolds stress. The dominant lengthscale in this flow is the radius of curvature R and the dominant velocity scale is the square root of the kinematic jet momentum divided by the radius of curvature. Entrainment of ambient fluid which causes the jet to adhere to the curved surface is also the main reason for its separation which is preceded by a rapid rate of spread of the flow leading to the failure of the boundary-layer approximation.