展向和流向间距不同的粗糙元壁湍流ADV实验研究

Experimental study of turbulence over roughened walls with transverse or longitudinal circular ribs with various spacings using an acoustic Doppler velocimeter

为了揭示粗糙元对壁湍流的影响,采用声学Doppler流速仪(ADV)对布有展向或流向圆柱形粗糙元的壁湍流进行了实验测量。研究了不同Reynolds数下不同间距粗糙元对壁湍流流向平均速度和湍流度的影响。结果表明:在同一Reynolds数下,粗糙元展向间距为7倍直径时的壁湍流流向平均速度最小,湍流度最大。粗糙元流向布置的壁湍流流向平均速度随粗糙元间距的减小而减小,湍流度随粗糙元间距的减小而增大。相比流向粗糙元,展向粗糙元对湍流流动特性影响更大。研究结果对壁湍流流动控制和强化换热的工程应用具有指导意义。

The wall turbulence over spanwise and streamwise circular cylinder roughness elements was measured using an acoustic Doppler velocimeter（ADV） to evaluate the effects of roughness on the turbulent boundary layer.The effects of the roughness element patterns on the mean velocity and turbulence intensity were investigated for various Reynolds numbers.The results show that the mean streamwise velocity is reduced the most while the turbulence intensity is increased the most for w/k=7 for a given Reynolds number when the wall is roughened with spanwise ribs.The mean streamwise velocity decreases,while the turbulence intensity increases with decreasing w/k when the wall is roughened with streamwise ribs.The streamwise roughness elements have more influence on the turbulence characteristics than the spanwise ones.This study provides guidable for flow control of wall turbulence and heat transfer enhancement.