风洞边壁对挟沙气流流速分布的影响

鉴于现有挟沙气流流速分布研究中对风洞边壁影响的认识不足，本文通过改变风洞宽度的方法对风洞边壁的影响进行了探索性实验研究。在五种宽高比条件下，对风洞断面挟沙气流流速分布进行了测量。发现风洞边壁对挟沙气流流速分布有较为明显的影响。在风洞宽度比相同的条件下，断面内中垂线上的有效粗糙度系数大于其它垂线上对应的系数。从靠近边壁的垂线到断面中垂线，各垂线对应的跃移层内区及外区流速分布的上界高度、气流摩阻速度均逐渐增大。随着风洞宽高比的减小，断面内中垂直线上的气流摩阻速度与自由流速的比值以及受风洞边壁影响的气流厚度均增大。

Sidewall Effects of Wind Tunnels on Velocity Profiles in Blown-Sand Flow

This paper presented the sidewall effects of wind tunnels on velocity profiles of airflow with saltating grains. Wind velocity profiles in cross sections were measured in terms of five aspect ratios (width/height) of 1.00, 0.83, 0.67, 0.50, and 0.33, respectively. Results show that the sidewall exerts significant effects on the parameters of vertical profiles of wind velocity. In a cross section, the effective roughness corresponding to the central vertical profile is greater than those in other vertical profiles. The wind friction velocity as well as the upper edge heights for velocity profiles in either inner or outer saltation regions increase from the sidewall to the central line of wind tunnels. Both the ratio of friction velocity to free stream wind velocity and the thickness of airflow are subject to the sidewall effect, showing the increase trend with the decreasing aspect ratios.