不同下垫面对风沙流特性影响的风洞模拟研究

Wind Tunnel Simulation about the Effects of the Different Underlying Surfaces on the Features of Drifting Sand Current

通过对戈壁、草方格和流沙地表风沙流特性的风洞模拟实验 ,探讨不同性质下垫面对风沙流结构和风沙活动层风速廓线的影响 ,从而为野外工程防沙的优化设计及其应用提供理论依据。实验结果表明 :戈壁地表风沙活动层主要集中在距地表 2 0cm高度范围内 ;由于沙颗粒与戈壁地表的砾石发生碰撞 ,输沙率随高度的分布不再简单的遵循对数关系 ,其极值出现的高度随风速的增加而上移。由于草方格构成的下垫面复杂多变 ,其对风沙流结构与风沙活动层风速廓线的影响很难确定。但对于特定的下垫面 ,在不同风速下 ,同一高度层含沙量具有很大的相关性。

In this paper, the effects of the different underlying surfaces on the structure of drifting sand current and the wind speed profile in the sand-moving region are researched by wing tunnel simulation and experiment of the different underlying surfaces including the Gobi surface, straw-break surface and mobile-sand surface so as to provide the theoretical basis for the optimal design and construction of sand control projects. The results show that the sand-moving region over Gobi surface is mainly in height of 20 cm from ground surface: the sand transport over Gobi surface with the increase of height does not follow the logarithmic reduction because sand grains collide with gravels on Gobi surface, and the height where the maximum value of sand transport occurs is increased with the increase of wind speed. It is difficult to determine the effects of straw-break surface on the structure of drifting sand current and the wind speed profile in the sand-moving region due to the complexity of straw-breaks. For a certain underlying surface, however, the sand transport at a certain height is closely related to wind speed.