树木对风沙流场影响的风洞试验研究

Wind tunnel experiments on the influence of trees on wind-sand flow field

本文以豆瓣黄杨苗为试验树,在边界层风沙风洞落沙条件下模拟沙尘暴气候,研究了树后的风沙流场特性,包括树木对风速、沙浓度和湍流度的影响规律。在风速12m/s下,通过控制不同落沙量形成各类风沙流场,测量三种树后间距处的风沙流场情况,并与无树时对比。结果表明:树后D=1H位置树冠以下(<0.2H)风速、沙浓度略有增大,树顶以上(>1H)风速、沙浓度基本无变化;树冠层高度(0.2H-1H)风速、沙浓度显著减小,树木中间位置(0.5H)减小比例最高,减小程度随落沙量的增加而增大,随树后间距的增加而减小;树木后风沙流场的湍流度有明显的增大,且树后各高度湍流度全部增大,增大程度变化规律与前两者的影响规律相似。研究结果将为树木防风阻沙提供科学依据。

In this paper,the buxus sinica are used as test trees to simulate the wind-sand flow field of sandstorm climate under the conditions of falling sand in the boundary layer wind tunnel.The characteristics of wind-sand flow field behind the trees are studied,including the distribution law of wind velocity,sand consistency and turbulence intensity.Under the wind speed of 12m/s,by controlling different sand falling amount to form various kinds of wind-sand flow fields,the wind-sand flow field at the three kinds of distance behind trees was measured and compared with the condition without tree.The results show that the wind speed and sand consistency under the canopy(<0.2H)behind the tree increase slightly,and there was basically no change above the tree top(>1H);the wind speed and sand consistency in the canopy height(0.2H-1H)decrease significantly.The middle part of the tree(0.5H)has the highest reduction ratio,and the reduction degree increases with the increase of the amount of falling sand,and decreases with the increase of the distance behind the tree.The turbulence intensity behind the tree increases significantly,and the turbulence intensity increases at all heights behind the tree.The change law of the increase degree is similar to the influence of the former two.The research results will provide scientific basis for trees to prevent wind and sand.