垄状微地形对近地表空气动力学特征的影响

Effect of transverse ridge microtopography on aerodynamic characteristics of near-surface air

在旱作农田中,耕作土垄常被用作风蚀控制系统的一部分,但其对近地表风速的影响机制尚不明确。基于此,文中利用风洞实验,测量了不同结构垄状微地形条件下的近地表风速。结果表明:气流通过垄覆盖区域时,在第一行垄周围风速变化最大,之后风速变化逐渐减小,趋于稳定,近地表风速沿风向表现为规律性的波动变化特征。相对于无垄状态,所有垄结构的风速降低率均在33%以上。垄结构不同,对近地表气流的影响机制不同。垄间距较小时,风速廓线形态以两段式为主,垄以粗糙元的形式影响气流;垄间距较大时,垄间风速减弱和恢复的水平距离增加,风速廓线形态以三段式为主,此时垄则起到风障的作用。

In dryland farmland,tilled soil ridges are often used as part of a wind erosion control system,but the mechanism of their effect on near-surface wind velocity is not yet clear.So,we used a wind tunnel experiment to measure the near-surface wind velocity under ridge microtopographic conditions.The results showed that the airflow passes through the surface covered with ridges,the wind velocity changes mostly around the first row of ridges,and then gradually decreases and stabilizes,showing a regular fluctuation in near-surface wind velocity along the wind direction.Compared to the no-ridge condition,the wind velocity reduction rate of all ridge structures is more than 33%.Different ridge structures have different impact mechanisms on near-surface airflow.When the ridge spacing is smaller,the wind profile is mainly in two segments,and the ridge affects the airflow in the form of rough elements.When the ridge spacing is larger,the horizontal distance of the wind velocity reduction and recovery between the ridges increases,and the wind profile is mainly in three segments,at which point the ridge acts as wind barriers.