植被条件对下垫面空气动力学粗糙度影响实验研究

Studies on Influences of Vegetation on Aerodynamic Roughness Length

通过风洞实验,对风速廓线测定结果应用最小二乘法进行相关性分析,由拟合方程系数得到了植被覆盖的下垫面空气动力学粗糙度,并重点讨论了粗糙度与输入风速、植被特征参数的关系.研究结果表明:(1)无植被覆盖和有植被覆盖的下垫面粗糙度均随输入风速的增大而减小;(2)有植被覆盖的下垫面空气动力粗糙度随植被侧影盖度的增大而增大,其变化规律符合指数函数形式,增加率随植被侧影盖度的增大而逐渐减小,并最终趋于零,表明下垫面空气动力学粗糙度有一个极值;(3)在植被侧影盖度相同的情况下,错落排列的植被模型其下垫面的空气动力学粗糙度要高于重合排列的植被模型.

By imitating the activity of dust storm under natural condition in wind tunnel, a series of experiments were carried out to research the relationship between aerodynamic roughness length, wind velocity and vegetation coverage characteristics. The experimental results reveal that aerodynamic roughness length decreased with the increase of wind velocity when vegetation coverage or bare ground. Aerodynamic roughness length under the vegetation coverage goes up with the increase of lateral coverage, and its changing follows the rule of exponential curve. It means the aerodynamic threshold value. It is roughness length is impossible to grow infinitely but gradually close to a found that the value of aerodynamic roughness length in stagger distribution is higher than the value of superposition pattem.