低覆盖度不同配置灌丛内风流结构与防风效果的风洞实验

Wind Tunnel Experiment on Wind Flow Structure and Windbreak Effect within Low-covered Shrubs under Different Arrangements

低覆盖度灌木群丛是干旱、半干旱区广泛分布且具有重要意义的植被，也是人工修复沙地应遵从的植被。通过风洞试验模拟了覆盖度在20％左右的三种水平配置格局的灌木群丛内风流结构与防风固沙效果。结果表明：①水平配置格局不同，低覆盖度灌木群丛的防风效果差异显著，行带式模式具有非常显著的阻碍和降低风速的作用（风速降低36％～43％）；等株行距模式次之，风速降低7％～28％；随机不均匀配置模式内局部有风速抬升现象，②行带式模式内形成规整的随灌丛带波动的流场结构，而随机不均匀配置模式内形成由多个风影区和风速加速区组合的非常复杂的流场结构，等株行距模式居于二者之间。③带间宽度在56cm和64cm时的防风效果较带宽为32cm和40cm好。说明覆盖度降低到11％～13％，行带式模式的防风效果仍然不会降低。④两行一带配置均表现防风效果优于单行配置，且随试验风速的增大防风效果更好。

Low-covered shrub is a kind of vegetation that widely distributes and has important significance in arid and semi-arid areas, and is also the reference vegetation that should be obeyed in restoring. The paper simulated the wind flow structure and windbreak effect of different arranged shrub at about 20 % coverage in wind tunnel. Results have been obtained as follows： ①The windbreak effect of the three patterns is the best within the belt pattern, reducing wind speed at 36 % -43 %; second within the equal-distance pattern, reducing wind speed at 7 % -28 % ; the worst within the random-distributing pattern, and even wind speed increased in some places. ②The flow field structure of belt pattern is regular, that of random pattern is complicated, and that of equal-distance pattern lies between the above two. ③As for belt pattern, the windbreak effect is better when inter-belt distance is 56 cm or 64 cm than is 32 cm or 40 cm, showing that the wind- break effect didn＇t weaken when the vegetation coverage decreased to 11% - 13 %.④The windbreak effect of ＂two-row in one-belt pattern＂ is better than that of single-row pattern, and even more effective when wind speed increased to some extent.