单一行带式乔木固沙林内风速流场和防风效果风洞实验

Windbreak effects and wind velocity flow field of one-line-shelter belt

文中研究在风速为10m/s和15m/s的风洞实验条件下,覆盖度为20%和25%的两种单行一带模式固沙林内的水平和垂直空间的风速变化情况,达到对两种不同模式的风速流场和防风效果进行比较分析的目的。通过分析可以得出,两种配置模式都形成了风影区和风速加速区相互组合的复杂的水平流场结构。两种模式对垂直空间风速影响相近,根据对不同高度风速的不同影响划分为地表加强层(0.8 cm以下)、微变化层(1.2 cm)、显著变化层(1.6 cm和3 cm)和稳定变化层(6 cm-35 cm)这四个变化层。从距地表1.6 cm高度开始,垂直空间风速变化沿来风方向的风速总体上是逐步减小的趋势,且在林带处会出现一个峰值。总的来讲两种模式降低水平空间和垂直空间风速的效果都相同,但沿林带方向降低水平空间风速的效果有所不同,两种模式降低垂直风速的效果从地表向上都表现出先增加后减少的趋势。

For understanding the flow field and windbreak how the two difference one - line - one - belt （OLOP） effect of the sandbreak forest, we studied the changes space wind velocities with wind speeds of 10 and 15 distribution patterns affect of horizontal and vertical m/s under the coverage of 20% and 25% of each distribution pattern. It was found that two disposition models both formed level space flow field which was combined by the wind shadow and the wind speed acceleration area. The two patterns formed the similar effect on vertical wind speeds. We divided the vertical space into four layers according to the different effect on vertical wind speeds,which were the reinforce layer near the ground （0.8 cm to the ground）, the tiny change layer （ 1.2 cm to the ground）, the observably change layer （ 1.6 to 3 cm above the ground）, and the stability of change layer （6 to 35cm above the ground）. From 1.6 cm to the ground, the change of the vertical space wind speed along the direction of the wind was decreased gradually, and it appeared a peak in forest belt place. In a word, the effect of reducing the horizontal and vertical space wind speed in two kinds of pattern were identical, but the effect of reducing the level space wind speed along the forest belt direction was different, and the effect of reducing the vertical space wind speed increased first and then decreased from the ground.