直压立式纱网沙障风洞试验研究

Wind-Tunnel Experiment by using Vertical PE-Yarn-Net Sand-barrier

风蚀危害是影响流动沙丘造林成效的关键因素。在跟踪调查纱网沙障野外固沙造林良好成效的基础上,进行了纱网沙障固沙成效的风洞模拟试验。结果表明:设置带状纱网沙障后改变了地表风沙流结构,并对拦截地表风沙流具有显著的效果。在距离地表0~40cm高度范围内,沙障高度10、15和20cm时,其总输沙量分别为0.9、1.11和0.56g·cm^(-2)·min^(-1),而无沙障对照为4.47g·cm^(-2)·min^(-1)。在纱网沙障迎风侧2 H、1.5 H和1 H处的平均风蚀深度分别为0.47、0.4和0.2cm,在背风侧0.5H、1H、1.5 H、2 H和3 H处的平均积沙厚度分别为1.7、1.1、1.0、1.3和1.4cm。此外,由于沙障高度不同,沙障迎风及背风侧风速流场的变化特征不同,并在沙障背风侧近地表形成弱风区。其中,沙障高度10cm时,在设置沙障位置的上空10cm高度范围形成1个高风速涡旋;沙障高度15cm时,在沙障及沙障背风侧上空10cm高度范围形成3~4个高风速涡旋;沙障高度20cm时,在沙障位置及沙障背风侧上空10cm高度范围形成8~9个高风速涡旋,反映出纱网沙障具有随风摆动的特点,对空中气流的扰动作用强烈。

Wind erosion is a key factor to influence the effect of forestation in moving sand dune.Based on investigating the good effect of sand-fixing forestation with PE yarn net sand-barrier in field,the wind tunnel simulation experiment has been conducted.The results show that it can change the structure of surface wind sand flow to set up the banding PE yarn net sand-barrier,at the same time,it has a significant effect for intercept surface sand flow.When the yarn net sand-barrier is higher than the ground by 20 cm,15 cm and 10 cm,the total sediment discharge occur at 0-40 cm away form the ground is 0.9 g·cm^(-2)·min^(-1),1.11 g·cm^(-2)·min^(-1) and 0.56 g·cm^(-2)·min^(-1),respectively.But it is 4.47 g·cm^(-2)·min^(-1) without sandbarrier being the CK.In PE yarn net sand-barrier,the wind erosion depth at 2 H,1.5 Hand 1 Hon the windward side is0.47 cm,0.4 cm and 0.2 cm,separately,and the average thickness of deposited sand at 0.5 H,1.0 H,1.5 H,2 Hand 3 H on the leeward side is 1.7 cm,1.1 cm,1.0 cm 1.3 cm and 1.4 cm,separately.In addition,due to the sand-barrier high difference,change characteristics of wind flow field is difference in over and windward side of sand-barrier,at the same time a weak wind speed area is formed in near surface of windward side.When sand-barrier high is 10 cm,a high wind vortex was formed on 10 cm high range of sand-barrier over.When sand-barrier high is 15 cm,3 or 4 high wind vortex were formed on10 cm high range of sand-barrier over and windward side of sand-barrier.When sand-barrier high is 20 cm,8 or 9 the high wind vortex were formed on 10 cm high range of sand-barrier over and windward side of sand-barrier.The forming high wind vortex reflect characteristics of swing with the wind for PE yarn net sand-barrier,and it has strongly disturbing for air flow.