风向对Y型街道交叉口污染物扩散影响的研究

Study on Pollutant Dispersion in Y-type Intersections of Flow Directions

文章采用CFD(计算流体力学)技术,构建Y型城市道路交叉口内气流运动和人行高度污染物扩散的三维数值仿真模型。研究采用了3种不同风向,分别为θ=0°,45°和90°。模拟结果表明道路交叉口内气体流动形态和人行高度处污染物扩散情况与来流风向紧密相关。风向改变使得街道内气流产生不同形态旋涡,多数情况下,旋涡的形成使得入口处迎风面的流场强度大于背风面。在人行高度上污染物C_2H_2扩散能力随风向角度的增大而增强,当θ=90°时,污染物扩散辐射度呈最大。

The article adopts the method of CFD numerical simulation, build Y-type air flow movement and three-dimensional numerical simulation of contaminant distribution in the model. The study includes three wind direction, 0=0°, 45° and 90°, respectively. The results show that airflow in intersectio movement, vortex structures, air exchange capacity and pollutant distribution is closely related to the direction of the wind. And wind flow to the unparallel stre~ entrance is often easier to form vortex, at the same time because of the influence of vortex at the entrance, the windward surface flow field intensity is often grcater than the leeward side. When 0=90°, because wind flow is parallel to the pollution source, pollutant C2H2 diffusion is most powerful.