关于风速对狭长街谷内污染物扩散影响的研究

Study on the influence of wind speed on pollutant diffusion in street valley

以CO为代表污染源,探究不同来流风速下街谷内风场和污染场分布特征。污染物浓度由低向高逐渐降低,且向背风面堆积。随着风速增加,中心面处回流作用增加,迎风面污染物浓度稀释;端口面处,顺时针大涡旋持续向左移动,风速高于5 m/s时该涡旋无法起到封闭作用,加速街谷内部与外界空气交换速度。污染物主要受三个区域控制,随着风速增加,整个街谷回流作用持续增加,区域3的涡旋右移,区域1的两个涡旋相互靠近。此结果可以深入了解污染物扩散规律,为城市环境管理提供有效参考,降低空气污染物对人类健康带来的危害。

In this study,CO was taken as the representative pollution source to explore the distribution characteristics of wind field and pollution field in street valley under different incoming wind speeds.The results showed that the pollutant concentration gradually decreased from low to high,and accumulated to the leeward side.With the increase of wind speed,the effect of backflow on the central surface increased,and the concentration of pollutants on the windward surface was diluted.At the port surface,the large clockwise vortex continues to move to the left.When the wind speed is higher than 5m/s,the vortex cannot play a sealing role and accelerates the air exchange velocity between the inside and outside of the street valley.Pollutants are mainly controlled by three regions.With the increase of wind speed,the backflow of the whole street-valley continues to increase.The vortices in region 3 move to the right,and the two vortices in region 1 are close to each other.The results can provide an effective reference for urban environmental management and reduce the harm of air pollutants to human health.