声屏障对城市道路环境空气质量的影响规律研究

为研究声屏障对道路交通污染扩散和空气质量的影响规律，基于三维计算流体动力学理论，运用Fluidyn-Panache仿真及CFD求解器进行数值模型计算分析，对比有、无声屏障情况下的风速矢量图与PM_2.5、CO、NO_x 3种主要污染物浓度分布图，并对仿真区域污染物浓度进行现场监测，得出声屏障对城市道路环境空气质量影响规律.研究结果显示，有声屏障时道路内侧风速由2m/s降低至0.02m/s；CO、NO_x浓度上升40%~50%，道路内侧PM浓度下降50%；道路外侧CO、NO_x浓度下降20%~50%，PM浓度下降20%~38%.声屏障的存在会阻挡风的流动，减弱风的强度，使风向从垂直于道路上升转变为沿着道路方向流动，风向改变使污染物聚集在道路内，增加道路内的气体污染物浓度，减弱风往道路外侧流动，同时也降低了气体污染物向道路外侧扩散的程度.声屏障对PM_2.5的影响显著，设置声屏障的道路内侧和道路外侧建筑群内，PM的浓度相较于无声屏障均得到大幅度降低.

The impact of sound barriers on air quality of urban road environment

To precisely quantify the impact of sound barriers on air quality of urban road, we applied the fluidyn-Panache simulation and CFD solver to launch numerical models and analysis based on the three-dimensional computational fluid dynamics theory. We compared the wind velocity vector maps and contaminant concentration nephograms of PM_2.5, CO and NO_x near the road under both presence and absence of noise barriers, monitored the contaminant concentration in the simulation area on the spot, and evaluated the regularity of impacts of barriersbarriers on air quality of urban road environment. Our results showed that 1) the wind speed inside the road decreased from 2m/s to 0.02m/s; 2) the concentration of CO and NO_x inside the road increased by 40% to 50%;3) the concentration of PM inside the road dropped by 50%;4) the concentration of CO and NO_X3 outside the road decreased by 20% to 50%; and 5) the concentration of PM outside the road reduced by 20% to 38%. We found that 1) the noise barriers blocked the flow of wind, weakened the intensity of wind, and changed the direction of wind from vertical to upward to along the road; 2) by changing the direction of wind pollutants gather in the road, the concentration of gas pollutants rises; and 3) the flow of wind to the outside, gas pollutants out of the road, as well as the extent of lateral diffusion drop. Noise barriers has a significant effect on the PM_2.5 concentration in the buildings on the inside and outside of the road that PM_2.5 decreases significantly compared with that of the silent barriers.