城市街道峡谷内污染物扩散分布的数值模拟

A Numerical Simulation of Pollutant Distribution inside an Urban Street Canyon

采用通过实测分析得到的机动车综合排放因子表达式,实现了交通流性态参数与CFD仿真系统的联接,在此基础上模拟了不同车流量和平均车速组合下城市斜顶建筑物街道峡谷内机动车排放污染物(一氧化碳)的扩散分布。结果表明:(1)在自由来流风速一定时,峡谷内的一氧化碳浓度随平均车速的提高而降低(保持车流量不变),随车流量的增加而升高(保持平均车速不变);(2)联接交通流性态参数与CFD仿真系统而开展数值模拟,可为基于环境容量和道路交通容量双约束条件下的交通配流过程提供不同交通流分配方案下的大气环境质量评价信息。

Traffic flow parameters were firstly linked to CFD system by using an empirical expression for vehicle emission factors.The pollutant including carbon monoxide concentration distributions inside an urban street canyon formed by slanted roof buildings were simulated under various traffic flow characteristics.Results revealed that carbon monoxide concentration in the canyon,under a given free-stream wind velocity,decreased with increasing traffic velocity for a given traffic volume and increased with traffic volume for a given traffic velocity.Numerical simulations linking the traffic parameters to CFD software package can predict air quality under each scenario of traffic flow assignment.