城市信号交叉口机动车尾气扩散特性研究

Research on vehicle exhaust dispersion modeling at urban signal intersection

为了精确地模拟机动车尾气污染物在城市道路信号交叉口附近区域的扩散规律,通过在杭州市实际道路交叉口的实验调研,对CAL3QHC交叉口线源扩散模型的源强计算方法进行了改进.考虑机动车在交叉口排队后的加速过程对车辆尾气污染物排放的影响,将车辆在交叉口的行驶排放作为一条分段线源处理,并设计各分段的源强计算方法.并将监测点处的CO污染物质量浓度模拟值与实际检测值进行对比,结果表明:模型改进前在高峰和平峰时段的平均模拟误差分别为14.6%和10.6%,改进后分别为7.3%和6.2%;改进后的排放源强计算方法更加接近城市交叉口机动车尾气排放的真实状况;在高峰时段,改进效果更加明显.

To model vehicle exhaust dispersion at signal intersection accurately, the intersection line source dispersion model CAL3QHC was modified by a field investigation at an actual intersection in Hangzhou. Considering the effect of vehicle acceleration after queuing on exhaust emission, a novel piecewise finite line source method was proposed and the calculation method of source intensity for each segment was developed. The simulation CO concentration was compared with actual test value . The results showed that the modeling errors of CAL3QHC model in mean and rush hours were 14. 6% and 10. 6% respectively, and became 7. 3% and 6. 2% after modified; the model with the method proposed had a better performance in urban intersection dispersion modeling, especially in rush hours.