Francisco Dianna M, Heist David K, Venkatram Akula, Brouwer Lydia H, Perry Steven G
ORAU ORISE Research Participation Program hosted at U.S. EPA, Research Triangle Park, NC, USA.
U.S. EPA ORD/CEMM, 109 T.W. Alexander Dr., MD 81, Research Triangle Park, NC, USA.
Atmos Pollut Res. 2022 Mar 16;13(4):1-101385. doi: 10.1016/j.apr.2022.101385.
New results are presented from wind tunnel studies performed at the United States Environmental Protection Agency (U.S. EPA), which include cases with solid roadside barriers of varying heights and cases with varying distances between the line source (roadway) and a 6-m-tall barrier. The cases include seven lanes of traffic with each lane acting as an independent source of continuous emissions along a line (i.e., line source). A mixed-wake algorithm that accounts for barrier effects within a steady-state air dispersion model was updated based on the recent wind tunnel studies. To study the effects of a solid roadside barrier, varying barrier heights and varying distances between the line source and barrier were modeled with the U.S. EPA regulatory air dispersion model AERMOD (v. 21112) using the line-source option that includes an experimental barrier option (RLINEXT). The mixed-wake algorithm reproduced the shape of the vertical concentration profiles observed in the wind tunnel data, including the uniform concentration profile from the ground vertically to a height somewhat greater than the height of the barrier. The algorithm responded appropriately to changes in barrier height and source-to-barrier distance, producing greater reductions in ground-level concentrations for taller barriers and for shorter source-to-barrier distances. Additionally, a rule of thumb that approximates the effect of a downwind barrier was formulated by converting an estimated vertical dispersion into an additional travel distance. The wind tunnel results, the update to the mixed-wake algorithm, and a comparison of the two data sets are described in this paper.
本文展示了美国环境保护局（U.S. EPA）进行的风洞研究的新结果，其中包括不同高度的固体路边屏障的情况以及线源（道路）与6米高屏障之间不同距离的情况。这些情况包括七条车道的交通，每条车道沿一条线作为连续排放的独立源（即线源）。基于最近的风洞研究，对稳态空气扩散模型中考虑屏障效应的混合尾流算法进行了更新。为了研究固体路边屏障的影响，使用美国环境保护局监管空气扩散模型AERMOD（版本21112），通过包含实验屏障选项（RLINEXT）的线源选项，对不同的屏障高度以及线源与屏障之间的不同距离进行了建模。混合尾流算法再现了风洞数据中观察到的垂直浓度剖面的形状，包括从地面垂直向上到略高于屏障高度的均匀浓度剖面。该算法对屏障高度和源到屏障距离的变化做出了适当响应，对于更高的屏障和更短的源到屏障距离，地面浓度降低得更多。此外，通过将估计的垂直扩散转换为额外的传播距离，制定了一个近似顺风屏障效应的经验法则。本文描述了风洞结果、混合尾流算法的更新以及两个数据集的比较。
