建设活动对街道峡谷固体颗粒物影响的数值模拟

发布时间：2018-02-04 08:16

本文关键词： 街道峡谷轨道交通施工颗粒物PM_(10) 流体力学CFD 高度比风向污染源位置　出处：《武汉大学》2017年硕士论文　论文类型：学位论文

【摘要】：颗粒物引起的环境污染问题已成为全球共同关注的问题,城市房地产和基础设施建设正如火如荼的进行着,其建设施工产生的扬尘对颗粒物贡献较大,同时,街道峡谷是较为常见的街道形式,由于其特殊的形态特性,颗粒物在其中更容易积累,从而出现严重颗粒物污染问题,并对周边住宅区居民和街道峡谷内行人健康产生危害,因此,研究街道峡谷内的颗粒物分布情况具有重要的意义。本文选取湖北省武汉市洪山区光谷商圈中,正在建设的轨道交通2号线延长线某段街道峡谷为研究对象,颗粒物选取PM10,通过仪器实际测量和数值模拟对比分析,对影响颗粒物扩散的街道峡谷高度比、风向及污染源位置三个方面进行具体的分析讨论,为城市街道峡谷内临街建筑物布局及其颗粒物的防治措施提供理论依据。本文案例中街道峡谷可简化为递增型街道峡谷模型,网格划分采用ICEM软件,后处理运用流体力学软件FLUENT,采用TECPLT对图形处理。街道峡谷内的空气流场选用标准K-ε模型,颗粒物运动选用离散相模型中的拉格朗日方法跟踪颗粒物的轨迹,运用有限体积法对所求的控制方程进行离散。将仪器测量值与街道峡谷内机动车尾气产生颗粒物加和,与本文数值模拟得到的颗粒物浓度值进行对比检验,结果表明数值模拟的结果可靠性较好。将数值模拟得到的主要结论归纳如下:(1)污染源位于北侧时:西风条件下,递增型街谷的颗粒物主要聚集在峡谷中部,对称型和递减型街谷,颗粒物相对分散。递增型街谷影响高度较均匀,约为20m。对称型和递减型街谷,从前端15m到尾端30m呈现平缓上升的趋势。北风下,街谷内颗粒物浓度值较高区域均明显增多,在街谷前后两侧和南侧背风区域的颗粒物影响范围很广泛,北侧建筑物行人区域的颗粒物污染情况严重。南风下,递增型和对称型街谷颗粒物分布规律一致,集中在街谷中部,南侧较大间距可以适当减缓颗粒物污染水平,且北侧建筑物背风区域的颗粒物浓度水平与间距处气流溢出带出颗粒物的能力相关。(2)针对颗粒物污染情况:街谷进深方向时,平行风条件下街谷高度比对进深方向颗粒物分布几乎无影响;垂直风条件下,递减型和对称型街谷在进深方向的颗粒物分布规律相似,建筑物凹凸处和间距会改变颗粒物浓度水平。平行风条件下,三类街谷在南北向的颗粒物浓度水平几乎一致;北风条件下,街谷南侧到北侧颗粒物浓度值逐渐升高,递减型、对称型和递增型街谷浓度水平逐渐下降;南风条件下,街道中间Y=0m处达到最高值,北侧浓度水平较南侧低。影响高度方面,不同高度比和风向条件下,颗粒物在垂直高度的扩散规律较相似,整体上呈现逐渐下降趋势,其中5米以下随垂直高度浓度下降最快,之后出现平稳缓慢下降。(3)污染源为南侧时,对称型街谷在三种风向条件下,颗粒物污染情况均变严重,递增型和递减型街谷,颗粒物聚集位置发生微调。在街道峡谷内人呼吸平面的颗粒物,北风条件下递减型街谷颗粒物污染最为严重,南风时递减型街谷颗粒物污染最轻。
[Abstract]:The problem of environmental pollution caused by particulate matter has become a global concern, the city real estate and infrastructure construction is carried out like a raging fire, the construction produces dust particles on the larger contribution, at the same time, the street canyon is the more common form of the street, due to its special morphological characteristics, particles more easily in the the accumulation, thus serious particulate pollution, and the surrounding residential area residents and pedestrian street canyon harm, therefore, has an important significance to study the distribution of particles in street canyon. This article selects the Hubei province Wuhan city Hongshan District Optics Valley District, is the construction of the Metro Line 2 extension line a section of a street canyon as the research object, selects the PM10 particles, through the instrument measurement and numerical simulation, influence of particle dispersion in street canyons high ratio, wind To the three aspects of pollution sources and the position of the specific analysis and discussion, and provide a theoretical basis for the city street canyon in the street the building layout and particulate control measures. In this case the street canyon can be simplified as increasing street canyon model, mesh by using ICEM software, postprocessing using CFD software FLUENT, using TECPLT graphics the air flow field in street canyon. The selection of standard K- turbulence model, particle motion using Lagrange method of discrete phase model of particle trajectory tracking, the control equations for the discretized using the finite volume method. The measurement value and the street canyon vehicle exhaust particles and values are compared to test in this paper, and numerical simulation of particle concentration, the results show that the numerical results of the numerical simulation is reliable. The main conclusions are summarized as follows : (1) the source is located in the north side: Westerly wind conditions, particles increasing mainly gathered in the street canyon Valley in central, symmetric and decreasing the street canyon, the particles are relatively scattered. Increasing the street canyon height is uniform, about 20m. symmetric and decreasing Street Valley, showing increased slowly. The trend from the front to the end of 15m 30m. The north wind, the particle concentration in the street canyon high region increased significantly, is widely used in street canyon before and after particles on both sides and on the south side of the leeward region influence scope, the particulate pollution on the north side of building pedestrian areas. Under the severe wind, increasing and symmetrical street canyon particles physical distribution, concentrated in the Central Valley of South Street, the larger distance can be appropriate to reduce particulate pollution levels, the particle concentration level and on the north side of building area and leeward spacing gas emanating out of the ability of particles. The particles (2) Pollution: Street Canyon depth direction, parallel valley wind conditions Xia Jie height ratio on the depth direction of the particle size distribution has almost no influence; vertical wind conditions, particle distribution decline and symmetrical street canyon in the depth direction of similar buildings, convex and concave and spacing will change the particle concentration level. Parallel wind conditions three types of street canyon in the north and south, the particle concentration level to almost the same; north wind conditions, on the south side of the street canyon to the north of the particle concentration increased gradually, decreasing type, symmetric type and incremental street canyon concentration level decreased gradually; wind conditions, the middle of the street at Y=0m reached the highest value, the concentration level is the south is low. Influence of height, different height ratio and wind conditions, particles are similar in the height of the vertical diffusion, showing the overall trend of gradual decline, of which 5 meters with the vertical height of the fastest decline in the concentration. After a steady decline slowly. (3) the pollution source for the south side, symmetrical street canyon in the three wind conditions, situation of particulates became serious, increasing and decreasing the street Valley, particle aggregation occurs in fine-tuning. Particles of street canyon people breathing plane, the condition of decreasing the street canyon particulate pollution is most serious, the decreasing street canyon particulate pollution is the lightest.

【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X513;X169

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