【作者】 刘宁；

【导师】 于慧俐；

【作者基本信息】 青岛理工大学 ， 供热、供燃气、通风及空调工程， 2018， 硕士

【摘要】 城市地铁站内颗粒物污染程度是评价一个城市环境质量的重要指标。由于列车在行驶和制动过程中时刻存在着钢铁机械的磨损,使地铁内空气颗粒中重金属元素显示出较为明显的富集特征,且此类重金属颗粒物比室外大气颗粒物更具毒性。地铁制动过程发生在列车进站时刻,闸瓦磨损产生的重金属粉尘会伴随活塞风运动到站台,从而对站台的空气品质与乘客的身体健康造成影响。在此背景下,亟需对地铁列车制动过程产生的颗粒物的浓度及其分布特征进行研究。本文以地铁制动过程产生的颗粒物为研究对象,建立颗粒物扩散的理论模型,模拟颗粒物扩散过程,分析影响颗粒物分布的主要因素。以现场调研及文献资料为基础对地铁列车制动过程进行CFD仿真计算,在数值模拟结果得到有效性验证的前提下,对不同工况下不同平面的颗粒物组分、浓度及分布逐一进行分析讨论。在Matlab平面网格上生成三维可视化图像,对特殊平面的颗粒物浓度分布进行可视化对比分析,并找出影响颗粒物浓度分布的主要因素。将代表性数据导入到Matlab中,采用最小二乘法拟合得出站台颗粒物浓度随影响因素的变化曲线,并利用该曲线对列车制动过程中产生的颗粒物浓度分布进行预测。对模拟所得颗粒物的质量浓度数据进行处理,依据健康风险评价体系对颗粒物进行暴露评价与风险计算,探究地铁车辆制动过程产生的颗粒物是否会对站台乘客的健康造成危害。在模拟与研究过程中得出以下主要结论:(1)设置屏蔽门会极大地降低站台的颗粒物浓度,改变气制动初速度也会对站台颗粒物浓度的大小产生一定的影响,而更换闸瓦材料几乎不改变站台颗粒物的浓度值。(2)屏蔽门的设置对站台颗粒物的分布范围及规律产生较大影响,而改变气制动初速度、闸瓦材料对其影响不大。(3)站台横向距离与颗粒物浓度的拟合方程为三次曲线,气制动初速度与颗粒物浓度的拟合方程为二次曲线。(4)颗粒物的暴露量与颗粒物的质量浓度呈正相关关系。经口摄入的颗粒物量>经皮肤接触而摄入的颗粒物量>经鼻吸入的颗粒物量。儿童在颗粒物中的暴露量明显大于成人。(5)暴露风险与暴露量呈正相关关系,经口摄入的暴露风险最大。儿童相对于成人面临着更大的健康风险。另外,镍存在致癌风险,对人体健康产生了较严重的负面效应。更多还原

【Abstract】 The degree of particulate pollution in urban subway stations is an important index of the city environmental quality evaluating.Due to the wear of iron and steel in the process of running and braking,the heavy metal elements in the air particles of the subway show obvious enrichment characteristics,and these particles have higher toxicity than outdoor atmospheric particles.The subway braking process occurs at the arrival time of the train,and the heavy metal dust generated by the brake shoe wear will move to the platform with the piston air,which will affect the air quality of the platform and the passengers’ health.In this context,it is urgent to study the concentration and distribution characteristics of particulates produced by the braking process of Metro trains.This paper takes the particulate matter generated by subway braking process as a research object.The theoretical model of particle diffusion was established to simulate the diffusion process of particles,and the main factors affecting particle distribution were analyzed.The CFD simulation of braking process of metro train is carried out based on field investigation and literature data,Under the premise of validation of numerical simulation results,the composition,concentration and distribution of particles in different planes under different working conditions were analyzed and discussed.The 3D visualization images are generated on the Matlab plane grid,and the concentration distribution of the particles in the special plane is visualized and compared,the main factors affecting the concentration distribution of particles are also found out in the paper.The variation curve of the particle concentration with the influence factors was fitted by the least square method,and using the curve to predict the concentration distribution of particles during train braking.The mass concentration data of the simulated particles were processed,the exposure assessment of particulate matter and the risk calculation are based on the health risk assessment system,to explore whether the particulate matter produced by the braking process of subway vehicle will harm the health of passengers on the platform.In the process of simulation and research,the main conclusions are asfollows:(1)Set the screen door will greatly reduce the particle concentration in the subway platform;Change the gas initial braking speed will also have a certain impact on the concentration of the subway platform particles size;Replace the brake materials will hardly change subway platform particles value.(2)The setting of screen door has a great influence on the distribution range and regularity of the particle in the subway platform.But the change of air brake initial speed and brake shoe material have little influence on it.(3)The fitting equation of the subway platform’s horizontal distance and particle concentration is three times curve,and the fitting equation of initial velocity and particle concentration is two times curve.(4)There is a positive correlation between particulate matter exposure and mass concentration of particulate matter.The amount of particles ingested through the mouth > the amount of particles ingested through skin contact > the amount of particulate inhaled through the nose.The exposure of children to particulate matter was significantly greater than that of adults.(5)There was a positive correlation between exposure risk and exposure,oral intake has the greatest risk of exposure.Children face greater health risks than adults.In addition,there is a carcinogenic risk of nickel,which has a serious negative effect on human health.更多还原