【作者】 陶红歌；

【导师】 陈焕新；

【作者基本信息】 华中科技大学 ， 制冷及低温工程， 2011， 博士

【摘要】 地铁车厢内良好的空气分布对于维持车厢内良好的热舒适条件和清新的空气品质至关重要,保证风道送风均匀是维持车厢内良好气流分布的前提条件,在风道送风均匀的前订提下,如何选择送风速度、主风道送风口数量和主风道与扁风道的送风量分配比将直接影响车厢的送风系统性能,进而影响车厢内的气流分布情况。同时,掌握车厢内污染物CO2的扩散情况也将对改善车厢内的气流组织提供重要的指导意见。因此,本研究将从风道结构优化入手,对地铁车厢内的送风系统性能优化和污染物CO2的扩散规律进行研究。为了更方便的衡量地铁车厢送风风道多送风口的送风均匀性,提出了基于面积加权平均速度和质量加权平均速度的气流分布均匀性关联式。由于截面上的面积加权平均速度和质量加权平均速度可以由模拟结果直接给出,因此,使得整个速度分布均匀性的计算过程大为简化。为了检验提出的新关联式衡量气流分布均匀性的合理性,新关联式分别被应用于假定的速度分布和模拟的速度分布进行速度分布均匀性的评价,评价结果与文献中已有公式进行的相应的评价结果进行对比,结果表明：新关联式的评价结果在整体趋势上与文献中两个公式的评价结果完全一致。对地铁列车车厢内某段独立风道送风进行了数值模拟和试验研究,以风道各送风口的送风速度和送风量为考察目标,对模拟结果和试验结果进行了对比分析,检验了数值模拟应用于地铁车厢风道结构优化的可靠性。对提出的新的风道结构优化思路——主风道中采用穿孔板代替导流板、扁风道中采用与送风口齐宽的挡板——应用于某段地铁车厢风道内进行模拟优化分析,研究发现：主风道内设置穿孔板可以有效的平衡风道内各段的压力,使得每段的静压都比较均衡,从而为保证送风口的送风均匀性提供了良好的前提条件；扁风道内设置挡板可以有效的改善扁风道各送风口的送风方向,同时通过调整挡板的高度并结合扁风道顶板后半段向末端倾斜可以很好的调整各送风口的送风量,并改善送风均匀性。为了了解送风速度、主风道送风口数量和主风道与扁风道的送风量分配比三个设计变量同时改变时对地铁车厢内的空气分布性能的影响,采用中心组合设计方法对三因素各三个水平安排了15组三因素不同组合的方案,通过数值模拟得到15组方案的空气分布性能,采用商业统计软件MINITAB对15组数据进行响应曲面法统计分析,得到了响应曲面法预测的空气分布性能模型,对模型进行方差分析,结果表明：送风速度对地铁车厢内的空气分布性能指标影响最大,而且,送风速度与主风道送风口数量对空气分布性能指标的交互影响比较明显。当送风速度一定时,主风道与扁风道的送风量分配比和主风道送风口数量对空气分布性能指标也有一定的交互影响。同时,根据获得的空气分布性能指标的响应曲面模型,送风系统的设计者可以很容易选择出最佳的影响送风系统性能的设计变量组合来得到最大的空气分布性能指标值。最后研究了地铁车厢内在乘客满员的情况下,乘客位置变动对车厢内污染物C02扩散规律的影响。根据车厢内乘客可能采用的站立方式设置了四种方案,采用数值模拟方法,分别研究了这四种方案下车厢内站立空间区域距地板上方1.7m上的污染物CO2的扩散情况,和车厢内两侧的坐姿区域距地板上方1.1m上的污染物CO2的扩散情况,结果发现：在1.7m高度上,在目前顶部送风、回风、两侧顶部排风的送风模式下,车厢内远离回风口、靠近车厢外端面的区域污染物CO2的浓度明显低于靠近回风口和内端面区域的污染物CO2浓度。在1.1m高度上,靠近车厢回风口区域两侧乘客坐姿呼吸高度上的污染物C02的浓度整体上高于远离回风口区域两侧乘客坐姿呼吸高度上的污染物C02的浓度。乘客位置变动对车厢内C02扩散的整体的分布趋势没有太大的影响,而对局部会有一定的影响。研究结果可以为地铁列车车厢内污染物的检测测点设置及气流组织的改善提供参考依据。更多还原

【Abstract】 The good air distribution is essential for maintaining the good thermal comfort conditions and fresh air quality inside the subway cars. To ensure uniform air supply through the air duct is a prerequisite to maintain good airflow distribution inside the subway cars. On the premise of uniform air supply through the air duct, that how to choose the velocity of supplying air, the number of the supplying air outlets of the main air duct and the ratio of the supply air volume of the main air duct and the flat air duct will directly affect the performance of air supply system of the subway car, thereby affect air distribution inside the subway car. Meanwhile, the knowing of pollutant CO2 diffusion inside the subway car will also provide important guidance for improving airflow inside the subway car. Therefore, the paper will start with duct structure optimization and further study the performance optimization of supply air system and the diffusion law of pollutant CO2 in the subway car.In order to facilitate quantifying the uniformity of supply air through lots of air outlets of supply air duct in the subway car, a correlation measuring the uniformity of air distribution is proposed based on area-weighted average velocities and mass-weighted average velocities in this paper. Since area-weighted average velocity and mass-weighted average velocity at the supply air outlets can be computed directly in numerical simulation, the correlation can be used to analyze velocity distribution uniformity of the simulation results more conveniently. To test the proposed approach to quantifying airflow distribution uniformity, the correlation is applied in two studies-one based on assumed velocity distribution, another based on the simulated velocity distribution- in comparison with two existing formulae from prior studies. The results show that the evaluation results of the proposed correlation are in complete agreement with that of the two formulae from prior studies in the overall trend.The supplying air through a certain independent air supply duct in the subway car is simulated and tested, the simulation results are compared with the experimental results according to the velocity of supply air and the supply air volume through air outlets of the air duct, the results verify the reliabilty of the numerical simulation that is used to the optimization of air duct structure in the subway car.A new idea on the optimization of air duct structure—guide plates in the main air duct will be replaced with perforated plates, the baffles are used in the flat duct and its width is the same with the width of supply air outlet of air duct—is used in a air duct of the subway car and its results on the optimization are analyzed by simulation optimization, the results found that the perforated plate set within the main duct can effectively balance the pressure within various sections of air duct and make the static pressure within each section of air duct relatively balanced, which provides a good prerequisite for ensuring the uniformity of supply air through each air outlet. The baffle set in the flat duct can effectively improve supply air direction through each air outlet in the flat duct, at the same time, supply air volume through each air outlet can be good adjusted and the uniformity of supply air through each air outlet can be improved by adjusting the height of the baffle and making the second half of the roof of flat duct tilt to the end of flat duct.In order to understand the effect of simultaneously changing of air supply velocity, the number of the supplying air outlets of the main air dudct and the ratio of the supply air volume of the main air duct and the flat air duct on the air distribution performance inside the subway car, the three factors with the three levels seperately are arranged 15 different combinations of three factors by central composite design. The air distribution performance of 15 schemes are obtained by the numerical simulation. Based on the response surface methodology,15 sets of data are analyzed by the commercial statistical software MINITAB, air distribution performance model predicted is obtained. Analysis of variance on the predicted model is implemented, the results show that the supply air velocity has greatest impact on the performance index of air distribution in the subway car. Moreover, the interaction effect of supply air velocity and the number of the supplying air outlets of the main air duct on the air distribution performance index is more obvious. When the supply air velocity is constant, the interaction effect of the number of the supplying air outlets of the main air duct and the ratio of the supply air volume of the main air duct and the flat air duct has a certain influence on the air distribution performance index. Meanwhile, according to the response surface model of the air distribution performance index obtained, the designer of air supply system can easily choose the best combination of the design variables affecting the performance of air supply system to obtain the maximize air distribution performance index value.Finally, the paper study the effect of changing the location of passengers on pollutant diffusion inside the subway car when the subway car is at full strength. According to the standing way adopted possibly by passengers in the subway car, the four schemes are set, the dispersion of pollutant CO2 at the 1.7m height from the floor in the standing room and at the 1.1m height from the floor in sitting areas inside the subway car is studied on the four schemes by numerical simulation, respectively. The results show that at the 1.7m height from the floor, under the mode of supplying air and returning air from the top of subway car and exhausting air from the top of both sides of subway car, the pollutant CO2 concentration in the region away from the return air inlet and near the end of subway car is significantly lower than that in the region near the return air inlet and the inner end of subway car. the pollutant CO2 concentration in the region near the return air inlet and at the 1.1m height of the passengers sitting of both sides in the subway car is overall higher than that in the region away from the return air inlet and at the 1.1m height of the passengers sitting of both sides in the subway car. The changing of the passenger location have not significantly influence on the overall distribution trend of the dispersion of pollutant CO2, but have some impact on the dispersion of local pollutant CO2 in the subway car. The study provides the theoretical base for arranging measurement points to monitor contamination content and improving airflow in the subway car.更多还原