【作者】 李旋；

【导师】 伍钒；

【作者基本信息】 中南大学 ， 交通运输（专业学位）， 2023， 硕士

【摘要】 呼吸道传染性疾病的频发引起公众对公共交通工具内部环境卫生安全的关注。地铁客室高度密闭且乘员密度高,客室气流处于复杂的湍流状态。飞沫在客室气流作用下运动,容易造成交叉感染风险,威胁乘员安全。本文针对降低地铁客室内呼吸道传染病交叉感染的关键问题,构建地铁客室内飞沫传播仿真方法,探索典型地铁列车客室复杂流场中呼吸道飞沫的传播规律,研究飞沫的时空分布特性。基于分析结果,提出客室内飞沫流动控制方法,对客室内飞沫实现有效抑控,对于降低客室内呼吸道传染疾病的交叉感染风险,保障乘员安全具有重要意义。本文主要的研究内容如下:(1)构建地铁列车客室飞沫传播仿真方法,建立地铁客室几何模型和人体模型,明确数值模拟方法湍流模型、离散网格、边界条件以及求解参数。用已有研究结果对飞沫蒸发模型进行验证,同时开展地铁列车内流场试验,对客室的气流温度和速度进行了现场测量,与仿真结果进行对比,进一步验证本文地铁客室飞沫传播数值模拟方法的可靠性。(2)对地铁客室内飞沫传播规律展开研究,明确客室内飞沫的分布特性。系统探究飞沫初始粒径、初始释放位置、释放方向、释放速度、不同乘员密度等因素对飞沫释放规律的影响。通过对这些影响因素进行详细分析,揭示了它们对飞沫传播特性的影响机制,从而为深入理解地铁客室内飞沫传播机理提供了重要参考。(3)基于地铁客室飞沫传播规律,提出地铁客室内飞沫流动控制方法。采用散送-散回-散排的优化方案,形成局部断面内送-回-排平衡的气流组织,飞沫传播得到抑控,显著减小了飞沫的扩散效率、传播范围、呼吸区粒子浓度,降低了交叉感染风险和影响人员数量。图60幅,表3个,参考文献110篇更多还原

【Abstract】 The frequent occurrences of respiratory infectious diseases have arisen public concern over the health safety of the internal environment of public transportation.The subway passenger compartment is highly enclosed with high passenger densities,and the air flow in the passenger compartment is in a complex turbulent state.The droplets transmit under the action of air flow in the passenger compartment,which is easy to cause the risk of cross infection and threaten the safety of passengers.This paper focuses on the key issues of reducing the crossinfection of respiratory infectious diseases in the passenger compartment,a numerical method that is capable of reflecting droplet transmissiom is constructed.This method is used for exploring the spreading patterns and distribution characteristics of respiratory droplets in the complex flow field of typical subway train carriages.Based on this,the flow control method of droplets in the passenger compartment is proposed to effectively control the droplets in the passenger compartment,which is of great significance for reducing the risk of cross-infection of respiratory infectious diseases in the passenger compartment and ensuring the safety of passengers.The main contents of this paper are described as follows:(1)The numerical simulation method of droplet propagation in the passenger compartment of the subway train is constructed and the geometric model of the passenger compartment and human body model is eatablished.The turbulence model,discrete grid,boundary conditions and solution parameters in the numerical simulation are clarified.The existing research results are used to verify the droplet evaporation model.At the same time,the flow field experiments are conducted to measure the temperature and velocity of the air flow in the passenger compartment on the spot.The comparison with the simulation results further verifies the reliability of the numerical simulation method for droplet propagation in the subway passenger compartment.(2)Conduct research on the propagation law of droplets in the subway passenger compartment to clarify the distribution characteristics of droplet in the passenger compartment.Systematically explore the impact of initial droplet diameter,release location,release direction,release velocity and different occupant densities on the release patterns of droplets.By conducting a detailed analysis of these influencing factors,their impact mechanisms on the characteristics of droplet transmission are elucidated,offering crucial references for a comprehensive comprehension of the droplet transmission mechanism in subway cabins.(3)Based on the above research,a method to control the flow of droplets in the subway passenger compartment is proposed.By adopting an optimized scheme of dispersion-removal-discharge,a locally balanced airflow organization of supply-return-discharge is formed within a local cross section,which effectively suppresses the spread of droplets.This significantly reduces the efficiency of droplet diffusion,the range of spread,and the concentration in the breathing zone,thereby reducing the risk of cross-infection and the number of affected individuals.更多还原