沙尘及霾过程中建筑物固壁缝隙气溶胶渗透的动力学机理研究

Mechanism of outdoor pollutant particles through the cracks of the building envelope into the interior is not clear, especially analytical results for describing the dynamic behavior of particles due to the combined mechanism of several factors have not been seen in literature. The mechanism research of particulate matter within the idealized crack is first carried out in this Fund, establishing steady transport equation under the no-slip condition of particulate matter with external field, obtaining accurate theoretical penetration expression and simple formula easy to use through interpolation. Based on the results for a smooth crack mode, amendment scheme are proposed to describe particulate matter dynamics by considering the relationship between the wall material roughness and concentration boundary layer for the real building envelope. Quantitative research on penetration of particulate matter through architectural cracks with complex shape is carried out on the platform of hydrodynamics simulation. Aerosol particles information under simulated storms and haze conditions are monitored to provide data and support discussion for different crack modes. Integrate and develop a visualization software package, and initially realize the engineering applications. This study aimed to explore the mechanism of outdoor particulate matter penetrating through the crack into the interior of the building envelope by theoretical analysis and numerical simulation, and propose solutions to improve the design of the building envelopes in order to protect human health from contaminant particles impact and injury.

室外污染物颗粒经建筑物固壁缝隙进入室内的机理研究尚不明确，尤其是颗粒物在多个因素制约下的动力学行为并未有理论解析结果。本项目首先开展理想化缝隙内颗粒物穿透机理研究，建立无滑移条件下颗粒物受外力场作用的稳态输运方程，通过理论解析得到精确的浓度分布公式，进而试图通过插值拟合得到易于推广使用的简介形式；针对真实建筑围护结构缝隙，考虑壁面材料粗糙度及浓度边界层之间关系，在光滑缝隙结论基础上提出修正方案，以更加准确的方式描述颗粒物输送规律；基于流体力学模拟平台开展形状较为复杂的建筑缝隙内颗粒物穿透过程的定量描述；实测沙尘暴及霾天气条件下的颗粒物信息，为不同缝隙所得结果讨论提供数据支持；整合并开发各种缝隙模型的可视化分析软件包，初步实现工程应用。本研究旨在通过理论解析与数值模拟探究室外颗粒物经建筑物固壁缝隙进入室内的物理机理，提出并改善建筑物固壁的设计方案以保护人体健康不受污染物颗粒的影响与伤害。

开展大气颗粒物经建筑围护结构缝隙进入室内的渗透率研究，对于改善室内空气品质，保护人体健康有重要意义。颗粒物随渗风气流通过时，在布朗扩散与重力沉降机理作用下发生壁面沉积。项目主要就四个具体问题开展研究。第一，理论求解方形扁平通道内颗粒物在扩散与重力联合作用下的沉积损失问题，得到了颗粒物浓度、穿透率及沉积速度解析式，并对相关研究开展了分析和比较。结果表明，本项目开展的研究，是对此类科学问题真正理论意义上的严格求解，不仅给出了较为简介的扩散沉积穿透率关系式，而且对已有几种常见穿透率耦合方法作了比较。第二，借鉴等效壁面思想，通过严格的理论解析，对大气颗粒物经建筑粗糙壁面缝隙的沉积损失问题开展研究，得到了颗粒物联合沉积作用条件下的穿透率形式。与已有实测和模型估计结果的比较表明，在全粒径范围内，本项目得到的理论估计值与实测值吻合更好。第三，通过严格的理论分析，提出了一种用于有效估计PM2.5经弯曲型建筑缝隙穿透率的理论方法。与已有研究结果的比较表明，本项目提出的方法能够快速有效地估计粒子穿透率，而不必通过大量的数值模拟。第四，在理论解析给出活塞流和泊肃叶流条件下颗粒物经建筑缝隙穿透率基础上，数值分析和比较了两种情形下粒子穿透率估计值之间差异。结果表明，在一些条件下采用活塞流描述气流型式可能比泊肃叶流更准确。