【作者】 尹景娟；

【导师】 宁智；

【作者基本信息】 北京交通大学 ， 环境工程， 2007， 硕士

【摘要】 大气污染对人类健康的影响早已引起世界各国的广泛关注,大气中的悬浮颗粒物是引起大气污染的主要因素之一。其中,可吸入颗粒物是大气中能够吸入下呼吸道的颗粒物,大量流行病学研究表明它与呼吸系统疾病有关。因此,对人体上呼吸道内流场及可吸入颗粒物运动沉降规律的研究具有十分重要的意义。本文在总结了国内外研究工作的基础上,建立了一个完整的从人体口腔到前三级支气管的3维几何模型,运用CFD商业软件分别对稳态呼吸时三种呼吸强度(Q = 30 L/min、Q = 60 L/min和Q = 90 L/min)下气道内的流场特性以及非稳态呼吸时不同时刻气道内的流场特性进行了数值模拟研究。基于上述研究,在拉格朗日框架下追踪研究了可吸入颗粒物的运动轨迹,并统计了颗粒在气道内不同部位的沉积分数。将数值模拟结果与已有的实验数据进行了对比,表明数值模拟结果与实验结果吻合良好。利用建立的模型,分别采用标准k ?ω和RNG k ?ε湍流模型对人体上呼吸道内的流场进行了模拟计算。通过分析流场特性得知,呼吸过程中气流速度的最大值出现在喉部区域;咽部及喉部声门处由于气道截面的缩小形成了喷射结构,并对其下游流场产生影响;支气管分支内靠近上一级支气管中心轴线一侧的气流速度较大。基于以上流场研究,对人体上呼吸道内可吸入颗粒物的运动沉积过程以及影响因素进行了分析和研究。研究结果表明,呼吸强度、颗粒粒径以及颗粒密度是影响可吸入颗粒物沉积的关键因素。本文的研究成果可以为治疗学以及颗粒物对人类健康影响的研究提供一定的理论依据。更多还原

【Abstract】 The serious influence of atmospheric pollution to human body health has already aroused worldwide attention, and aerosol is the main reason of atmospheric pollution. Among all kinds of aerosol, inhalational particle is the one which can be inhaled into lower respiratory tract and is related to respiratory system disease according to epidemiology research. Therefore, it is with great necessity to study flow field of human upper respiratory tract and deposition characteristic of inhalational particle.Based on the present reseach, a new entire 3-dimensional geometry from mouth, pharynx, larynx, trachea to triple bifurcation was proposed in this study. Commercial software CFD was utilized to solve primary flow under steady respiration which include three breathing intensity (Q = 30 L/min、Q = 60 L/min and Q = 90 L/min) and primary flow under unsteady respiration at different time. In succession, particles were traced in the Lagrangian frame, and at the same time, particle deposition fraction and position were recorded. The deposition fraction of inhalational particles obtained from numerical simulation show relatively good agreement when compared with the experimental data in the literature.Standard k ?ωand RNG k ?εturbulence model were used in the numerical simulation to solve the flow field in the upper respiratory tract. By analyzing the characteristic of flow field, a conclusion can be drew that the maximum velocity appears at larynx during breathing; a spray structure appears respectively at pharynx and larynx because of their cross-sectional reduction of the tract; the higher flow velocity in bronchia bifurcation appears in the direction of approaching central axis of the upper bifurcation. Based on the study above, the characteristic of transportation and deposition of inhalational particles and its influencing factors have been simulated and analyzed. The result shows that breathing intensity, particle diameter and particle density are the three key factors influencing the deposition of inhalational particles. The conclusion of this paper can be a foundation for therapeusis and study on inhalational particles health effects.更多还原