Cheng K H, Cheng Y S, Yeh H C, Swift D L
Department of Environmental Health Sciences, School Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
J Biomech Eng. 1997 Nov;119(4):476-82. doi: 10.1115/1.2798296.
This paper presents measurements of the geometric shape, perimeter, and cross-sectional area of the human oral passage (from oral entrance to midtrachea) and relates them through dimensionless parameters to the depositional mass transfer of ultrafine particles. Studies were performed in two identical replicate oral passage models, one of which was cut orthogonal to the airflow direction into 3 mm elements for measurement, the other used intact for experimental measurements of ultrafine aerosol deposition. Dimensional data were combined with deposition measurements in two sections of the oral passage (the horizontal oral cavity and the vertical laryngeal-tracheal airway) to calculate the dimensionless mass transfer Sherwood number (Sh). Mass transfer theory suggests that Sh should be expressible as a function of the Reynolds number (Re) and the Schmidt number (Sc). For inhalation and exhalation through the oral cavity (O-C), an empirical relationship was obtained for flow rates from 7.5-30.0 1 min-1: Sh = 15.3 Re0.812 Sc-0.986 An empirical relationship was likewise obtained for the laryngeal-tracheal (L-T) region over the same range of flow rates: Sh = 25.9 Re0.861 Sc-1.37 These relationships were compared to heat transfer in the human upper airways through the well-known analogy between heat and mass transfer. The Reynolds number dependence for both the O-C and L-T relationships was in good agreement with that for heat transfer. The mass transfer coefficients were compared to extrathoracic uptake of gases and vapors and showed similar flow rate dependence. For gases and vapors that conform to the zero concentration boundary condition, the empirical relationships are applicable when diffusion coefficients are taken into consideration.
本文介绍了人类口腔通道（从口腔入口到气管中部）的几何形状、周长和横截面积的测量结果，并通过无量纲参数将它们与超细颗粒的沉积传质联系起来。研究在两个相同的复制口腔通道模型中进行，其中一个垂直于气流方向切成3毫米的单元进行测量，另一个保持完整用于超细气溶胶沉积的实验测量。将尺寸数据与口腔通道两个部分（水平口腔和垂直喉气管气道）的沉积测量结果相结合，以计算无量纲传质舍伍德数（Sh）。传质理论表明，Sh应该可以表示为雷诺数（Re）和施密特数（Sc）的函数。对于通过口腔（O-C）的吸入和呼出，在7.5 - 30.0升/分钟的流速范围内获得了经验关系：Sh = 15.3 Re^0.812 Sc^-0.986。在相同的流速范围内，对于喉气管（L-T）区域也获得了类似的经验关系：Sh = 25.9 Re^0.861 Sc^-1.37。通过众所周知的传热与传质类比，将这些关系与人类上呼吸道的传热进行了比较。O-C和L-T关系的雷诺数依赖性与传热的依赖性吻合良好。将传质系数与气体和蒸气的胸外摄取进行了比较，结果显示出相似的流速依赖性。对于符合零浓度边界条件的气体和蒸气，在考虑扩散系数时，这些经验关系是适用的。
