College of Civil Engineering, Hunan University, Changsha, China.
Indoor Air. 2015 Apr;25(2):198-209. doi: 10.1111/ina.12135. Epub 2014 Jul 7.
The characteristics of contaminant transport and dispersion of exhaled flow from a manikin are thoroughly studied in this article with respect to the influence of two important factors: air stability conditions and metabolic rates. Four cases with the combinations of stable and neutral conditions as well as lower (1.2 met) and higher (2 met) metabolic rates for a breathing thermal manikin are employed. The exhaled contaminant is simulated by smoke and N2 O to visualize and measure the contaminant distribution both around and in front of the manikin. The results show that the microenvironment around the manikin body can be affected by different air distribution patterns and metabolic heating. Under stable conditions, the exhaled contaminant from mouth or nose is locked and stratified at certain heights, causing potentially high contaminant exposure to others. In addition, velocity profiles of the pulsating exhaled flow, which are normalized by mean peak velocities, present similar shapes to a steady jet. The outlet velocity close to the mouth shows decrement with both exhalation temperature and body plume. The velocity decay and concentration decay also show significant dependence on air stability and metabolic level.
本文针对两种重要因素——空气稳定条件和代谢率，深入研究了模拟人呼吸流中呼出气流污染物传输和扩散的特征。实验采用 4 种情况，分别为呼吸热模拟人处于稳定和中性条件以及较低（1.2 met）和较高（2 met）代谢率下。采用烟雾和 N2 O 模拟呼出污染物，以可视化和测量模拟人周围和前方的污染物分布。结果表明，不同的空气分布模式和代谢加热会影响模拟人身体周围的微环境。在稳定条件下，来自口鼻的呼出污染物在特定高度被锁定和分层，导致其他人可能面临较高的污染物暴露风险。此外，脉动呼出流的速度分布，通过平均峰值速度进行归一化，呈现出类似于稳定射流的相似形状。靠近口鼻的出口速度随呼气温度和体羽的增加而减小。速度衰减和浓度衰减也显著依赖于空气稳定性和代谢水平。
