人体呼出的污染液滴在空气中的蒸发和沉降特性

Evaporation and settling characteristics of contaminated respiratory droplets

人体呼吸、咳嗽、说话排出的含病原体的液滴是许多疾病的传染源.本文采用含固体成分的液滴的质量、能量、动量的理论模型编制了计算程序,对液滴排入空气后的蒸发和运动进行了数值计算.研究表明初始直径大于50μm的液滴会明显地相对于空气下沉,而大于150μm的液滴则会沉降到地面.空气的湿度对液滴的蒸发速率有很大的影响,并因此影响到液滴的下沉高度.由于液滴中含有固体成分,所以大于50μm的液滴,即便是其中的水分全部蒸干后,其固体残留物因大于15μm而具有不容忽视的相对于空气的下沉速度,这个速度将影响到液滴残余物在空气中的传播.

It has been known that droplets containing pathogens from breath, cough and talking may provide the vectors for many transmissible diseases. The mathematical model for droplets containing solids was used to calculate the mass and heat transfer of the contaminated droplets from human respiration. The settling characteristics of droplets of different initial sizes were also studied. The calculation results indicate that droplets with an initial diameter larger than 50 μm present obvious settling features, while the droplets with initial diameter lager than 150 μm will finally drop to the ground. The humidity of the ambient air has a great influence on the evaporation rate and the settling distance of droplets. For the droplets initially larger than 50μm, even after the water is totally evaporated, the settling velocity of solid residue of the droplets still can not be neglected.