Characteristics of Droplet Transmission in Buses in Different Air Supply Modes

doi:10.16183/j.cnki.jsjtu.2021.318

Abstract

Abstract:

In order to study the spread characteristics of virus droplets in the bus and predict the risk probability of airborne virus infecting passengers in the bus, a numerical model of the bus with the refrigeration and air conditioning on in summer is established based on the numerical simulation of computational fluid dynamics (CFD) in combination with the Wells-Riley equation. Through the analysis of the characteristics of the flow field in the bus in combination with the Lagrangian method, the spread process of the droplets produced by the cough of the virus carrier in the bus is calculated. The infection risk of virus-carrying droplets to the passengers in the bus in the four ventilation mades is analyzed. It is found that the longitudinal airflow in the bus is a key factor affecting the spread of droplets. Compared with the asymmetrically arranged circular air outlets, the longitudinal airflow in the bus can be reduced by the use of slit-type air outlets. Only 6% of passengers have a higher than 5% probability of contracting diseases in the bus with displacement ventilation, which is more effective in reducing the risk of droplet-borne infection. The research results can provide guidance for the structural design of bus air supply systems and reduce the risk of droplet-borne infections.

Key words: computational fluid dynamics (CFD), bus ventilation, droplet spread, Wells-Riley equation, infection risk prediction

CLC Number:

TB71

CHEN Zhixin, WANG Yiping, YANG Yafeng, SU Jianjun, YANG Bin. Characteristics of Droplet Transmission in Buses in Different Air Supply Modes[J]. Journal of Shanghai Jiao Tong University, 2022, 56(11): 1532-1540.

Figures/Tables 12

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边界	设置值
地板、车身和天花板	对流换热系数5 W/(m²·K)^[9],室外温度40 ℃
窗户	对流换热系数10 W/(m²·K)
座椅	绝热
人体	人体热流密度20 W/m^{2 [20]}
送风口	送风温度20 ℃;入口速度:模型1、2为3.5 m/s^[21],模型3为0.46 m/s,模型4为0.23 m/s
回风口	压力出口为0 Pa

设置项	参数设定
湍流模型	RNG k-ε
壁面函数	标准壁面函数
空间离散格式	二阶迎风格式
计算方法	SIMPLE算法