Numerical simulation of effect of fresh air rates on transmission of cough droplet transmission in subway passenger cabin
Optimizing ventilation system parameters to reduce the risk of respiratory infectious diseases among passengers is crucial for creating a safe and comfortable travel environment in subway carriages.The Euler-Lagrange numerical simulation method was used to simulate the spread of respiratory droplets in subway carriages focused on the diffusion patterns and spatiotemporal distribution characteristics of passenger cough-generated droplets at different air supply rates.The results show that the carriage ventilation system's effectiveness in clearing droplets increases with the increase of the fresh air rate.For a fresh air volume of 2 000 m3/h,only 3.9%of droplets enter the exhaust outlets within 30 s,while at a fresh air volume of 8 000 m3/h,38.9%of particles can be expelled by the exhaust outlets within 10 s.The proportion of suspended particles inside the carriage does not linearly decrease with the increase of the fresh air volume but exhibits a complex variation.As the fresh air volume increases,the dominant airflow for droplet movement within the carriage shifts from the return air to the exhaust outlet-generated airflow.Simultaneously,the vortex region created by the exhaust outlet-generated airflow gradually enlarges,prolonging the suspension time of droplets that fail to enter the exhaust outlet quickly.The proportion of inhaled particles by passengers near the exhaust outlets demonstrates significant differences with the increase of the fresh air rate.In the infected passenger side,the infection risk for passengers gradually decreases with the increase of the fresh air rate.In the region facing an infected passenger,the infection risk for nearby passengers initially increases and then decreases with the increase of the fresh air rate.The results can provide reference for formulating strategies to prevent airborne transmission of respiratory viruses in subway carriages.
subway trainsfresh air ratescoughdropletsnumerical simulation
国家科技期刊平台
NSTL
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