基于病毒传播风险的地铁车厢通风系统优化研究OA北大核心CSTPCDEI

The subway transportation system provides convenience to people but may also accelerate the spread of viruses.Optimizing the carriage ventilation system is an important method to reduce the risk of virus transmission.A numerical model of a typical subway carriage with the concentrated air recirculation(CAR)mode was constructed using numerical simulation methods,and the accuracy of the model was verified using field measurement data.Based on the CAR mode,the study proposed a dispersed air recirculation(DAR)mode.A comparative analysis of the flow characteristics and droplet dispersion features in subway carriages under these two air recirculation modes was conducted.Furthermore,the risk of infection for passengers was discussed in conjunction with an infection risk assessment model.Results indicate that regarding the airflow and temperature fields in the carriage,the average airflow velocity and temperature at 15 measurement points under the CAR mode are(0.27±0.13)m/s and(26.4±1.35)℃,respectively.In contrast,in the DAR mode,they are(0.25±0.08)m/s and(26.2±0.94)℃,respectively.In terms of droplet dispersion,under the CAR mode,droplets are influenced by the longitudinal airflow generated by the centralized air vents,resulting in a greater spread distance than that in the DAR mode.In the CAR mode,the area of droplet dispersion is 1.45 times that of the DAR mode.Regarding passenger infection risk,passengers in both standing and sitting positions under the DAR mode have a lower risk of infection than passengers under the CAR mode.Within 0～20 seconds after droplet release,the risk of infection for standing passengers under the CAR mode is 1～2 times that of standing passengers under the DAR mode.Compared to the CAR mode,the DAR mode can improve the uniformity of the velocity and temperature fields inside the carriage.It can also help with more rapidly removing droplets from the breathing zones of passengers,thereby reducing the risk of infection for both standing and seated passengers.The research findings provide a reference for further optimizing subway carriage ventilation systems and ensuring the safety of passenger travel.