ABSTRACT
COVID-19 is a respiratory infectious disease that spreads readily between people, and an urgent issue of passengers' exposure risk assessment in commercial aircraft has been raised because an aircraft cabin as a confined space may carry and transmit the disease worldwide. In this study, the droplets transmission process under different ventilation systems in a twin-aisle wide-body aircraft was studied using CFD simulations and the infection risk of passengers was assessed by the improved Wells–Riley model. Numerical results found that the transmission mechanism of droplets in the aircraft cabin was different depending on the type of ventilation systems and the location of the infectious source. Annular airflow could effectively enhance the ability of droplets transmission, while direct airflow, represented by displacement ventilation, could significantly inhibit droplets transmission. Accordingly, a new type of ventilation system was proposed based on the concept that the overall space is organized by annular airflow and the local area is direct airflow. Compared with sidewall mixing ventilation system, the infection risk of the new ventilation system presented in this study is reduced by 27%.