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Recurrent epidemics of respiratory infections have drawn attention from the academic community and the general public in recent years. Aircraft plays a pivotal role in facilitating the cross-regional transmission of pathogens. In this study, we initially utilized an Airbus A320 model for computational fluid dynamics (CFD) simulations, subsequently validating the model's efficacy in characterizing cabin airflow patterns through comparison with empirical data. Building upon this validated framework, we investigate the transport dynamics of droplets of varying sizes under three air supply velocities. The Euler-Lagrangian method is employed to meticulously track key parameters associated with droplet transport, enabling a comprehensive analysis of particle behavior within the cabin environment. This study integrates acquired data into a novel PCR (Personal Contamination Rate) equation to assess individual contamination rates. Numerical simulations demonstrate that increasing air supply velocity leads to enhanced stability in the movement of larger particles compared to smaller ones. Results show that the number of potential infections in the cabin decreases by 51.8% at the highest air supply velocity compared to the base air supply velocity, and the total exposure risk rate reduced by 26.4%. Thus, optimizing air supply velocity within a specific range effectively reduces the potential infection area. In contrast to previous research, this study provides a more comprehensive analysis of droplet movement dynamics across various particle sizes. We introduce an improved method for calculating the breathing zone, thereby enhancing droplet counting accuracy. These findings have significant implications for improving non-pharmacological public health interventions and optimizing cabin ventilation system design. [ABSTRACT FROM AUTHOR]

With airborne transmissions found as one of the major transmission routes of SARS-CoV-2, its transmission in airliner cabin environments drew special attention due to high number of imported cases and in-cabin transmissions. This study numerically investigated the transmission of COVID-19 by cough-induced particles in a cabin section of Boeing 737 model. One passenger was coughing in each case, while cough particles with measured size distributions were released during coughs and were tracked using the Lagrangian framework. Outcomes revealed that cough flow released by passengers could develop rapidly into a strong turbulent cough jet, breaking up the local airflow field. The released cough particles were largely dominated by the cough jet within 5 s, especially the first 1.5 s. Deposition of particles under 100 µm were relatively delayed when released from a window-seat location. Small particles (under 50 µm) released by a window-seat passenger were more likely to spread widely in the studied cabin section, which could lead to the highest exposure risks to nearby passengers. Also, due to ventilation design and seating arrangement, cough particles released by the middle-seat passenger were found easily trapped in his/her own local environment. Cough particles released from aisle-seat passengers had the least exposure risk to adjacent passengers. [ABSTRACT FROM AUTHOR]

Airflow in the cockpits of commercial airliners could be substantially different and more complex than it in passenger cabins, while simply referring to the standard of passenger cabin may not effectively achieve optimum ventilation or ensure a comfortable working environment for pilots. This study numerically investigated the ventilated Boeing 737 cockpit by analysing its airflow and thermal distribution inside, especially in pilots' micro-environments, under various in-flight conditions (number of personalised jet-inlets, window heat exchange, etc.). Gaseous contaminant CO 2 released from pilots was analysed in relation to its concentration distribution and potential lock-up phenomena in pilots' micro-environments, followed by quantitative analysis of pilots' thermal comfort and air quality. The outcomes demonstrated that the window heat exchange had significant impacts on pilots' thermal sensation and could induce severe thermal stratification around pilots' head level. The most effective CO 2 removal rate was achieved by initiating windshield inlets in combination of the side diffusers. Further adding personal gaspers did not significantly alleviate the CO 2 concentration in pilots' micro-environment but may potentially compromise their thermal comfort. Also, the overwhelming numbers of personalised inlets could hardly provide superior ventilation performance or ensure consistent air quality and could be impractical to use sometimes. It is suggested that future optimisation of the environmental control system could rely more on the global airflow circulations induced by larger or wider diffusers rather than the local complex jet flows from high number of personal gaspers. [Display omitted] • Pilots' micro-environments in terms of thermal comfort and air quality are assessed. • Window heat exchange is a vital factor and may propel thermal stratification. • Air change efficiency and age of air in the upper region is seemingly unsatisfactory. • Contaminants removal is ineffective in pilots' breathing zone with diffuser open only. • Adding windshield inlets significantly improve air exchange and contaminants remove. [ABSTRACT FROM AUTHOR]