Interaction of Exhalation Jets With Airflow in an Airliner Cabin

Abstract

This study investigates how exhalation flows generated by passengers in an airliner interact with the airflow in the cabin and jets emitted from personalized overhead vents (gaspers). The spread of airborne pathogens like SARS-CoV-2 and influenza viruses through exhalation events poses a significant health risk to passengers. Although several studies have examined exhalation jets in isolation, a gap remains in understanding their characteristics in the confined space of an aircraft cabin, particularly how they interact with the airflow from gaspers. To simulate exhalation flows generated during coughing, sneezing, and talking, a computer controlled exhalation flow simulator was developed using an electromechanical piston-cylinder apparatus connected to a 3D-printed, subject-specific human airway model, consisting of a mouth-to-glottis section and trachea. This model is connected to a mouthpiece shaped for each activity and then attached to a dummy, referred to as the index passenger. We conducted two-dimensional, two-component particle image velocimetry (PIV) experiments inside an MD-80 airliner cabin. We varied gasper operational configurations (all closed, all opened, and a single gasper opened) and seating positions of the index passenger (middle, aisle, window), with passive (no exhalation) human dummies positioned in neighboring seats. Experiments were conducted at a cabin pressure equivalent to 2,000 feet above sea level, with the environmental control system operational to maintain standard cabin conditions. Results reveal that a opening only a single gasper is most effective in redirecting exhalation jets downward by increasing vertical momentum flux towards floor vents and decreasing horizontal momentum flux. When all gaspers are closed, exhalation jets are directed towards the window along the port-starboard axis, in the same direction as cabin ventilation driven air circulation. When gaspers are used, exhalation jets disperse along this axis, spreading towards both the window and the aisle. The jet width and angle of deflection indicate that gaspers can increase the dispersion of exhalation jets, particularly when the index passenger is seated in the aisle. To further investigate this finding, we employed data-driven agent-based modeling to examine particle deposition under different gasper configurations. The results show that gaspers promote dispersion of particles along the port-starboard axis and increase downward movement. These findings can aid in the design and operation of ventilation systems in airliner cabins and other enclosed spaces to minimize the dispersion of infectious particles.