Influence of seating position and ventilation on aerosol dispersion in a passenger aircraft

Abstract

The spread of exhaled particles in a passenger aircraft cabin is an important parameter for evaluating infection risk modelling or the spread of other contaminants and odours. It is well known that the ventilation concept has a significant influence on this process and therefore also on the direct transmission of the contaminants. The present experimental study, conducted in the ground-based Do728 research aircraft cabin of the DLR, compares the aerosol spread under state-of-the-art mixing ventilation (MV) conditions with cabin displacement ventilation (CDV) and a combined CDV-MV ventilation (hybrid ventilation - HV). Various source positions in longitudinal direction and in the cross-section as well as different airflow distributions were investigated. Furthermore, the dynamic influence of people walking in the aisle was analyzed. This study shows that the spread of particles in a short-range aircraft is strongly affected by the installed ventilation system. Compared to the state-of-the-art MV, the mean concentration can be reduced by up to 80% under CDV conditions. Furthermore, the number of seats where certain thresholds are exceeded can be significantly reduced. By combining the systems to HV, the mean concentration can be reduced by 10% compared to MV. However, this results in a 130% increase in the maximum value. The spread of particles in case of MV and HV is strongly influenced by the source position, in both the longitudinal and in cross-sectional directions. Movement in the aisle has only a minor influence on the mean particle load and the number of seats above a certain threshold under MV conditions. However, the direction of spreading within the cabin is changed by the movement, decreasing the particle load in front and increasing it in the rear of the cabin. A considerably stronger effect was measured under CDV conditions, where the induced air flow by the manikin movement leads to increased particle concentrations in large area of the cabin. Here, the otherwise well-defined, upward-directed buoyancy driven flow which transports the exhaled particles directly to the exhaust, is now disturbed by the movement and thus more spreading of particles occurs in the breathing zone of the passengers.