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Experiments in Fluids. September 2012, Volume 53, Issue 3, pp 747-763
Poussou, Stephane B. (1); Plesniak, Michael W (2).
1. School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
2. Department of Mechanical and Aerospace Engineering, The George Washington University, 801 22nd Street, N.W., Washington, DC, 20052, USA
Abstract
The air ventilation system in wide-body aircraft cabins provides passengers with a healthy breathing environment. In recent years, the increase in global air traffic has amplified contamination risks by airborne flu-like diseases and terrorist threats involving the onboard release of noxious materials. In particular, passengers moving through a ventilated cabin may transport infectious pathogens in their wake. This paper presents an experimental investigation of the wake produced by a bluff body driven through a steady recirculating flow. Data were obtained in a water facility using particle image velocimetry and planar laser induced fluorescence. Ventilation attenuated the downward convection of counter-rotating vortices produced near the free-end corners of the body and decoupled the downwash mechanism from forward entrainment, creating stagnant contaminant regions.
Additional Information
Research on aircraft cabin ventilation has increased in the past few years in the wake of global pandemics such as the H1N1 strain of influenza in 2009. Commercial airplane cabins are highly confined spaces with a high density of occupants sharing the same air for hours at a time, thus amplifying the risks of contamination by airborne diseases. Although aircraft environmental control systems and filtration techniques are very effective in limiting passengers’ exposure to harmful particles, the ventilation air flow in the cabin may be disrupted by people moving up and down the aisles. As a result, airborne particles may be spread to multiple seat rows and infect passengers that would have been safe otherwise. This research article sheds new light on how airborne germs like influenza viruses spread on airplanes and other forms of public transportation. The understanding of governing fluid mechanisms is necessary for aircraft manufacturers and regulatory bodies in order to improve air travel conditions and ensure public health. A scaled model of an aircraft cabin was immersed in a water-filled tank, and optical measuring techniques were used to simulate and investigate the spread of germs. It was found that walking passengers create eddies in their wake that can entrain contaminants much further. For instance, if someone happens to cough or sneeze while a passenger is walking by, the walker’s wake can transport pathogens up to seven to eight rows. Swirling eddies were also found to create stagnant zones in the air where suspended germs are present at just the wrong place – at the nose and mouth breathing level of seated passengers. This may explain the infectious spread of severe acute respiratory syndrome (SARS) on a plane during the global outbreak in 2003. One person on a flight from Hong Kong to Toronto contaminated 20 other passengers, four of whom later died from the disease and passengers seated as far as seven rows were infected.
