Computational Airflow Models to Evaluate Biological Agent Transport in Cargo Aircraft
Technical Report,01 Feb 2019,31 Jul 2019
711 HPW/RHM Wright-Patterson AFB United States
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There is currently a lack of real-world data and computational models aimed at characterizing Air Force cargo aircraft cabin ventilation. A better understanding of the flow physics could be used to identify hot spots where contaminants introduced into the aircraft are likely to accumulate, which would inform sampling strategies to confirm decontamination after an incident. Further, an in-depth flow understanding could be used to improve strategies for infectious patient transport to mitigate cross-contamination. In the absence of available data, a set of numerical Lagrangian Multiphase aerosol transport models were completed to investigate various flow and aerosol metrics in a C-130 cabin outfitted for aeromedical evacuation. The transport properties, including residence time, deposition and clearance of 100,000 polydispersed 0.1, 1.0, 10.0 micrometer expiratory particles that mimicked wet microorganism-bearing droplets were examined in four distinct models in which aerosolization occurred at different time points 1,41, 81, 121 s. In each model, the simulated bioaerosols were released from the same single location and tracked for up to three minutes. Simulation results were investigated in the following manner air velocity and direction on cut planes throughout the cabin, randomly sampled particle trajectories, particle deposition rates, particle deposition location binning and particle maximum velocities. Cabin air exhibited a combination of positive and negative forward to aft flow in the cabin which fluctuated in time. Analysis of single-particle trajectories revealed low travel distance from the point of expiration with the particles being continually re-entrained into rotating vortices in the flow. The highest rates of deposition occurred directly following each expiration however, the majority of all particles 70 percent on average remained suspended in vortices for the duration of the simulations.
- Chemical, Biological and Radiological Warfare
- Transport Aircraft