Effects Of Airflow On The Airborne Contaminant Transmission In Aircraft Cabins

With the development of globalization,increasing people are travelling by air.The air travel decreases the distance between peoples,while it also makes some disease transmit more easily.In aircraft cabins,contaminants can spread due to the ventilation system and make the passengers sick and uncomfortable.Therefore,it is important to study and contain the airborne contaminant transmission in the aircraft cabin.This study first investigated the flow structure feature and contaminant measurement method through the experiment in a 7-row cabin mockup.We analyzed the coupling effect of double sources,the tracking behavior of particles with different diameters and compared the flow structure between the aircraft and built environments.It was found that the flow structure in the aircraft cabin was more diversified and intermittent.Based on the experimental data,the turbulent diffusion term in CFD model was modified.A more complete particle deposition model was also proposed and applied in the numerical simulation.Then,the predicted data were compared with the experiment through the confidence analysis,and its results suggested RNG k-ε could provide reasonable data.According to the simulated data,we further investigated the methods for setting sampling points and the contaminant distribution scales.Based on the experimental and simulated data above,effects of diversified and intermittent flow structure on contaminant spreading were studied.For the diversified flow structure,we calculated the vortexes in the cabin and contaminant distributions for different source locations;for the transient flow structure,we used Monte-Carlo simulation to analyze the effect of lognormal fluctuant concentrations on the passengers‘ exposure risk.In addition,based on the concept of ?entropy‘,we proposed two new concepts ?vortex entropy‘ and ?exposure entropy‘ to qualify the simulation system confidence between the cabin mockup and actual aircraft cabin.Finally,based on the simulation system confidence analysis and the feature of the actual aircraft cabin,we developed a practical method to measure the longitudinal flow rate in it by tracer gas method and proposed a method to control the longitudinal flow.Two simplified models(one-dimensional model and Markov Chain model)were suggested to quickly calculate the contaminant transport in real aircraft cabins.