Research On Turbulent Thermal Movement And Thermal Environment Of Different Ventilation Systems In A Commercial Airliner Cabin Mockup

The ventilation system in the airliner cabin mockup is the key to ensuring the health and comfort of passengers and crew.However,with the outbreak of some epidemics in recent years,the existing ventilation system cannot guarantee the health of passengers and crew in airliner cabins.The flow field in cabin mockups affects the velocity,temperature and pollutant concentration distribution.Therefore,the study of the flow field in cabin mockups is very significant.Although the large-scale vortex structure in the cabin has been measured and simulated at this stage,due to the unstable and uneven boundary conditions in the airliner cabin mockup,it is hard to carry out accurate experimental measurement and simulation analysis with the flow under the influence of the small-scale vortex structure.Therefore,this paper established a sevenrow airliner cabin mockup with stable boundaries,which measured the velocity,temperature and particle concentration distribution stable with different ventilation systems.Moreover,this paper analyzed the time-averaged flow field characteristics and instantaneous flow field characteristics.Finally,the simulation method was used to analyze the flow field characteristics.For practical applications,pollutant exposure risks in the thermal environment of the airliner cabin were evaluated.The main contributions and innovations of this paper are summarized as follows:1)The study designed a boundary calibration system suitable for the airliner cabin mockup to calibrate the air supply velocity boundary and the thermal boundary.The standard deviation of the calibrated boundary velocity was less than 0.08 m/s(mixing ventilation)and 0.08 m/s(displacement ventilation).The geometric boundaries of the 42 thermostatic dummies have been simplified.The temperature fluctuations of 42 thermostatic dummy can be controlled within ± 1℃,and the standard deviation was less than 0.36℃.Compared with previous study,after the boundary conditions were calibrated,the accuracy of the simulation results can be increased by nearly 100%.2)A set of high-precision experimental data has been provided.Moreover,the characteristics of the air distribution with different ventilation systems(mixing ventilation,displacement ventilation)were given,especially the instantaneous characteristics of the flow field with displacement ventilation system in the cabin mockup.The energy ratio of mixing ventilation on the low-frequency scale was greater than that of displacement ventilation.In addition,there are two large-scale vortex structures in flow field with mixing ventilation,which caused residence time of pollutants to be long.There was basically no large-scale vortex structure with displacement ventilation,and the pollutant residence time is shorter than that with mixing ventilation,which was beneficial to the discharge of pollutants.And this paper found it is necessary to distinguish the grid size between mixing ventilation and displacement ventilation when meshing in simulations.3)Combined with experimental data and simulation results of a large number of polydisperse particles,this study used the Wells-Riley method to assess the COVID-19 exposure risk of passengers in the cabin mockup,and the impact of medical surgical masks on the exposure risk with COVID-19 was quantified.This study found that the exposure risk with displacement ventilation was significantly lower than that with mixing ventilation.In addition,this study found that in the middle and late stages of the epidemic,the exposure risk of masked-passengers were greatly reduced.However,compared with displacement ventilation,it reduced more in mixing ventilation.