Study Of Particle Deposition In The Environmental Control System And Cabin Of Commercial Airplanes

The environmental control system(ECS)in a commercial airliner is to maintain safety,thermal comfort,and air quality for passengers and crew by supplying conditioned air into airliner cabins.Serious air pollution on airport ground and longwaiting time due to traffic control after boarding in China result in more particles being deposited in ECS and entering air cabin.The particle deposited in the ECS could cause performance issues of the airplanes.The particles entered the cabin could be deposited in cabin walls which are very unsightly and difficult to remove.This study is to to understand where,what,and how many particles are deposited in the ECS and air cabin of commercial aircraft,and to find an efficient prediction model and to provide guidline for the operation and maintenance of ECS.This study has conducted the following investigations: 1)This study has experimentally investigated the particle deposition in the ECS by using a retired commercial airplane(MD-82)from our research group and also in 64 commercial flights.2)In order to identify where the particles were deposited in ECS,we developed a CFD model combined with Lagrangian method that can predict the particle deposition in the complex ECS with high accuracy.After comparing with our experimental data,we proposed the most suitable turbulence model and near-wall correction model.CFD simulation provided detailed information about the particle deposition distribution inside the complex ECS componants.3)This investigation has measured particle emission rate in multiple commercial flights during boarding,cruising,meal servicing,and deplaning.With the measured data,this investigation developed a CFD model to predict the particle concentration inside airplane caboin and accumulation of particles deposited inside an airplane,taking into account flight routes and the outdoor particle concentrations at the airports where the airplanes were parked.The following conclusions can be reached: 1.The particle deposition rate in the ECS was serious,and the PM2.5 mass concentration deposition in the ECSs of these airplanes ranged from 50% to 90%.For particles with a diameter of 5 ?m or larger,the deposition rate was greater than 90%.For particles with a diameter of 0.5 ?m or less,the deposition rate was less than 25% so they entered into the aircraft cabin.2.The RNG k-? model with near-wall correction provided the most accurate prediction of the particle deposition fraction in complex ECS components.The relative error between the simulated and measured data was less than 5%.3.The in-cabin sources emitted more particles during boarding/deplaning than during meal servicing and sitting.The average particle emission rate from in-cabin sources varied seasonally and was the highest in winter.4.The calculation method proposed in this study can quantitatively predict the particle concentration inside aircraft cabin during different flight phases in different seasons.The average relative error between the estimated and the measured data was less than 15%.5.For the most polluted airplane in China,the dirty areas were found to be around the nozzles and they became visible after six months.The deposition was very much related to the diffuser design and airflow pattern.