Research On The Monitoring Method For Gas Pollutant Distribution In Aircraft Cabin

Toxic and harmful gas pollutants discharged from the cabin will affect the health and even life of the crew and passengers stay in the cockpit and cabin for a long time.Therefore,the monitoring of air pollutant in the cabin of aircraft is of great significance to ensure the health and safety of passengers.Firstly,a complete economy class model of a Boeing b737-700 with 20 rows of seats was established.Fluent was used to simulate the diffusion process of air pollutants while the cabin air conditioning system was working.In order to study the influence to the cabin environment by the air pollutants released from a single point source,the differences of pollutant distribution resulted from three different positions of pollution source were compared.and the relationship between the release rate of pollution source and the pollutant distribution range that exceeding the threshold of dangerous concentration was analyzed.At the same time,multiple sampling observation points were set to analyze the horizontal and vertical concentration distribution rules of pollutants in aircraft cabin.Secondly,on the Matlab simulation model of tunable diode laser absorption spectroscopy(TDLAS)technology is established.The simulations,such as the modulated light source of gas monitoring system,wavelength modulation,absorption spectrum and signal demodulation were conducted based on the principle of the lambert-beer law and the technology of wavelength modulated.and the second harmonic component signals were finally output.Because the second harmonic peak is the related to gas concentration,the integrated gas concentration on the light path was derived by the concentration inversion algorithm.Then the cross section of the cabin is scanned by TDLAS,and the concentration distribution in the section is reconstructed based on the scan data.Finally,the visualized image of two-dimensional distribution of pollutants is realized.Comparison between the simulated concentration distribution and reconstructed distribution shows the effectiveness of the proposed method.