Aircraft new fuel consumption model and induced pollutant emission assessment. Environmental benefits

Author(s): S.Khardi

Environmental impact of atmospheric emissions from aircraft can be addressed in two separate ways. Air quality impact occurs during landings and take-offs while in-flight impact during climbs and cruises influences climate change, ozone andUVradiation. The aim of this paper is to investigate airport related emissions in the local environment. Flight path optimization is designed forminimizing aircraft fuel consumption and environmental impact around airports. This paper gives flight path optimizationmodel linked to a Lagrangian dispersionmodel aswell as numerical methods and algorithms. Difficulty concerns the usage of the bestmodel for piloting the aircraft. Operational factors including configuration, engine functionalities, weather limits, visual aids and crew qualifications are considered. The cost function integrates the objectives taking into account pollutant emission concentrations and fuel consumption. Formulation of this problem is designed with partial empirical data. Its effective resolution makes comparisons possible with existing empirical models.We have compared pollutants emitted during LTO cycles, optimized flight path and with analysis by Döpelheuer. Comparisons concern the reduction of SO2, NOx, HC, CO, PM10, O3 and CO2.Analysis of pollutants appearing fromincomplete and complete combustion processes has been discussed. Because of calculation difficulties, no assessment has been made for the soot, H2O and PM2.5. In addition, because of the lowreliability of the availablemodels quantifying pollutant emissions of theAPU, an empirical evaluation has been done. This is based on Benson’s fuel flowmethod applied to aircraft operations on the ground.Anewmodel, giving fuel consumption and predicting in-flight aircraft engine emissions, has been developed and coupled with flight and dispersion of pollutants models. Our model fits with the fuel consumption model performed by Boeing. We have confirmed that fuel consumption can be reduced by 3% for takeoffs and 27% for landing. This finding contributes to analyzing the coming intelligent fuel gauge computing the in-flight aircraft fuel flow. Further research is needed for incoming alternative fuels. Itwill be also necessary to define the role of NOx which is emitted during the combustion process derived fromthe ambient air, not the fuel.Models are needed for analyzing the effects of fleet composition in terms of aircraft types and engine combinations on emission factors, fuel flowassessment using performance and operationalmodes. Development of new optimized APU, reducing ground pollutant emissions, is necessary.

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