Influence of atmospheric conditions on contrail formation: 3D simulation versus Schmidt- Appleman criterion
Influence des conditions atmosphériques sur la formation des traînées de condensation : comparaison entre la simulation 3D et le critère de Schmidt-Appleman
Résumé
Condensation trails, usually called contrails, represent an increasing issue for aeronautics. Contrail formation and properties depends on several factors such as ambient atmospheric conditions (temperature and relative humidity), mainly, but also possibly on engine characteristics (e.g. bypass ratio, exhaust temperature), fuel type (e.g. kerosene or alternative fuels), and aircraft geometry (e.g. driving mixing in the aircraft wake). Therefore, parametric studies allow for a better understanding of contrails onset mechanisms and assessment of their properties sensitivity in the aircraft near field. This can help to find out smart mitigation solutions to reduce the environmental impact of contrail/induced cirrus by better controlling their formation. In this context, reliable prediction tools as well as technologies input are urgently needed for decision makers. Using the computational fluid dynamics code CEDRE, developed at ONERA and adapted for contrail issues, 3D simulations have been carried out to address this need. It takes into account the dynamical evolution of the jet plume, the chemical transformations of the exhaust after ejection and the microphysical processes driving contrails formation. The simulations are performed on a realistic aircraft configuration. The objective here is to confront 3D simulation approach with the Schmidt-Appleman criterion, widely used to determine contrails formation areas.
Condensation trails, usually called contrails, represent an increasing issue for aeronautics. Contrail formation and properties depends on several factors such as ambient atmospheric conditions (temperature and relative humidity), mainly, but also possibly on engine characteristics (e.g. bypass ratio, exhaust temperature), fuel type (e.g. kerosene or alternative fuels), and aircraft geometry (e.g. driving mixing in the aircraft wake). Therefore, parametric studies allow for a better understanding of contrails onset mechanisms and assessment of their properties sensitivity in the aircraft near field. This can help to find out smart mitigation solutions to reduce the environmental impact of contrail/induced cirrus by better controlling their formation. In this context, reliable prediction tools as well as technologies input are urgently needed for decision makers. Using the computational fluid dynamics code CEDRE, developed at ONERA and adapted for contrail issues, 3D simulations have been carried out to address this need. It takes into account the dynamical evolution of the jet plume, the chemical transformations of the exhaust after ejection and the microphysical processes driving contrails formation. The simulations are performed on a realistic aircraft configuration. The objective here is to confront 3D simulation approach with the Schmidt-Appleman criterion, widely used to determine contrails formation areas.
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