Date de présentation: Septembre 2022
Auteur(s): Sébastien Cantin, Adrien Misandeau, Mohamed Chouak, François Garnier
Conférence: ISABE 2022, Ottawa, ON, Canada
Abstract
The formation of ice-particles in near-field aircraft plumes at cruise altitudes generates contrails. The latter trigger the formation of large cirrus clouds, called aircraft-induced clouds (AICs). These artificial clouds result in a net positive radiative forcing (warming) effect. Furthermore, the use of chevrons in modern jet engines helped to reduce jet noise of ‘separate-flow’ nozzles; however, the impact of this technology on near-field contrail properties has not been investigated. In this context, this paper presents a CFD-microphysics coupling strategy to model the 3-D dynamics and microphysical transformations in the near-field plume of an aircraft engine. The study investigates the effect of implementing the chevron technology in both fan and core nozzles on plume and ice-particle properties. For this purpose, 3-D unsteady Reynolds-Averaged Navier-Stokes simulations were carried out behind a realistic LEAP-1A engine geometry (high bypass-ratio 10.5:1) at cruise conditions. The microphysical modeling accounts for the main process of water-vapor condensation on pre-activated soot particles known as heterogeneous condensation. The plume dilution and ice crystals formation in the engine near-field jet were validated using available numerical and in-flight data to demonstrate the predictive capabilities of the proposed modeling strategy. Different geometrical parameters of fan- and core-nozzles were investigated by varying the number and the penetration angle of chevrons. The comprehensive analysis showed that core-chevron nozzles lead to higher kinetic turbulent energy, higher liquid saturation ratio, larger ice particles and thicker contrails than chevron fan-nozzles and the baseline nozzle without chevrons. The proposed model can be hence used in future studies to characterize the impact of tabs or lobed nozzle-exit parameters on the optical and microphysical properties of near-field contrails.
Cantin, S., Misandeau, A., Chouak, M., Garnier, F. (2022). Effect of nozzle chevron technology on the near-field contrail properties behind an aircraft engine using a CFD-microphysics coupling. ISABE 2022. Ottawa, ON, Canada.
