Parametric Study of High-Resolution Simulations of Contrails During the Vortex Phase with Emphasis on Initial Conditions

Abstract

Large-eddy simulations (LES) with Lagrangian ice microphysics were employed to examine contrail evolution during the vortex phase. The wake vortices were initialized using two methods: an analytical Lamb-Oseen vortex profile and a more refined approach utilizing velocity fields generated a priori by Computational Fluid Dynamics (CFD) near-field simulations, based on Reynolds-Averaged Navier-Stokes (RANS) equations that account for the actual aircraft geometry. A comparison of these two initialization methods revealed that the initialization method has an impact on the evolution of the contrail during the vortex phase, in particular on the formation of the secondary wake. The ice crystal loss is reduced for the initialization with a CFD simulation generated input field. Additionally, simulations were conducted for both a conventional kerosene combustion system and a hydrogen fuel cell propulsion system to examine how these different propulsion methods affect vortex phase simulation outcomes. The results for the hydrogen fuel cell propulsion system indicate that the fraction of ice crystals surviving the vortex phase is significantly lower. However, the total number of ice crystals remains higher due to the greater initial number of ice crystals. Finally, the impact of a variation of the engine positions on the vortex phase was analyzed. The results suggest that ice crystal loss may be higher when engines are positioned closer to the aircraft fuselage.