Numerical investigation of engine position effects on contrail formation and evolution in the near-field of a realistic aircraft configuration

TL;DR

This study uses detailed numerical simulations to examine how engine placement on a Boeing 777-like aircraft affects contrail formation and evolution, revealing significant impacts on ice crystal growth and optical properties.

Contribution

It provides new insights into the influence of engine position and microphysical activation scenarios on contrail microstructure and optical characteristics using advanced RANS simulations.

Findings

Engine placement significantly affects plume saturation and ice crystal growth.

Dilution and wake interactions influence contrail optical thickness.

Activation scenarios alter ice crystal size distribution and water vapor access.

Abstract

The present study investigates the impact of engine position on contrail formation and near-field evolution in a realistic three-dimensional aircraft configuration. Detailed numerical simulations are conducted using a Reynolds-Averaged Navier-Stokes (RANS) approach coupled with mesh adaptation techniques. A Eulerian microphysical model is used to characterize contrail ice crystal properties and their evolution under varying dilution conditions. The setup is based on a Boeing 777-like geometry, including fuselage, wings, engines, and tailplane. Two microphysical activation scenarios are considered: one incorporating adsorption-based ice nucleation and the other assuming fully activated soot particles. The latter for two soot number emission indices. The dilution process and wake structure exhibit a strong dependence on engine placement, which significantly influences plume saturation. In highly diluted configurations, enhanced early-stage mixing reduces plume temperature and increases relative humidity, favoring the growth of larger ice crystals. Depending on the soot number concentration, vapor depletion effects may outweigh dilution-driven changes in water vapor availability. In adsorption-limited activation scenarios, increased dilution reduces the concentration of sulfur species, leading to a lower activation fraction and the formation of smaller ice crystals. Additionally, across the scenarios, the modified jet-vortex interaction alters particle distribution and their access to water vapor, further shaping their growth. These effects ultimately impact the contrail's optical properties, particularly its optical thickness.