摘要

In order to understand the process of formation of condensation trail (contrail), the flow in the near field of an engine jet is studied by using the Large Eddy Simulation technique. The configuration consists of a hot round jet laden with soot particles. The particles are tracked by the Lagrangian approach and their growth is calculated by a microphysics model of water vapour condensation and ice formation. A series of simulations has been performed with a low Mach number (M = 0.2 ) and a moderate one (M = 1) at realistic Reynolds number (Re = 3.2·10⁶). Whatever the Mach number used the ice crystals first appear at the edges of the jet where the hot and moist flow mixes with the cold and dry ambient air. The simulations show that the growth process is controlled both by the thermal transfers and the mass coupling which are more important for the low Mach number case.