A computational study of the influence of evaporation and molecular transport on temporally-evolving droplet-laden plane jets

Abstract

Numerical simulations of temporally-evolving droplet-laden plane jets are performed in conditions relevant to rocket main engines fed with liquid oxygen (LOx) and gaseous methane (CH₄). The computations are performed using a direct numerical simulation (DNS) solver with the liquid phase represented within the discrete particle simulation (DPS) framework. Considering the multiplicity of the physical phenomena that are involved in such conditions – e.g., atomization, dispersion, evaporation – a progressive and phenomenological methodology is retained to proceed with a complexity-increasing set of computations. Thus, the development of a purely gaseous jet is first studied with the corresponding set of data providing a reference or baseline condition. Then, other conditions are considered to analyze the influence of (i) liquid droplet evaporation and (ii) molecular mixing processes as described by two distinct multicomponent transport models. The analysis of the obtained results shows that both evaporation and molecular transport representation play a crucial role in the plane jet development and may drastically alter its characteristics before ignition and subsequent combustion stabilization may take place. Finally, the obtained results also unambiguously put into evidence the influence of the Lewis number onto the vaporization rate.