Large eddy simulation of turbulent spray breakup and evaporation

Abstract

This paper is on the modelling and large eddy simulation (LES) of very high speed evaporating sprays. The spray is simulated with a Lagrangian droplet transport and a stochastic breakup model together with finite rate heat and mass transfer models. The droplet transport, breakup, wake, collision/coalescence, heat transfer and evaporation models are used together with a compressible gas phase LES solver for numerical simulations of high pressure liquid jets sprayed into a high temperature and pressure gas chamber. The numerical results are compared with the available experimental results for global spray variables such as the spray penetration length. Various non-evaporating and evaporating sprays at different ambient gas pressures and temperatures are considered. In all cases, the gas velocity and turbulence generated by the spray are found to be very significant. A broad spectrum of droplet sizes is also generated by the complex and coupled effects of the gas flow turbulence, droplet breakup and evaporation. Droplet wake interactions are shown to be important to the spray evolution. The effect of subgrid turbulence model on the global spray parameters, like the spray penetration, is also shown to be significant at lower gas temperatures.