Spray Vaporization and Combustion in Large Vortical Structures

Abstract

Abstract : Numerical studies were performed to investigate interactions between large scale vortical structures and droplets in two phase shear flows. A generic configuration consisting of a droplet laden heated air jet in a coflowing air stream was used to analyze several two phase flows. A time accurate, axisymmetric, two phase algorithm was developed for the simulations. Detailed numerical experiments were used to examine the dispersion of evaporating droplets in the presence of vortex structures, the effects of droplet vortex interactions on the dynamic and steady structure of nonevaporating and evaporating sprays, and the transient and time averaged structure of a swirling two phase jet. Results demonstrated that the dispersion of evaporating droplets can be characterized in terms of their lifetimes and Stokes numbers. In addition, it was shown that for a dispersed to gas phase mass loading ratio of unity, the shear layer stability and mixing behavior can be modulated by changing the droplet injection characteristics. Finally, the simulations of a droplet laden swirling jet revealed that the dynamics of large scale structures was strongly affected by the amount of swirl imparted to the incoming flow, and that the effects of two way momentum coupling on jet dynamics and mixing were markedly different for nonswirling and swirling jets.