Numerical Modeling and Study of Vaporization of Single Droplet and Mono-dispersed Spray Under Mixed Convection Conditions

Abstract

An approach to account for combined convection during droplet evaporation and study of pure component droplets and mono-dispersed sprays is presented. The classical gas-phase and infinite conductivity liquid-phase model are extended, with the use of an effective Reynolds number, to conflate the combined effects of forced and natural convection. The current model, after validation with experimental and numerical data using an independent code, is incorporated into a commercial CFD software, ANSYS Fluent, via user-defined functions with the Eulerian–Lagrangian numerical scheme. A validation study is carried out by comparing with available experimental, numerical, and analytical data on pure component droplets and a mono-dispersed spray, respectively, for without and with droplet dynamics. The results are shown in terms of mass fraction, droplet velocity, droplet diameter square, and droplet temperature. The validation shows reasonably good match between the present numerical data and experimental and analytical data, respectively, for initial Red/Grd 0.09, 2.12, and 60 evaporating droplets/sprays. It is concluded that the biofuels, for example, ethanol with a lower latent heat of vaporization, burn much like mono-component droplets and the blowing effect can be important in their modeling in the spray combustion.