Multicomponent-fuel film-vaporization model for multidimensional computations

A multicomponent-fuel film-vaporization model is developed to be used in multidimensional spray and combustion computations. For the gas phase the vaporization rate was evaluated using the turbulent boundary-layer assumption and the Prandtl mixing-length theory. A third-order polynomial was used to model the temperature and species concentration profiles within the liquid film in order to predict accurate surface temperature and surface mass fractions, which are crucial to evaluating the species vaporization rates. By this approach the governing equations for the film were reduced to a set of ordinary differential equations. The new model offers a significant reduction in computational cost and sufficient accuracy compared to solving the governing equations for the film directly. The new model was verified against exact numerical solutions with excellent agreement for several cases concerning the vaporization process of a film on a flat plate. The results were also compared with the solutions obtained using an infinite-diffusion model. The new model predicted the vaporization history more accurately than the infinite-diffusion model. Finally, the new model was applied to study the film evolution for a spray/wall impingement case, and physical insight was gained from the study.