Multi-Dimensional Modeling of Fuel Films and Spray-Wall Interactions Resulting from Impinging Sprays

The focus of this work is to formulate and validate a multi-dimensional, fuel film model to help account for the fuel distribution during combustion in internal combustion engines. Spray-wall interaction and spray-film interaction are also incorporated into the model. The fuel film model simulates thin fuel film flow on solid surfaces of arbitrary configuration. This is achieved by solving the continuity, momentum, and energy equations for the two dimensional film that flows over a three dimensional surface. The major physical processes considered in the model include mass and momentum contributions to the film due to spray drop impingement, splashing effects, various shear forces, piston acceleration, dynamic pressure effects, gravity driven flow, conduction, and convective heat and mass transfer. In order to adequately represent the drop interaction process, impingement regimes and post-impingement behavior have been modeled using experimental data and mass, momentum and energy conservation constraints. The regimes modeled for spray-film interaction are stick, rebound, spread, and splash. In addition, modified wall functions for evaporating, wavy films are provided and tested. Multicomponent fuel behavior is incorporated in the spray as well as the fuel film. The fuel film model is validated through a series of comparisons to experimental data for secondary droplet velocities, secondary droplet sizes, spray radius, spray height, film thickness, film spreading radius, and percent of fuel adhered to the surface.