1998-02-23

Development of a Three Dimensional Model of Wall Fuel Liquid Film for Internal Combustion Engines 980133

To simulate the air-fuel mixing in the intake ports and cylinders of internal combustion engines, a fuel liquid film model is developed for integration in 3D CFD codes. Phenomena taken into account include wall film formation by an impinging spray, film transport such as governed by mass and momentum equations with wall and air flow interactions and evaporation considering energy and convection mass transfer equations.
A continuous-fluid method is used to describe the wall film over a three dimensional complex surface. The basic approximation is that of a laminar incompressible boundary layer; the liquid film equations are written in an integral form and solved by a first-order ALE finite volume scheme; the equation system is closed without coefficient fitting requirements.
The model has been implemented in a Multi-Block version of KIVA 2 (KMB) and tested against problems having theoretical solutions. Then, it has been compared to measurements obtained in a cylindrical pipe fitted with an injector and reproducing the main characteristics of engine intake pipe flow of port injected SI engines. The film thickness, such as measured by a LIF technique, is satisfactorily reproduced by the computations for a set of operating conditions.
Finally, engine calculations were conducted showing the importance of including a liquid film model for the simulations.

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