MODELLING THE COMBUSTION CHAMBER OF AN ALUMINIUM CASTING FURNACE: A METHODOLOGY

Abstract

Mathematical modelling of the phenomena occurring in a combustion chamber is a very difficult task. Recently, computational methods have been developed allowing the simulation of all the processes involved in a more elaborate and reliable manner than ever before. These methods however often present weaknesses originating from their lack of gener- ality and prohibitive computation time. Our aim was to come up with a technique that could be applied to rectangular furnaces of any size and characteristics, and that would require a reasonable computation time. The technique is based on combining the PHOENICS code (used for velocity and combustion fields) with a new radiation method, the so-called imaginary planes method. Results are presented for an aluminium melter/holder furnace. Comparison between the imaginary planes method and the zone method illustrates the excellent agree- ment obtained for the radiative transfer. The technique used for the coupling of PHOENICS with the radiative part is explained. Provisions are made to take care of the unsteady state regime often encountered in such furnaces where several different operations are performed in a row. The simulation of a transient operation is presented and it is found that a single determination of the velocity pattern on the basis of a steady state assumption is sufficient to simulate adequately time dependent gas temperature and heat flux distributions.