Application of the first combustion model to spray combustion

Liquid fuel is of interest to apply to gas turbines. The large advantage is that liquids are easily storable as compared to gaseous fuels. Disadvantage is that liquid fuel has to be sprayed, vaporized and mixed with air. Combustion occurs at some stage of mixing and ignition. Depending on the efficiency and design of these processes the combustor performs better or worse with a view to emission of nitric oxides, unburnt hydrocarbons or soot. In this project the design of gas turbines is investigated with improved efficiency by steam injection. The spectrum of phenomena is described by models for the chemistry, flow and heat transfer. The turbulent combustion process is to be predicted by numerical simulation. This article discusses the possibilities to use the FIRST combustion model for spray combustion. This model determines the complicated chemistry by the use of reaction progress variables. In fact a very complicated chemical system is mapped on these variables via a thermo chemical database. Results of simulations are presented for a first draft model. For completely pre-vaporised, but still mixing, combustible mixtures, no evaporation effects are taken into account when combustion occurs. If pre-vaporisation is only partial, evaporation and mixing effects play an important role during combustion and will have to be taken into account.