Chemical Modeling for Large-Eddy Simulation of Turbulent Combustion

摘要

In the present project the focus was on developing advanced combustion models for large-eddy simulations (LES) and to develop automatic chemistry reduction techniques and reduced chemical mechanisms for JP-8 surrogate fuels. The aim of the combustion LES modeling part was to advance the models for non-premixed and premixed combustion towards a generalized combustion model that covers all combustion regimes. Towards this end, for the premixed regime, a dynamic model for the turbulent burning velocity was developed, which eliminates adjustable coefficients from the premixed combustion model, and a flame structure model was presented, which considers local broadening of the flame preheat zone. Further, based on asymptotic arguments, a formalism to identify the correct combustion regime was developed, which will be an important element in a future generalized combustion-regime independent combustion model. In the second part of the project, several advancements led to a fully automatic chemistry reduction method. New developments include a refined DRGEP method for species and reaction elimination, a chemical lumping procedure, and an automatic procedure for selecting steady state species. Further, several potential surrogate fuel components have been included in the component library, and a reduced JP-8 surrogate mechanism was constructed and tested with experimental data.