A partially stirred reactor model for turbulent combustion closure using detailed chemical time scales

The closure of the reaction term in modeling turbulent combustion systems is crucial when dealing with the Reynolds-averaged Navier-Stokes (RANS) approaches. The partially-stirred reactor model (PaSR), that explicitly includes the characteristic chemical time of the system in the expression of the mean reactive term is one of the most commonly used approaches in the description of turbulence-chemistry interaction. The model showed limitations in predicting some key phenomena, such as Nitrogen Oxides (NOx), which have distinct characteristic time scales compared to that of the main combustion process. The present study proposes a refined PaSR model with incorporating detailed chemical time scales in the description of the reaction source term closure. A stochastic reactor is used as a representation of the target turbulent combustion system and its results are compared with data given by a perfectly stirred reactor whose reactive term is modeled according to the proposed formulation of PaSR. The model is tested with reaction schemes describing different common kinetic pathways. Overall, good agreement is found between PaSR and the stochastic reactor.