A method for optimizing reaction progress variable and its application

Abstract

This paper presents a practical method for optimizing reaction progress variables for FPV models, and the potential of this method is demonstrated in the application of a scramjet model combustor simulation. Reaction progress variable is commonly employed in flamelet-based models as a reaction tracker, while it is normally given with less verifications. Focusing on the global reaction process, this optimization method is proposed with respect to the constraint of monotonicity and the target of the heat release rate, using a hybrid PSO/GA algorithm to quickly give the weighting factors. Consequently, the optimized progress variable together with another three progress variable expressions are utilized and compared in the simulations of a supersonic combustor with vaporized RP-3 injection upstream of dual parallel cavities. Noting that, a pressure-related FPV model is presented and adopted here to consider the effect of pressure pulsations in the combustion flow field. It is shown that the progress variables appear to be specifically coupled with the heat release process and the extent of reaction proceeding, thus affecting the temperature, pressure, and components. Significant improvements brought by the optimized progress variable over the conventional expressions are presented, and it is noteworthy that this method is also applicable to the original FPV model.