Assessment of Rate-Controlled Constrained-Equilibrium Method for Implementation of Detailed Kinetics in Turbulent Combustion Simulations

摘要

The Rate-Controlled Constrained-Equilibrium (RCCE) method is applied to represent comprehensive chemical kinetics in combustion calculations. In RCCE, the total number of rate equations is smaller than the number of species included in the detailed kinetics model but the concentration of all species are predicted. This methodology is a logical extension of classical thermodynamics and is based on the maximization of entropy subject to the instantaneous values of constraints. In this work, the RCCE method is implemented and its performance is investigated. The accuracy of the method is demonstrated in a perfectly stirred reactor involving kinetics of hydrogen/oxygen (with 9 species and 22 reactions) and methane/oxygen (with 29 species and 133 reactions). The results show excellent agreement with those obtained by direct integration of the same kinetics. The method is further applied to predict oxidation of methane in a constant pressure partially stirred reactor, in which mixing frequency is varied to study the effect of mixing on combustion. RCCE calculations are carried out using 12 constraints and 133 reactions over a wide range of initial temperatures and equivalence ratios. It is demonstrated that, with the set of constraints chosen, RCCE accurately represents the methane oxidation kinetics. Results obtained demonstrate the predictive capability of RCCE for incorporation in actual turbulent combustion simulations.