A Comparison of Rate-Controlled Constrained-Equilibrium Formulations

In this study, constraint potential and constraint forms of the Rate-Controlled Constrained-Equilibrium (RCCE) method have been investigated in terms of accuracy and performance. Although the two formulations are equivalent mathematically, they show quite different performances from the computational standpoint. The main objective of this work is to determine the most efficient implementation of RCCE to be used in turbulent combustion simulations. Simulations are conducted of an adiabatic, isobaric stirred reactor. The kinetics includes methane oxygen combustion using 133 reaction steps and 29 species. RCCE calculations are performed by 12 constraints. The simulations are carried out over a wide range of initial temperatures for stoichiometric gas mixtures. Performance studies of the two RCCE formulations are carried out and the results are compared with those obtained by direct integration of detailed kinetics.