Manifold-based Modeling for Supersonic Turbulent Combustion

A methodology to incorporate high-speed compressibility effects into manifold-based models for supersonic turbulent combustion simulations is presented. The methodology jointly evaluates the simulation equation-of-state (EOS) and the manifold equations to ensure consistency of the thermodynamic state. In practice, the algorithm iteratively adjusts manifold inputs (fuel/oxidizer temperature and pressure) to reflect the non-negligible variations in thermodynamic state (expressed in terms of density and energy in the simulation), and is significantly more accurate (by over a factor of 10) than existing methods that only partially couple the EOS and the manifold, as demonstrated using data from high-speed nonpremixed-flame simulations. The validity of key modeling assumptions, notably a presumed relationship between enthalpy and mixture fraction, is critically assessed in the context of strong compressibility effects, such as shock-flame interactions, to provide potential model improvements.