High Performance Simulation Tool for Multiphysics Propulsion Using Fidelity-Adaptive Combustion Modeling

The innovation proposed here is a fidelity-adaptive combustion model (FAM) implemented into the Loci-STREAM CFD code for use at NASA for simulation of rocket combustion. This work will result in a high-fidelity, high-performance multiphysics simulation capability to enhance NASA's current simulation capability of unsteady turbulent reacting flows involving cryogenic propellants. This novel FAM model utilizes a combustion submodel assignment, combining flamelet-based combustion models (such as inert-mixing models, equilibrium chemistry, diffusion-flame Flamelet/Progress Variable (FPV) or premixed-flame models) for the computationally efficient characterization of quasi one-dimensional, steady, and equilibrated combustion regimes, with combustion models of higher physical fidelity (such as thickened flame models, reduced/lumped chemistry models) for accurate representation of topologically complex combustion regions (associated with flame-anchoring, autoignition, flame-liftoff, thermoacoustic coupling, and non-equilibrium combustion processes) that are not adequately represented by the current flamelet model in Loci-STREAM. In FAM, the selection of a combustion submodel from a set of models available to a CFD-combustion solver is based on user-specific information about quantities of interest and a local error control. With this information, FAM performs an identification procedure for an optimal combustion submodel assignment from the available combustion models that. This simulation capability will have direct impact on NASA's ability to assess combustion instability of rocket engines.