Multi-Fidelity Framework for Modeling Combustion Instability
AFRL/RQR Edwards AFB United States
Pagination or Media Count:
A multi-fidelity framework for combustion instability modeling is established by integrating a reduced order model ROM for combustion response into the linearized Euler equations. The ROM is developed from CFD simulations of periodic forcing on a reduced domain using Galerkins method to reduce the high-order PDEs to a lower-order ODE system via POD eigen-bases generated from the reduced-domain dataset. Evaluations of the framework are performed based on simplified test problems for a model rocket combustor showing distinguishable instability behaviors. The coupling between the ROM and the Euler equations requires two-way information transfer between the two systems. Results show that the fraction of the complete domain represented by the ROM can be chosen to simplify the interaction between the two levels of solution. The multi-fidelity model is capable of capturing the overall instability trends although some discrepancies due to unstable generic responses arising from the reduced-domain simulations.