A Level-Set based Simulation Tool for Rapid Characterization of Combustion-Instability

This work presents the efforts of the development of a numerical framework for the study of combustion instability. A level-set solver serves as the core of this framework, which solves the G-equation in order to describe the flame dynamics and behaviors under the impact of acoustic perturbations. Theoretical models are employed to delineate the acoustics propagation, reflection, and transmission along the outflow nozzle and combustion injection systems. The level-set solver is coupled with the theoretical models through carefully prescribed boundary conditions. The developed framework is validated in several canonical test problems, and then applied to a study of rocket-type combustion configuration. A parametric study is performed in particular to understand the effects of flame-shape, injection-system impedance, and nozzle operation conditions on the thermoacoustic behaviors. This numerical tool established from this work is expected to be effectively used to enable fast and basic characterization of combustion instability in realistic systems.