Numerical Investigation of Combustion Dynamics in a Multi-element Combustor Using Flamelet Approach

This paper investigates combustion dynamics in a complex multi-injector element combustor using a flamelet approach in a large eddy simulation (LES) framework. The capability of computationally less expensive chemistry tabulation method to capture the interaction between unsteady heat release and acoustics is investigated. A non-adiabatic steady flamelet-based tabulated chemistry closure is invoked to simulate hydrogen–oxygen reactions in mixture fraction space. The model incorporates flow-induced non-equilibrium flame effects through scalar dissipation rate and the turbulence-chemistry interaction using a probability density function (PDF). A multi-element combustor dynamic study captures the first tangential mode close to 4000 Hz and corresponding high-frequency harmonics appropriately. Spectral analysis of the pressure variation displays similar frequency features in chamber and injector sections, suggesting the possibility of injector-chamber coupling. The coupling of the transverse pressure waves in the combustion chamber with the longitudinal pressure oscillations in the oxidizer post was probed as the reason for the pressure dynamics observed in the combustor.