Large-Eddy Simulations of Unsteady Reaction Flow Characteristics Using Four Geometrical Combustor Models

Abstract

Combustion instability constitutes the primary loss source of combustion chambers, gas turbines, and aero engines, and it affects combustion performance or results in a sudden local oscillation. Therefore, this study investigated the factors affecting flame fluctuation on unsteady combustion flow fields through large-eddy simulations. The effects of primary and secondary holes in a triple swirler staged combustor on flame propagation and pressure fluctuation in a combustion field were studied. Moreover, the energy oscillations and dominant frequencies in the combustion field were obtained using the power spectral density technique. The results revealed a variation in the vortex structure and Kelvin–Helmholtz instability in the combustion field, along with a variation in the pressure pulsation during flame propagation under the influence of the primary and secondary hole structures. Additionally, the spatial distributions of pressure oscillation and heat release rate amplitude were obtained, revealing that the foregoing increased owing to the primary and secondary holes in the combustion field, reaching a peak in the shear layer and vortex structure regions.