Numerical simulation of self-excited combustion oscillations in a non-premixed burner

Self-excited combustion oscillations or instabilities in combustion chambers are generated by periodical and feedback interactions between flow, acoustics, and the heat released by combustion, As a consequence, pressure pulsation with high amplitudes may arise, leading to substantial noise and, sometimes, to mechanical and/or thermal damage for the combustion system concerned. Self-excited oscillations in a nonpremixed burner were numerically simulated, based exclusively on the unsteady conservation equations of fluid dynamics and simple models for combustion and turbulence. The equations were solved by means of a commercially available CFD (Computational Fluid Dynamics) code, which uses a control volume based finite difference method, In the simulation. self-excited amplitude growth, limit cycle, and acoustic eigen-modes, as well as the interaction between acoustics and flow and the periodic heat release rate of the flame. are obtained.