Study on the coupling mechanism and suppression characteristics of swirl premixing combustion self-excited oscillation

Abstract

The numerical simulation method was used to study the mutual influence of flow field disturbance, vortex change, flame structure change, heat release pulsation, and pressure pulsation on the coupling mechanism and suppression characteristics of self-excited oscillations. The results indicate that perturbations from the jet have a direct impact on the structure of the flame and the alteration of the vortex. Vortex changes have a direct impact on heat release and flame structure. Changes in flame structure can cause pulsations in heat release. Oscillatory combustion is caused by the coupling of multiple factors, including heat release pulsations, flow field perturbations, acoustic vibrations, vortex variations, and flame variations. Pressure pulsations can be suppressed by a circumferentially arranged jet. The optimal solution for suppressing pressure pulsations can be achieved by adjusting the optimal jet angle (φ) and jet rotation direction. Adjusting the value of |φ| can solve the problems of poor local ΔPmax suppression caused by upstream swirled interference and the narrow range of downstream influence of the jet, at |φ| = 10°, the suppression effect is more pronounced in the counter-rotating direction than in the forward-rotating direction.

Keywords

• Self-excited oscillation
• Q-criterion
• Multi-field coupling
• Oscillation suppression