Flame synchronization and flow field analysis of double candles

Abstract

Abstract Flame instability is an interesting topic in combustion science, and it is also of great practical significance for designing high-performance burners. In recent years, the synchronization phenomenon caused by a pair of coupled candles has aroused widespread attention, among which in-phase and anti-phase are two notable examples. In order to understand the flow structure of the flashing flame and the reasons for the synchronization of the flame oscillator, COMSOL flow field analysis technology and MATLAB grey analysis technology were used to analyze the flow field of candles in three combustion states and the change of candle combustion state respectively. By analyzing the flow structure of flashing flame, the reasons of different burning states of candles are explained. Moreover, the experimental and numerical simulation results show that the in-phase mode is characterized by the symmetrical formation of vortex concerning the centerline of two groups of flames, and the flames are vertically stretched under the vortex action. The characteristic of the anti-phase mode is that the vortex alternately forms asymmetrically concerning the centerline of two groups of flames, and the non-uniformity and asymmetry of the vortex lead to the instability of the flame surface. The characteristic of the incoherent mode is that the vortices generated by the two candle groups no longer act on each other, and the airflow field between the two candle groups remains approximately unchanged.