Synchronization of dual diffusion flame in co-flow

Abstract

In this study, the interaction of two adjacent diffusion flames (dual flame) were experimentally investigated using the direct imaging method and particle image velocimetry (PIV) measurements for varied distances between the two flames under the influence of the co-flow. The direct imaging method indicates the presence of various synchronization modes, such as merging, in-phase synchronization, amplitude death, anti-phase synchronization, and desynchronization, as the distance between the flames was increased. The dual flame synchronization was characterized using an image analysis of the time-series variation of flame heights summarized by the mean flame height, root-mean-square of the flame height, Strouhal number, and the cross-correlation coefficient of flame heights against the burner distance. Furthermore, the unsteady velocity fields of the synchronized flames were measured using PIV combined with the proper orthogonal decomposition (POD) analysis to extract the flow structure of the dual flame. The experimental results indicated that the in-phase mode is characterized by the formation of symmetrical vortices, whereas the anti-phase mode features the formation of asymmetrical vortices inside and outside of the flame. The POD analysis demonstrated higher fluctuating energy in the anti-phase mode than in the in-phase mode, which suggested the formation of a highly organized flame structure in the anti-phase mode.