Effect of flame interaction on swirl-stabilized mesoscale burner array performance

Individual flames in a swirl-stabilized mesoscale burner array can interact with neighboring flames for optimum burner array operation, particularly at lean equivalence ratios. Understanding these interactions are therefore critical for optimizing the mesoscale burner array. This study probes the effect of burner performance and stability based on experimental data of two burner array configurations (dense and sparse) under steady and acoustic perturbation conditions. First, the dense lean blow off equivalence ratios and flame temperatures were examined. The dense burner array lean blow off limits were 8.8 % lower than the sparse burner array. Maximum flame temperature of the dense burner array was 56.4 K higher compared to its sparse counterpart at the equivalence ratio of 0.65. Second, various flame structures from both mesoscale burner arrays were visualized using OH planar laser induced fluorescence imaging. Results showed that flame structures from the dense mesoscale burner array produced a wider range of stable power outputs. Lastly, proper orthogonal decomposition, phase-averaging, and Rayleigh index-based stability analyses were performed using 10 kHz OH* chemiluminescence imaging. Results showed that the dense mesoscale burner array exhibited better thermal-acoustic damping with smaller heat release fluctuations under acoustic perturbation range from 80 to 270 Hz compared to the sparse mesoscale burner array.