Response Behavior of Inverse Diffusion Flame to Low Frequency Acoustic Field

Conducting the investigation of flame dynamics perturbed by acoustic waves had guiding significance for flame extinguishing technology. In this paper, the behavior of inverse diffusion flame under the influence of 200–300 Hz sound waves was reported for the first time. Detailed analysis of the entire process of flame from steady state to extinction, including flame structure, periodic characteristics, temperature and KL factor distribution. The relationship between flame morphology parameters and acoustic parameters was established through dimensionless analysis. In addition, the flame extinguishing performance of sound waves in this frequency band was measured and analyzed. The results indicated that the flame could still maintain the typical inverse diffusion flame shape under low sound pressure, and the pulsation frequency was stable. However, when the sound pressure rose to a certain level, the flame began to pulsation in a disorderly manner. In addition, with the increase of sound pressure, the flame morphology would undergo significant changes, and the temperature and KL factor showed a trend of first increasing and then decreasing. The mechanism of sound wave suppression of flames was related to the unsteady flow generated by sound waves. Through dimensionless analysis, it was found that the intensity of this disturbance was directly proportional to the arithmetic square root of sound pressure and inversely proportional to frequency.