Response of Triple Flame to Acoustic Oscillations

Abstract

The flame curvature and the lift-off height of a triple flame under acoustic oscillations are investigated. The multi-slot burner, which can make uniform streamwise flow velocity and stabilize the triple flame two-dimensionally is employed. The triple flame is formed at the anti-node of velocity oscillations. The flame curvature and the lift-off height of the triple flame are measured from images that are taken by a high speed camera. The fuel concentration gradient of the mixing layer which flows into the flame surface with acoustic oscillations is calculated by using the model of the meandering mixing layer. As a result, the flame curvature changes periodically and its period of change corresponds with that of acoustic oscillations approximately. When the triple flame moves in the direction of the air flow, the flame curvature increases. When the triple flame moves in the direction of the mixture flow, the flame curvature decreases. It is estimated that the fuel concentration gradient changes in the half-period of acoustic oscillations. However, the flame curvature changes in the same period of acoustic oscillations.

Soot control of laminar jet-diffusion lifted flame excited by high-frequency acoustic oscillation

“…The stability of the flame base is improved by changing the concentration gradient of the unburned mixture ahead of the flame using ultrasonic waves. In the present study, when the lifted flame height is low, the initial concentration gradient is not as large as in the previous study (Sugiu, et al, 2016). Thus the effect of sound did not appear clearly, and stability was not improved.…”

“…This work was supported by Grant-in-Aid for Young Scientists B (23760171), 2011-2013, and Scientific Research C (25420143), 2013-2016 from the Japan Science and Technology Agency (JST), and by an ISIJ Research Promotion Grant (incl. Ishihara/Asada Grant), 2010-2012.…”