정상초음파가 개재하는 예혼합화염의 전파특성 고찰

Abstract

An experimental study has been conducted to investigate the effects of an ultrasonic standing wave on the combustion efficiency of premixed flame at various equivalence ratios in half-open chamber. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in unprecedent detail throughout the post-processing analysis. The flame fronts affected by the standing wave are clearly distorted. Also, vertical locations of the wave-affected frontal distortions do not vary appreciably, unless the propagating-mode characteristics (pressure amplitude and driving frequency) of ultrasonic standing wave were not changed. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancements of combustion reaction and flame propagation velocity. Effects of the standing wave on the flame velocity decreases as the equivalence ratio approaches 1.14. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratio.