프로판/공기 예혼합화염의 전파특성에 대한 정상초음파의 간섭효과

Abstract

An investigation into the influence of ultrasonic standing wave on the dynamic behavior of premixed propane/air flame propagating in half-open horizontal duct has been made at various equivalence ratios to get a clue to the deterioration of flame stability as well as combustion reaction acceleration. These results may apply to several applications like ramjet, afterburner, gas turbine, and chemical rocket engine for active controlling of the instability which frequently occur in those systems. Visualization technique utilizing the Schlieren photography was employed for the observation of structural variation of the flame reaction zone. The propagating flame was caught by the high-speed Schlieren images, through which local flame velocities of the moving front were analyzed in detail. The images reveal that the flame front distortion and horizontal splitting in burnt zone are made by the ultrasonic standing wave. The vertical locations of distortion and stripe are intimately dependent on the frequency characteristics of ultrasonic standing-wave. Also, the propagation velocity of flame front floored with the standing wave is greater than that without the acoustic excitation caused by the wave. As expected, influence of the ultrasonic standing wave on premixed-flame propagation becomes more prominent as the frequency increases.