Experimental Studies on Acoustic Oscillation Angles and Positions on Soot Suppression from Acetylene Laminar Diffusion Flames

In this study, the relation of acoustic oscillation angles (the angle between the acoustic oscillation direction and horizontal axis) and positions (the acoustic oscillation applied to the top, average, and bottom regions of the flame) with the soot suppression efficiency was investigated for acetylene laminar diffusion flames. The soot suppression efficiency depends on acoustic oscillation angles. With an increase in the flow rate, the angle required for optimum soot suppression increased. At the flow rate of 50 mL/min, the acoustic oscillation angle required for the optimum suppression efficiency was 0°. The angle increased to 15° when the flow rate increased to 70 mL/min. Further increase in the flow rate to 90 mL/min leads to an increase in the angle to 30°. Moreover, acoustic oscillation positions affect the soot suppression efficiency. When the acoustic oscillation acts on the top region of the flame,the effect of soot suppression is substantial. The top region of the flame is the soot oxidation zone. The bottom and average regions of the flame are soot formation and growth zones, respectively. The application of acoustic oscillations on the soot oxidation zone can effectively increase the soot oxidation reaction rate. Furthermore, when the acoustic oscillation is applied to the top region of the flame, the flame temperature is higher than that when theacoustic oscillation is applied to the average and bottom regions of the flame.