Abstract
Effects of swirl number on flame tip oscillation of a Bunsen type premixed flame with burner rotation are experimentally investigated. The flame tip oscillation frequency v remains unchanged as the Swirl number S is bellow 0.11, and decreases with increasing S for S>0.11. This suggests that the effect of burner rotation on the flame tip oscillation frequency becomes significant as S exceeds 0.11. When S=0, value of St^<*2>/Ri almost coincides with an empirical correlation (St^<*2>/Ri=0.00028Re^<*2/3>, here, St^*, Rt, and Re^* are, the Strouhal number normalized by the heat release ratio, the Richardson number, and the Reynolds number normalized by the heat release ratio, respectively) proposed by Kostiuk and Cheng. As S is further increased, the gradient of the relationship between St^<*2>/Ri and Re^<*2/3> decreases and finally becomes flat as S exceeds around unity. These results indicate that the Swirl number plays an important role in determining the flame tip oscillation frequency as well as the Reynolds number.
