抄録
Lift-off height and flame curvature of a triple flame formed with methane-air and propane-air mixture are investigated experimentally in various fuel concentration gradients and sound pressures. Burning velocity of the triple flame has strong correlation with fuel concentration gradient, and lift-off height is determined by balanced position between the burning velocity and unburned gas velocity just ahead of the leading edge of triple flame. Therefore, to investigate the influence of acoustic oscillation on fuel concentration gradient, multi slot burner which can make mixing layer with uniform distribution of streamwise flow velocity is employed. Fuel concentration gradient is calculated by numerical simulation in various sound pressures. The lift-off height decreases and the flame curvature is slightly changed by increase in sound pressure. It is thought that the acoustic oscillations change the fuel concentration gradient and flame moves to upstream where the fuel concentration gradient is steep originally without sound. The flame curvature slightly changes by sound, whereas it is thought that the influence of change in the flame curvature by acoustic oscillation does not dominate the change in the lift-off height.
