The “On–Off–On” flame formed in the acoustic standing wave field

We, herein, reported the discrete flame with the “On–Off–On” structure in the standing wave field. It was found that this phenomenon was caused by the acoustic radiation force generated by the nonlinear effect of a high-intensity acoustic field. Furthermore, the simulation showed acoustic streaming driven by acoustic radiation force was balanced with flame propagation at the edge of the acoustic field. Meanwhile, the fuel jet was less hindered by the radial direction because of its large density. In addition, it had enough initial velocity so it could continuously supply fuel to the suspension section through the acoustic field to maintain combustion. Thus, there was a positive correlation between the length of the discrete flame and the intensity of the acoustic field. This work presented a new method of discrete flame control, which may have industrial importance.