Velocity Profile of Bifurcating Jet inside Diffusion Flame under Acoustic Excitation

Abstract

Measurement of velocity profile of a fuel jet bifurcating inside a diffusion flame under acoustic excitation is conducted by means of particle tracking velocimetry. It is confirmed prior to the detailed examination that the addition of particles to the fuel gas has negligible effect on the behavior of the jet, and that the measured velocity by this method is reasonably accurate. The results indicate that the velocity profile is not altered by the acoustic forcing in the region in which shadowgraphy shows the jet going straight before meandering. This infers that the bifurcating behavior is originated from not the effect of steady streaming but that of linear instability. On the other hand, the velocity profile oscillates synchronically with the acoustic forcing in the region in which the shadowgraphy shows the jet meandering. A qualitative explanation of the bifurcation of the jet is successfully obtained by considering the probability density distribution of the oscillating fuel jet based on the interpretation of the experimental results.