レーザシート法による噴流拡散火炎の基部構造の解明 : 第2報, スピーカ加振による火炎安定化のメカニズム  [in Japanese] Investigation of the Near-field Structure of Jet Diffusion Flames by the Laser Sheet Method : 2nd Report, Mechanism of Flame Stabilization by Speaker Excitation  [in Japanese]

The near-field structure of jet diffusion flames excited by a speaker has been investigated to make clear the mechanism of flame stabilization obtained by the excitation. Vortices in flames induced by the excitation were visualized using laser sheet method. The acoustic excitation lifts flames off under the stretch of large scale vortices, but the higher frequency excitation leads reattachment of lifted flames. This phenomenon has been reproduced by the numerical approach under the axisymmetric assumption. Consequently, the vortex push mechanism of flame propagation caused by small-scale vortex rings has been clarified. Moreover, the laser sheet visualization unveiled azimuthal structures attributed to streamwise vortices. Roles of baloclinic torque and pressure pushes related to the azimuthal structure have been also discussed.