Physical Mechanisms of a Lifted NonPremixed Flame Stabilized in an Acoustic Field

摘要: Main acoustic effects on a nonpremixed lifted flame in the hysteresis zone are analyzed by means of high speed tomography and LDA techniques. A burner with convergent profiled tube is designed to obtain jet organized eddy structures, even no excitation. chart summarizes different responses sine-shaped forcing. Depending ranges amplitudes frequencies, acoustics either can prevent reattachment enhance combustion, or weaken stability (large fluctuations liftoff height and/or reattachment). In all cases, behavior driven organization vortices, which differs from one case another: Without low excitation, streamwise vortices due secondary instabilities paramount importance stabilization flame; for amplitudes, it rather oscillating column that acts flame.