Simultaneous high-speed SO2 PLIF imaging and stereo-PIV measurements in premixed swirling flame at 20  kHz.
Interactions between flow structures and premixed swirling flame were investigated using simultaneous sulfur dioxide (SO2) planar laser induced fluorescence (PLIF) and stereoscopic particle imaging velocimetry (PIV) with high temporal resolution at 20 kHz. In this work, a premixed swirling flame was operated with methane and air doped with 0.5% (volume fraction) SO2 at ambient pressure under different equivalence ratios (ϕ=0.7-1.2). The results show that global SO2 PLIF signal shows a consistent response to the density ratio with the change of equivalence ratio, making it a good indicator for the high temperature zone and a very useful tool to study the global effect of equivalence ratio. In addition, the three-component flow structure is affected by the varying equivalence ratio and the structure of the inner recirculation zone changes accordingly. The transient results show that the circumferential velocity of some vortices outside the flame zone is inconsistent with that of the main flow and these vortices cause local flame contour curling and shedding. The high temporal resolution measurements provide more details for the study of the evolution of some isolated flame isles.