中心分级旋流火焰中热声不稳定分岔现象研究

Thermoacoustic instability of methane flames was experimentally investigated in atmospheric conditions in a centrally-staged swirl burner, mainly focusing on the bifurcation occurring with the variation of the equivalence ratio. It is observed that with the increase of global equivalence ratio, bifurcation occurred twice to the thermoacoustic system, and thus the stability regimes of the thermoacoustic system can be classified into three types: quiet, moderate instability, and strong instability. In the latter two unstable regimes, obvious thermoacoustic instability can be observed, which means that limit cycle oscillations had occurred according to the results from the phase space reconstruction. Besides, the flame dynamics and thermoacoustic coupling mechanism in the two unstable regimes were compared based on the flame images captured by a high-speed camera.