Low-frequency combustion instabilities were studied experimentally in a model lean-premixed stepped combustor. The PLIF technique was used to characterize the flame structure. The PIV technique, associated with high-speed visualization of the OH* radical chemiluminescences emission, allowed to investigate the flow field during the quasi-periodic unsteady flashback when the flame lifted from the edge of the step and moved periodically in and out of the premixing duct. Results strongly suggest that impact of acoustic waves on the flame structure 首ld be taken into account when applying LES approach to industrial gas turbines. 德國LaVision PIV/PLIF粒子成像測速場儀 Imager SX PIV相機(jī) 用于粒子成像測速(PIV)的熒光示蹤粒子