Effect of combustion of propane-air mixture in a weakly and strongly swirling jet was studied. The rate of swirl was classified in terms of the absence / presence of a stable recirculation zone in the non-reacting jet flow. Sequences of the instantaneous velocity fields were measured in lean and rich flames at atmospheric pressure, and also in the non-reacting flow, by using a high-repetition stereoscopic particle image velocimetry system. Spatial distributions of the time-averaged velocity and Reynolds stresses, calculated from the sequences, revealed that combustion of rich mixture dramatically affected structure of flow and type of vortex breakdown
Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow