Structure of a reacting flow of a turbulent swirling jet during combustion of a syngas-air mixture

The paper presents the results of an experimental study of the flow structure and features of combustion in a turbulent swirling lean pre-mixed syngas flame using modern planar optical laser-based methods. The measurement of the instantaneous velocity field was carried out using the particle image velocimetry (PIV), and location of the OH radicals in the jet were determined by the method of laser-induced fluorescence (PLIF). A comparison of the averaged flow characteristics of a high-swirl flame with an equivalence ratio Phi = 0.45 for syngas and Phi = 0.7 for methane are performed. Presence of a recirculation zone in the jet core is typical of both cases, however, the size of the central recirculation zone for the methane flame are approximately 1.5 times larger than that for the synthesis gas flame in both dimensions. The average distributions of the intensity of fluorescence signal of the OH radical shows a good coincidence of the position of the flame front in both cases, and lower fluorescence signal intensity for the synthesis gas flame.