Experimental and numerical study of the effect of main stage stratifier length on lean blow

The lean blow-out performance of the pilot flame in a stratified partially premixed injector is studied in this work considering the influence of the main stage stratifier length. Particle image velocimetry and kerosene planar laser-induced fluorescence experiments at nonreacting conditions were carried out to give an explanation of the combustion performance. The evolutions of spray and velocity in space are discussed in detail to find out the inherent correlations of combustion stability, spray distribution, and flow structures. Moreover, special attentions are paid to the variation of primary recirculation zone with the increase of the stratifier length and its driving factors. Specifically, by lengthening the stratifier of the main stage, the primary recirculation zone is enlarged both axially and radially, and this creates an advantageous flow topology for the anchoring of the pilot flame. Finally, the dominating mechanisms for the primary recirculation zone that are responsible for the alteration of the primary recirculation zone size are pointed out with the assistance of computational fluid dynamics