Experimental and numerical investigation of non-reaction flow characteristics in a concentric staged dual-swirl combustor

In order to deeply understand the complex swirling flow characteristics of the typical staged and zoned combustor, particle image velocimetry measurement and large eddy simulation were used to study the steady and instantaneous flow field. The results show that an obviously central recirculation zone (CTRZ) cannot be formed by the single pilot stage swirler. When a main stage swirler with strong swirling flow is added, a large CTRZ appears in the concentric staged dual-swirl combustor. The CTRZ size in the co-rotating combustor is obviously larger than that in the counter-rotating combustor. The development process of the CTRZ is divided into three stages: P, P-M and M. The stages P and M are mainly dominated by the pilot stage and main stage swirling air, respectively. In addition, it can be seen from the instantaneous flow field that there is a single spiral precessing vortex core in the co-rotating and counter-rotating combustor.