Effect of boundary conditions on downstream vorticity from counter-rotating swirlers

Abstract

Particle image velocimetry (PIV) is utilized to measure the non-reacting flow field in a reflow combustor with multiple and single swirlers. The velocity field, vortex structure and total vorticity levels are experimentally obtained using two different boundary conditions, representing a single confined swirler and multiple swirlers in an annular combustor. The influence of the boundary conditions on the flow field at several locations downstream of the swirlers is experimentally investigated, showing that the central vortex in the multi-swirler case is more concentrated than in the single-swirler case. The vorticity of the central vortex and average cross-sectional vorticity are relatively low at the swirler outlet in both cases. Both of these statistics gradually increase to the maximum values near 20 mm downstream of the swirler outlet, and subsequently decrease. It is also found that the central vortex in the multi-swirler case is consistently greater than the single-swirler case. These results demonstrate the critical influence of boundary conditions on flow characteristic of swirling flow, providing insight into the difference of the experiments on testbed combustor and the full-scale annular combustors. ª 2015 Production and hosting by Elsevier Ltd. on behalf of CSAA & BUAA.

The Effects of Strong-Weak Swirling Interaction on Emissions in a Multi-Nozzle Combustor

“…As a result, the flame structures and flow fields of multi-nozzle combustors are significantly different from that of the single nozzle combustors [2][3][4][5][6]. Zhang et al [7] conducted a PIV experimental study on the vorticity variation of single-nozzle and three-nozzle combustors, and the results showed that the vorticity of the center nozzle was obviously stronger than that of the single nozzle due to the change of boundary conditions. Villalva et al [8] conducted a study on a multi-nozzle combustor and results showed that the interaction between nozzles could improve combustion stability and reduce emissions.…”