Flow stability and complex network analysis in a swirl combustor with dump and slope confinement

Ziyu Qin, Yuzhen Lin, Heng Song and Xiao Han

Energy, 2025, vol. 325, issue C

Abstract: The lean-premixed swirl combustor with slope confinement (SC) exhibits significant potential in attenuating thermoacoustic instability compared with traditional dump confinement (DC). In this study, we scrutinize the stability origin from the perspectives of flow stability and complex network analysis. First, the dominant temporal and absolute growth rates of SC are respectively reduced by 68.0% and 86.6% compared to DC. These reductions quantitatively demonstrate the superior capability of SC in suppressing temporal and absolute instability. Then, we propose a backflow ratio to distinguish the absolute instabilities in two cases. The stability enhancement in SC is characterized by a backflow ratio less than a critical value of 2, which stems from a less pronounced flow recirculation through eliminating the corner flow. Additionally, the flow complex network changes from a dual-ring structure in the DC case to a straight-chain structure in the SC case. The weighted closeness centrality measurement implies that the corner recirculation zone (CRZ) is responsible for self-excited flow oscillation. The network without CRZ features more difficult disturbance propagation, which is further conducive to mitigating instability.

Keywords: Swirl combustor; Thermoacoustic instability; Flow instability; Complex network (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:325:y:2025:i:c:s0360544225016123

DOI: 10.1016/j.energy.2025.135970

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