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<p>To investigate the influence of primary hole structures on the flow characteristics of a high-temperature-rise combustor, this study uses PIV to measure the flow-field structures with three different structures of primary hole under cold-flow and reacting conditions. Proper Orthogonal Decomposition (POD) is subsequently applied to the measured data. The results show that changes in the primary hole structure have a significant impact on the structure of the central recirculation zone, as well as the distribution of local recirculation zones in the primary and intermediate combustion zone. Under cold-flow conditions, the central recirculation zone in the three-hole symmetric configuration (Case-I) is terminated by the primary hole jets, whereas in the four-hole symmetric configuration (Case-III) the recirculation zone extends to the dilution jets. In the staggered configuration (Case-II), the height of the central recirculation zone is approximately 23% greater than that of the symmetric arrangements.&#xa0;Even when both the primary and dilution holes are arranged symmetrically, the flow field exhibits pronounced asymmetry. Under reacting conditions, fuel injection modifies the flow structure on both the top and bottom of the swirler exit, causing local recirculation zones to shrink or even disappear. Except for these local zones, the overall velocity distributions under reacting and cold conditions exhibit similar trends, although the velocity magnitudes in the reacting case are substantially higher, with the axial velocity in the downstream dilution zone increasing by a factor of 3–5 relative to the cold-flow condition. In the symmetric primary hole configurations, the axial velocity on the lower side is approximately 15–20% higher than that on the upper side. Enhancing the shear interaction between jets and mainstream improves the stability of shear vortices. A three-hole symmetric primary hole arrangement proves beneficial for&#xa0;enhancing the large-scale vortex structure in the primary zone, whereas a staggered arrangement promotes the merging of small-scale vortices, exhibiting the highest dominant frequency (5.4&#xa0;Hz) in the first POD mode, with a pronounced coexistence of high- and low-frequency peaks in the higher-order modes.&#xa0;In the four-hole symmetric primary hole arrangement, the dominant vortex evolution occurs mainly in the vicinity of the dilution jets, with its first POD mode showing the lowest dominant frequency (2.85&#xa0;Hz), indicating the most stable shear vortex structure.</p>

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Analysis of Flow Characteristics in High Temperature Rise Combustor Under Different Primary Hole Structures

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Jian Chen,
  • Qingqing Dong

摘要

To investigate the influence of primary hole structures on the flow characteristics of a high-temperature-rise combustor, this study uses PIV to measure the flow-field structures with three different structures of primary hole under cold-flow and reacting conditions. Proper Orthogonal Decomposition (POD) is subsequently applied to the measured data. The results show that changes in the primary hole structure have a significant impact on the structure of the central recirculation zone, as well as the distribution of local recirculation zones in the primary and intermediate combustion zone. Under cold-flow conditions, the central recirculation zone in the three-hole symmetric configuration (Case-I) is terminated by the primary hole jets, whereas in the four-hole symmetric configuration (Case-III) the recirculation zone extends to the dilution jets. In the staggered configuration (Case-II), the height of the central recirculation zone is approximately 23% greater than that of the symmetric arrangements. Even when both the primary and dilution holes are arranged symmetrically, the flow field exhibits pronounced asymmetry. Under reacting conditions, fuel injection modifies the flow structure on both the top and bottom of the swirler exit, causing local recirculation zones to shrink or even disappear. Except for these local zones, the overall velocity distributions under reacting and cold conditions exhibit similar trends, although the velocity magnitudes in the reacting case are substantially higher, with the axial velocity in the downstream dilution zone increasing by a factor of 3–5 relative to the cold-flow condition. In the symmetric primary hole configurations, the axial velocity on the lower side is approximately 15–20% higher than that on the upper side. Enhancing the shear interaction between jets and mainstream improves the stability of shear vortices. A three-hole symmetric primary hole arrangement proves beneficial for enhancing the large-scale vortex structure in the primary zone, whereas a staggered arrangement promotes the merging of small-scale vortices, exhibiting the highest dominant frequency (5.4 Hz) in the first POD mode, with a pronounced coexistence of high- and low-frequency peaks in the higher-order modes. In the four-hole symmetric primary hole arrangement, the dominant vortex evolution occurs mainly in the vicinity of the dilution jets, with its first POD mode showing the lowest dominant frequency (2.85 Hz), indicating the most stable shear vortex structure.