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<p>Combining swirl and micro-mixing diffusion combustion is a new approach to hydrogen gas turbine combustion. For swirl micro-mixing diffusion combustion, swirl intensity variation impacts the flow field, flame structure and NO<sub><i>x</i></sub> emissions. In this study, four micro-mixing diffusion burners with the swirl number (<i>Sn</i>) of 0.62/0.45/0.3/0 are designed for the experiments. The effects of swirl intensity on micro-mixing diffusion combustion are investigated experimentally using OH* chemiluminescence and Particle Image Velocimetry (PIV). In addition, CFD calculations are used to clarify the mechanism of swirl intensity’s effect on NO<sub><i>x</i></sub> emissions. The results indicate that the weakening of swirl intensity leads to the evolution of the swirl recirculation vortex to the dual recirculation vortex and finally to the bluff body recirculation vortex, which causes the radial contraction of the flame and induces combustion oscillation. When <i>Sn</i> decreases from 0.62 to 0.45, the flame spread angle <i>θ</i> decreases by 10.7%; the unit flame rotation angle <i>ψ</i> decreases by 9.0%, and the unit flame length <i>L</i><sub>F</sub> increases by 8.0%. The increase in <i>L</i><sub>F</sub> causes an increase in residence time, ultimately leading to a rise in NO<sub><i>x</i></sub> emissions. Meanwhile, the reduced swirl intensity leads to increased mixing time scale and spatial mixing deficiency, which is another contributor to the deterioration of NO<sub><i>x</i></sub> emission performance.</p>

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Effects of Swirl Intensity on Flame Structure and NOx Emissions of Hydrogen Micro-Mixing Diffusion Combustion

  • 期刊论文

  • 发表日期：

    2025年8月9日

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  • Ting Shi,
  • Yi Liu,
  • Shiqi Jia,
  • Bing Ge,
  • Dongxia Duan,
  • Shusheng Zang

摘要

Combining swirl and micro-mixing diffusion combustion is a new approach to hydrogen gas turbine combustion. For swirl micro-mixing diffusion combustion, swirl intensity variation impacts the flow field, flame structure and NOx emissions. In this study, four micro-mixing diffusion burners with the swirl number (Sn) of 0.62/0.45/0.3/0 are designed for the experiments. The effects of swirl intensity on micro-mixing diffusion combustion are investigated experimentally using OH* chemiluminescence and Particle Image Velocimetry (PIV). In addition, CFD calculations are used to clarify the mechanism of swirl intensity’s effect on NOx emissions. The results indicate that the weakening of swirl intensity leads to the evolution of the swirl recirculation vortex to the dual recirculation vortex and finally to the bluff body recirculation vortex, which causes the radial contraction of the flame and induces combustion oscillation. When Sn decreases from 0.62 to 0.45, the flame spread angle θ decreases by 10.7%; the unit flame rotation angle ψ decreases by 9.0%, and the unit flame length LF increases by 8.0%. The increase in LF causes an increase in residence time, ultimately leading to a rise in NOx emissions. Meanwhile, the reduced swirl intensity leads to increased mixing time scale and spatial mixing deficiency, which is another contributor to the deterioration of NOx emission performance.