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<p>On one hand, the combustion utilization of hydrogen and ammonia (carbon-free fuel) is a practical way to reduce CO<sub>2</sub> emissions. On the other hand, the ultra-lean premixed combustion near the flammability limit is a promising technology to achieve cleaner utilization of gaseous fuels. Therefore, this work investigates the ultra-lean premixed combustion characteristics of 40%H<sub>2</sub>-60%NH<sub>3</sub>-air by means of numerical simulation. It is observed that the 40%H<sub>2</sub>-60%NH<sub>3</sub>-air premixed flame can remain stable at the ultra-lean fuel condition, and its behavior and structure are revealed in detail. It is observed that the flame root is anchored by the recirculation zone. H<sub>2</sub> tends to be consumed more upstream compared with NH<sub>3</sub>. Both H<sub>2</sub> and NH<sub>3</sub> arrive at the flame front primarily through diffusion rather than convection. The amount of H<sub>2</sub> arriving at the flame root and waist is larger than that of NH<sub>3,</sub> primarily owing to its faster diffusion velocity. The preferential transport of H<sub>2</sub> contributes to the larger reaction rate of H<sub>2</sub> around these regions. In addition, the negative flame displacement speed appears in the vicinity of the flame root and tip. Then, the factors contributing to the residual flame stabilization are analyzed. For the flame root, the strong preferential transport effect moderates the decrease in the flame displacement speed with decreased equivalence ratio and generates a relative fuel-rich region contributing to the flame root stabilization. For the flame tip, the significant heat recirculation and preferential transport effects contribute to its stabilization. The present study helps us to further understand the ultra-lean H<sub>2</sub>-NH<sub>3</sub>-air premixed flame dynamics.</p>

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Stability Analysis of Hydrogen Enriched Ammonia Premixed Flame Stabilized on a Bluff-Body

  • 期刊论文

  • 发表日期：

    2025年8月27日

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  • Wenquan Yang,
  • Aiwu Fan,
  • Jianlong Wan

摘要

On one hand, the combustion utilization of hydrogen and ammonia (carbon-free fuel) is a practical way to reduce CO2 emissions. On the other hand, the ultra-lean premixed combustion near the flammability limit is a promising technology to achieve cleaner utilization of gaseous fuels. Therefore, this work investigates the ultra-lean premixed combustion characteristics of 40%H2-60%NH3-air by means of numerical simulation. It is observed that the 40%H2-60%NH3-air premixed flame can remain stable at the ultra-lean fuel condition, and its behavior and structure are revealed in detail. It is observed that the flame root is anchored by the recirculation zone. H2 tends to be consumed more upstream compared with NH3. Both H2 and NH3 arrive at the flame front primarily through diffusion rather than convection. The amount of H2 arriving at the flame root and waist is larger than that of NH3, primarily owing to its faster diffusion velocity. The preferential transport of H2 contributes to the larger reaction rate of H2 around these regions. In addition, the negative flame displacement speed appears in the vicinity of the flame root and tip. Then, the factors contributing to the residual flame stabilization are analyzed. For the flame root, the strong preferential transport effect moderates the decrease in the flame displacement speed with decreased equivalence ratio and generates a relative fuel-rich region contributing to the flame root stabilization. For the flame tip, the significant heat recirculation and preferential transport effects contribute to its stabilization. The present study helps us to further understand the ultra-lean H2-NH3-air premixed flame dynamics.