掺氨乙烯同轴扩散火焰碳烟微观特征研究

Soot Morphology in Ammonia/Ethylene Co-flow Diffusion Flames

摘要

基于CoFlame程序对掺氨乙烯同轴扩散火焰中碳烟颗粒的微观结构特征开展数值模拟研究,系统探讨了掺氨比例对碳烟粒径、数密度、分形维数等参数的影响规律.结果表明,氨的掺入显著改变了碳烟的形成与演化过程.随着掺氨比例由0增至5%、30%和50%,碳烟平均粒径分别下降65%、73.5%和75.3%,呈现先快速下降后趋于平缓的趋势.掺氨显著降低了初级颗粒与团簇的数密度,抑制了颗粒的团聚行为.进一步分析表明,氨的加入有效抑制了碳烟成核过程,从而减少新生颗粒数量,降低团簇数密度.此外,掺氨使碳烟的分形直径和体积直径减小,表明其凝并与表面生长过程受到抑制,导致团簇结构更为疏松、紧密度下降.

Abstract

This study investigates the microstructural characteristics of soot particles in ammonia-doped ethylene co-flow diffusion flames using the CoFlame code, with a focus on the effects of ammonia blending ratio on parameters such as soot particle size, number density, and fractal dimension. The results indicate that ammonia addition significantly alters the formation and evolution of soot. As the ammonia blending ratio increases from 0% to 5%, 30%, and 50%, the average soot particle size decreases by 65%, 73.5%, and 75.3%, respectively, showing a trend of rapid initial decline followed by gradual stabilization. Ammonia blending markedly reduces the number density of both primary particles and aggregates, suppressing particle agglomeration. Further analysis reveals that ammonia addition effectively inhibits the soot nucleation process, thereby reducing the number of nascent particles and decreasing aggregate number density. In addition, ammonia blending leads to a reduction in both fractal diameter and volume diameter of soot, indicating suppressed coagulation and surface growth processes, which result in more loosely packed, less compact aggregate structures.

关键词

NH₃/C₂H₄ / 碳烟 / 粒径 / 颗粒密度

Key words

NH₃/C₂H₄ / soot / particle diameter / particle number density

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基金资助

国家自然科学基金资助项目(52376088)

安徽省高校协同创新项目(GXXT-2022-025)