【摘要】 针对声场作用下氨氢旋流预混火焰NO_x生成特性，基于OH-PLIF图像测试技术，对声频率为180 Hz和压力振幅为200 Pa的火焰结构进行了分析，通过图像处理技术得到火焰结构及表面密度分布，探讨了不同当量比和掺氢比下燃烧和声场脉动耦合作用对NO_x排放的影响。结果表明：声场作用能在一定程度上抑制氨氢旋流预混火焰NO_x的生成，其减排效果受到当量比Φ和掺氢比Z_f的影响；声场对燃烧流场的影响主要作用于火焰周围的空气，形成周期性脉动流，因此声场对低当量比(Φ≤0.8)、以空气动量主导的燃烧场下产生的NO_x有较好的减排作用，对高当量比(Φ>0.8)、以燃料化学反应主导的燃烧场下产生的NO_x影响较小；声场作用下贫燃火焰表面密度增大，平均OH强度降低，这是因为声场强化了火焰燃烧强度，加快了燃烧速率以及与周围流场的传热传质；当掺氢比较低(0.20≤Z_f<0.30)时，声场作用使火焰面积缩小，NO_x减排幅度相对较高；当掺氢比较高(0.30≤Z_f≤0.35)时，对火焰面积的压缩效应减弱，NO_x减排幅度略有降低。更多还原

【Abstract】 To investigate the NO_x formation characteristics of ammonia-hydrogen swirl premixed flames under acoustic excitation, hydroxyl radical plannar laser induced fluorescence(OH-PLIF) imaging technology was used to analyze the flame structure at the sound frequency of 180 Hz and the pressure amplitude of 200 Pa. Flame structure and surface density distribution were obtained through image processing techniques. The effects of combustion and acoustic field pulsation coupling on NO_x emissions under different equivalence ratios(Φ) and hydrogen blending ratios(Z_f) were explored. Results show that the acoustic field can suppress the formation of NO_x in ammonia-hydrogen swirl premixed flames to some extent, with the reduction effect influenced by Φ and Z_f. The acoustic field mainly affects the combustion flow field by creating periodic pulsating flows around the flame, thus demonstrating a better NO_x reduction effect in combustion fields dominated by air momentum at low equivalence ratios(Φ≤0.8). In combustion fields dominated by fuel chemical reactions at high equivalence ratios(Φ>0.8), the effect on NO_x emissions is less significant. Under the influence of the acoustic field, the surface density of lean flames increases, and the average OH intensity decreases, as the acoustic field enhances flame combustion intensity, accelerates the combustion rate, and improves heat and mass transfer with the surrounding flow field. When the hydrogen blending ratio is low(0.20≤Z_f<0.30), the acoustic field causes the flame area to shrink, leading to a relatively higher NO_x reduction. When the hydrogen blending ratio is high(0.30≤Z_f≤0.35), the compressive effect on the flame area weakens, and the NO_x reduction effect is slightly reduced.更多还原