声场作用下氨氢旋流预混燃烧NO_x排放特性研究

To investigate the NO.r 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 NC), emissions under different equivalence ratios (ä>) and hydrogen blending ratios (Zf) were explored. Results show that the acoustic field can suppress the formation of NO, in ammonia-hydrogen swirl premixed flames to some extent, with the re-duction effect influenced by <P and Zf. The acoustic field mainly affects the combustion flow field by crea-ting 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 (<£>^0. 8). In combustion fields domi-nated by fuel chemical reactions at high equivalence ratios (

0. 8), the effect on NO, 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=£^Zf<C0. 30), the acoustic field causes the flame area to shrink, leading to a rel-atively higher NO, reduction. When the hydrogen blending ratio is high (0. 30^Zf^0. 35), the compres-sive effect on the flame area weakens, and the NO, reduction effect is slightly reduced.