贫燃预混旋流火焰的燃烧不稳定性

Combustion Instability of Lean Premixed Swirl Flame

在低污染模型燃烧室上,从实验角度研究了常温常压下贫燃预混旋流火焰燃烧不稳定性.主要着眼于当量比、旋流数和掺混段结构对于燃烧不稳定性的影响.结果表明,当量比对燃烧的稳定性具有重要影响,随着当量比的提高,燃烧经历了稳定-不稳定-极限环,振荡的频率变化不大,而脉动压力幅值显著增大,最终达到极限环状态.旋流强度增大会导致压力脉动增大,进入不稳定的最小当量比降低.实验所采用的开孔掺混方式与开放式的自由混合方式相比,对燃烧不稳定压力脉动有减小的效果.

An experimental study was conducted on combustion instability in a lean-premixed swirl-stabilized com-bustor at atmospheric pressure and temperature. The primary objectives were to study the influence of equivalence ratios,swirl number,geometry of premixed sector on combustion instability. The result also revified the influence of equivalence ratios on combustion instability,demonstrating that the combustion process consisted of stable,pause oscillation,instable steps with little variation of frequency and great expansion of peak value of oscillation pressure, finally achieving limit cycle. With the rise of swirl number,the pulsation of oscillation pressure increased signally while the lowest equivalence ratio of combustion instability decreased gradually. Compared with the open geometry of premixed section,the polyporous structure of premixed section could reduce the oscillation pressure in combustor and premixed section.