贫燃预混旋流火焰燃烧不稳定性的实验

实验研究了常温常压条件下贫燃预混旋流火焰的燃烧不稳定性.结果表明:不稳定燃烧时,火焰结构发生显著变化,呈现大尺度运动的特点,燃烧室所发生的燃烧不稳定件是纵向自激式振荡,是燃烧室与预混段之间的耦合,振荡频率由整个系统决定,随着当量比的提高,燃烧经历了由稳定到不稳定,并达到有限循环脉动的过程,流动脉动和火焰的相互作用,是激发和维持振荡的主要原因,需要深入研究不稳定燃烧性产生和得以维持的机理.

Experimental study on combustion instability of lean premixed swirl flame

An experimental study was conducted on combustion instabilities in a lean-premixed swirl-stabilized combustor at atmospheric pressure and temperature.The result shows that the combustion instability occurred in the model combustor is self-excited under longitudinal oscillation mode,the premixing section resonates with the combustor at the unstable mode of the system,and the oscillation frequency depends on the whole system.The equivalence ratio was identified to have major impact on the onset of instabilities.With equivalence ratio increase,the combustion was transited from stable to unstable states,and reached a limit cycle at last.In the occurrence of instability,the flame became much shorter and penetrated into the corner recirculation.The instability mechanism probably stems from the strong interaction between flame dynamics and flow oscillations inside the combustor,but more work is needed to provide an in-depth physical understanding of the mechanisms to initiate and sustain combustion instabilities.