Inlet temperature driven supercritical bifurcation of combustion instabilities in a lean premixed prevaporized combustor
Inlet temperature driven supercritical bifurcation of combustion instabilities in a lean premixed prevaporized combustor
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贫油预混预汽化燃烧器中入口温度驱动的燃烧不稳定性的超临界分叉
DOI：
10.1016/j.expthermflusci.2019.109857
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发表时间：
2019-12-01
影响因子：
3.2
通讯作者：
Sung, Chih-Jen
中科院分区：
文献类型：
--
作者：
Han, Xiao;Laera, Davide;Sung, Chih-Jen
本文报道了由空气入口温度（T-a）触发的燃烧不稳定性的超临界分叉的实验观察和分析。这些研究是在高温下运行的加压煤油燃料贫油预混预蒸发（LPP）燃烧室中进行的。与以往的一些研究不同，从系统的不稳定状态开始，当T-a超过临界值T-a = 570 K时，燃烧不稳定性的幅度突然减小。当温度降低时，系统返回到不稳定状态，而没有任何滞后行为，正如在超临界分叉的情况下所预期的那样。不稳定火焰具有周期性的轴向升离和重燃运动，其特征为Helmholtz模式。发现当温度高于570 K时，化学发光信号和压力信号之间的相位差随着T-a、T-a超过90度（异相）而增加。低阶网络框架进行，说明当T-a增加时，该模式的稳定性移动的预测在T-a附近570 K，与实验观察到的良好一致。同时还研究了T-a对喷雾特性的影响，发现较高的T-a促进了燃油蒸发，减小了旋流器出口处当量比的波动。
The present article reports experimental observation and analyses of a supercritical bifurcation of combustion instabilities triggered by the air inlet temperature (T-a). The studies are performed with a pressurised kerosene fuelled Lean Premixed Prevaporized (LPP) combustor operated under elevated temperature. Unlike some previous studies, starting from an unstable condition of the system, the amplitude of combustion instabilities suddenly decrease when T-a exceeds a critical value of T-a = 570 K. When the temperature is lowered back the system returns to being unstable without featuring any hysteresis behaviour, as expected in case of a supercritical bifurcation. The unstable flames feature a periodic axial motion of lift-off and re-ignition, characterized as Helmholtz mode. The phase difference between chemiluminescence and pressure signals is found to increase with T-a,T- exceeding 90 degrees (out of phase) for temperatures higher than 570 K. A low order network framework is conducted, illustrating that when T-a is increased a stability shift of this mode is predicted at T-a near 570 K, in good agreement with the experimental observations. The impact of T-a on the spray characteristics is also examined, finding that higher T-a promotes fuel evaporation and reduces equivalence ratio fluctuation at the exit of the swirler.