OH与CH2O双组分平面激光诱导荧光对旋流燃烧室火焰结构与脉动特征的研究

介绍了利用平面激光诱导荧光(PLIF)技术对航空发动机的旋流燃烧室模型在贫燃状态下工作特性的研究。通过对OH与CH2O双组分进行同步PLIF测量,获得了不同工况下燃烧室反应区以及预热区的瞬态结构信息。应用本征正交分解(POD)方法对OH PLIF的图像进行处理,得到了旋流火焰的主要脉动模态,并通过扩展本征正交分解(EPOD)方法计算出了相应POD模态的CH2O荧光信号分布。实验结果表明:随着燃烧室热功率的增大,火焰的整体结构、脉动模式均出现了明显的变化。在火焰高度增加的同时,轴向不稳定性逐渐增强,涡核旋进(PVC)的脉动特征相对减弱。在较大的热功率下,在燃烧室的外回流区(ERZ)出现未燃烧的燃料。 

Flame structure and dynamics characters investigation by OH and CH2O planar laser-induced fluorescence in the swirl combustor

The swirl combustor model of aircraft engine under fuel-lean condition was characterized by planar laser-induced fluorescence (PLIF) technique. By taking PLIF measurements of OH and CH2O simultaneously, the transient structures of the reaction zone and preheat zone were investigated under various operation points. By applying proper orthogonal decomposition (POD) method to the OH PLIF data, the main dynamics modes of the swirling flame were extracted, and by applying extended proper orthogonal decomposition (EPOD) method, CH2O PLIF signal distribution for each POD mode was unveiled. The experimental results indicate that as the thermal power of the combustor increases, the time-averaged structure and dynamics modes experience notable transitions. As the flame elevated, the flame exhibits stronger axial instability, while the deformation caused by precessing vortex core (PVC) is decreased. At relative high thermal power, unburnt fuel emerges in the external recirculation zone (ERZ).