贫燃预混旋流火焰PIV和OH-PLIF瞬态同步测量

为了研究贫燃预混旋流火焰流场与火焰结构特性,设计了强受限预混旋流燃烧器,搭建了PIV(粒子图像测速)和OH-PLIF(平面激光诱导荧光)瞬态同步测量系统。针对典型贫燃工况开展了瞬态同步测量研究,获得了多个截面的瞬态和时均流场速度和OH分布信息。研究表明:低当量比不稳定燃烧工况下,伴随着角涡回火现象,燃烧室底部角落存在明显火焰反应区;由于旋流拉扯效应导致OH分布结构边缘产生褶皱,并出现多个OH“孤岛”;旋流火焰外沿位于喷嘴射流的内侧剪切层;增加当量比,火焰流场结构与反应区分布与低当量比类似,但燃烧更稳定,火焰高度有所增加;内部回流区的经典双涡结构分裂为多个旋涡,存在旋涡进动、破碎的现象。

Instantaneous and simultaneous PIV and OH-PLIF measurement for lean premixed swirl flame

To better study the flame flowfield and structure in lean and premixed swirling flames,a premixed swirling burner with strong confined combustor was designed,and the experimental instantaneous and simultaneous system of PIV (particle image velocimetry) and OH-PLIF (planar laser-induced fluorescence) was built. With this system,the measurement research was carried out in swirling flame under typical operating condition,meanwhile time-averaged and instantaneous simultaneous flame velocity flowfield and OH distribution structures in multiple sections were obtained. Results showed that multiple flame reaction zones existed in the bottom corners of combustor under condition of unsteady combustion at low equivalence ratio,accompanied by flash back in corner vortices. Due to shear effect of swirling flow,lots of wrinkles appeared along the edge of OH distribution structure,and many isolated OH blocks were observed. The root of swirling flame lied at inner side of shear layer of the jet flow. As equivalence ratio increased,the swirling flame velocity flowfied and OH distribution structures were similar to low equivalence ratio. But the combustion was more stable,and the flame height increased somehow. It was found that the typical two vortices were split into multiple vortices sometime. There were phenomena with vortex moving and breaking down.