平面激光诱导荧光技术在超声速燃烧火焰结构可视化中的应用

Visualization of flame structure in supersonic combustion by Planar Laser Induced Fluorescence technique

平面激光诱导荧光(PLIF)技术能够高时空分辨成像火焰结构并用于研究超声速燃烧机理。利用OH-PLIF与CH-PLIF技术研究了超声速燃烧的火焰结构。其中,利用OH-PLIF技术对燃烧室中3个展向截面与2个流向截面的凹腔稳定火焰反应区结构进行成像,利用CH-PLIF技术观测凹腔火焰放热区结构。实验结果表明:全局当量比较低时燃烧主要发生在凹腔中,OH沿中轴线对称分布;高当量比时火焰位置更高,OH主要沿燃烧室两侧壁面分布;CH所存在的超声速燃烧放热区呈现高度褶皱和破碎结构,放热区分布在比反应区更窄的区域。

Planar Laser Induced Fluorescence(PLIF)can be used to visualize the flame structure with high temporal and spatial resolution and investigate the mechanism of supersonic combustion.In this paper,OH-PLIF and CH-PLIF techniques were used to study the flame structure in supersonic combustion.The cavity-stabilized reaction zone structure of the three streamwise sections and two spanwise sections in a supersonic combustor was obtained by using the OH-PLIF technique.The experimental results show that the combustion occurs in the inner cavity and the OH radicals are distributed symmetrically along the central axis at a low global equivalence ratio.The OH radicals are primarily distributed at two-side-wall of the combustor and the location of the flame is higher than that of the cavity at a high equivalence ratio.The heat-release structure of the cavity-stabilized flame was observed by the CH-PLIF technique.It is found that the heat-release zone is highly wrinkled and distorted in the supersonic combustion and it is distributed in a narrower region than the reaction zone.