同心旋流分层火焰的外激脉动特性统计学分析

为了更深入地理解民用航空发动机低排放燃烧室中的同心旋流分层火焰脉动机制，以丙烷为燃料，在100Hz频率的外激条件下对该类旋流火焰的CH*化学发光图像进行高频采样，重点通过本征正交分解法（POD）的统计学分析，提取其时间和空间域内的脉动特征。分析结果表明，旋流火焰中4个最主要的脉动模态分别是轴向振荡、径向振荡、火焰脱落和非对称螺旋运动，并且模态1轴向振荡和模态2径向振荡之间具有显著相关性。POD分析方法可作为中心分级贫油预混燃烧不稳定性机理探索的有效手段。 

Statistical analysis on the forced dynamic of internally-staged-swirling stratified flame

To understand the dynamic mechanism of internally-staged-swirling stratified flame used in civil aero-engine low emissions combustor, high-speed CH* chemiluminescence images of this swirling flame fueled with propane were recorded under the forced condition with 100Hz frequency. Then the temporal and spatial dynamic features of the flame could be extracted by using statistical analysis of proper orthogonal decomposition (POD). The analysis results indicated that the most important 4 dynamic modes in the swirling flame are axial vibration, radial vibration, flame shedding and asymmetric helical motion, respectively. And the axial vibration of mode 1 and radial vibration of mode 2 have significant correlation. The POD analysis could be an effective method for the mechanism exploration of combustion instability in the internally-staged lean premixed combustion.