基于5 kHz平面激光诱导荧光的射流火焰局部熄火时空特性分析  

Spatiotemporal distribution characteristics analysis of local flameout in jet flames based on 5 kHz planar laser-induced fluorescence

作　　者：高龙[1] 彭江波[1] 于欣[1] 杨超博[1] 曹振 袁勋 刘文备 GAO Long;PENG Jiangbo;YU Xin;YANG Chaobo;CAO Zhen;YUAN Xun;LIU Wenbei(Institute of Opto-electronics,School of Astronautics,Harbin Institute of Technology,Harbin 150006,China)

机构地区：[1]哈尔滨工业大学航天学院光电子技术研究所,黑龙江哈尔滨150006

出　　处：《光学精密工程》2024年第9期1307-1319,共13页Optics and Precision Engineering

基　　金：国家自然科学基金面上项目(No.62175053);黑龙江省自然科学基金资助项目(No.LH2021F028)。

摘　　要：基于高频光学测量手段研究射流火焰局部熄火的分布特性,对于分析燃烧场不稳定性机理有重要意义。建立5 kHz的平面激光诱导荧光测量系统,对高速射流火焰开展实验研究,并获得火焰结构的动态发展过程;将双边滤波、竖直滑窗局部自适应阈值等图像处理方法引入平面激光诱导荧光图像的预处理,在局部断裂结构数量特征的基础上,提取局部断裂结构长度和空间位置等特征;基于上述特征深入解析局部熄火的时空分布特性,进一步完善高频平面激光诱导荧光诊断与分析方法。研究表明:双边滤波算法处理后,图像峰值信噪比为34.3 dB,结构相似度为0.93,噪声水平显著降低,获得了较好的去噪效果;使用竖直滑窗局部自适应方法进行图像分割的F1分数达到93.30%;断裂结构累计数量随时间线性增加,当射流马赫数由0.5增至1.6时,单侧图像断裂结构的每秒累计数量从790.7增至9 217.2,并且局部熄火频率与射流马赫数呈指数关系;断裂结构主要分布区域为火焰臂及上侧中央燃料区。本研究进一步拓展了高频平面激光诱导荧光技术的应用能力,证明了高频平面激光诱导荧光技术用于局部熄火时空分布特性研究的可行性。Studying the distribution characteristics of local flameout using high-speed optical measurement methods is crucial for understanding jet flame instability mechanisms.Initially,a planar laser-induced fluo⁃rescence(PLIF)measurement system operating at 5 kHz is set up.An experimental study on high-speed jet flames is conducted with OH-PLIF to monitor the dynamic development of the flame structure.Image processing techniques like bilateral filtering and local adaptive thresholding with vertical sliding windows are then applied to preprocess PLIF images.Innovative features such as the length and spatial location of local fracture structures are extracted.Subsequently,the temporal and spatial distribution characteristics of local flameouts are analyzed, enhancing the high-speed PLIF diagnostic and analytical methods. Results in⁃dicate that the bilateral filtering algorithm significantly improves image quality, achieving a peak signal-tonoiseratio of 34.3 dB and a structural similarity index of 0.93. The algorithm effectively reduces noise lev⁃els. The F1 score for the adaptive image segmentation method using vertical sliding windows reaches93.30%. Moreover, the count of fractured structures linearly increases over time. As the jet Mach numberrises from 0.5 to 1.6, the number of fractured structures per second in the unilateral image jumps from790.7 to 9 217.2, showing an exponential relationship with the jet Mach number. Predominant areas forfracture structures include the flame arms and the upper central fuel zone. This research validates the effec⁃tiveness of high-speed PLIF technology in assessing the spatial and temporal distribution of local flameout,broadening its potential applications.

关 键 词：激光诱导荧光 光谱诊断 高速射流火焰 OH基 局部熄火 图像特征 

分 类 号：TN249[电子电信—物理电子学] TK16[动力工程及工程热物理—热能工程]