摘要
为了探究强迫对流下燃料液滴的火焰结构和波动特征,利用被正庚烷浸润的多孔球来充当液滴,在环境压力下对其火焰施加不同温度和强度的气流(温度T=420~720 K和对流速度U=0.6~7.1 m/s)。使用高速摄影仪捕获火焰的实时图像,并通过自编Python-OpenCV程序对表征火焰结构的参数进行提取,进而分析火焰的结构演化和瞬时波动特征。对火焰瞬时数据进行傅里叶变换处理。研究结果表明:随着对流速度增加,火焰几何结构变化剧烈,而雷诺数Re=300之后,其变化则趋于平缓。对于燃烧状态,火焰从黄色火焰到黄-蓝分层火焰、再到蓝色火焰的转变随雷诺数的变化呈阶跃型规律进行,在这个过程中Re=200及Re=400为两个关键转变点。处于强迫对流下的多孔球尾迹火焰的瞬时波动呈现明显的周期性,其频率主要由球后卡门涡旋的脱落频率决定。
To study structure and flicker characteristics of flames of fuel droplets during forced convection, herein,the flame behavior experiments under different forced convection conditions(T= 420-720 K, U=0.6-7.1 m/s) at ambient pressure were carried out using porous spheres infiltrated with n-heptane as droplets. During the experiment, a high-speed camera was used to capture the flame images, and the time-averaged and instantaneous feature data of the flame were extracted by the self-compiled Python-OpenCV program, and then the structural evolution and instantaneous flicker behavior of the flame were analyzed. The Fourier transform was performed on the instantaneous flame data. The results show that with the increase of convection velocity, the flame geometry changes dramatically, while after Reynolds number Re=300, the change tends to be gentle. For the combustion state, the transition of the flame from the yellow flame to the yellow-blue stratified flame and then to the blue flame follows a step law with Re. In this process, Re=200 and Re=400 are two key transition points. The instantaneous oscillation of the porous sphere flame during forced convection shows obvious periodicity, whose frequency is mainly determined by the shedding frequency of the Karman vortex behind the sphere.
作者
张亚杰
穆志强
魏衍举
杨亚晶
刘圣华
ZHANG Yajie;MU Zhiqiang;WEI Yanju;YANG Yajing;LIU Shenghua(School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049,China;State Key Laboratory of Mechanical Strength and Vibration,School of Aerospace,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2022年第12期4934-4943,共10页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(52176128)
陕西省重点研发计划项目(2019ZDLGY15-10)。
关键词
火焰结构
火焰波动
多孔球
正庚烷
flame structure
flickering
porous sphere
n-heptane
作者简介
通信作者:魏衍举,博士,副教授,从事液滴燃烧以及液滴动力学研究:E-mail:weiyanju@xjtu.edu.cn。
