湿壁氛围甲烷预混火焰传播的可视化试验研究

Visualized Experimental Research on the Propagation of Methane Premixed Flame in Wet Wall Atmosphere

针对壁面油膜对受限空间内预混火焰燃烧过程的影响机理,设计开发了基于定容燃烧弹和纹影法的燃烧可视化试验系统,研究了不同初始压力条件下正十二烷/正十四烷油膜对甲烷预混火焰燃烧过程的影响,通过背景建模与背景差分预处理和粒子群优化算法改进OTSU自适应阈值算法,开发了一种适用于纹影图像的火焰轮廓分割算法,基于火焰前锋面轮廓提取结果定量研究火焰传播速度和火焰面积.结果表明湿壁氛围下油膜蒸发过程对预混火焰燃烧过程影响有限,壁面油膜蒸气对混合气当量比的影响是预混火焰燃烧强度的主要影响因素.

Aiming at the influence mechanism of wall fuel film on the propagation process of premixed flame in confined space,a combustion experiment visualization system based on constant volume combustion vessel and schlieren method was designed and developed.The effect of n-dodecane/n-tetradecane fuel film on the combustion process of methane premixed flame under different initial pressures was studied.The OTSU adaptive threshold algorithm was improved through background modeling,background differential preprocessing and particle swarm optimization algorithm,and a flame contour segmentation algorithm suitable for schlieren images was developed.Based on the extraction results of the flame front contour,the flame propagation speed and flame area were quantitatively studied.The results show that the fuel film evaporation process has limited influence on the premixed flame combustion process in the wet wall atmosphere,and the influence of the wall fuel film vapor on the mixture equivalent ratio is the main reason for the change in combustion intensity.