低压条件下线性浮力主控湍流扩散射流火焰行为实验研究

Experimental Study on Flame Height and Oscillation Behavior of Linear-source Buoyant Turbulent Diffusion Jet Flame Under Sub-atmospheric Pressures

本文利用不同线性比的燃烧器,以丙烷为燃料,开展了不同压强条件下浮力主控扩散射流火焰燃烧实验,研究了火焰高度和火焰振荡频率随燃烧器线性比、环境压强和热释放速率的演化规律。实验结果表明:火焰高度随燃烧器线性比的增加而降低,随压强的减小而增大,随热释放速率的增加而增大,而火焰振荡频率随燃烧器线性比的增加而略微减小,随压强的增加而增大,与热释放速率的相关性不大。基于空气卷吸机制分析,以及斯特劳哈尔数(St)和弗劳德数(Fr)之间的无量纲关系,建立了耦合环境压强影响的线性火源火焰高度与火焰振荡频率无量纲模型。

In this paper,experiments of linear buoyant turbulent propane jet fire at various subatmospheric pressures were carried out,and different aspect ratios of burners were considered.The evolutions of flame height and flame oscillation frequency with the burner aspect ratio,ambient pressure and heat release rate are studied.The experimental results show that the flame height decreases with the increase of burner aspect ratio or pressure,and it increases with the increase of heat release rate.However,the flame oscillation frequency decreases with the increase of burner aspect ratio and increases with the increase of pressure,and heat release rate has no significant effect on the flame oscillation frequency.Based on the analysis of air entrainment mechanism and the dimensionless relationship between Strouhal number(St)and Froude number(Fr),non-dimensional models of flame height and flame oscillation frequency of linear source jet flames coupled with the ambient pressure effect are established.