坡度条件下不同长宽比矩形火源燃烧火焰贴地长度实验研究

Flame Attachment Length of Rectangular Fire Sources with Different Aspect Ratios Under Slope Conditions

利用可变角度实验台,改变斜坡角度(10°~50°)、热释放速率(12.3~24.6 kW)以及燃烧器长宽比(1~6),开展了一系列燃烧实验,研究了火焰贴地长度随这3个因素的演变规律.结果表明,随着斜坡角度、火源热释放速率及燃烧器长宽比的增加,火焰贴地长度增加.对于相同的坡度和火源热释放速率,随长宽比增大,贴地长度增幅范围在65%~105%之间.基于斜坡诱导压差与火羽流浮力共同作用的物理机制分析,并考虑到燃烧器长宽比对火焰卷吸行为的影响,提出了无量纲火焰贴地长度预测模型.

In this paper,a series of combustion experiments were carried out by changing the slope angle(10°—50°),heat release rate(12.3—24.6 kW)and burner aspect ratio(1—6)using a variable angle test bench,and the evolution law of flame attachment length with these three factors was studied.The results showed that the flame attachment length increases with the increase of slope angle,fire heat release rate and burner aspect ratio.With the increased aspect ratio,the increment range of flame attachment length was about 65%—105%at a given slope angle and heat release rate.Based on the analysis of the physical mechanism of slope-induced pressure difference and fire plume buoyancy,and considering the effect of burner aspect ratio on flame entrainment behavior,a dimensionless flame attachment length prediction model was proposed.