不同管径的Y形微燃烧器内氢气-空气非预混燃烧的火焰传播特性

Propagation Characteristics of Non-premixed H_(2)/air Flames in Y-shaped Micro-combustors with Different Channel Diameters

实验研究了内径分别为1 mm、2 mm和3 mm,水平通道长度为200 mm的Y形微燃烧器内氢气/空气扩散燃烧的火焰传播特性。首先,d=2 mm的燃烧器内的火焰传播模式最为丰富。其次,当燃烧器管径较大时,火焰更容易因扰动而发出噪音。在d=2和3 mm的燃烧器内能观察到两个阶段的噪音,而当d=1 mm时只有一个阶段的噪音。d=2 mm的燃烧器内平均火焰传播速度最小。而且,随着管径的增大,边界火焰更长。值得注意的是,在d=1 mm的燃烧器内,实验观察到了移动的"火焰街"。最后,基于系统的实验观察绘制了八种火焰传播模式的分布图。总之,本文不仅揭示了火焰传播特性与运行参数和尺度效应之间的关系,而且能为Y形微燃烧器的设计和运行提供指导。

Characteristics of non-premixed H2-air flames in three Y-shaped cylindrical microcombustors with a diameter of d=1,2 and 3 mm and a horizontal channel length of 200 mm were investigated experimentally.First,it is found that more flame propagation modes appear in the combustor with d=2 mm.Moreover,noise emission commences earlier in larger combustors.Two stages of noise emission are detected in the combustors with d=2 and 3 mm,whereas only one stage appears under d=1 mm.In addition,the mean flame propagation speed in the combustor with d=2 mm is the minimum.Furthermore,the results show that the edge flame length becomes longer in the combustor with a larger diameter.Interestingly,traveling isolated flame cells,which is termed"traveling flame street",is observed in the micro-combustor with d=1 mm.Finally,the regime diagrams of flame propagation modes are drawn for the three micro-combustors.In conclusion,the present study not only reveals the relationship between flame characteristics and physical and geometrical parameters,but also provides useful guidance for the design and operating of such kind of micro-combustors.