基于PLIF技术测试壁面附近处火焰中OH自由基活性分布的研究

Research on OH Free Radical Behavior of Flame Near Wall Surface based on PLIF Testing Technology

利用OH-PLIF技术在狭缝火焰实验台上测量不同壁面条件下壁面附近处火焰中OH浓度分布情况,分析了贴壁处自由基浓度的变化趋势。实验结果表明:随着壁面温度的升高及两测试板间距的减小,贴壁处的OH浓度下降趋势顺序分别为:不锈钢、硅以及氧化锆陶瓷,这主要是因为不同材料对OH消耗速度不同。对比3种材料的熄火间距,可以发现壁面附近OH浓度下降趋势越快,火焰越不稳定,熄火距离越大。壁面附近的OH浓度下降趋势是决定熄火间距的关键因素。

In order to investigate the behavior of free radical near wall surface during the quenching of micro flame,effects of different wall surface conditions on OH concentration distribution near wall of premixed flame at a slit burner between two parallel walls were evaluated by using OH-PLIF( Planar Laser-Induced Fluorescence) testing technology.The change trend of free radial concentration at the wall surface was analyzed.The obtained results showed that OH free radical concentrations near wall decrease quickly to lowly in the order of stainless steel 304,silicon,and zirconia ceramic with the decrease in the distance between the walls when surface temperature of test pale is increased.The main reason is that the OH consumption rate is different for different material.Comparing with quenching distance of three materials,it can be found that at a same plate temperature,the more decreasing tendency of OH free radical concentration near wall surface,the larger quenching distance,and the more instability of flame.The decreasing tendency of OH free radical concentration near wall surface is the key factor deciding quenching distance.