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利用OH-PLIF火焰结构激光诊断技术获得了不同当量比下CO:H_2为1:4的合成气预混层流本生灯火焰OH基分布。结合STAR-CD模拟结果,分析了拉伸率和优先扩散随当量比的变化规律,以及变当量比条件下拉伸率和优先扩散的相互作用机理。结果表明,本生灯火焰顶端是强烈负拉伸,由火焰弯曲引起的强负拉伸和流动引起的微弱正拉伸共同作用。在稀燃条件下,随当量比的减小,顶端负拉伸作用增强,加剧局部优先扩散作用,引起未燃混合气中的燃料比例下降,削弱顶端局部燃烧强度,导致顶端开口现象。
The OH radical distribution in the flame of pre-mixed laminar flow Bunsen burner was obtained by OH-PLIF flame laser diagnosis technology under the different equivalence ratio of 1: 4 with CO: H_2. Combined with the results of STAR-CD simulation, the variation law of the elongation ratio and the priority diffusion with equivalence ratio and the interaction mechanism between the elongation ratio and the preferential diffusion under the equivalent ratio are analyzed. The results show that the flame front of the Bunsen burner is strongly negative tensile, and the strong negative tensile caused by the flame bending and the weak positive tensile caused by the flow act together. Under the condition of lean burn, with the decrease of equivalence ratio, the effect of negative tensile at the top increases and the local preferential diffusion aggravates, causing the proportion of fuel in the unburned mixture to drop, weaken the local combustion intensity at the top and lead to the top open phenomenon.