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为研究受限空间内甲烷与空气预混气体火焰结构及传播速度特性,建立小尺寸开口管道燃烧爆炸试验平台。采用高速纹影摄像技术,研究甲烷与空气质量浓度当量比对甲烷预混气体火焰在开口管道内传播结构的影响。根据离子探针技术监测燃烧反应区的离子产物浓度变化,分析燃烧反应区特性。试验结果表明:火焰结构受甲烷/空气预混气体中甲烷的质量浓度当量比的影响较大,在贫燃或富燃条件下,火焰阵面受湍流和浮力的作用效果明显,火焰结构发生不规则变化;甲烷/空气质量浓度当量比达到1.06时,预混气体充分燃烧,火焰传播速度较快,预热区厚度达到最小值,火焰传播速度与预热区厚度存在此消彼长的变化趋势。甲烷与空气预混气体发生完全燃烧时,火焰传播速度较快,引发火灾的危害性较大,降低或增大甲烷浓度均可使燃烧反应不充分,有助于降低危险性。
In order to study the flame structure and propagation velocity characteristics of methane and air premixed gas in confined space, a small-scale open-mouth combustion and explosion test platform was established. The influence of methane to air mass concentration equivalence ratio on the propagation structure of methane premixed gas flame in open pipe was studied by using high-speed schlieren photography technology. According to the ion probe technology to monitor the change of ion product concentration in the combustion reaction zone, the combustion reaction zone characteristics were analyzed. The experimental results show that the flame structure is greatly influenced by the mass concentration equivalence ratio of methane in the premixed methane / air mixture. Under lean or rich conditions, the turbulence and buoyancy of the flame front are significantly affected, and the flame structure does not occur The results show that when the methane / air mass concentration ratio reaches 1.06, the premixed gas is fully burned and the flame propagation speed is fast, the thickness of the preheating zone reaches the minimum, and the flame propagation velocity and the thickness of the preheating zone have the tendency to shift. . Methane and air premixed gas combustion occurs, the flame propagation speed, the greater the danger of fire, reduce or increase the methane concentration can make the combustion reaction is inadequate, helps to reduce the risk.