摘要
为探究甲烷在富氧条件下的火焰动力学规律,以CH_(4)/O_(2)/CO_(2)预混体系为研究对象,在小尺度方形透明管道中进行了一系列爆炸实验,探讨了初始环境温度波动对爆炸参数的影响,并对预混体系的燃烧机理进行分析。结果表明:在273 K的环境温度下,化学当量比φ=0.8~1.0且氧气相对比γ<0.30和φ=1.2且γ<0.35的预混体系不能被点燃,而其他预混体系均可被点燃,最终产生郁金香与非郁金香两种火焰类型,并且根据郁金香火焰独特的演变特征,又划分为T形郁金香火焰和不对称郁金香火焰;随着γ的增大,无量纲火焰传播速度v/(S_(L)σ)的变化趋势由“两升两降”转变为“一升一降”。初始环境温度的升高并未对火焰传播速度和爆炸超压的变化趋势产生影响,但是会导致最大爆炸超压p_(max)和最大火焰传播速度降低。值得注意的是,初始环境温度对爆炸强度的影响随化学当量比的减小而增强。另外,与最大爆炸超压相比,最大火焰传播速度与层流燃烧速度之间的关系更紧密。从敏感性分析中可知:层流燃烧速度对自由基链式反应R38(即H+O_(2)=O+OH)表现出最大的正敏感度,对R52(即H+CH_(3)(+M)=CH_(4)(+M))表现出最大的负敏感度,并且对自由基OH的生成速率最敏感,当初始环境温度升高至303 K时,层流燃烧速度对R38(正)和R52(负)的敏感度降低;H、O和OH自由基总摩尔分数的增大会削弱热扩散的不稳定性,增强流体力学的不稳定性。
In order to explore the flame dynamics of methane under oxygen-rich conditions,a series of explosion experiments were carried out in a small-scale square transparent pipe with a CH_(4)/O_(2)/CO_(2)premixed system as the research object.Through the analysis of explosion parameters,the influence of the fluctuation of initial ambient temperature on explosion intensity was revealed,and the micro-combustion mechanism of premixed system was discussed.The results show that under the ambient temperature of 273 K,the mixtures with the equivalence ratioφfrom 0.8 to 1.0,the oxygen relative ratioγ<0.30 andφ=1.2,γ<0.35 could not be ignited,but other premixed systems could,and tulip and non-tulip flames were produced.According to the unique evolution characteristics of the tulip flame,the tulip flame can be divided into T-shaped tulip flame and asymmetric tulip flame.As the magnitude ofγincreases,the evolution of the maximum normalized flame propagation velocity shifts from a two rises-and-two drops mode to a one rise-and-one drop mode.The increase in the initial ambient temperature has no effect on the evolutions of flame propagation velocity and explosion overpressure,but it reduces the maximum explosion overpressure and the maximum flame propagation velocity.It is worth noting that when the equivalence ratio is lower,the initial ambient temperature has stronger influence on the explosion intensity.In addition,compared with the maximum explosion overpressure,the maximum flame propagation velocity displays a closer relationship with laminar burning velocity.The chemical kinetics calculations show that the laminar burning velocity is most positively sensitive to the free-radical chain reaction R38(namely,H+O_(2)=O+OH)and is most negatively sensitive to R52(namely,H+CH_(3)(+M)=CH_(4)(+M)),and is most sensitive to the rate of production of the free radical OH.When the initial ambient temperature increases to 303 K,the sensitivity of the laminar burning velocity to R38(positive)and R52(negative)are reduced.The increase in the total mole fraction of the free radicals H,O and OH weakens the thermal diffusion instability,but enhances the hydrodynamic instability.
作者
钟飞翔
郑立刚
马鸿雁
杜德朋
王玺
潘荣锟
ZHONG Feixiang;ZHENG Ligang;MA Hongyan;DU Depeng;WANG Xi;PAN Rongkun(State Key Laboratory Cultivation Base for Gas Geology and Gas Control,School of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454003,Henan,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Jiaozuo 454003,Henan,China)
出处
《爆炸与冲击》
EI
CAS
CSCD
北大核心
2022年第1期1-14,共14页
Explosion and Shock Waves
基金
国家自然科学基金(51674104,51874120)。
关键词
富氧甲烷
郁金香火焰
初始环境温度
敏感性分析
oxygen-enriched methane
tulip flame
initial ambient temperature
sensitivity analysis
作者简介
第一作者:钟飞翔(1996-),男,硕士研究生,390057630@qq.com;通信作者:郑立刚(1979-),男,博士,教授,zhengligang97@163.com。
