【作者】 喻健良；

【导师】 丁信伟；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2008， 博士

【摘要】 研究预混爆燃火焰在微小通道内的传播与淬熄过程，对管道内或开敞空间可燃气体的防燃抑爆均具有重要的意义。本文主要针对爆燃火焰在微小通道中的传播机理与淬熄条件进行了实验和理论研究，旨在为可燃气体燃烧爆炸的防治以及阻火器的设计应用提供理论和实验依据。本文主要工作和结论如下（1）建立了管内可燃气体爆炸与爆炸抑制试验装置，实现了计算机程控点火和同步采集测点的压力和火焰速度。通过结构设计，避免了非测点火焰信号的干扰，保证了采集系统获得的火焰信号与测点火焰信号相对应，为确定管内火焰的平均传播速度提供可行的方法，从而能够研究火焰和压力的传播与发展过程。对预混火焰在圆管内的爆炸传播进行了实验研究，获得了圆管内火焰传播的规律，总结了关系式。（2）对管内预混爆燃火焰在多层丝网结构中的传播与淬熄进行了实验研究，得到了淬熄压力和淬熄速度与丝网几何参数如丝网层数、丝网目数等之间的关系。引入熄爆参数来反映丝网结构抑制火焰和爆炸压力的效果，熄爆参数可解释为被淬熄的预混火焰进入丝网结构前的能量。实验研究发现，用熄爆参数能够更全面反映丝网抑制火焰和爆炸压力的效果。熄爆参数越大，丝网结构的熄爆能力越强，对相同预混火焰，丝网结构能够淬熄的火焰压力和传播速度越大，而对不同预混火焰，丝网结构能够淬熄活性更大的预混火焰。该研究思路为确定其他微通道阻火抑爆结构的抑爆性能提供了可行的方法。（3）建立了预混火焰在狭窄通道的淬熄计算模型，计算结果与实验结果的最大误差为16．1％。对预混爆燃火焰在平行板狭缝结构中的传播和淬熄进行了数值模拟，分析了火焰在狭缝中传播的4种不同状态。获得了火焰传播速度V、狭缝淬熄间距G、狭缝壁面温升△T_w与淬熄长度Lq之间的关系在固定狭缝间距G时，相同预混火焰的淬熄时间Lq/V是定值。狭缝间距G增加，参数C减小，淬熄困难。对CH₄/Air对C₃H₃/Air对C₂H₂/Air狭缝壁面温度上升导致f2（△T_w）减小，淬熄性能下降。对CH₄/Air和C₃H₈/Air预混火焰同等条件下，反应活性高的气体，参数C越小，相应淬熄长度也越长，淬熄越困难。利用上述关系，可确定平行狭缝阻火装置的几何参数。该方法可推广应用到淬熄不同C-H预混火焰的阻火装置设计。（4）对预混爆燃火焰在微小圆管内的淬熄进行了数值模拟。得到了火焰速度V、圆管管径D、预混气初始温升△T与淬熄长度Lq之间的关系同等条件下，反应活性高的气体，C越小，淬熄越困难。在固定圆管直径D的条件下，火焰速度V对参数C有影响，火焰速度V提高，会使淬熄时间Lq/V减小，参数C增加。对CH₄/Air、C₃H₈/Air和C₂H₂/Air预混火焰管内预混气体初始温度上升导致圆管的淬熄性能下降。随着温度升高，C₂H₂/Air温度系数f₃（△T）下降显著，淬熄更困难。对CH₄/Air和C₃H₈/Air对C₂H₂/Air（5）在混有惰性气体条件下，对预混爆燃火焰分别在微小圆管和平行板狭缝中的淬熄进行了数值模拟，得出了惰性气体的最佳淬熄浓度，总结了在该浓度下气体淬熄的规律。在狭缝中，C₃H₈／O₂／Inert Gas的淬熄特性与C₃H₈/Air的淬熄特性相似。狭缝间距G和参数C可表示为：在相同条件下，He、Ar、N₂惰性气体对应的C值依次减小，说明He淬熄能力最强，Ar次之，N₂的淬熄能力最弱。在圆管中，C₃H₈／O₂／He与C₃H₈/Air的淬熄特性相似。惰性气体He的加入，使参数C值变大，改善了淬熄效果。上述研究结果对设计微小复杂通道阻火抑爆结构具有指导意义。特别为研究阻火抑爆结构长期阻火性能，考察阻火元件温度升高后阻火抑爆效果的变化提供了研究基础。更多还原

【Abstract】 The investigations into premixed flame propagation in tubes or channels are significant to the deflagration suppression of flammable gas clouds in vessels or unconfined space. To provide theoretical and laboratorial references for deflagration suppression and the design of flame arresters, propagation mechanism and quenching condition of premixed unsteady flames in narrow channels were researched experimentally and then simulated numerically in this paper. The main work and conclusions are as follows（1） The experimental apparatus for flammable gases explosion and deflagration suppression in pipe were set up, realizing computer controlled ignition and synchronized measuring of the pressure and flame speed of the test points. The flame detector was designed to only measure the flame signal at right point, hence made the research on the process of flame and pressure propagation and development possible. Experiments were done on the explosion of premixed flame in a long pipe, from which the rules of flame propagation were obtained, and a semi-empirical equation was therefore concluded.（2） The propagation and quenching of premixed flame in multilayer wire mesh were studied experimentally, and the relation was got between quenching pressure or quenching speed and wire mesh parameters such as layers or meshes. A concept, suppression parameter, was introduced to indicate the effects of suppressing explosion pressure and flame speed for a multilayer mesh. The suppression parameter can be explained as the energy of the premixed flame before entering the multilayer wire mesh, and which will be quenched. Experiment showed that the suppression parameter could reflect the effects of suppressing explosion pressure and flame speed.The higher the suppressing parameter, the higher the suppressing explosion capacity of the multilayer wire mesh, and it means that for same premixed flames, the higher pressure and flame speed can be suppressed, for different premixed flame, the higher active premixed gas can be suppressed. This research method can provide a better way to determine the suppressing explosion capacity of other narrow channels.（3） Propagation and quenching of deflagration were modeled in narrow parallel plate channels. The maximum error between numerical simulation and experiment was 16.1%. Flame propagations under different conditions were considered, four modes of flame propagation in narrow parallel plate channels were discussed, and relationship among flame speed V, plate gap G, the value△T_w of rised wall temperature and quenching length Lq was got as followsFor a detemined plate gap G, the quenching time Lq/V was constant for a premixed flame.The larger the plate gap G, the lower parameter C, the more difficult to quench.For CH₄/Air premixed flameFor C₃H₈/Air premixed flameFor C₂H₂/Air premixed flameThe wall temperature rise T_w could make the coefficient f₂（△T_w） of parameter C lower, and decrease the quenching capacity.For CH₄/Air and C₃H₈/Air premixed flameThe higher the chemical activity of premixed flame, the lower the parameter C, the larger queching length was required, and it’s more difficult to quench.Known parameter C above relationship, the quenching parameters of narrow channel can be determined. This method can be used to design the narrow channel to quench other premixed C-H flames.（4） Quenching of premixed falme deflagration in precision tubes were investigated. The relationship among flame speed V, value△T of initial gas temperature rised, diameter D of tube and quenching length Lq was got as followsFor a premixed flame with higher chemical activity, its parameter C was lower, quching this flame was more difficult.For a detemined tube diameter D, a higher flame speed V made the quenching time Lq/V smaller, and parameter C higher.For premixed flame CH₄/Air, C₃H₈/Air and The initial gas temperature rise could decrease the quenching capacity in precision tubes. The higher initial gas temperature T, the much lower temperature coefficient f₃（△T） for C₂H₂/Air premixed flame, which showed that higher initial gas temperature T makde it more difficult to quench this premixed flame.For CH₄/Air and C₃H₈/AirFor C₂H₂/Air（5） Mixing different inert gases in premixed flammable gases, quenching of deflagration were numerically simulated both in narrow parallel plate channels and tubes respectively, getting the optimal quenching concentrations of inert gases, and the quenching rules of the flammable gases in their optimal quenching concentrations as well.The quenching properties in narrow channels among differrent gases of C₃H₈/O₂/Inert gase and C₃H₈/Air were similar.The relaltionship between channel gap G and parameter C was shown as followsAmong the C₃H₈/O₂/Inert gas He, C₃H₈/O₂/Inert gas Ar and C₃H₈/O₂/Inert gas N₂, the parameter C of C₃H₈/O₂/Inert gas He was maximum, that of C₃H₈/O₂/Inert gas N₂ was minimum, which showed that quenching capacity of He was the highest, that of N₂ was the lowest.The quenching properties in tubes between gases of C₃H₈/O₂/Inert gas He and C₃H₈/Air were similar. But the Inert gas He made the parameter C higher, which improved the quenching effects.The conclusions above are of great significance to the design of micro deflagration suppressing constructions in complex narrow channels, providing references to the research on their long term-performance as well as suppression effect change due to temperature raise, especially.更多还原