【作者】 宋占兵；

【导师】 丁信伟；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2006， 博士

【摘要】 研究非稳态预混爆燃火焰在狭窄通道中传播,对于工业阻火器的设计与应用,以及管道或开敞空间中可燃气体的防燃抑爆等,均具有重要的意义。本文主要针对二维非稳态爆燃火焰在狭缝中的传播机理与熄灭条件进行研究,旨在为可燃气体燃烧爆炸的防治以及阻火器的设计和应用等提供理论依据。本文主要工作和结论如下。 (1)基于Arrhenius燃烧模型、流体力学控制方程组、气体组分方程,建立了模拟预混非稳态爆燃火焰在平板狭缝中传播的二维理论模型。在改进的SIMPLE算法的基础上,采用VC++语言自己编制了适用于模拟爆燃火焰传播的二维数值计算程序。 (2)通过模拟质量传递、热量传递、动量传递、定容燃烧及空气在平板通道中的瞬态流动等算例,验证本文计算程序的有效性。然后,对一维预混乙炔—空气爆燃火焰的传播过程进行模拟,在计算燃烧速度和火焰厚度等火焰特性参数的同时,对数值解进行网格独立性分析。 (3)对预混乙炔—空气爆燃火焰在封闭—开放平板狭缝中的传播机理与熄灭条件进行了数值模拟。 1)研究了质量扩散和壁面散热对火焰形状形成的影响。结果发现,质量扩散的增强有利于郁金香状火焰的形成:当质量扩散系数小于或等于热扩散系数, 即Lewis数大于或等于1时,火焰倾向于形成蘑菇形状;而当质量扩散系数大于热扩散系数,即Lewis数小于1时,火焰倾向于形成郁金香形状。壁面散热则不利于郁金香状火焰的形成:在绝热壁面条件下,当狭缝长高比小于40时,就可以形成郁金香状火焰;而在等温壁面条件下,只有当狭缝长高比小于30时,郁金香状火焰才能形成。 2)通过引入无因次准熄间距、热量补给速率等概念,综合研究了化学反应放热、更多还原

【Abstract】 The investigations into premixed flame propagation in tubes or channels are great important for design and application of flame arresters, and deflagration suppression of flammable gas clouds in vessels or unconfined space. Aiming to provide theoretical references for deflagration suppression and the design of flame arresters, propagating mechanism and quenching condition of premixed unsteady flames in narrow plate channels are simulated numerically in this paper. The main work and conclusions in this paper are as follows.(1) Based on Arrhenius combustion model, governing equations of hydrodynamics and species equations, two-dimensional theoretical model for propagation of premixed unsteady flames in narrow channels is built. Based on improved SIMPLE algorithm, a two-dimensional program code applicable to simulating deflagration flame is compiled in VC++ language.(2) Some computational problems, such as mass diffusion, heat transfer, Stokes’ first problem, combustion in constant volume, and transient flow of air in plate passage are simulated to validate the procedure. In the simulation to one-dimensional deflagration of premixed acetylene-air flame, combustion speed and flame thichness are computed, and grid independence of numerical solution is analyzed.(3) Flame propagation and quenching in closed-open narrow channels are simulated, main conclusions are as follows.1) Effects of mass diffusion coefficient and heat loss on walls on flame shape are investigated. The results show that the increase of mass diffusion coefficient contributes to tulip-shaped flame. As mass diffusion coefficient is smaller than heat diffusion coefficient, named as Lewis number is bigger than or equal to one, mushroomed-shaped flame tends to form, while tulip-shaped flame tends to form as Lewis number is less than one. Heat loss at the cold walls is adverse to the formation of tulip-shaped flame. For adiabatic wall, tulip-shaped flame forms as length heightratio of narrow channels is less than 40, while, for isothermal wall, tulip-shaped flame forms as length height ratio of narrow channels is less than 30.2) By introducing non-dimensional quasi-extinction space, heat supply rate into analysis, the relationship of heat release of chemical reaction, heat loss on wall and flame propagation and quenching in narrow channels are analyzed systematically, and the criterion of flame propagation and quenching in narrow channels is put forward.(4) Flame propagation and quenching in open-open narrow channels are studied experimentally and theoretically. Experimental results show that, as channel height is given, quenching length is proportional to critical flame propagation speed approximately. The computed results show the same conclusion. The computed results are consistent with the experimental results as a whole.更多还原