特征管内H2/Air预混气体燃爆特性数值模拟研究

Numerical Simulation of Combustion and Explosion Characteristics of Premixed H2/Air Gas in Characteristic Tubes

基于标准k-ε湍流模型和EBU-Arrhenius燃烧模型,利用流体动力学软件Fluent数值模拟研究两种管(水平直管和直角弯管)内H2/Air预混气体燃爆过程中火焰锋面传播及演变过程以及燃爆特征参数的动态分布情况,并进一步研究不同初始温度(300K、373K、413K和475K)和初始压力(1.0Atm、1.5Atm和2.0Atm)对预混H2/Air燃爆特征参数的影响。研究结果表明:水平直管内H2/Air预混火焰锋面经历了球形火焰、椭圆形火焰、平面火焰、褶皱“V”形火焰和光滑“V”形火焰的演变过程,而直角弯管结构促使对称的“V”形火焰锋面演变为上火舌长、下火舌短的非对称“V”形火焰锋面结构。两管中点火前初始温度对管内峰值压力和气流峰值速度的影响呈现负相关性;而初始压力对管内峰值压力的影响呈现正相关性,但对管内峰值温度和气流流速的影响并不明显。水平直管内燃烧反应和预混火焰的传播以及直角弯管内上弯壁面阻碍反射和下弯壁面的突扩诱导作用是H2/Air预混气体燃爆过程湍流涡运动的产生、运动、转变及消散的动态演变过程的根本。

Numerical simulation of the flame front propagation and evolution during the combustion and explosion process of premixed H2/Air gas in two kinds of tubes(straight tube and right-angle tube) is conducted through fluid dynamics software Fluent,which based on the standard k-ε turbulence model and EBU-Arrhenius combustion model.Such simulation is also applied on the analysis of the dynamic distribution of characteristic parameters of combustion and explosion for the same premixed H2/Air gas.Furthermore,the influence of different initial temperatures(300 K,373 K,413 K and 475 K) and initial pressures(1.0 Atm,1.5 Atm and 2.0 Atm) on the characteristics of premixed H2/Air gas combustion and explosion parameters are considered.The results show that the flame front in straight tube experiences an evolution process of spherical flame,oval flame,plane flame,folded "V" flame and smooth "V" flame,while in the right-angle tube, the symmetrical "V" shape flame front evolves into an asymmetric "V" shape with long upper flame tongue and short lower flame tongue due to the right-angle structure.The initial ignition temperature shows negative correlation with the peak pressure and flow velocity in the two tubes.The initial pressure shows positive correlation with the peak pressure without significant influence on the peak temperature and airflow velocity in the two tubes.The reason for the generation,movement,transformation and dissipation of turbulent vortex during the premixed H2/Air gas combustion and explosion process maybe as follows:the combustion reaction and premixed flame propagation in the horizontal straight tube;the obstruction of reflection from the upper curved wall and the sudden expansion induced in lower curved wall in the right-angle tube.