稀释气体对甲烷层流预混火焰燃烧速度的影响

Effects of Diluents Addition on Laminar Burning Velocity of Premixed Methane Flames

摘要:

基于GRIMech 3.0详细化学反应机理,利用预混燃烧模型(PREMIX Code)研究了甲烷空气稀释气层流预混火焰燃烧特性及火焰结构.重点探讨了不同化学当量比(0.5～1.5)、初始压力(0.05～0.40 MPa)、稀释气体种类(N2,CO2及H2O)和稀释摩尔比(0~0.35)对甲烷空气稀释气混合气层流预混火焰结构、层流燃烧速度、火焰厚度的影响.研究结果表明:随着稀释比的增加,层流燃烧速度逐渐变小，火焰厚度增大,火焰流动不稳定性得到抑制;CO2作为稀释气时对层流燃烧速度及火焰厚度影响最为显著.随着初始压力提高,层流燃烧速度及火焰厚度均变小;进一步提高初始压力,对火焰厚度影响并不明显.

Abstract:

Based on the GRIMech 3.0 mechanism,the premixed laminar combustion characteristics of methaneairdiluent mixtures were investigated by using PREMIXED Code.Several fundamental parameters,such as flame structure,laminar burning velocity,and flame thickness,were calculated at different equivalence ratios,initial pressures,and dilution ratios.It was found that increasing the dilution ratio in the mixture would lead to a decrease in laminar burning velocity and an increase of flame thickness.As a result,the hydrodynamic instability of methaneair laminar flame was suppressed with the addition of diluents,especially in the condition of CO2 dilution.When the initial pressure increased,the laminar burning velocity and flame thickness decreased accordingly.However,a further increase of the initial pressure did not have much effect on the flame thickness.