高压甲烷射流冲击预混火焰过程中涡量的变化

Vorticity Variation of High-Pressure Methane Jet Impinging on Premixed Flame

基于CONVERGE软件开展三维仿真计算,分析了定容燃烧弹内高压甲烷射流撞击当量比为1的预混气体燃烧过程中的涡量变化特征.根据射流前锋面与火焰的位置关系,将火焰发展全过程分为射流前峰面未接触火焰阶段、进入火焰阶段和离开火焰阶段3个阶段.相比于自由射流贯穿速度,在射流进入火焰阶段射流燃烧平均贯穿速度显著增加,并大于自由射流的贯穿速度和预混燃烧速度之和.产生此结果的原因是此阶段动量参数涡量的大幅增加;在轴向距离为40 mm处、火焰发展时间为1.6 ms时,射流燃烧模式平均涡量值与自由射流模式差值最大,约为260 s^(-1),是此时此截面预混燃烧模式平均涡量值6 s^(-1)的43倍.

Based on the software CONVERGE,a three-dimensional simulation was carried out to analyze the characteristics of vorticity changes during the combustion of premixed gas with a constant volume incendiary bomb when the high-pressure methane jet impinges on the premixed gas with an equivalence ratio of 1.According to the position relationship between the front surface of the jet and the flame,the whole flame development process is divided into three stages:the none-contact frame stage before the jet front meeting the flame,the entering flame stage and the leaving flame stage.Compared with the free jet penetration velocity,the average penetration velocity of jet combustion increases significantly at the stage of jet entering the flame,and is greater than the sum of the free jet penetration velocity and premixed combustion velocity.The reason for this result is that the vorticity of momentum parameter increases greatly at this stage.At an axial distance of 40 mm with a flame development time of 1.6 ms,the maximum difference between the average vorticity value of jet combustion mode and that of free jet combustion mode is about 260 s^(-1),which is 43 times of the average vorticity value of premixed combustion mode at this section at this time.