湍流射流扩散火焰的层流火焰面模拟

Flamelet modeling of turbulent jet non-premixed flame

采用双尺度k ε湍流模型 ,标量联合的概率密度函数 (PDF)输运方程和层流火焰面模型相结合 ,模拟湍流射流扩散火焰。比较了几种不同k ε湍流模型对轴对称湍流射流速度场模拟的结果 ,建立了混合物分数和湍流频率的联合PDF输运方程 ,并假定湍流频率和标量频率的线性关系 ,得到标量耗散率的概率分布 ,化学组分的浓度和温度由层流火焰面系综的平均得到。

A turbulent jet non-premixed flame was numerically simulated by the combination of a two-scale κ-Ε turbulence model, the scalar joint PDF transport equation and the laminar flamelet model. The velocity field results calculated by several different κ-Ε turbulence models were compared. The joint PDF equation of mixture fraction and turbulence frequency was derived. And with the assumption of linear relation between turbulence frequency and scalar frequency, the probability distribution of scalar dissipation rate was obtained. Consequently, the species concentration and temperature were computed according to the ensemble average of the laminar flamelets. The numerical results were compared with results from direct chemical reaction calculations and the experimental data.