湍流加速火焰的三维数值模拟

Numerical simulation of turbulent accelerating flame in three dimensi onal flows

火焰在设有障碍物的管内传播时会自身加速 ,并可能导致爆炸。本文基于湍流 k-ε模型和改进的 EBU-Arrhenius反应模型 ,对该现象进行了三维空间的数值模拟。计算结果反映了障碍物、湍流和火焰之间相互作用的正反馈机理 。

Based on the κ-Ε turbulent model and improved EBU-Arrhenius combustion model, the three dimensional numerical calculations were performed by using SIMPLE schemes for simulating the self-accelerating flame in a rectangular tube installed with an obstacle, where the wall function methods were used to deal with the effects of the surfaces of the tube wall and the obstacle. The calculated results show that before the flame front crosses the obstacle, the flow induced by the expansions of combustion products has been affected by the obstacle, which causes the variations in the shape of flame front. The back flow and the recirculation will occur above and in front of the obstacle respectively, when the flame front passes through the obstacle. The propagating velocities of the flame front near the center line and the upper corners are much higher than that on the other parts of the flame front. The mechanics of the flame accelerations and the positive-feedback interactions among the obstacle, turbulence and flame have been also discussed.