方形管内楔形障碍物对火焰结构与传播的影响

Effects of a wedge obstacle on flame propagation and its structure

通过实验与数值模拟方法对CH4/空气预混火焰在有楔形障碍物的卧式燃烧方管内的传播进行了研究。采用多镜头Cranz&Schardin高速摄像机和压力传感器等实验设备获得了高清晰度的障碍物诱导火焰失稳的分幅时序照片以及障碍物背风表面压力变化曲线。数值模拟则基于RANS方法与EDU-Arrhenius燃烧模型,计算结果与实验结果基本相符,反映了火焰在管内传播与变形的详细过程。通过综合分析实验与计算结果,得到了由楔形障碍物导致的火焰加速与变形的内在机理,揭示了火焰传播过程中由层流燃烧向湍流燃烧转捩的本质。

Experimental and numerical investigations were performed on the CH4/Air mixture premixed flame propagation in a horizontal rectangle tube with a wedge obstacle mounted at the bottom. The multiple-lens, Cranz ＆ Schardin high speed video system and pressure transducer etc experimental equipment were adopted to visualize the interaction between the wedge block and flame and to measure the flow parameters. Sequences of high-speed images with high definition showing the process of a flame losing its stability under the action of the wedge obstacle and pressure history on the backside of the obstacle were gained. Based on RANS method and EBU-Arrhenius combustion model, a numerical simulation was carried out to simulate the above complex physical phenomenon. Both experimental and numerical results are in good agreement, which show the inherent mechanism of flame acceleration and its front distortion, as well as the nature of a transition from laminar combustion to turbulence during its propagation.