甲烷-空气预混火焰越过不同形状障碍物的实验研究

对甲烷-空气预混火焰越过安装于燃烧室内底壁的多种形状障碍物进行了系列实验。以高速阴影摄影获取火焰阵面变化的序列相片,准确地记录了流场和火焰的变化过程。结果表明,障碍物的上表面对诱导湍流具有十分重要的影响,而障碍物下游的回旋区会导致火焰的翻卷和弯曲。变形火焰在未燃气体中产生的压缩波在壁面进行反射并在燃烧区反复穿越,也大大破坏了火焰的稳定性。不同形状的障碍物对火焰稳定性的影响呈现的特点不同,但最终均能导致湍流燃烧和加速。

Experimental investigation of CH4-air premixed flame-obstacle interaction

Series of experiments have been performed to investigate the premixed flame behavior during its propagating in a rectangular chamber with various obstacles mounted on the bottom wall.A high speed shadowgraph system was used to obtain the sequential images of flame front development,and to record correctly the interaction process between the fluid flow and flame.The measured results show that upper surface of the obstacles has an important influence on the induction of turbulence,while the recirculation zone behind the obstacle can lead to the convolution and curvature.The compressed waves,which produced by deformed flame in the unburnt gas,reflect on the wall and travel through the combustion zone.These processes significantly result in the instability of the flame.The effects of different shapes of obstacle on the flame instability are examined,and it is found that all of these obstacles can lead to the turbulent combustion and flame propagation acceleration.