直线运动火源扩散火焰结构特征的试验研究

Experiment Study of Diffusion Flame Features on Linear Mobile Fire

运动火源燃烧引起的空气湍动受火源运动和燃烧双重影响,导致其火焰结构变得更加复杂。采用数字摄像系统,对风洞中直线运动蜡烛火源的扩散燃烧过程进行了拍摄。运用图像对比和一阶Robert算子边缘检测,对火焰结构的静态特征和动态特征进行了分析,以探究直线运动火源扩散火焰结构特征,及其与绝对静止扩散火焰结构的内在物理本质区别。研究结果表明:风洞内做直线运动的蜡烛在火源燃烧的过程中,蜡烛运动速度会对流动、传热和燃烧产生明显影响,从而引起火焰形状、边缘和面积均发生规律性变化。通过对火源相对静止和绝对静止的对比发现:火源运动与外界风速引起的火焰面形态变化不是完全等效的,即移动火源与静止火源燃烧产生的火焰结构存在差异,采用相对运动概念来分析移动火源扩散火焰结构特征,可能与实际情况不吻合。

Air turbulence caused by the burning of mobile fire and affected by fire movement and fire burning makes the flame structure more complicated.In this paper,a digital cameral system was used to shoot the diffusion flames process of mobile fire in wind tunnel.At the same time by using image comparison and edge detection of Robert operator,static and dynamic characters of the flame structure were analyzed to study the diffusion flame structural characters of the mobile fire and essential distinction compared with diffusion flame structural characters of the absolute rest.The results show that the velocity of fire movement has appreciable effect on flow,heat transfer and burning in process of mobile fire in wind tunnel.These causes the change of flame shapes,edges and areas regularly.By comparing relative rest of the fire with absolute rest,the fire movement is not equal to the change of flame shapes caused by external wind.So the concept of relative motion cannot be used to analyze mobile fire burning.