钝体燃烧器火焰变化过程的速度分布特性

实验测量了变工况钝体回流扩散燃烧速度场，定量确定钝体回流燃烧火焰和中心射流主导火焰的转换曲线，分析了燃空速度比对燃烧稳定性的影响。实验中利用粒子图像速度场测量(PIV)技术对不同燃空速度比下的钝体回流扩散燃烧流场进行了测量，考察不同火焰的结构特性及其内部流动状况。由火焰的速度场出发，确定了钝体回流燃烧火焰和中心射流主导火焰的转换曲线。根据测量所得数据发现燃空速度比是决定钝体轴线上最小速度大小及相对位置的主要因素，燃空速度比是决定钝体轴线最小速度与钝体表面距离的重要参数：随着燃空速度比的增加，轴线上最小速度与钝体表面的相对距离先迅速增加，后略有降低，然后再次迅速增加；轴线上最小速度与燃空速度比成线性关系，随着燃空速度比的增加，轴线上最小速度不断增加。

Velocity Characteristic Distribution With Variation of Flames in Bluff-body Burner

Experiments were performed to investigate the characteristic modes and structures of non-premixed circular-disc stabilized flames under different operation conditions,and a detail regime diagram between recirculation zone flame and central-jet dominated flame was presented.By particle image velocimetry(PIV)technique,the experiment measured the velocity distributions of the non-premixed circular-disc stabilized flames with different fuel jet to annular air flow velocity ratios,and the characteristic modes and structures were observed.The results show the fuel jet to annular air flow velocity ratio is a controlling parameter to the velocity distributions and characteristic modes of the non-premixed circular-disc stabilized flames.With the increase of the fuel jet to annular air flow velocity ratio,minimum axial velocity on centerline adds;the distance between bluff-body and the position of minimum axial velocity on centerline increases.The experiment also shows that there is a function relationship between the velocity ratio and the distance from bluff-body surface to the point of the minimum mean axial velocity of centerline.The regime diagram between recirculation zone flame and central-jet dominated flame can also be plotted precisely according to the relationship curves of the velocity ratio and the minimum mean axial velocity of centerline.