湍流射流与扩散火焰大涡拟序结构的波动特性研究

THE STUDY ON WAVE CHARACTERISTICSOF THE COHERENT STRUCTURE INTURBULENT JET ANDDIFFUSION FLAME

１前言湍流射流扩散燃烧方式提供了射流火焰与涡团相互作用的最基本形式，对研究在湍流射流剪切边界层内的反应物的卷吸混合、热量及动量的输运及湍流射流结构方面具有其特殊的意义。Ｋａｔｔａ［１］利用浮力与单步反应机理模型对Ｎ２－Ｈ２射流扩散火焰进行了直接数值模...

Using the quasi-high speed image collecting technology and the digital image processingtechnique, the clear image sequences of 2-dimension large scale coherent vortex structure inshearing boundary layer of turbulent jet and diffusion flame were acquired. Three regionswere divided in streamwise according to the evolving procedure of coherent structure, whichnamed as the inducing region, the developing region and the breaking region. The obviouswave characteristics developed from Kelvin-Helmholtz type instability were observed in theshearing layer of developing region. The scale of coherent structure in cold jet were smallerthan that in diffusion flame, but the structure can maintain for a longer distance in streamwise. The influence of shearing velocity of the coherent structure shows that the instabilityof wave may be the crucial factor which control the coherent phenomena.