若干湍流间歇性的射流火焰熄火机理研究

利用数字图像技术和激光层析技术，提出了利用大尺度涡团结构和湍流间歇性来揭示火焰脱火和熄灭现象的新思路，通过对射流浓度场的空间相关性分析发现，在射流内部存在着大惊讶浓度涡团，这些涡团结构在不同的射流高度上的分布和尺度均有自相似性，建立了等温射流混合的简化模型，利用标量浓度场和涡旋动量场来描述由大尺度涡团的运动所造成的射流边界的间歇性，利用这一模型对射流边界的卷吸、燃料与氧化剂的混合，以及这种作用对扩散火焰点火条件的影响进行了解释，对模型与试验中获得的临界熄火现象进行了对比，结果令人满意。

Mechanism of Extinction in Turbulent Jet Flame Based on the TurbulentIntermittence

Using the digital image processing technique and the laser tomography technique, a novel approach based on the turbulent intermittence was proposed here to describe the extinction process of turbulent flame. The spatial correlation analysis on the concentration field of the jet showed that there were large scale vortexes with self?similar distribution and scale in both radial and axial directions of the jet. The isothermal mixing model was established to describe the intermittency resulted from the movement of vortexes at the jet boundary using scalar conentration field and vorticity momentum field. The effects of engulfment at jet boundary on the extinction and ignition were explained theoretically. The comparison between theoretical and experimental results was satisfactory.