Based on the image processing technology and the largest Lyapunov exponent, this paper proposes a novel method for quantitative characterization of flame images to reflect flame instability in combustion chamber. The best threshold is obtained by an iterative method of red component to separation flame region. The combustion index is defined as the ratio of proportion of flame pixels to gray standard deviation of flame region for characterization spatial distribution of flame. Unsteady motions of the flames are characterized by the nonlinear time series of combustion index and largest Lyapunov exponent. Results show that the linear relation between combustion index and largest Lyapunov exponent are noticeable with a correlation coefficient of 0.7874 under same work condition. With quantitative research for the relationship between chaos and combustion state, The largest Lyapunov exponent not only can judge whether the flame is nonchaotic or chaotic, the value of it also reflected the combustion state, the chaometry.

中文翻译：

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非预混生物柴油/喷气火焰不稳定燃烧过程的可视化研究▴

基于图像处理技术和最大的李雅普诺夫指数，提出了一种新颖的火焰图像定量表征方法，以反映燃烧室内火焰的不稳定性。最佳阈值是通过红色分量与火焰区域分离的迭代方法获得的。燃烧指数定义为火焰像素比例与火焰区域灰度标准偏差之比，用于表征火焰的空间分布。火焰的非定常运动的特征在于燃烧指数的非线性时间序列和最大的Lyapunov指数。结果表明，在相同工作条件下，燃烧指数与最大李雅普诺夫指数之间存在线性关系，相关系数为0.7874。