利用高速摄影法及数字图像处理技术得到生物柴油燃烧火焰图像，并通过Matlab软件求取火焰长度和面积，研究了空气预热温度对火焰形态、长度、面积的影响。实验中共设定了9个空气温度：20℃、80℃、140℃、220℃、290℃、350℃、400℃、450℃和500℃。结果表明：空气预热温度较低时，生物柴油火焰结构分散、主要燃烧区（火焰亮度较高区域）面积较小且连续性差；空气预热温度升高后，火焰结构更紧凑、主要燃烧区面积增大、亮度明显增加、连续性变好。各个工况下火焰长度和面积不是一个定值，而是在一定范围内剧烈地震荡，随着空气预热温度的升高，火焰平均长度和平均面积有相近的变化趋势：先明显减小，再逐渐上升。%The flame images of biodiesel were obtained by using high-speed photography method and digital image processing technique, and the length and area of the flame were calculated by Matlab software. The effects of preheated air temperature on shape, length as well as area of the flame were discussed. 9 preheated air temperatures were set up in the experiment: 20oC, 80oC, 140oC, 220oC, 290oC, 350oC, 400oC, 450oC and 500oC. Results show that at low preheated air temperature, the flame of biodiesel has a dispersed format and poor continuity and the main combustion area, that is the high brightness area, is small. As the preheated air temperature increases, the flame is more compact and in good continuity, the main combustion area is larger and the brightness increases significantly. The length and area of flame vibrate intensely at each working condition, the mean length and area of flame have the same trend:with the increase of temperature, the mean length and area first decrease obviously, and then increase gradually.
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