基于MATLAB图像处理的层流火焰传播速度研究

为了减小传统本生灯火焰法测定层流预混火焰传播速度的误差,基于MATLAB图像处理技术提出了一种改进火焰图像处理及提取火焰边界线数据的方法。该方法对图像进行优化处理后运用LOG算子检测边缘信息,并为其添加平滑曲线;然后将散点拟合为函数表达式,选用Polynomial逼近方式修正拟合曲线误差;换算为实际坐标后对拟合函数进行面积积分计算,即得更接近真实的火焰外表面积。利用该方法对不同当量比下甲烷燃烧的本生灯火焰图像进行处理,求取其层流火焰传播速度,并与前人结果进行对比。结果表明,传统全面积法所得结果普遍偏高;相比于Vagelopulous利用平面火焰法所得结果,该方法获取的层流火焰传播速度在贫燃侧与之相近,在富燃侧则较之略低。

On the laminar flame spreading speed based on the MATLAB image processing technology

The given article is to make a comparative study for the disadvantage of the conic surface areamethod in calculating the surface area of Bunsen burner flame.To promote the calculating accuracy of the traditional method,we have proposed an innovated method known as the MATLAB image processing technology in hoping to improve the said technology so as to heighten theaccuracy of the flame boundary line.For this purpose,we have,first of all,managed to optimize the image quality of the Bunsen burner flame through image cutting and filtering in addition to the screen enhancement.To be accurate,the operator can manage to identify and determine the edge information,so that the LOG edge detection operator can obtain the most suitable approach to precising the boundary line of the Bunsen flame image,and then we may try to set the threshold at 1/255 to get the optimistic results.In addition,we may choose the second smooth method to connect the scatter extracted by LOG,so as for the scatter to be fitted into the function expression,leaving the error of the fitting curve to be corrected by the method of polynomial approximation.Transformed into the actual value,the surface area of the flame can then be obtained by the integral calculation of the fitting function to be made closer to the true size.In so doing,it would be possible for the flame image of methane Bunsen burner under different equivalence ratio to be further processed to reach a more accurate laminar flame speed.Thus,the results of the traditional surface area method can be made generally of greater efficiency.Moreover,incomparison with the results given by Vagelopoulos by using the plane flame method,the laminar flame speed obtained by using the former method turns to be similar to those on the fuel-lean side and slightly lower on the fuel-rich side.In spite of this,the experimental results of this paper prove on the whole tends to be lower,which may come up to because the surface area of the flame obtained by the image processing technique according to the shape of the real flame turns to begreater than that calculated by the conicsurface area method.