定容燃烧火焰传播半径测量准确度的研究

Study on Accuracy of Measuring Propagation Radius of Constant Volume Combustion Flame

利用MATLAB软件编写了纹影图片批量处理程序,从火焰传播各方向上获得半径值,提出以半径均值、半径均值相对误差和半径提取值标准偏差3个指标来评价火焰传播半径的分布状态.研究表明:点火电极是导致火焰传播失真的重要原因,通过优化排除点火电极的影响角度范围(γ为65°~115°和245°~295°)来减小测量误差;优化后,半径均值增幅为0.96%~2.08%,半径均值相对误差减小为-0.06~0.86,半径提取值标准偏差减幅为44.20%~71.33%.综合考虑,在初始温度Tu=323 K、初始压力pu=0.1 MPa、当量比φ=1.0和稀释率φr=6%工况下,优化选择的火焰传播半径测量角度步长Δθ=6°.

A program of batching schlieren photographs was compiled on MATLAB software to get flame propagation radius values in all directions.The distribution of flame propagation radius was evaluated by three parameters:the mean value of flame propagation radius,the relative error of mean value of radius and the standard deviation of radius.It is found that the ignition electrode is an important cause for flame propagation distortion.Therefore,the measurement error could be reduced by optimizing the range of influence of the ignition electrode(γ=65°~115°andγ=245°~295°).After optimization,the mean value of flame propagation radius increases from 0.96%to 2.08%,reduction range of the relative error of mean value of radius is from-0.06 to 0.86,and the standard deviation of radius decreases from 44.20%to 71.33%.Based on the above analysis,the measurement angle step selected by optimization isΔθ=6°under the condition of Tu=323 K,pu=0.1MPa,φ=1.0 andφr=6%.