纹影定量化在火焰温度测量中的应用

基于传统“Z”字形纹影系统,采用标准光度法对火焰温度进行了定量化。标准光度法通过一个标定镜片来建立火焰纹影图像的灰度值和光线偏转角之间的定量关系,并利用轴对称假设建立光线偏转角和折射率之间的关系。最后通过盖斯定律和理想气体方程得到火焰温度。对其中涉及到的反演算法进行了比较,结果显示直接积分法和 Abel 逆变换法误差最小,Radon 逆变换受滤波函数影响较大,而迭代重建法在离散点数量较少的情况下误差最大。将纹影定量化所得到的温度曲线和热电偶所测结果值比较,证明了标准光度法对纹影火焰定量化的有效性。

Application of quantitative schlieren method in flame temperature measurement

The frame temperature is measured using ‘Z’type schlieren by standard photomet-ric method.The relationship between the grayscale value of flame schlieren image and the deflec-tion angle is established through a calibration lens.The refraction index is obtained by using axi-symmetric assumption.Then by using the Gladstone-Dale relationship and the ideal gas law,the flame temperature is obtained.The comparison of involved inversion algorithms shows that,the direct integral method and the Abel inversion method can both achieve the least error,however, the Radon inversion strongly depends on the filter function and the algebraic reconstruction de-pends on the numbers of discrete points.The temperature reconstructed by the quantitative schlieren technique is compared to thermocouple measurements.The results prove the validation of this quantitative technique.