基于背景导向纹影的火焰三维温度场重建

3D Reconstruction of Flame Temperature Distribution Based on Background Oriented Schlieren

火焰三维温度场测量对揭示燃烧反应机理和传热规律具有重要作用,背景导向纹影层析技术(BOST)可通过对非定常三维流动的折射率场重建进一步获取流场的密度、温度等参数。本文采用镜头等效光学系统模型代替针孔模型,并使用龙格库塔光线追迹方法对背景导向纹影的成像过程进行了更精确的模拟。讨论了基于光流方程的BOST模型中有效光线数和图像像素位移对测量区域设置和图像采样分辨率的影响规律。基于光流方程重建模型对旋流火焰的温度场进行了重建模拟,重建温度场较好地反映出旋流火焰的褶皱和涡旋等边缘区域的轮廓结构,对火焰边缘区域的重建效果优于中心区域。

The measurement of 3D flame temperature distribution plays an important role in revealing the combustion reaction mechanism and heat transfer law. Background oriented schlieren tomography(BOST) can further obtain the density, temperature and other parameters of the flow field by reconstructing the refractive index field of the unsteady 3D flow. In this paper, the lens equivalent optical system model is used to replace the pinhole model, and the Runge Kutta ray tracing method is used to more accurately simulate the imaging process of background guided schlieren.The influence of effective light number and image pixel displacement in BOST model based on optical flow equation on measurement area setting and image sampling resolution is discussed. The reconstructed temperature field can well reflect the contour structure of the edge area such as the fold and vortex of the swirling flame, and the reconstruction effect of the edge area of the flame is better than that of the center area.