炉膛燃烧温度场三维可视化监测方法模拟研究

Numerical Simulation on a Visualization Monitoring Method of Three-Dimensional Temperature Distribution in Furnace

为了利用火焰图像监测装置检测到的炉膛燃烧辐射能分布图像信息重建三维燃烧温度场 ,作者提出了一种针孔成像条件下的快速方法计算 CCD (Charge-Coupled Device,电荷耦合器件 )靶面接收的辐射能。成像像素接收到的系统网格单元的辐射能的份额的计算结果和辐射能图像计算结果均体现了成像过程的方向选择性和辐射能传递规律的作用。针对炉膛燃烧三维温度场重建的严重病态问题建立了一种基于Tikhonov正则化的求解方法。对于单峰型三维温度分布重建模拟计算结果表明 :即使辐射图像检测包含均方差达到 0 .1 1的误差 ,温度场重建误差仍能维持与测量误差基本相当的水平 ,温度分布可视化质量较高。各种图像检测组合方式的重建结果比较显示 ,炉膛四角沿高度方向每隔 5 m左右交叉对角布置两个辐射图像采集装置 ,能够获得较好的全炉膛温度场可视化结果。图 6参 1

In order to reconstruct three dimensional combustion temperature distributions in furnaces through using radiative energy images detected by flame image monitoring devices, the radiative energy received by the target of CCD(Charge Coupled Device) is calculated by the fast algorithm proposed by the authors under pinhole image formation conditions. Calculation results for the energy ratio received by the image elements from the energy emitted by the furnace mesh elements and the radiative energy images can demonstrate the directionally selective characteristics and the influence of radiative heat transfer during the image formation processes. For the solution of the 3 D temperature distribution which is an ill posed problem, a modified Tikhonov regularization method is established. For a 3 D single peaked temperature distribution, the numerical simulation results show that the reconstruction errors for the 3 D temperature distribution can be maintained at the levels similar to the measurement errors up to 0.11, and the visualization quality of the temperature distribution is satisfactory. Comparative studies show that every tow image detectors mounted diagonally in one layer with about 5 meters between adjacent layers can lead to a good visualization result. So the method developed in this paper can be used to monitor the 3 D temperature distribution of large scale utility boilers, which will improve the diagnostics and optimal control of combustion and the operation of boilers.Figs 7 and refs 12.