基于双色法的层流扩散火焰温度场和烟黑浓度场重构

高温和烟气是火灾事故中造成人员伤亡的两个重要因素,能快速准确地获取火焰温度和烟黑浓度的分布,是对燃烧产热量和发烟量的控制方法进行深入研究的前提。根据双色法的理论基础,结合火焰单元的划分方法,整理并简化了火焰温度和烟黑浓度求解过程。利用自主开发的软件进行重构计算,并选取甲烷/空气轴对称层流扩散火焰为例进行试验。重构结果表明,烟黑浓度和温度的分布在轴向方向上均呈现双峰到单峰的特点。将重构结果和数值模拟的结果进行对比,发现温度峰值和烟黑浓度峰值的相对误差分别低于1.59%和6.08%,表明重构结果和模拟结果具有较好的一致性。因此,可认为该重构方法具有可行性。

Reconstruction of temperature field and soot concentration field of laminar diffusion flame based on two-color method

The paper is devoted to the study of a measurement method of flame temperature and soot concentration,which should be taken as a precondition of controlling the heat generation and soot formation in combustion. In this paper,we have adopted the two-color method as the basic algorithm for solving flame temperature value and soot concentration value. In order to minimize the experimental error caused by CCD spectral sensitivity,we have proposed a method to calibrate the correction coefficient based on simulation. Firstly,combined on the discretization method of the flame unit,we have simplified and collated the two-color theory, and obtained the mathematical model to solve the temperature field and the soot concentration field based on the flame radiation intensity. Then,we have chosen the methane axisymmetric laminar diffusion flame to carry out the experiment,which contains four groups of different conditions,the one was used for calibration and the other three were used for actual testing. On the one hand,we have used the CCD to capture the flame images and transferred its to the computer. The entire calculation process was executed through the self-developed program. On the other hand, for the purpose of calibrating the spectral correction factor and verifying the test results,we have used the Fluent numerical simulation software to simulate the same conditions as the above tests. The calibration results show that when the red light correction coefficient Kr = 2. 28,and the green light correction coefficient Kg = 1. 78,the results of the reconstruction and the numerical simulation are in good agreement in this condition. Finally, we have put the above calibration results as correction factors for the remaining three groups of conditions to solve. From the results, it can be found that the distribution of the temperature and the soot concentration in the axisymmetric laminar diffusion flame exhibits the structural feature from double peak to single peak. What's more,according to the comparison of the reconstruction results and the simulation results,the relative error of peak value of temperature and soot volume fraction is less than 1. 59％, 6. 08％. In summary,it can be seen that the proposed two-color method based on simulated calibration is feasible.