【作者】 李慧勇；

【导师】 陈冬林；

【作者基本信息】 长沙理工大学 ， 动力机械及工程， 2007， 硕士

【摘要】 电站锅炉炉内流场的分布对锅炉运行的安全性和经济性有重要影响,而燃烧器区域流场的调控几乎是工程应用中改善全炉膛流场分布特性的唯一有效手段,因此对燃烧器区域流场进行监控和研究意义重大。本文构建了炉内冷态流场可视化系统,并借助可视化手段获取了燃烧器出口冷态射流图像;开发了射流图像处理软件,设计并优化了燃烧器射流流场分析及特征参数提取算法,并用这些算法对所得射流图像进行分析,最终成功提取了射流的边缘轮廓及其它几何参数。算法实现具体流程如下:①用加权中值滤波算法抑制射流图像离散点噪声;②种子区域生长算法将射流从图像背景中分离出来;③自适应边缘检测算法检测射流边缘像素点;④广义最小二乘法对射流边缘点进行线性拟合;⑤确定射流的几何中心线位置、中心角及射流扩展角等特征参数,这些特征参数可用于定量分析燃烧器区域冷态流场分布特性,并能较精确的预测热态工况下炉膛内流场的组织合理性。图像处理过程表明:以10×10窗口处理图像噪声,选择射流图像中亮度值最高的像素为种子并以5%为误差限确定生长准则,整个流程消耗时间与处理精度的匹配最优。以配置为AMD3000+处理器,512M内存的个人计算机测试,整个算法流程耗时2～4秒。该方法数据处理的快捷性、算法的稳定性和可靠性,为燃烧器射流流场的实时分析提供了保证。可视化技术的引入使流场的实时监控成为可能,而图像处理技术又为电站锅炉炉内流场的计算机辅助分析提供了充分的数据支持。与传统研究方法相比,基于可视化技术的射流图像处理方法,融合了光电信息、计算机视觉、图像处理等前沿学科的研究成果,不但注重从外形轮廓的角度直观反映流场特性,同时还可以用射流的几何特征参数对流场特性作定量描述。本论文的研究为电站锅炉炉内流场的可视化提供了一种新的研究思路,也为流场的计算机辅助分析及自动控制提供了一条可行的研究途径。更多还原

【Abstract】 The distribution of flow fields in burners is of vital importance for the safety and economic performance of PC-fired boilers. However, the only effective approach in approving the overall flow-field structure in the furnaces seems to be the adjustment of the flow field near the burner zone. Therefore, monitoring and studying the flow field in the burner zone is of great significance.In this thesis, a system for the visualization of cold flow-field in furnace is constructed, and visualization methods are applied to obtain image of the cold-state jet flow at the burner’s outlet; a software for the processing of the jet images is developed and algorithms are designed and optimized so that digital image processing techniques are used to analyze the obtained image and at the same time extract geometric parameters such as the edges of the jet. The procedure of the algorithms steps as follow:①discrete-points noise denoising based on weighted mean filter algorithm;②image segmentation based on region growing algorithm;③acquiring edge pixels based on adaptive edge detection algorithm;④linear model based on generalized least square method;⑤locating the centerline position of jet and extracting other geometric parameters such as the angle between two linear edges and angle information of the jet geometric centerline, and these parameters can be used for the quantitative analysis of the distribution characteristics of the cold-state flow at the burner zone, also more accurately predict how reasonable the structural organization of the flow field inside the furnace is under heat-state conditions. Research results show the relationship between time-consuming and data precision is optimum when a 10×10 filter operator is chosen and a 5% tolerance of image dynamic is set between the seed value and the edge pixel value according to the growing rule. Time-consuming is about 2~4 seconds to complete the all image processing procedure in a personal computer equipping an AMD 3000+ CPU and a 512MB memory. Considering the shortcutting in data-processing and the stability and reliability of the algorithm, the approach has a potential meaning for real-time analysis of flow field of a burner’s jet in furnaces.The introduction of visualization techniques make real-time monitoring of the flow possible, and digital image processing techniques provides sufficient data to support computerized analysis of the flow field. Compared with traditional research methods, the novel method of visualization combined with digital image processing integrates photoelectric information, computer vision, image processing techniques and other cutting-edge research results. It not only enables direct visualization of the flow field, paying attention to the qualitative geometric characteristics the qualitative geometric characteristics, but also allows quantitative description of the flow characteristics by using the geometric parameters obtained from the jet. Fast data processing, stable and reliable feature extraction algorithm of this method is bound to give it broad practical application prospects.This thesis studies the visualization of flow fields inside boilers in power stations. It provides the topic with a new research idea, and a new feasible research approach for the computer-aided analysis of flow field characteristics.更多还原