多相流体积区域内流动特征三维测量理论与方法

The modality and motion parameters of flow characteristics in volumetric region of multiphase flow, are of great importance on theoretical research and application to understand multiphase flow systems. In the project, a novel solution to measuring volumetric three-dimensional structure is proposed, and key technologies are studied further. ①An optical system of volumetric measurement based on continuous scanning of multi-edge flat crystal and simultaneous capturing of multi-view splitter is presented. The mathematical model is established, and laser, flat crystal system and multi-view vision sensor are optimized. The method breaks through the measurement limitation of particular cross-sections and huge difficulties in volumetric flow regions due to the block of concentrated particles. ② For the three-dimensional measurement of flow structures, a feature extraction method based on Gaussian regression is presented to achieve flow features in the structured light plane accurately, and a non-parameter calibration method of high-speed camera is proposed to reconstruct spatial features with high precision and without principle error. Combined with stereo matching based on Epipolar constraint, motion matching based on the most simulation of moving and gray values, and three-dimensional reconstruction method based on voxel, the volumetric three-dimensional flow characteristics are measured precisely. The project would provide a novel approach to measuring volumetric flow structure in multiphase flow, and offer a novel means to understand the flow characteristics and mechanism in the scientific research and engineering applications.

多相流体积区域内流动特征形态及运动参数，对研究多相流动系统具有重要的理论意义和研究价值。本项目针对体积区域流动特征可视化三维测量提出新的解决思路，并围绕关键技术进行深入研究。①提出并研究多棱平晶连续扫描，结合分幅多视角同步采集的体测光学系统，建立数学模型并对激光发射、平晶光路、分幅多视角传感器进行优化，突破传统流场只能针对特定截面，或在体积区域内无法实现有效测量的局限性；②针对流动参数三维测量，提出基于高斯衰减的结构光平面特征提取方法，准确获取流动特征；提出高精度、无原理误差的相机非参数模型校准新方法，准确、快速实现空间特征点三维重构；结合极线约束立体匹配，基于运动或灰度最大相似跟踪匹配，以及基于体素的三维映射及重建方法，实现体积区域流动参数的高精度三维测量。本项目将为多相流体积区域流动特征三维测量提供新的技术途径，并为科学研究和工程应用中深入认识两相/多相流动特性和机理提供新的研究手段。

针对目前多相流动过程中，体积区域内流动特征三维测量存在的不足及应用局限性，围绕多棱平晶高精度扫描提出一系列新的解决思路，研究了一种新的体积区域内流动特征三维测量理论与方法。建立了基于多棱平晶连续扫描的体测光学系统，实现了多棱平晶的连续光学扫描，并建立了相应的理论数学模型和近似数学模型，对入射角、平晶转速与相机帧频之间的关系等参数进行了分析和优化；对层间偏移进行了理论分析，并研究了层间偏移补偿方法，通过补偿因子对切片位置进行修正，实现了特征区域的准确对齐，提高了三维重建精度；采用纯光学方法模拟相机成像过程，研究了精确校准新方法，实现了角秒级别非参数模型相机校准；研究了切片层间插值技术、匹配和流场三维可视化技术，对密集泡状流的流场结构进行了三维重建，并对扫描区域内流场的体积空隙率参数等流动特性进行了分析。研究表明，采用基于激光扫描的流场三维可视化测量法，不仅可以重建流场的三维结构，而且可实现流场任意区域及全场流动状态的分析，相比传统方法，具有更大的测量范围和更高的分辨率，优势明显。本项目不仅为科学研究和工程领域中两相/多相运动特性研究提供了一种新的技术手段，也进一步推动了多相流检测技术的发展。围绕本项目研究内容，申请发明专利12 项，已授权4 项，在国内外核心刊物和国际会议上发表学术论文21 篇，其中SCI 收录9 篇、EI 收录9篇、ISTP收录2篇，培养硕士研究生8 名。