基于CT系统的两相流包络检测系统研究

Research of two-phase flow boundary detection method based on CT system

计算机断层扫描技术(CT)是有效的非接触测量手段。论文设计了一套用于检测管道中两相流介质占比包络的CT图像重建系统。管道中流体即测量目标的状态随时间不断变化,传统的旋转CT系统由于需要等待照影过程实时性不足。本系统使用五边形结构的探测器组,相比传统的旋转CT系统优点是位五个方向的探测器立即获得照影数据,在探测器数据的基础上实时生成CT重建图像,不必等待探测器完成照影。重建图像的质量由照影数据量决定,不同于旋转CT系统长时间照影获得丰富的数据能得到高质量图像,本系统照影时间短,实时性高,数据不足将导致图像失真。为消除图像失真对测量结果的不利影响,CT重建系统在图像后期处理算法中使用数据反演技术和系统校准两种手段修正图像失真。重建系统的目的在于确定密封管道中两相流流体包络,根据管道尺寸等先验信息确定图像边界,丢弃多余的失真图像数据保留需要的流体边界,完成对管道中两相流流体边界包络检测。

Computerized tomography(CT)is an effective non-contact measurement method.Paper has designed a boundary detection system based on CT technique for two-phase flow in pipeline.The object which is flow material in the pipeline is changed in every minute.Traditional CT system structure as source and sensor group mounted on a rotation holder which is move surround object need long projection time.CT system use five source and sensor group in a pentagon structure which be used to reconstruct real-time flow picture through projection data.It is known that the reconstructed picture quality is based on projection data,more data means higher quality reconstructed picture and longer processing time.Due to short projection time,system’s data acquired is insufficient which will naturally leads to image distortion.Data expansion technique and system calibration had been used in data processing system to correct image distortion.The goal of hole system is to acquire data through a CT system to find out two-phase flow boundary in pipe line.Consider prior information like geometry of pipeline it is possible to abandon distortion image data out of area of interest without process and focus on flow material boundary detection.