颗粒两相流超声过程层析成像系统研究(英文)

An investigation on ultrasonic process tomography system for particle two-phase flow measurement

本文主要介绍了一种基于透射模式的超声波层析成像系统的设计与研究.针对Radon变换与Radon反变换对获得精确重建图像所提出的无限多的投影数据要求,系统在以下几个方面做了改进:系统换能器阵列由16个换能器组成,每个换能器均可以作为发射端和接收端,可发射的扇形波束角度为150°;基于LabVIEW软件和2块高速同步数据采集卡,设计了16通道的数据同步采集和信号处理装置;利用单片机89S52设计了切换电路,可以实现16换能器的激励和接收功能的自动切换.经实验验证,系统结构简单,实时性好,获得了足够多有效的信号数据,通过二值化逻辑反投影图像重建算法实现了研究物体横断面的图像重建.

Ultrasonic process tomography has revealed many advantages and promising applications in industry process on line measurement and environmental monitoring. However, what still remains as a crucial problem in this technology is the quick and synchronous acquisition of useful and sufficient experimental data,which play a key role in the mathematical inversion and image reconstruction. This work presented a transmission-mode ultrasonic process tomography system consisting of a sensor array with a high speed data acquisition card（DAQ）and signal processing devices with switching device. The sensor array contains 16 ultrasonic transducers and each transducer can emit fan-shaped beams with angle as large as 150 degrees, A personal computer is used for recording experimental data and communicates with the other device as a host. By implementing a LabVIEW-based program it can synchronously acquire the real time data of 16 channels of two DAQ cards at 12 bit resolution, where the multiple-channels switching device with microprogrammed control unit（MCU）is of utmost importance for real-time measurements. Though the configuration of this system has feature of simple and easy operation, an experiment on Teflon cylinder has demonstrated that it can work well in one transmitting and multi receiving mode in which the attenuated ultrasonic waves from the transmitting transducer can be received by other transducers simultaneously. More significantly, an accurate cross-section image of the object under investigation can be reconstructed using the experimental data.