气液两相流超声过程层析成像理论与实验

Theory and experiment of ultrasonic process tomography for gas-liquid two-phase flow measurement

采用超声过程层析技术对气泡流动进行理论和实验研究。为提高气液两相流超声层析成像的重建精度,在二值反投影(BBP)基础上发展了边缘增强反投影(EEBP)。为模拟投影数据,采用有限元分析给定气泡分布下声压场。仿真结果表明,EEBP的空间成像误差明显小于BBP。搭建一套气液两相流超声层析成像系统,可实现对24个换能器组成阵列的投影信号获取。利用该系统进行单、双气泡流测试,通过提出的EEBP重建算法与硬件系统的结合,可准确得到流动中的气泡空间位置、尺寸以及形状。仿真与实验中EEBP算法重建图像的最小空间成像误差为2.03%,表明在气泡流动稳定的情况下,该系统具备可行性与可靠性。

The bubble flow is studied theoretically and experimentally based on the ultrasonic process tomography. To improve the reconstruction accuracy of ultrasonic tomography in gas-liquid two-phase flow, the edge enhanced back projection(EEBP) is developed on the basis of binary back projection(BBP). To simulate the projection data, finite element analysis is utilized to calculate the sound pressure field under the given bubble distribution. Simulation results show that the spatial image error of EEBP is significantly smaller than that of BBP. A set of gas-liquid two-phase flow ultrasonic tomography systems are designed and built, which can collect the projection signals of 24 transducers array. By combining the EEBP reconstruction algorithm and hardware, the bubble position, size and shape in the flow can be accurately achieved. The minimum spatial imaging error of reconstructed images by EEBP is 2.03% in simulations and experiments. It shows that the system is feasible and reliable when the bubble flow is stable.