Abstract:

Digital in-line holography has been found to be a powerful tool in 3D diagnostics of gas-solids flows.A study on particle sizing in gas-solids flows using a digital holographic system was presented.The recorded particle hologram was numerically reconstructed by using wavelet transform algorithm.A 2D interpolation method was used to measure particle image size based on the identification and 3D location of particles，and the real sizes of particles were obtained based on the point spread function theory of numerical reconstruction of particle in-line hologram.Gas-solids flows produced by an annular nozzle and in the upper dilute zone of a cold CFB riser were tested by using a digital in-line holographic measurement system.Glass beads with sizes of 20-100μm were used，and a volume of 10 mm×10 mm×100mm in the flow space was measured.It was found that the particles in the measurement volume were successfully reconstructed.The measurement results of particle size distribution agreed with those obtained by a Malvern sizer，which showed excellent capability of digital in-line holography in particle sizing.

Key words:

数字全息, 小波变换, 气固两相流, 颗粒粒径

摘要：

激光数字全息技术在颗粒场三维诊断领域具有巨大的应用潜力。对激光数字全息技术应用于两相流颗粒粒径及其空间分布测量进行了研究。在利用小波函数重建颗粒全息图和颗粒识别定位的基础上，利用全息成像的点扩散理论获得颗粒粒径，并采用二维插值方法提高测量精度。利用所搭建的激光数字全息测量系统对一环形喷嘴产生的颗粒场以及冷态循环流化床稀相区流场进行实验测试，固相为20～100μm的玻璃珠，所测流场空间尺度约为10 mm×10 mm×100mm。测量系统成功地对被测流场区域的颗粒场进行了重建，将获得的颗粒粒径统计分布与Malvern粒度仪测量结果进行了对比，基本吻合，表明激光数字全息测量系统可以很好地进行颗粒场粒径及其空间分布的测试。

关键词:

数字全息, 小波变换, 气固两相流, 颗粒粒径