微焦点X射线测量微细颗粒沉淀两相流

Sedimentation measurements of small particle suspensions by a microfocus X-ray tomography system

建立了微焦点X射线测量微细颗粒沉淀两相流的实验系统,测量了不同粒子体积份额的TiO2变压器油悬浮液在小容器中的沉淀过程,并对所得的图像进行分析处理,获得了两相流内部颗粒体积份额的分布。实验结果表明,颗粒沉淀的速度取决于局部颗粒体积份额,局部颗粒体积份额越大,颗粒的沉淀速度呈非线性地急剧变慢,颗粒体积份额沿高度方向分布也因此呈波状分布。基于微焦点X射线透视成像的技术,在解决物质/密度场测量问题时有着不可替代的优势。

The sedimentation of micro-TiO2 particles in mineral oil suspensions was studied using a microfocus X-ray tomography system. The tomography system produced images of the two-phase flow fields with different mean particle volume fractions. The images were then analyzed by an image processing program to obtain the volume fraction distribution of particles in the suspensions and its evolution during the sedimentation process. The results showed that the locally averaged settling velocity of the particles dramatically decreased as the particle volume fraction increased and that the relation between the two parameters was strongly non-linear. As a result, the particle volume fraction distribution along the vertical direction of the vessel had a wave-like shape. The experiments also showed the effectiveness of the microfocus X-ray tomography system for measuring micro-multiphase flow fields.