喷动床内颗粒浓度的实验测量和理论模拟

颗粒浓度对于稠相流动体系中颗粒应力本构方程建立具有决定性的作用。本文采用双流体模型,并结合颗粒流动力学理论来描述固相应力的基础上实现了对喷动床的数值模拟,探讨了从喷射区到环隙区颗粒浓度的理沦变化趋势。同时采用自主开发的电容探针技术,不仅颗粒浓度测量值和理论值吻合较好,而且也准确地验证了颗粒非均匀夹带这一现象。电容探针还可灵敏地分辨出环隙区内不同床高处以及接近壁面处的颗粒浓度的细微变化。

EXPERIMENTAL AND THEORETICAL STUDIES ON PARTICLE CONCENTRATIONS IN SPOUTED BED

The particle concentration plays an important role in the establishing of the constitution equations of solid phase stress especially in the dense-phase particulate flow system. In this paper, both Eulerian simulation and experimental studies of spouted bed were presented. The CFD model was based on the two-fluid model incorporating the kinetic theory of granular flow. The variation of simulated particle concentration in the distinct zones, i.e., spout, annulus and fountain, were discussed. The phenomenon of non-uniform entrainment, which had a sharp increase at the very bottom of the spout, was confirmed by both numerical simulation and experimental data from self-developed needle-type capacitance probe. Not only the experimental data agreed well to simulated ones, but also the fine difference of particle concentration at various annulus depths as well as those between near-wall region and main annulus region can be sensitively tested by capacitance probe.