表观气速对密相气力输送流型影响的模拟

摘要

Due to the problem in available numerical simulations of flow patterns in dense pneumatic conveying, a new mathematical model, which uses solid-phase volume concentration of local space and kinematic characteristics of clusters to describe the interactions between particles, was proposed in this paper. This model was first used to numerically simulate the dense pneumatic conveying (even for the packing of particles), and then used to numerically study the flow behavior of dense phase pneumatic conveying in horizontal pipe at high pressures, in which the separation and sedimentation between gas phase and solid phase in the conveying process were investigated. The simulation results also illustrated the evolving characteristics of flow patterns such as dune flow and plug flow, which are consistent with the experimental phenomena. Moreover, some rules of flow patterns were revealed by qualitatively analyzing the distribution of solid-phase flow patterns at different superficial gas velocities. The results show that the new model is appropriate and can be used to study the dense pneumatic conveying.%针对目前密相气力输送数值模拟关于流型演变方面所存在的问题,提出了一种基于颗粒所在局部空间的固相浓度及颗粒群运动特征来描述颗粒间相互作用的数学模型.该模型能够对气力输送,甚至是颗粒发生大量堆积情况下的密相输送进行数值模拟,使得长期以来缺乏有效模型对密相输送流型进行数值模拟研究的问题得到一定解决.利用该模型,对水平管中煤粉高压密相气力输送的颗粒流动过程进行了数值模拟,获得了输送过程中管道内所发生的气固两相之间的分离、沉积现象,展现了沙丘流及栓寒流等流型的演变特征,模拟结果与实验观察到的现象吻合较好,从而进一步验证了新数学模型的有效性.此外,通过对不同表观气速下固相流态分布的定量分析,揭示了输送流型变化的一些内在规律.