Abstract:

Water-glass bead system and Euler-Euler dual-fluid model were used to simulate liquid-solid two-phase flow at fully developed stage of a vertical narrow channel with a dimension of 240 mm in length, 12 mm in width and 1800 mm in height. The results show that the liquid-solid two-phase flow enters full development stage after 0.7 m in vertical direction of the narrow channel. At cross section of the full development stage, particle velocity and concentration in both wide and long axial directions were high in central region but low near wall area. With increase of inlet liquid velocity, solid particle velocity increased at each position of the cross section, while particle concentration decreased at center but increased near wall. With increase of initial solid phase volume fraction, solid particle concentration increased at each position of cross section, while particle velocity decreased slightly at center but increased slightly near wall. Particle thickening effect was observed in the region near three wall junction at both long axial ends of the channel cross-section. In the region of large particle velocity distribution and high concentration gradient along the wide direction of channel cross-section, non-dimensional proportion increased with increase of inlet liquid velocity but decreased with increase of initial solid volume fraction.

Key words: narrow channel, full development section, two-phase flow, flow, CFD

摘要：

采用欧拉-欧拉双流体模型，基于水-玻璃珠体系，对长×宽×高尺寸为240 mm×12 mm×1800 mm的竖直窄通道充分发展段内液固两相流动特性进行了数值模拟。结果表明，沿窄通道竖直方向0.7 m以上液固两相流动进入充分发展阶段，在充分发展阶段的窄通道截面上，狭长方向与狭窄方向各位置颗粒速度及浓度均呈中心区域高、贴近边壁区域低的分布趋势；随着入口液速提高，截面各位置颗粒速度均提高，而颗粒浓度在流道中心区域降低，在贴近壁面区域升高；随着初始固相体积分数增加，截面各位置颗粒浓度均提高，而颗粒速度在流道中心区域略有降低，在贴近壁面区域略有升高；在窄通道截面狭长方向两端靠近三边壁影响的区域存在颗粒增浓效应，在截面狭窄方向颗粒速度和浓度分布梯度较大的区域无量纲占比随着入口液速的提高而提高，随着初始固相体积分数的提高而减小。

关键词: 窄通道, 充分发展段, 两相流, 流动, 计算流体力学