气固垂直并流向上两相流流体动力学模型

FLUID DYNAMIC MODEL OF CONCURRENT-UP GAS-SOLID TWO-PHASE FLOW

运用能量最小多尺度 (EMMS)模型 ,推导出滑移速度及颗粒速度的径向分布 ,并进一步计算了径向空隙率、流体速度、团聚物直径、流体对颗粒的悬浮输送能量和颗粒的质量流率等相关的动力学参数 .模型计算结果反映了气固垂直两相流的径向不均匀性 (稀、密两相共存 )及环 /核结构的存在 .计算值与实验结果相吻合 .滑移速度的计算结果表明在核心区内也存在着团聚物 ,并不是呈现单一颗粒运动形态 ,这与实验现象一致 .该模型不仅克服了原有EMMS模型求解困难的问题 ,而且其计算不依赖于核心区半径等任何待定参数 ,只需物性参数、床层截面平均空隙率和操作参数即可 ,方便了实际应用 .

Radial slip velocity and solid velocity are formulated by using the energy-minimization multi-scale (EMMS) model, leading to analytical solutions for radial distribution of voidage, fluid velocity, cluster diameter and particle mass flux, and indicating the existence of radial heterogeneity and annulus/core structure. Model calculation is well consistent with experimental data. The model overcomes the difficulty in solving the original EMMS model, and makes it possible to predict patterns in gas-solid two-phase systems without using adjustable parameters.