基于能量守恒的鼓泡塔双尺度流体力学模型

New two-scale hydrodynamic model based on energy balance in bubble column

提出了同时描述鼓泡塔宏观流动及气泡尾涡小尺度湍动的双尺度流体力学模型,其中大尺度剪切流通过经典k-ε模型描述,而小尺度尾涡湍动则由'尾涡温度'传输方程确定。通过在运动方程添加'尾涡压力'源项,构建大小双尺度流体运动的相互作用,解释鼓泡塔内含率非均匀分布的机制。模型将鼓泡塔内的能量耗散分解3种作用机制:大尺度剪切流引起湍动耗散;小尺度尾涡湍动耗散;尾涡与壁面作用的能量耗散,较好地解决了现有鼓泡塔模型能量不守恒问题。模型计算稳定性高,模拟结果与实验结果吻合良好。

A new two-scale hydrodynamic model was proposed to describe large-scale motion and small-scale bubble wake turbulence. The large-scale shear induced turbulence was resolved by classical k-εturbulence model, while the small-scale bubble wake turbulence was quantitively described by wake temperature transport equation. A wake pressure gradient source term was added to the motion equation to reflect the mutual influence between small scale turbulence and large scale fluid motion and to explain the mechanism of holdup non-uniform distribution in the bubble column. The model classified the energy dissipation into three kinds of mechanism：large-scale shear induced turbulence dissipation, small-scale wake turbulence dissipation, energy dissipation due to interaction between bubble wake and solid wall. The model well resolved the issue about energy balance. Simulation results agreed well with experiment data.