搅拌器内部三相流场特性模拟研究

Simulation Study on the Internal Three-phase Flow Field Characteristics of Agitator

针对搅拌器内部复杂湍流流场特性研究对提高其工作性能的重要意义,应用标准k-epsilon湍流模型,基于欧拉-欧拉法描述固-液-气三相流,并采用VOF模型捕捉气-液自由液面,离散相零方程模型解算颗粒运动行为,对容积为9L的实验室型搅拌器内部多相流场特性进行了模拟研究。研究结果表明,桶体挡板能有效防止漩涡产生,搅拌器内部流场呈上、下两循环分布,且下循环流速高于中、上部区域;流体运动速度与搅拌强度和正相关性,在较小粒径范围内,颗粒运动速度与其粒径呈正相关性,但其速度差异较小。小粒径颗粒体积分数分布相对较均匀,增大搅拌强度有助于提高颗粒分散性。搅拌器内部流场数值模拟研究可为提高搅拌器工作性能提供理论指导和技术依据。

Based on the significance of investigating the fluids characteristics in agitator,the complex flow field of a lab-scaled agitator of 1 Lwas numerically simulated using standard kturbulence model and Euler-Euler method.VOF model was used to capture the air-liquid free surface.The dynamic behaviors were resolved by discrete phase zero equation.The investigation results indicated that the baffle could avoid the vortex effectively,and the internal flow field within the agitator was constructed by upper and downward circulating flow.The velocity of the downward circulating region was higher than that of the upper region.The fluids velocity had a positive correlation with the stirring intensity.Within a limited range of particle size,the velocity of particles had a positive correlation with its size but with a small difference.The solid volume fraction distribution of smaller size was much evener than the bigger.Also increasing the stirring intensity could improve the dispersing performance.Thus,the numerical simulation of the flow field in agitator could improve the working efficiency by providing theory guide and technical base.