固液两相体系中双层搅拌桨叶的结构优化数值模拟

Structure Optimization of Dual Impellers in Solid-Liquid System by Numerical Simulation

应用多重参考系法以及欧拉多相流模型,对双层搅拌釜内固液两相流进行CFD数值模拟,考察了不同桨叶组合形式及其安放角(θ)对固体颗粒悬浮以及功率消耗的影响。结果表明:在双层下压式斜桨中,上下层桨叶间的协同作用可以有效促进主体循环流动,提高釜内整体湍动程度,改善颗粒悬浮状况;安放角对釜内整体流型无明显影响,但体系的轴向速度、湍动能以及功率消耗都随着θ的增大而增大,其中θ为45°时可以适宜的功率获得较强的轴向流动和湍流脉动,有利于实现固体在釜内的均匀分布。

The performance of solid-liquid suspension flow in a stirred tank with dual impellers was simulated numerically by Computational Fluid Dynamics（CFD）using Multiple Reference Frame（MRF）and Eulerian multiphase flow model.Effects of impeller combination and blade angle（θ）of dual impellers on solid suspension and power consumption are analyzed.The simulated results indicate that the synergistic effect generated by the combination of two pitched blade turbines can efficiently improve the main cycling flow,the degree of turbulent in the tank and the solid suspension performance.Though blade angels have little effect on flow pattern,axial velocity,turbulent kinetic energy and energy consumption are found to increase with blade angles.Dual impellers with blade angle of 45°can generate strong axial flow and turbulent fluctuation with lower energy consumption which is favorable for homogeneous distribution of solid particle in the tank.