Based on two cases of the double impellers on different shafts in the co-rotating and counter-rotating, the distribution of the velocity, streamline, turbulent kinetic energy, and turbulent energy dissipation rate are obtained through three-dimensional unsteady numerical simulation. Very good agreements between experimental and numerical results have been obtained. The hydrometallurgy purification experimental platform was built with the size of one third of the simulated. The results show that the mechanical string mixing system with double impellers on different shafts can form a more obvious convection effect in the central area of the double impellers, which can effectively break the mixing isolation region and improve the mixing effect. In the co-rotating case, the two impellers can generate strong convection in the central area and form an interactive vortex and a high-speed flow channel between the two impellers. while the convection formed by counter-rotating case is weaker and the vortex structures are independent of each other. The counter-rotating system performs better in the macro momentum transfer and the co-rotating system performs better in the micro-mixing level. In the experiments of hydrometallurgy purification, 7.93% more energy is used in the co-rotating system than that of the counter-rotating system. The average energy consumed by co-rotating in the process of purifying every one percent of Cd 2+ ions are 8.65% lower than that of counter-rotating. The co-rotating system can improve microscopic mass transfer effect and finally save energy and time compared to the counter-rotating system.

中文翻译：

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不同弦轴双叶轮正反转混合流型特征及强化机理分析

基于双叶轮在不同轴上的同向和反向旋转两种情况，通过三维非定常数值模拟得到速度、流线、湍动能和湍能耗散率的分布。实验结果和数值结果非常吻合。搭建了模拟量三分之一大小的湿法冶金净化实验平台。结果表明，双叶轮在不同轴上的机械串混合系统可以在双叶轮中心区域形成更明显的对流效应，可以有效打破混合隔离区，提高混合效果。在同向旋转的情况下，两个叶轮可以在中心区域产生强对流，并在两个叶轮之间形成相互作用的涡流和高速流道。而反向旋转外壳形成的对流较弱，涡流结构相互独立。反向旋转系统在宏观动量传递中表现更好，同向旋转系统在微观混合水平上表现更好。在湿法冶金净化实验中，同向旋转系统比对向旋转系统多消耗7.93%的能量。同向旋转在净化每百分之一Cd 2+ 离子的过程中平均消耗的能量比对向旋转低8.65%。与反向旋转系统相比，同向旋转系统可以提高微观传质效果，最终节省能源和时间。