刚柔组合搅拌桨强化流体混沌混合及放大规律研究

Development and application of high performance stirred reactor contribute to chemical process intensification and energy saving and emission reduction, and the key is to rationally design the impeller, to develop fluid chaotic mixing intensification theory and to master scale-up law for mixing technology. For the traditional rigid impeller, energy transfer mainly depends on shearing action, and the isolated mixing region can be formed around the tip region of the impeller, which does harm to good mixing performance and energy saving. In the present proposal, the rigid-flexible combination impeller will be designed and optimized, and the intensified chaotic mixing performance by fluid structure interaction, as well as its scale-up law, will be studied in the stirred reactor. Comparative investigation will be carried out between rigid impeller and rigid-flexible combination impeller on energy efficiency, noise, vibration and abrasion during mixing process. Relationship will be studied between chaotic parameters (largest Lyapunov exponent, etc.) and stirred reactor structure as well as operation parameters. The study will be focused on fluid energy saving mixing performance of rigid-flexible combination impeller and its controlling methods. Influence of rigid-flexible-fluid coupling movement on energy transportation across scale in flow field will be studied with software ANSYS. Mechanisms energy efficiency, noise, shaft vibration, flow field structure, impeller corrosion and the relationships with the scale-up operation will be investigated, integrated with signal processing, imagine acquisition, and computational simulation. Mathematic model and operation methods will be established on intensified fluid chaotic mixing fluid with rigid-flexible combination impeller. Research fruits will supply the theoretic basis for design and scale-up for stirred reactor.

高效节能搅拌反应器的研发与应用有助于实现化工过程强化和节能减排，其突破点在于合理设计搅拌桨，发展混沌混合强化理论，掌握反应器的放大规律。传统刚性搅拌桨主要靠剪切作用向流体传递能量，在桨叶尖端附近区域形成隔离区，不利于高效节能混合。项目拟设计和优化刚柔组合桨，研究流固耦合运动强化流体混沌混合行为及放大规律；对比研究刚柔组合桨与刚性桨在能效、噪音、搅拌轴振动及桨叶磨蚀等方面的差异；研究刚柔组合桨搅拌反应器结构和操作参数与流体混沌特性（最大Lyapunov指数、混沌吸引子等）的相关性，重点研究刚柔组合桨强化流体节能混合机制及调控方法；采用ANSYS研究刚-柔-流耦合运动对跨尺度流场结构间能量传递的影响；结合信号处理、图像采集及计算模拟，研究节能、降噪、抗振、耐磨的原理及与搅拌反应器放大的关系；建立刚柔组合搅拌桨强化流体混沌混合的数理模型和操作方法。研究成果将为搅拌反应器的设计和放大提供理论支持。

高效节能搅拌反应器的研发与应用有助于实现化工过程强化和节能减排，其突破点在于合理设计搅拌桨，发展混沌混合强化理论，掌握反应器的放大规律。传统刚性搅拌桨主要靠剪切作用向流体传递能量，在桨叶尖端附近区域形成隔离区，不利于高效节能混合。项目首先是对搅拌桨结构进行设计，研发出刚柔组合搅拌桨和穿流刚柔组合搅拌桨，并搭建单相体系、固液体系、液液体系和气液体系的实验装置。采集单相体系、固液体系、液液体系和气液体系内的扭矩时变信号和压力脉动信号，通过MATLAB获得最大Lyapunov指数和混沌吸引子等混沌特性参数表征各体系混沌状态。并且以混合效率数来表征单相流体混合效果，以悬浮度表征固液体系颗粒悬浮效果，以局部气含率和局部气泡尺寸表征气液体系气体分散效果。研究结果表明，刚柔组合桨体系的混合效率数最小，相比刚性桨降低了87.4%；穿流刚柔组合桨体系的固体颗粒悬浮度最大；刚柔组合桨体系的气体分散效果最佳，局部气含率最高，最大局部气含率能达到10%。另外，通过实验研究了搅拌体系的宏观不稳定性行为及装置的振动特性，相同转速下柔性桨的宏观不稳定性频率（fMI）都较刚性桨大，其值随转速的增加而增大，其增长率也随着转速的增大而增大。根据拟合直线公式可得，转速为 210 r·min-1时增长率为 15.62%。通过PIV技术研究了体系流场结构及其演变规律，结果表明刚柔组合桨体系，桨叶附近的循环流动范围较大。通过CFD模拟方法研究了刚柔组合桨的流固耦合行为及其降噪特性，结果表明，与刚性桨相比，刚柔组合桨的桨叶应力集中区域最大应力降低了1.94%。最后，对刚柔组合桨搅拌反应器进行了中试试验及工程放大应用。通过该项目的研究，加深了对流体混沌强化的认识，并获取混沌特性参数及相应的软件著作权；发现刚柔桨，柔性轴，混沌电机，都能实现耦合强化，并建立混合效率数表征混合效果；将刚柔组合桨应用于粉煤灰提铝，湿法磷酸浸出，锰矿浸出等在工业过程，通过流体混沌强化与反应过程动力学调控相结合，实现反应过程强化。