超声-撞击流微反应器中超声强化微观混合机理及模型研究

Recently, ultrafine powder and nanoparticle materials have played important roles in a wide range of industrial fields. However, traditional approaches such as macroscale impinging stream reactor and stirred tank reactor can’t effectively control the quality of particles synthesised, especially the specific surface area and particle size distribution due to the intrinsically relatively poor micro-mixing and mass transfer performances. Therefore, it is urged to develop new reactor technologies to effectively control and intensify the microscale mixing and mass transfer of reactor systems. Since hydrodynamic and mixing behaviours are significantly affected by the acoustic cavitation effects in ultrasonic-confined impinging stream reactor (UCIMSR), it is essential to investigate the hydrodynamics and mixing characteristics of the flow in the reactor to reveal the process-intensification mechanism of UCIMSR. This project will comprehensively employ theoretical analysis, numerical simulation and experimental approaches to study the hydrodynamic and multi-scale mixing behaviours of the flow in the UCIMSR, and reveal the intensification mechanism. A numerical model explaining the effects of acoustic cavitation on the local hydrodynamic field will be proposed based on the interactions of local velocity gradient generated by cavitation microbubbles and inherent Reynolds stress filed surrounding the bubbles. Combining the experimental and numerical simulation results, the mechanism how ultrasound acoustic cavitation affects the local turbulent vortex will be revealed. multi-scale mixing behaviours in the confined impinging stream reactor with ultrasound process intensification will also be investigated experimentally and numerically, in order to study the mechanism of ultrasound induced intensification in the multi-scale mixing processes. It is anticipated that the results of the project will make a great contribution to the theory of ultrasound process intensification in the hydrodynamic and mixing behaviours and improve the development of reactor technology, gaining a sound theoretical basis to reveal the intensification mechanism of ultrasound on the precipitation and crystallization process of confined impinging stream reactor, and finally obtaining an efficient, continuous and controllable preparation route for ultrafine powder and nanoparticle materials.

超细粉体及纳米材料已广泛应用于新能源、新材料等诸多重要领域。然而应用传统的撞击流或搅拌釜反应器制备超细粉体及纳米材料由于其微尺度混合和传质性能限制，往往不能有效地控制所制备的超细粉体材料的质量。应用超声可以显著强化撞击流微反应器内微观混合性能，然而当超声作用在该型反应器时，反应器内的流体动力学和化学动力学特性受到超声空化效应影响发生了巨大变化，其强化与控制机理亟需更深入探究。本项目针对典型超声-撞击流微反应器装置，结合理论分析、实验和数值模拟方法对反应器内的流体动力学和混合行为特性进行深入探究。构建超声空化效应对流体流场的过程强化模型，结合实验和模拟结果，分析并揭示该型反应器内超声空化效应与湍流涡旋流体力学特征之间的内在关联;研究超声强化撞击流微反应器内微观混合行为，揭示超声空化效应对该型反应器内多尺度混合过程的作用机制，並为揭示超声强化反应器内的沉淀与结晶过程奠定理论和技术基础。

以超声对撞击流反应器中流动混合的强化为研究对象，结合理论分析、实验和数值模拟方法对超声-撞击流反应器内的流体动力学和混合行为进行深入探究。建立了考虑超声空化效应作用于超声撞击流反应器内湍流涡旋和微观混合的强化作用的数值模拟方法，揭示了超声空化效应对该反应器内多尺度混合过程的强化作用。构建了考虑超声射流对流场和湍流涡旋的作用，基于非线性当地速度波动的物理模型和数值模拟方法，揭示超声射流对受限撞击流反应器湍流场和微观混合性能影响作用。研究结果将丰富对超声强化反应器内流体流动混合的认识，为揭示超声强化反应器内的沉淀与结晶过程奠定理论和技术基础。