多相微反应器内限域结构影响下的气泡形变与破裂机理研究

Multiphase microreactors, for example, fixed-bed microreactors, have extraordinary advantages and broad prospects for application. The hydrodynamic behaviors of dispersed phase play an important role in the transport and reaction process, while the transport mechanism research of complex system containing particles is still deficient. This study mainly investigates the deformation and breakup of bubbles under the influence of typical slits, throat structure, and fixed particles in microchannels, with exploring the mechanism of multiphase interaction force as the core. Methods including refractive index matching are used to enhance visualization experiments such as high-speed photography and micro-PIV. Targeted numerical methods, such as coupling multiphase models and improved interfacial force algorithm, combined with fluid dynamics and mathematical modeling, are comprehensively utilized to study the influence mechanism and change rule of the key forces. The mechanisms of drainage and breakup of liquid film being affected by particles as well as wall surface will be mainly analyzed. The research result will contribute to promoting the cognition and control of multiphase flow in microsystems, and eventually providing theoretical basis and technical guidance for the design and optimization of multiphase microreactors.

微固定床等多相微反应器具有高效、安全等优势与广阔的应用前景，其中分散相的形变、破裂等流体力学行为对反应体系具有非常重要的影响，而目前针对含有颗粒等复杂条件的传递机理研究仍较为欠缺。本项目以探索微通道中多相相间作用机制为核心，系统研究微通道中拟二维狭缝、“孔喉”结构乃至固定颗粒孔隙等受限狭窄空间内的气泡形变与破裂机理。项目利用折射率匹配等方法提高micro-PIV、高速摄像等可视化实验精度，结合针对性的多相耦合模型与界面作用力处理方法开展数值模拟，通过流体力学分析和数学模型化，深入分析界面演变过程关键作用力的影响机制及定量变化规律，凝炼颗粒及限域壁面作用下的气泡挤压排液及液膜不稳定断裂机理。本项目有助于丰富并加深多相流体力学机理认识，推进微通道内多相流动的精确控制与传递过程强化，为多相微反应器技术提供理论支撑和科学指导。

多相微通道体系中的气泡形变、破裂等流体力学行为对相关过程具有非常重要的影响。本项目以探索微通道中的相间作用机制为核心，从微狭缝与“孔喉”等典型限域结构切入，逐步深入拓展到固定颗粒体系受限空间内的气泡形变与破裂机理研究。项目主要研究内容及结果包括：开发了兼顾相含率守恒与界面拓扑的多相耦合模型，完成光学实验系统及图像处理算法构建，形成系统的微尺度研究平台；系统考察了典型狭缝和“孔喉”结构对气泡挤压、拉伸及破裂的影响规律，分析了液膜挤压排液与局部不稳定断裂机制；探究了颗粒间隙等限域条件的气泡破裂机制，得到了不同通道结构、颗粒填充特点及操作条件下多种破裂机制的发生条件及各阶段的转化规律，初步提出了微通道气泡流特征预测及控制方法；基于项目理论成果，设计了系列微反应结构，并成功应用于多种本质安全化微反应工艺过程；设计了新型微流控水质检测芯片，兼具强化混合与阻消气泡效果，成功应用于自主研发的便携式多参量水质检测仪。本项目研究有助于丰富并加深多相流体力学机理认识，推进微通道内多相流动的精确控制与传递过程强化，为相关微通道技术装备提供理论支撑和科学指导。