微孔介质预分散式轴向旋流微细气泡生成机理与特性研究

Because of its compact structure, high fine bubble quality and easy to realize the pipelining of equipment, the axial swirling foaming technology pre-dispersed by microporous media has showing strong development potential. But its synergistic mechanism and foaming properties are not clear yet. This project will carry out basic research on some key scientific issues involved during the fine bubble generation process. In terms the research on the generation characteristics of fine bubble, a method for predicting the generation process of fine bubbles passing through the complex porous of micro-porous media can be established by researching the mixing process of gas-liquid two-phase in a microporous. Thus, the mixing mechanism and characteristics of gas-liquid two-phase in the generation process of fine bubble thronging the microporous media can be revealed. The dynamic change characteristics including fragmentation and coalescence of fine bubble in the axial swirling flow field will be studied by means of experiment and CFD-PBM numerical simulation, so as to establish a real model to predict the flow process and clarify the influence mechanism of swirling flow characteristics on fine bubble quality. Finally, the influences of the properties of microporous media and the operating conditions on fine bubble quality will be researched, so as to clarify the synergy mechanism and establish the quality prediction model of the axial swirling foaming technology pre-dispersed by microporous media. The ways and methods for the control of fine bubble quality can be revealed. The research results will provide scientific basis, theoretical guidance and key data support for the research and development of high efficiency and compact fine bubble generation technology and equipment.

微孔介质预分散式轴向旋流发泡技术因具有结构紧凑、气泡质量高、易于实现设备管状化等优势，具有很好的发展前景，但其协同作用发泡机制和特性目前尚不甚明了。本项目拟围绕发泡过程所涉及的关键科学问题开展应用基础研究。在微孔介质发泡特性上，研究微孔流道气液流动及混合规律，建立复杂多微孔结构气泡形成过程预测模型，揭示微孔介质发泡过程中气液两相混合机理及发泡特性。然后通过实验手段和CFD-PBM数值模拟方法，研究轴向旋流流场内包含破碎与聚并过程的气泡动态变化特性，并建立真实旋流流动微细气泡动态变化预测模型，阐明旋流流动特性对微细气泡质量的影响机制。最后，研究微孔介质材料和流场特性对发泡质量的影响规律，建立微孔介质预分散式轴向旋流发泡技术的发泡质量预测模型，揭示协同作用机制以及微细气泡质量调控方法。研究结果可为设计研发高效紧凑型微细气泡发生技术与设备提供科学依据、理论指导和关键数据支撑。

微细气泡因具有选择性粘附强、界面ζ电位高、传质效率高及可产生羟基自由基等特性，广泛应用于污水处理、石油开采、卫生保健、船体减阻等领域。高效管式气泡发生技术是微细气泡技术大范围工业应用的前提和关键。本项目基于从简单到复杂、微观到宏观理念，理论分析了微孔介质发泡过程中复杂多微孔结构气液两相迁移及流动混合机理，建立了微孔介质材料复杂多微孔结构气液混合和气泡形成统计学预测模型，研究了不同微孔孔径下理想单微孔或多微孔流道气泡形成过程，揭示微孔介质发泡过程中气液两相迁移及流动混合特性。基于群落平衡理论模型(PBM)，研究分析了湍流强度可调工况下气液两相混合及气泡分散过程中微细气泡运动变形、破碎和聚并机理，同时搭建气液混合分散及微气泡形成过程在线测量评价系统，重点观测分析了湍流流场内气液混合过程中微细气泡运动变形、破碎和聚并等动力学行为，筛选出较为合理的湍流强度等流场特性参数，并验证了单纯依靠提高湍流强度难以实现产生大量高质量微细气泡。为掌握多技术协同耦合作用产生高质量微细气泡和气泡质量调控机制，以微细气泡粒径分布和压降等为目标，通过“初始气液分散成泡+气泡细化均质”的串联协同效应，开展高效管式气泡发生器研制，建立了管式气泡发生器结构设计和优化方法，搭建了管式微细气泡发生器在线测试评价试验系统，考察不同工况条件对微细气泡质量影响规律。结合室内实验数据，建立基于“CFD-PBM”数值模拟方法的管式气泡发生器发泡性能预测模型，揭示协同作用机制以及微细气泡质量调控方法，实现气泡平均粒径从毫米级别到微米级别的调控。研究结果可为设计研发高效紧凑型微细气泡发生技术与设备提供科学依据、理论指导和关键数据支撑。