玻璃基微流道相控空化增强磨粒微射流抛光方法研究

The current abrasive micro-jet exhibits low efficiency in polishing the glass-based micro-channel. To resolve this problem, an abrasive micro-jet polishing method based on the phase control cavitation is proposed. Phase control principle is adopted to generate the micro-scale cavitation bubbles, and the bubble size is controlled to guarantee the bubbles fully entering into the micro-channel with the flowing of the abrasive micro-jet. The cavitation impact caused by the bubble collapse can effectively improve the kinetic energy of the abrasive particles. The dynamic model of the cavitation bubble interface is set up based on the lattice Boltzmann method (LBM). Combining the LBM and micro particle image velocimetry (Micro-PIV) method, sound field regulating mechanism of the cavitation bubble size and cavitation impact strength in the near-wall region are studied, and the regulating method is established. A coupled computational fluid dynamics and discrete element method (CFD-DEM) modeling is proposed to set up the dynamic model of the cavitation impact particle, and the dynamic characteristics of the cavitation impact particle when the bubble collapsing are studied, then the distinguish of the effective cavitation impact zone can be realized, and the boundary control method is formed. Combining the stress-strain constitutive relationship of the material and the Bifano indentation theory, the evolution law of the residual particle-wall collision stress field and the critical indentation depth under the condition of phase control cavitation are studied, and the formation conditions of the high-productivity material ductile removal are obtained, then the material removal model of the particle-wall collision is built up. Based on the above work, the technology optimization and the polishing control method are studied, and implement the high-productivity fluid polishing of the glass-based micro-channel.

针对磨粒微射流在抛光玻璃基微流道时效率低下的问题，本项目提出一种相控空化增强磨粒微射流抛光方法：采用相控原理激发空化泡群，并控制空泡尺度，使空泡群随微射流充分进入微流道内，空泡溃灭产生的空化冲击对磨粒动能实现有效增强。基于格子Boltzmann理论建立空泡界面动力学模型，结合显微粒子图像测速（Micro-PIV）研究空泡尺度、空化冲击强度在近壁区的声场调控机制，形成主动控制方法；基于计算流体力学和离散单元法耦合（CFD-DEM）建立空化冲击磨粒动力学模型，研究空泡溃灭时的空化冲击磨粒动力学特性，实现近壁有效空化冲击区位置识别并形成边界控制方法；结合材料应力-应变本构关系及Bifano压痕理论，研究相控空化条件下磨粒冲击工件表面导致的残余应力场和临界压痕深度变化规律，建立材料高效塑性域去除形成条件及材料去除模型；在此基础上，进行工艺优化及控制方法研究，实现玻璃基微流道的高效流体抛光。

玻璃基微流控芯片在生化分析领域中有着重要的作用，而玻璃基微流道是流体输运、分析的主要场所，其内表面光滑程度决定了微流控芯片分析测试性能。流体抛光方法能够实现微流道高深宽比非连续内表面的仿形抛光，且柔性流体能够有效避免大尺度颗粒引起的划痕损伤，与其它抛光方法相比具有显著优势，但现有流体抛光方法在抛光玻璃等硬脆性材料时效率较低。本项目以此为切入点，通过引入空化及脉冲效应，提出了一种超声增强磨粒微射流抛光方法，所开展的创新性工作与重要结果如下：. （1）理论方面，建立空泡界面动力学模型，结合修正的可实现湍流模型，得到了超声场内空化冲击演化规律，形成了空泡尺度、空化冲击强度的声场调控方法；基于流体体积函数法，构建了磨粒、空泡组合模型，得到了空泡尺度与有效空化冲击区域临界阈值的关系；基于计算流体力学和离散单元法耦合（CFD-DEM），构建了磨粒流动力学模型，揭示了超声增强下的磨粒流演化规律；建立磨粒微射流材料去除函数模型，得到了超声增强下的微射流冲蚀规律。. （2）技术方面，针对空化效应的声场调控机制，搭建了流场高速拍摄平台，验证了理论建模的有效性；针对工件结构特点及超声振动原理，设计了两类超声增强磨粒流抛光模式，约束边界振动抛光及超声耦合微射流抛光，分别研发了适用于两类抛光模式的抛光实验平台，开展了系列对比抛光实验验证；基于田口实验及响应曲面法，开展了多工艺参数优化实验，形成了玻璃基微流道的流体抛光控制方法。. 本项目研究结果为玻璃基微流控芯片微流道的精密抛光提供了解决方案，研究过程中所涉及到的CFD-DEM耦合建模方法、空化流场观测、空化效应调控等技术方法，也能够为管道流体输运、多相耦合流动、空化冲击磨损等工业领域提供有益参考，具有较好的科研价值与实际意义。