基于聚焦型声表面行波微流控芯片的油液中磨粒分离机理研究

The feature information extraction of wear debris in oil is an important means of condition monitoring and fault diagnosis for marine power plant, and the separation of wear debris is an important step of feature information extraction. While the traditional methods could not separate non-ferromagnetic wear debris, this project would research on separation of non-ferromagnetic wear debris with different materials in oil by acoustophoresis based on focused travelling surface acoustic wave (FTSAW) microfluidic chip. Firstly, the propagation model of FTSAW at the base-oil interface would be established to study the influence of viscosity on energy transfer. The coupling mechanism between FTSAW and oil would be illuminated, and the distribution model of acoustic flow, acoustic energy density and acoustic interference field in oil would be built. Secondly, the acoustic flow viscous force and the acoustic radiation force acting on wear debris with irregular shape would be deduced. The model of translation and rotation of wear debris would be established. The motion trail of wear debris with different material would be investigated and the mechanism of wear debris separation would be revealed. Finally, an experimental platform for wear debris separation by FTSAW microfluidic chip would be built to verify or optimize the models of acoustic field distribution and wear debris movement in oil. The separation performance of the wear debris in simulated oil samples and real ship oil samples would be analyzed. This project would solve the coupling mechanism between FTSAW and high viscous fluid, the movement law of irregular shape particles in sound field, and lay a foundation for separating non-ferromagnetic wear debris in oil and extracting their feature information.

油液中磨粒特征信息提取是船舶动力装置状态监测与故障诊断的重要手段，而磨粒分离是特征信息提取的重要环节。针对传统方法不能分离非铁磁磨粒，本项目基于聚焦型声表面行波(FTSAW)微流控芯片，利用声泳分离油液中不同材质非铁磁磨粒。首先，建立FTSAW在基底-油液界面传播模型，研究粘度等因素对能量传递的影响规律，阐明FTSAW与油液耦合机理，构建油液中声流、声能量密度及声干涉场等分布模型；其次，推导作用于不规则形状磨粒的声流粘滞力、声辐射力等，建立磨粒平移运动和姿态转动模型，探究不同材质非铁磁磨粒运动轨迹，揭示磨粒分离机理；最后，搭建FTSAW微流控芯片磨粒分离实验平台，实验验证或优化油液中声场分布、磨粒运动等模型，并分析模拟油样、实船油样条件下磨粒分离性能。该项目将解决FTSAW与高粘度流体耦合机理、声场中不规则形状颗粒运动规律等科学问题，为油液中非铁磁磨粒分离及其特征信息提取奠定基础。

船舶动力装置是船舶的“心脏”，其安全可靠运行是保证船舶安全的重要前提。润滑油中磨粒携带了大量有关船舶动力装置运行状态的信息，因此及时了解润滑油中磨粒的信息对维护保养船舶动力装置具有重要意义。本项目基于微流控芯片平台，从油液中磨粒分离、检测两个方面开展研究工作。在磨粒分离方面，设计了基于尺寸差异的磨粒分离微流控芯片，构建了基于声泳的微通道中磨粒分离模型，并揭示了微通道结构参数、声压频率、样品流速等对磨粒分离的影响规律。研究结果表明，微通道入口尺寸参数对磨粒分离效果影响较大，缩小磨粒进入声场区域前的分布宽度，有利于磨粒的分离；磨粒的偏移距离随声压增加而增加，导致磨粒分离效果先变好再变差；样品流速决定了磨粒受声场作用时间，适当的流速才能满足尺寸差异的磨粒更好地分离。在磨粒检测方面，首先提出了基于电容优化的并联谐振磨粒电感检测技术，在不改变检测系统频率的前提下，实现了不同种类磨粒的高精度检测；其次提出了基于时分复用的多通道磨粒检测技术，通过理论分析，论证了该技术可集成上千路通道并联检测，且仅用一套输入输出设备，能大大提高检测系统的通量；最后研究了磨粒运动速度对电感检测的影响规律。本项目的研究成果有望为研发便携式油液磨粒检测装备奠定基础。