微流场中非球形颗粒体三维运动的可视化测量技术研究

Development for the quantitative visualization measurement technique of three-dimensional (3D) body motion of nonspherical particle is the important foundation of expriemental research for the fluid-particle dynamics, which will provide the direct observation data to the complex interaction mechanism between fluid and particles. In this project, the space-time evolution of three-dimensional body motion of nonspherical particle can be obtained from real time tracking three-dimensional translation and rotation of nonspherical particle based on High-speed 3D Defocusing Micro-PTV technique. In order to realize the aim, the optial defocusing principle is applied to make the defocusing particle image devices, and the high speed camera as well as continuous laser are employed to upgrade the existing Micro-PIV system to High-speed 3D Defocusing Micro-PTV system. The method of fabricating nonspherical partcles with the marks of fluorescent tracing particles will be researched. The parameter calibrating technique of particles position and localization algorithm of particles are developed. Hence, the complete supports of hardware and software are provided to realize the particles tracking with three-dimensional spatial distribution. Based on this, the quantitative visualization measurement technique of three-dimensional body motion of nonspherical particle will be finished. The research of this project will provide the important idea to solve the present situation of three-dimensional body motion research for the nonspherical particle without the surpport of experimental data, and will also lay a strong foundation for the development of full field visualization experimental technique for microscale liquid-particle flow at the same time.

发展非球形颗粒体三维运动的可视化测量技术是实验研究颗粒两相流动的重要基础，将为揭示颗粒与流体之间复杂相互作用机理提供直接的实验观测数据。项目在研究高速三维散焦显微粒子图像测速技术基础上，通过对非球形颗粒体三维平动和转动过程的实时追踪测速，获得微尺度颗粒两相流场中颗粒体三维运动的时空演化规律。为实现上述目标，项目应用光学散焦原理制作散焦粒子图像元件，配置高速相机和连续激光光源，将现有显微粒子图像测速系统升级为高速三维散焦显微粒子图像测速系统；研究具有表面荧光粒子标记的非球形颗粒制备方法；发展粒子空间位置参数标定技术与空间粒子群三维坐标定位算法，为实现空间粒子群三维追踪测速提供完备的软硬件支撑，最终完成微流场中非球形颗粒体三维运动和动力学的定量可视化测量。项目的研究将为解决微流场中非球形颗粒体三维运动研究缺乏实验支撑的现状提供重要思路，也为发展微尺度颗粒两相流全场可视化实验技术奠定坚实基础。

发展非球形颗粒体三维运动的可视化测量技术是实验研究颗粒两相流动的重要基础，将为揭示颗粒与流体之间复杂相互作用机理供直接的实验观测数据。根据项目的计划任务，主要开展了以下研究工作。. 一，在研究高速三维散焦显微粒子图像测速技术基础上，应用光学散焦原理制作散焦粒子图像元件，配置高速相机和连续激光光源，将已有显微粒子图像测速系统升级为高速三维散焦显微粒子图像测速系统，发展粒子空间位置参数标定技术与空间粒子群三维坐标定位算法，实现了空间粒子群三维追踪测速。针对Hele-Shaw通道及倒置台阶结构微通道对系统可靠性进行了验证实验，结果表明实测速度廓线与理论及数值模拟结果吻合良好。在验证实验的基础上首次开展了微通道内方块阵列结构的颗粒三维绕流轨迹的测量。实验结果发现，绕流轨迹总体呈现准周期模式，但由于障碍物绕流的强扰动，局部位置绕流流场的周期性被打破，呈现出非周期性轨迹模式。另外，针对复杂周期性壁面的流动开展了解析数值方法的研究。二，选取红细胞作为典型非球形颗粒，对其在体外毛细血管模型通道中的体三维运动开展了实验研究。实验结果表明，红细胞运动和受力是一类典型的随机过程，表现为细胞沿主流方向运动过程中叠加了展向的无规则涨落；合力表现为动力和阻力均匀分布的规律；转动角度的概率分布覆盖了0度~180度，大于10%的优势概率区间位于0度~90度，概率峰值出现在55度，其值约为18%；建立了红细胞主动扩散过程的郎之万方程，针对微通道内红细胞运动过程中的扩散过程进行了半解析分析，并与实验结果进行了比对。结果表明，理论与实验均方位移分别呈现出弱非线性和强非线性，红细胞的压力驱动扩散过程具有超扩散特征。三，开展了微通道分布式压力测量方法研究，有望结合全场可视化测量方法实现非球形颗粒流的流场和压力场联合测量。. 项目执行期间共发表11篇学术期刊和会议论文，其中国际流体力学主流期刊4篇，国内核心期刊《实验流体力学》2篇，授权专利2项，培养研究生4名，成果达到了预期目标。