CAREER: Quantification of the kinetic energy of particles in complex flows using magnetic particle tracking

微粒流在自然界和人类生活的许多方面无处不在。例如，沙尘暴具有严重的环境和经济后果，流化颗粒反应器的效率决定了许多化学和食品工业的生产率。一个关键的问题是，自然界中的粒子通常是非球形的，并且可能与理论预测的行为不同，因为现有的理论主要基于球形粒子模型。此外，这个问题具有挑战性，因为密集的颗粒流通常是不透明的，无法用先进的光流诊断技术进行测量。这个实验项目的目标是开发一种新的基于磁的技术来测量颗粒的形状和运动，并提供更好的理解复杂的颗粒流动。该项目还将包括重要的教育和推广活动，包括博物馆展览和访问代表性不足的少数民族社区。本研究旨在利用磁性粒子跟踪技术量化复杂流动中非球形粒子的动能和形状效应。磁场可以穿透不透明的材料，因此所提出的技术适用于任何形状或浓度的颗粒。为了获得更高的精度，将采用基于量子比特光致发光的高精度磁强计来重建剪切流中多个磁性粒子的运动。用这种方法可以得到粒子的拉格朗日轨迹方向和角速度。研究结果将用于验证大粒子长径比导致能量相等分配的假设，测量球度的影响，以及检查平动自由度和旋转自由度之间的能量传递。最后，该项目通过开发可用于各种多相流研究的非光学粒子跟踪技术，为实验流体动力学做出了贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Particulate flow is ubiquitous in nature and many aspects of human life. For example, sandstorms have severe environmental and economic consequences, and the efficiency of a fluidized particle reactor determines the production rates in many chemical and food industries. A critical issue is that particles in nature are usually non-spherical and may behave differently from theoretical predictions as existing theories are largely based on spherical particle models. Furthermore, the problem is challenging because dense particulate flows are usually opaque and cannot be measured with advanced optical flow diagnostic technologies. The objective of this experimental project is to develop a novel magnetic-based technology to measure the particle shape and motion and provide a better understanding of complex particulate flows. This project will also encompass significant educational and outreach activities, including museum exhibitions and visits to under-represented minority communities. The proposed research aims to quantify the kinetic energy and shape effect of non-spherical particles in complex flows using magnetic-based particle tracking. Magnetic fields can penetrate opaque materials, thus the proposed technique works with particles of any shape or concentration. For higher accuracy, a highly-accurate magnetometry based on photoluminescence of quantum bits will be employed to reconstruct the motion of multiple magnetic particles in a shear flow. The Lagrangian trajectory orientation and angular velocity of the particle will be obtained with this technique. The results will be used to test the hypothesis that a large particle aspect ratio leads to energy equal partition, to measure the influence of sphericity, and to examine the energy transfer among translational and rotational degrees of freedom. Finally, this project contributes to experimental fluid dynamics by developing a non-optical particle tracking technology that can be used in a variety of multiphase flow studies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.