EAGER: In-Lab X-Ray Particle Image Velocimetry

非侵入性测量流体流动特性的能力对于了解流体动力学，以及随后能够改进工业和医疗工艺和设备以造福社会来说往往至关重要。在许多涉及单相流的应用中，粒子图像测速仪使用激光通过跟踪粒子来推断流体速度。然而，许多多相流(如船舶尾流中的气泡流)很重要，但由于两相之间的折射界面，这些流动在可见波长是不透明的。幸运的是，在X射线波长下，大多数感兴趣的流体之间的折射率变化非常小；因此，基于X射线的粒子图像(或跟踪)速度计可以测量多相流中的流体流动特性。该项目将开发一种实用的实验室内X射线粒子图像测速技术。该项目将结合使用数值模拟和实验，希望能够更广泛地利用实验室内X射线粒子图像测速仪进行多相流体动力学研究。该项目将使用基于第一原理的建模和实验相结合，这将使人们对实验室内X射线粒子图像测速仪的物理和技术能力和局限性有更深入的了解。数值模拟将利用已建立的蒙特卡罗程序和基于Beer-Lambert定律的SIMPLE程序。这些实验将利用光子计数X射线探测器来确定信噪比，并引入小的示踪剂粒子，以便在不改变流动的情况下进行速度测量。该项目将开发算法和规则，以平衡来源、示踪剂和探测器的特性和设置。该项目将验证用于规范管道流动的实验室内X射线粒子图像测速技术。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The ability to measure fluid flow properties non-intrusively is often crucial for providing understanding of fluid dynamics, and subsequently to enable improving industrial and medical processes and equipment for the benefit of society. Particle image velocimetry uses lasers to infer fluid velocities by tracking particles in many applications involving single phase flows. However, many multiphase flows (such as bubbly flows in the wake of a ship) are important to understand, but these flows are opaque at visible wave lengths due to the refractive interfaces between the phases. Fortuitously, at X-ray wave lengths the change in refractive index between most fluids of interest is very small; therefore, X-ray based particle image (or tracking) velocimetry can measure fluid flow properties in multiphase flows. This project will develop a practical in-lab X-ray particle image velocimetry technique. The project will combine the use of numerical modelling and experiments to hopefully enable wider utilization of in-lab X-ray particle image velocimetry for multiphase fluid dynamics research.This project will use a combination of first principle-based modelling and experiments, which together will yield a deeper understanding of the physical and technical capabilities and limitations of in-lab X-ray particle image velocimetry. The numerical modeling will utilize both established Monte Carlo codes and simpler codes based on Beer-Lambert law. The experiments will utilize photon counting X-ray detectors to determine the signal to noise ratios and introduce small tracer particles to enable velocity measurements without altering the flow. The project will develop algorithms and rules for balancing source, tracer, and detector characteristics and settings. The project will validate the in-lab X-ray particle image velocimetry technique for the canonical pipe flow.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.