Visualization studies of forced flow liquid helium

题目：强迫流动液氦的可视化研究PI: Steven W. Van Sciver, FSUCo-PI: Sylvie Fuzier， fsu我们承担了一项实验研究工作，开发和应用粒子图像测速（PIV）技术来研究高雷诺数强迫流动液氦的流体动力学过程。这项工作很有趣，因为液氦是一种具有特殊性质的特殊流体。特别是氦有两种液相：He I是一种存在于温度在Tc = 5.2 K和T = 2.176 K之间的近经典流体，He II或超流氦，它是一种量子流体。He II表现出在任何其他流体中所未见的热流体性质。许多这些特性为大规模低温技术（如超导磁体和加速器）的运行提供了好处。尽管液氦中的流体动力学过程已经通过传统的宏观技术（如压力和温度测量）进行了广泛的研究，但直到最近才有人尝试调查支撑这些过程的微观尺度现象。这种现象最好使用现代流诊断技术，如PIV进行探索。推进我们对液氦流体动力学的基本的、微观尺度的理解代表了所提议项目的主要智力价值。这项工作主要是实验性的，旨在可视化贺一和贺二的流动现象。将研究两种结构：管道流动和管道中包含的无壁体（如圆柱体或球体）周围的流动，流速可达约0.5 m/s（对应于雷诺数在105至106范围内）。预期的结果之一是首次观测到河一和河二的速度边界层。随后，将圆柱体和其他钝体放置在流道中，并使用PIV再次研究体周围的条件。在更广泛的背景下，液氦具有所有凝聚流体中最低的粘度，从而为流体动力学和传热研究带来了在中等大小系统中获得非常高雷诺数的能力。这样的好处激发了世界上许多实验室建立高雷诺数流体动力学设施使用液氦。然而，先前在He II中的PIV研究表明，悬浮颗粒与液体之间的相互作用可能比假设的更复杂。因此，该项目的一个更广泛的影响将是通过提高对液氦系统的PIV测量技术的理解，使它们对该领域的所有研究人员都有用。除了这些技术发展之外，拟议的计划还应该对工程学生的教育经历产生重大影响，包括那些来自代表性不足的群体的学生。除了提案中描述的研究生PIV研究工作外，我们还将制作几个规模较小的项目，适合通过FAMU-FSU工程学院M - E系高级设计班的本科生参与，或通过附近国家高磁场实验室的REU/RET计划招募的暑期学生。这个独特的机会将为这些人提供在美国其他任何地方都无法获得的研究或设计经验；这段经历可能会让你从事低温学领域的工作。

Title: Visualization studies of forced flow liquid helium PI: Steven W. Van Sciver, FSUCo-PI: Sylvie Fuzier, FSUWe undertake an experimental research effort to develop and apply Particle Image Velocimetry (PIV) techniques to the fundamental study of fluid dynamic processes in high Reynolds number, forced flow liquid helium. This work is of interest because liquid helium is an exceptional fluid with exceptional properties. In particular, helium has two liquid phases: He I, a near classical fluid existing at temperatures between Tc = 5.2 K and T = 2.176 K, and He II or superfluid helium below T, which is a quantum fluid. He II displays thermal fluid properties not seen in any other fluid. Many of these properties provide benefits to the operation of large-scale, low temperature technologies such as superconducting magnets and accelerators. Although the fluid dynamic processes in liquid helium have been extensively studied by conventional macroscopic techniques like pressure and temperature measurement, only very recently have there been attempts to investigate the micro-scale phenomena that underpin these processes. Such phenomena are best explored using modern flow diagnostic techniques such as PIV. Advancing our basic, micro-scale understanding of liquid helium fluid dynamics represents the principal intellectual merit of the proposed project. The work is mainly experimental in nature, and is aimed at visualizing flow phenomena in both He I and He II. Two configurations will be studied: duct flow and flow around bluff bodies such as cylinders or spheres contained in a duct with flow velocities up to about 0.5 m/s (corresponding to Reynolds numbers in the range of 105 to 106). One of the expected outcomes is the first-ever observation of the velocity boundary layer in He I and He II. Subsequently, cylinders and other bluff bodies will be placed in the flow channel and the conditions around the body studied again using PIV. In the broader context, liquid helium has the lowest viscosity of any condensed fluid and thus brings to fluid dynamics and heat transfer studies the ability to achieve very high Reynolds number in moderate size systems. Such benefits have inspired a number of laboratories world-wide to establish high Reynolds number fluid dynamics facilities using liquid helium. However, previous PIV studies in He II in particular have shown that the interaction between the suspended particles and the liquid may be more complex than assumed. Thus, one of the broader impacts of the project will be through improving the understanding of PIV measurement techniques for liquid helium systems so that they useful to all researchers in the field.In addition to these technical developments, the proposed program should also have a significant impact on the educational experience of engineering students, including those from under represented groups. In addition to the graduate student PIV research effort described in the proposal, we will also craft several smaller scale projects suitable for undergraduate student participation through the Senior Design class in the M E Department of the FAMU-FSU College of Engineering or for summer students recruited through the REU/RET program at the nearby National High Magnetic Field Laboratory. This unique opportunity will provide these individuals with a research or design experience unattainable anywhere else in the US; an experience that may lead to a career in the field of cryogenics.