Visualization studies of forced flow liquid helium

标题：强制流动液氦的可视化研究。货车Sciver，FSUCo-PI：Sylvie Fuzier，FSU我们进行了一项实验研究工作，以开发和应用粒子图像测速（PIV）技术，在高雷诺数，强制流动液氦的流体动力学过程的基础研究。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。氦有两种液相：He I，一种在Tc = 5.2 K和T = 2.176 K之间存在的近经典流体，以及He II或低于T的超流氦，这是一种量子流体。He II显示了在任何其他流体中看不到的热流体性质。这些特性中的许多特性为大规模低温技术的操作提供了好处，例如超导磁体和加速器。 虽然液氦中的流体动力学过程已经通过压力和温度测量等常规宏观技术进行了广泛的研究，但直到最近才尝试研究支撑这些过程的微观现象。最好使用现代流诊断技术（如PIV）来探索此类现象。 推进我们对液氦流体动力学的基本、微观尺度的理解是拟议项目的主要智力价值。这项工作主要是实验性质的，旨在可视化He I和He II中的流动现象。将研究两种配置：管道流和非流线体（如管道中包含的圆柱体或球体）周围的流，流速高达约0.5 m/s（对应于雷诺数在105至106的范围内）。其中一个预期的成果是有史以来第一次观察到的速度边界层在他I和他II。随后，圆柱体和其他非流线体将被放置在流动通道中，并使用PIV再次研究物体周围的条件。 在更广泛的背景下，液氦具有任何冷凝流体的最低粘度，因此为流体动力学和传热研究带来了在中等尺寸系统中实现非常高雷诺数的能力。这些好处激发了世界各地的一些实验室建立高雷诺数流体动力学设施使用液氦。然而，以前的PIV研究，特别是在他二已经表明，悬浮颗粒和液体之间的相互作用可能比假设的更复杂。因此，该项目更广泛的影响之一将是通过提高对液氦系统PIV测量技术的理解，使其对该领域的所有研究人员都有用。除了这些技术发展外，拟议的计划还将对工程专业学生的教育经验产生重大影响，包括那些来自代表性不足的群体的学生。除了研究生PIV研究工作中所描述的建议，我们还将工艺几个较小规模的项目，适合本科生参与通过高级设计类在工程的FAMU-FSU学院的M E部门或夏季学生通过REU/RET计划在附近的国家高磁场实验室招募。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;这种经验可能会导致低温领域的职业生涯。

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.