High Reynolds Number Turbulence Research in Cryogenic Helium

低温氦中的高雷诺数湍流研究

• 批准号: 1801780
• 负责人: Wei Guo
• 金额: $ 37.5万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1801780&HistoricalAwards=false
• 关键词: Reynolds; Number; Turbulence; Research; Cryogenic

Many flows in nature, including those generated by aircraft, ships, and the atmosphere, have extremely high Reynolds numbers. The Reynolds number is the ratio of flow's inertial forces relative to viscous forces, and it determines important flow properties such as turbulence. Understanding flows with extremely high Reynolds numbers will increase efficiency in practical vehicle applications and improve understanding of the climate. However, high Reynolds-number flow in conventional fluids like air and water occurs on a relatively large scale thus is difficult to study on the laboratory scale. Fortunately, high Reynolds number flows can be achieved using lower-density fluids such as cryogenic helium-4 in, for example, a small-scale laboratory pipe flow experiment. But to unlock the full potential of cryogenic helium-4, suitable flow measurement tools to quantify the turbulence are also required. The proposed research will therefore develop advanced molecular tagging velocity measurement techniques and apply the technique to high Reynolds number cryogenic helium pipe flow. In terms of educational opportunities, the joint College of Engineering operated by Florida State University and Florida A&M University will be leveraged to recruit under-represented minorities to participate in the project. The PI and the co-PI's groups will also contribute educational demonstrations for public open-house events at the National High Magnetic Field Laboratory and at the Florida Center for Advanced Aero-Propulsion.The scientific goal of this project is to develop a state-of-the-art molecular tagging velocimetry technique for cryogenic helium and to demonstrate its usefulness by applying it in the study of high Reynolds number cryogenic helium pipe flow. Sophisticated patterns of the molecular tracer lines will be created by splitting and focusing a femtosecond laser beam in liquid helium. Advanced pattern-tracking algorithms will be incorporated, and the spatial and temporal resolutions of the tracer imaging process will be optimized. These developments will unlock the full potential of cryogenic helium in turbulence research and model testing. The planned study on high Reynolds number pipe flows in helium will allow an independent examination of the near-wall velocity field and the associated von K?rm?n coefficient, which may help resolve existing controversies regarding the universality of this coefficient. Also, new knowledge about the near-wall spatial velocity correlations will be produced by tracking the tracer lines created perpendicular to the wall. Furthermore, by measuring the pressure drop along the pipe, reliable friction factor data for high Reynolds number flows will be obtained, which will benefit the design of various engineering systems that exhibit high Reynolds numbers.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.

自然界中的许多流动，包括由飞机、船只和大气产生的流动，都具有极高的雷诺数。雷诺数是流动的惯性力相对于粘性力的比率，它决定了重要的流动特性，如湍流。了解具有极高雷诺数的流动将提高实际车辆应用的效率，并改善对气候的了解。然而，高雷诺数流动在空气和水等常规流体中发生的规模较大，因此很难在实验室规模上进行研究。幸运的是，在例如小规模的实验室管道流动实验中，可以使用较低密度的流体，如低温氦-4来实现高雷诺数流动。但为了充分发挥低温氦-4的潜力，还需要合适的流量测量工具来量化湍流。因此，这项研究将发展先进的分子标记速度测量技术，并将该技术应用于高雷诺数低温氦管流动。在教育机会方面，将利用佛罗里达州立大学和佛罗里达农工大学联合运营的工程学院，招收代表人数不足的少数族裔参与该项目。PI和共同PI的小组还将为国家强磁场实验室和佛罗里达先进航空推进中心的公开开放活动提供教育演示。该项目的科学目标是开发一种最先进的低温氦分子标记测速技术，并通过将其应用于高雷诺数低温氦管道流动的研究来证明其有效性。分子示踪线的复杂图案将通过在液氦中对飞秒激光进行分裂和聚焦来创建。将采用先进的模式跟踪算法，并优化示踪剂成像过程的空间和时间分辨率。这些进展将充分释放低温氦在湍流研究和模型试验中的潜力。计划中的高雷诺数氦管流研究将允许对近壁速度场和相关的von K？rm？N系数进行独立的检验，这可能有助于解决关于该系数普适性的现有争议。此外，通过跟踪垂直于墙创建的示踪线，将产生关于近壁空间速度相关性的新知识。此外，通过测量管道沿线的压力降，将获得可靠的高雷诺数流动的摩阻系数数据，这将有助于各种显示出高雷诺数的工程系统的设计。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。

项目成果

A cryogenic-helium pipe flow facility with unique double-line molecular tagging velocimetry capability

具有独特双线分子标记测速能力的低温氦管流设施

• DOI: 10.1063/5.0008117
• 发表时间: 2020
• 期刊: Review of Scientific Instruments
• 影响因子: 1.6
• 作者: Sanavandi, Hamid;Bao, Shiran;Zhang, Yang;Keijzer, Ruben;Guo, Wei;Cattafesta, III, Louis N.
• 通讯作者: Cattafesta, III, Louis N.

Molecular Tagging Velocimetry in Superfluid Helium-4: Progress, Issues, and Future Development

超流 Helium-4 中的分子标记测速：进展、问题和未来发展

• DOI: 10.1007/s10909-018-2102-1
• 发表时间: 2018
• 期刊: Journal of Low Temperature Physics
• 影响因子: 2
• 作者: Guo, Wei