Physical and Computational Concepts for Systematic Development of Drag Reducing Surfaces in Pipes

管道减阻表面系统开发的物理和计算概念

• 批准号: 1335731
• 负责人: Ronald Adrian
• 金额: $ 30万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-15 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335731&HistoricalAwards=false
• 关键词: Physical; Computational; Concepts; Systematic; Development

PI: Adrian, Ronald Proposal Number: 1335731 The broad goal of the proposed research is to investigate the structure of turbulence eddies in pipe flows for the purpose of developing passive drag reducing surfaces suitable for implementation in large-scale engineering systems such as the U. S. national network of pipelines. Despite the many drag reducing strategies that have been tried to reduce wall friction caused by turbulent flow over surfaces, it is difficult to find any clear, undisputed set of principles that explains how one should design surfaces to reduce skin friction drag. The surfaces that have been successful, such as riblets, have been devised by trial and error methods coupled with the knowledge of the simplest aspects of wall turbulence, or by bio-mimetic approaches that copy methods used by life forms such as shark skin. However, progress over the past decade in understanding the coherent structures responsible for creating friction stresses now brings the possibility of a systematic approach to drag reduction within reach. The matter of transition to turbulent flow in pipe flow is an especially vexing question that has remained open for more that a century. The answers to these questions seem likely to be essential, or at the least very valuable, to the invention of drag reducing agencies that operate by inhibiting the formation of turbulence or diminishing its strength. The specific goals are to investigate the transition to turbulence in pipe flow at Reynolds numbers well above the lower critical value; to investigate the eddy mechanisms leading to re-laminarization of accelerating turbulent flows; and to develop large eddy simulation methods capable of revealing, with high fidelity, the effects of drag reducing surfaces at high Reynolds numbers.Intellectual Merit :The transition to turbulence in pipe flow is one of the longest standing mysteries in fluid mechanics. Understanding the origins of turbulence in pipe flow will guide efforts to design drag reducing agents. Explaining the eddy mechanisms underlying the behavior of relaminarizing flow will test current physical models of wall turbulence such as the hairpin packet paradigm, and also provide insights into a form of turbulence behavior that reduces drag. Exploring singular perturbation methods for devising models for simulating high Reynolds number flow with fully resolved near-wall physics may improve our ability to simulate and model turbulent flow over surfaces, including complex drag reducing patterns.Broader Impacts :Tools that will contribute to the eventual development of drag reducing methods for pipe flow would enable economically valuable energy savings. Overcoming turbulent friction consumes a surprisingly large fraction of the United States' national energy budget. The system of pipelines carrying oil and natural gas throughout the U. S. requires 3% of the roughly 1 T$ annual energy expenditure to pump the fluids, corresponding about 30B$ per annum to overcome the flow resistance due to turbulence in the pipes.

PI：阿德里安（Adrian），罗纳德（Ronald）提案编号：1335731拟议研究的广泛目标是调查管道中湍流涡流的结构，目的是开发适合在美国国家管道网络等大型工程系统中实施的被动阻力降低表面。尽管已经试图减少由于表面上的湍流引起的壁摩擦而进行的许多阻力减少策略，但很难找到任何清晰，无可争议的原理集，这些原理解释了如何设计表面以减少皮肤摩擦阻力。已经成功的表面（例如Riblets）是通过反复试验和错误方法以及对壁湍流最简单方面的了解或通过复制鲨鱼皮肤等生命形式使用的方法来设计的。但是，在过去的十年中，在理解负责产生摩擦压力的连贯结构方面的进展现在使系统的拖动减少范围具有可能性。在管道流中过渡到湍流的问题是一个特别令人烦恼的问题，在一个世纪以来，它仍然持开放态度。这些问题的答案似乎可能是必不可少的，或者至少对于通过抑制湍流形成或降低其力量而运作​​的拖放机构的发明。具体目标是研究雷诺数在较低临界值较低的雷诺数字的管道流中的湍流过渡；研究导致加速湍流重新延伸的涡流机制；为了开发能够以高忠诚度揭示拖力减少雷诺数字表面的影响的大型涡流模拟方法。IntlectualFure：对管道流动中湍流的过渡是流体机制中最长的谜团之一。了解管道流动中的湍流的起源将指导设计减少阻力剂的努力。解释重新流动流动行为的涡流机制将测试当前的壁湍流物理模型，例如发夹包数据包范式，并提供对减少阻力的湍流行为形式的见解。探索奇异的扰动方法，以设计模拟高雷诺数量流量的模型，并完全解决近壁物理，可以提高我们模拟和模拟表面上的动荡流的能力，包括复杂的拖放模式。降低模式的影响：实现的工具：工具将有助于最终的减少管道流动方法来促进经济能源节省的拖动方法。克服湍流的摩擦消耗了美国国家能源预算的惊人一部分。在整个美国携带油和天然气的管道系统需要大约1 t $每年的能量消耗的3％才能泵送流体，相应每年约30b $，以克服由于管道湍流而引起的流动阻力。