The Role of Inlet Perturbations on Superstructures of Turbulent Boundary Layers- Toward Global Flow Control

入口扰动对湍流边界层上部结构的作用——面向全局流动控制

• 批准号: 1512393
• 负责人: Luciano Castillo
• 金额: $ 20.86万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1512393&HistoricalAwards=false
• 关键词: Role; Inlet; Perturbations; Superstructures; Turbulent

This proposal is about the investigation of a very fundamental issue in turbulent flows, the issue of the effects of small flow changes close to a solid wall on the development of very long eddies farther downstream. The practical outcome of such understanding would be the possibility to control turbulence downstream by small modifications of the flow upstream, leading to improvements in industrial applications, such as film cooling technology, commercial and military flight, design of wind energy turbine blades and saving energy in cases where fluid pumped over a solid surface is turbulent. Although turbulent boundary layers have been studied for over 50 years, the understanding of them remains the cause of ontroversy in the turbulence community. Such understanding is critical, however, if we are to develop practical control schemes that can help mitigate the energy penalty of turbulent boundary layers. Recent studies have shown that there are Large Scale Motions (LSMs) and Very Large Scale Motions (VLSMs) that carry more than 50% of the Reynolds stresses and kinetic energy. The largest of these motions have scales of the order of O(1δ) ≤ L ≤ O(10δ) and are often also referred to as superstructures. The hypothesis in the proposed study is to demonstrate the possibility to achieve Global Flow Control of the downstream flow by manipulating the inlet conditions in such a way to control the "superstructures". Our team from the USA and Australia seeks to explain the mechanisms by which such complex interactions are possible, and also to explore how these superstructures can modulate the inner region and vice versa. The proposed research consists of high Reynolds number wind tunnel experiments and high fidelity Direct Numerical Simulations (DNS) to study spatially-developing turbulent boundary layers under the influence of different inlet perturbations (e.g., including steady and unsteady). The low Reynolds number simulations will uncover the impact of inlet perturbations on superstructures and will provide optimum configurations to consider in the moderate and high Reynolds number studies. Recruitment of students and outreach will be facilitated by synergies with the ongoing Summer Research Institute established by the PI in 2013. In addition, there will be links to Puerto Rico institutions, where the co-PIs have a strong track record of student recruitment. The PIs also have a plan bringing K-12 teachers to Workshop on Wind Energy Turbulence each summer for the duration of the grant.

该提议是关于研究湍流中一个非常基本问题的调查，这是小流量变化的影响，几乎是固体壁上对较长涡流的发展。这种理解的实际结果将是通过对上游流动的小修改来控制下游的湍流，从而改善工业应用，例如胶片冷却技术，商业和军事飞行，设计涡轮机叶片的设计以及在固体表面上泵送的流体的情况下节省能源。尽管已经研究了湍流的边界层超过50年，但对它们的理解仍然是湍流社区中经历的原因。但是，如果我们要制定可以帮助减轻湍流边界层的能量惩罚的实践控制方案，那么这种理解至关重要。最近的研究表明，有大规模的运动（LSM）和非常大的运动（VLSM），载有超过50％的雷诺应力和动能。这些动作中最大的动作具有O（1＆＃948;）＆＃8804; L＆＃8804; o（10＆＃948;），通常也称为上层建筑。拟议的研究中的假设是证明通过操纵入口条件以控制“上层建筑”的方式来实现下游流动的全球流量控制的可能性。来自美国和澳大利亚的团队试图解释这种复杂互动的可能机制，并探讨这些上层建筑如何调节内部区域，反之亦然。所提出的研究包括高雷诺数风隧道实验和高富达直接数值模拟（DNS），以在不同的入口扰动（例如稳定和不稳定）的影响下研究空间发展的湍流边界层。低雷诺数模拟将揭示入口扰动对上层建筑的影响，并将在中等和高雷诺数研究中提供最佳的配置。与PI在2013年成立的正在进行的夏季研究所的协同作用将促进学生和外展的招聘。此外，还将有与波多黎各机构的链接，在该机构中，共同副作用具有较强的学生招聘记录。 PIS还制定了一个计划，将K-12老师带到每年夏天在赠款期间进行风能湍流的研讨会。