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.

这一建议是关于研究湍流中一个非常基本的问题，即靠近固体壁面的小流动变化对下游更远的非常长的涡流发展的影响的问题。这种理解的实际结果将是有可能通过对上游流动的微小修改来控制下游的湍流，从而导致工业应用的改进，如气膜冷却技术、商业和军事飞行、风能涡轮机叶片的设计，以及在泵送到固体表面的流体是湍流的情况下节省能源。尽管对湍流边界层的研究已有50多年的历史，但对其的理解仍然是湍流研究领域内的一大问题。然而，如果我们要开发实用的控制方案，帮助减轻湍流边界层的能量惩罚，这样的理解是至关重要的。最近的研究表明，存在大尺度运动(LSM)和超大尺度运动(VLSM)，它们承载着50%以上的雷诺应力和动能。其中最大的运动具有O(1&amp；)和L(10&amp；O)量级的尺度，通常也被称为上层建筑。拟议研究中的假设是通过操纵入口条件来控制“上层建筑”来实现下游水流的全局流量控制的可能性。我们来自美国和澳大利亚的团队试图解释这种复杂相互作用的可能机制，并探索这些超结构如何调节内部区域，反之亦然。该研究包括高雷诺数风洞实验和高保真直接数值模拟，以研究不同进口扰动(包括定常和非定常)影响下的空间发展湍流边界层。低雷诺数模拟将揭示入口扰动对上部结构的影响，并将为中等和高雷诺数研究提供最佳构型。通过与国际和平研究所2013年设立的暑期研究所的协同作用，将促进招生和外联工作。此外，还将与波多黎各各机构建立联系，在这些机构，联合个人投资机构在招生方面有着良好的记录。此外，私人机构亦计划每年夏天在资助期间，邀请幼稚园至幼稚园的教师参加风能湍流工作坊。