Turbulent Flow Drag Reduction Using Surfaces Exhibiting Superhydrophobicity and Riblets

使用具有超疏水性和沟槽的表面进行湍流减阻

• 批准号: 1066356
• 负责人: R Daniel Maynes
• 金额: $ 36万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1066356&HistoricalAwards=false
• 关键词: Turbulent; Flow; Drag; Reduction; Using

1066356MaynesThis project is aimed at characterizing the flow physics associated with turbulent liquid flow over superhydrophobic surfaces of various topologies and explores the combined passive drag reducing mechanisms of riblets and superhydrophobicity. The benefits of riblets on reducing the drag in turbulent boundary layers have been long understood, while superhydrophobic surfaces have recently emerged as a different mechanism for drag reduction. The coupling of these two drag-reducing mechanisms has not previously been explored, and it is expected that their combined benefit will be much greater than can be achieved by either mechanism alone. The impact of such surfaces on minimizing flow resistance is far reaching, ranging from microfluidic applications to large-scale liquid flows. The main technical objectives of the work are to provide significant characterization of the flow of liquids over superhydrophobic surfaces with and without riblets and to quantify their effectiveness in reducing drag in turbulent flows. Experiments are conducted in a small-scale turbulent channel flow where particle image velocimetry is employed to provide detailed characteristics of the flow field, in both streamwise and transverse planes. Upon elucidation of optimal parameter ranges from the PIV testing, experiments in a water tunnel will also be conducted, where the total drag on flat plates tiled with test surfaces will be measured. In parallel with the experimental program, direct numerical simulations of turbulent channel flow with surfaces exhibiting riblets and slip are performed. These simulations do not replicate exact experimental conditions, but rather provide additional fundamental insight into the coupling of riblets, which suppress spanwise motions, and slip derived from supherhydrophobicity in both the spanwise and streamwise directions. This work influences students at all levels of the educational system. In addition to the formal involvement of PhD students, undergraduate students are active participants in the work. Further, the work is integrated into Brigham Young University Summer of Academic Refinement (SOAR) program. In SOAR, minority high-school students spend several summer weeks on the BYU campus preparing for college admission tests, experiencing university life, and learning about the different programs of study. The students participate in workshops at various laboratories around campus, including the cleanroom where the superhydrophobic test surfaces are fabricated. The experience of SOAR students is further augmented by lab activities and experiments that explain superhydrophobic surfaces and drag reduction.

1066356 Maynes该项目旨在表征与各种拓扑结构的超疏水表面上的湍流液体流动相关的流动物理学，并探索沟槽和超疏水性的组合被动减阻机制。 沟槽对减少湍流边界层中的阻力的益处早已被理解，而超疏水表面最近出现作为一种不同的减阻机制。这两种减阻机制的耦合以前没有被探索过，并且预计它们的组合益处将比单独使用任一机制所能实现的益处大得多。这种表面对最小化流动阻力的影响是深远的，范围从微流体应用到大规模液体流动。这项工作的主要技术目标是提供显着的表征的超疏水表面上的液体流动，并没有肋，并量化其有效性，在湍流中减少阻力。实验进行了小规模的湍流槽道流的粒子图像测速提供详细的流场特性，在流向和横向平面。根据PIV试验确定的最佳参数范围，还将在水洞中进行试验，测量铺有试验表面的平板上的总阻力。与实验程序并行，对表面呈现沟槽和滑移的湍流槽道流动进行了直接数值模拟。这些模拟不复制精确的实验条件，而是提供额外的基本洞察力的耦合肋，抑制展向运动，和来自超疏水性在展向和流向的方向上的滑移。这项工作影响到教育系统各级的学生。 除了博士生的正式参与外，本科生也积极参与这项工作。此外，这项工作被纳入杨百翰大学夏季学术精炼（SOAR）计划。 在SOAR，少数民族高中生在杨百翰大学校园度过几个夏季周，准备大学入学考试，体验大学生活，并了解不同的学习课程。学生们参加校园周围各种实验室的研讨会，包括制造超疏水测试表面的洁净室。SOAR学生的经验通过解释超疏水表面和减阻的实验室活动和实验进一步增强。