Collaborative Research: Experimental Studies to Reveal the Boundary Layer Control Mechanisms of Shark Skin

合作研究：揭示鲨鱼皮肤边界层控制机制的实验研究

• 批准号: 0931787
• 负责人: Robert Hueter
• 金额: $ 7.53万
• 依托单位: Mote Marine Laboratory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0931787&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; Studies; Reveal

Hueter,0931787 This experimental work will study a new and unique passive boundary-layer separation control methodology derived from shark skin, functioning at the micro-scale level. The skin and denticles (scales) of sharks represent over 400 million years of natural selection for swimming efficiency. Evolutionary adaptations in the morphological structure of the shark skin, to develop unique boundary layer control (BLC) mechanisms, stem from the ensuing decrease in drag, probable increase in fin performance (e.g. thrust production) and enhanced turning agility for fast-swimming sharks. Previous work, confirmed by the PIs, has shown the capability for shark denticles to bristle. The PI discovered that a bristled microgeometry results in the formation of a system of interlocking embedded cavity vortices. Three mechanisms are hypothesized which lead to boundary layer control via deterrence of separation over the shark skin. The first mechanism is the formation of embedded micro-vortices that increase momentum in the very near-wall region due to the partial slip condition resulting on the outer boundary layer flow. The second mechanism is that the preferential flow direction inherent in the surface geometry inhibits global flow reversal. The third mechanism, occurring during transitioning and turbulent boundary layer conditions, involves an exchange of flow with the cavities resulting in turbulence augmentation, or an additional energizing of flow in the near-wall region and cavities. The study involves engineers, working together with biologists, to fully comprehend the morphological bristling mechanism of shark denticles. This study will provide the first comprehensive characterization of the morphological mechanism resulting in denticle bristling and will classify the scope and degree (or angle) of bristling, yielding data for the building of shark skin models for hydrodynamic testing. The three passive BLC mechanisms will be evaluated through flow visualization and measurement using Time-Resolved Digital Particle Image Velocimetry (TR-DPIV). Innovations in the field of BLC are needed to provide efficient methodologies to decrease drag (resulting in increased payload, range or fuel savings), improve performance of control surfaces and enhance turning agility of modern technologies (e.g., submarines, aircraft). Dissemination of results will occur in journals/conference proceedings and the public media (e.g. Discovery Channel Canada). Undergraduate student involvement will take place through participation with two NSF REU programs (University of Alabama and Mote Marine Laboratory) with a focus on involving underrepresented groups; an REU supplement will also be sought to involve additional underrepresented undergraduates. Finally, the results from this research will be incorporated into educational outreach programs/exhibits at the Mote Marine Laboratory on sharks by the co-PIs and at the McWane Science Center in Birmingham, AL by the PI. Outreach through these two outlets alone should educate over 700,000 people each year about the drag-reducing properties of shark skin.

Hueter,0931787 这项实验工作将研究一种源自鲨鱼皮的新型、独特的被动边界层分离控制方法，在微观尺度上发挥作用。鲨鱼的皮肤和细齿（鳞片）代表了超过 4 亿年的游泳效率自然选择。鲨鱼皮肤形态结构的进化适应，发展出独特的边界层控制（BLC）机制，源于随后的阻力减少、鳍性能（例如推力产生）的可能增加以及快速游动鲨鱼的转弯敏捷性的增强。先前的研究已得到 PI 的证实，表明鲨鱼的小齿具有竖立的能力。 PI 发现，毛状微观几何形状会导致形成互锁嵌入式空腔涡流系统。假设了三种机制，通过阻止鲨鱼皮上的分离来实现边界层控制。第一种机制是嵌入微涡流的形成，由于外边界层流产生的部分滑移条件，该微涡流增加了非常靠近壁面区域的动量。第二种机制是表面几何形状固有的优先流动方向抑制全局流动逆转。第三种机制发生在过渡和湍流边界层条件期间，涉及与空腔的流动交换，导致湍流增强，或者在近壁区域和空腔中额外激发流动。这项研究涉及工程师与生物学家的合作，以充分理解鲨鱼小齿的形态竖立机制。这项研究将首次全面描述导致齿状竖立的形态机制，并对竖立的范围和程度（或角度）进行分类，为建立用于水动力测试的鲨鱼皮肤模型提供数据。这三种被动 BLC 机制将通过流可视化和使用时间分辨数字粒子图像测速 (TR-DPIV) 的测量进行评估。 BLC 领域的创新需要提供有效的方法来减少阻力（从而增加有效载荷、航程或节省燃料），提高控制面的性能并增强现代技术（例如潜艇、飞机）的转向灵活性。结果将在期刊/会议记录和公共媒体（例如加拿大探索频道）中传播。本科生将通过参与两个 NSF REU 项目（阿拉巴马大学和莫特海洋实验室）来参与，重点关注代表性不足的群体； REU 还将寻求补充，让更多代表性不足的本科生参与进来。最后，这项研究的结果将被纳入联合 PI 在 Mote 海洋实验室关于鲨鱼的教育推广计划/展览，以及 PI 将纳入阿拉巴马州伯明翰麦克韦恩科学中心的教育推广计划/展览。仅通过这两个渠道进行宣传，每年就应该让超过 70 万人了解鲨鱼皮的减阻特性。