COLLABORATIVE RESEARCH: THE BENEFICIAL AERODYNAMIC EFFECT OF BUTTERFLY SCALES

合作研究：蝴蝶鳞片的有益空气动力学效应

• 批准号: 1335848
• 负责人: Amy Lang
• 金额: $ 28.17万
• 依托单位: University of Alabama Tuscaloosa
• 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: 2013-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335848&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; BENEFICIAL; AERODYNAMIC; EFFECT

Lang/Slegers1335848/1335572The wings of the Monarch butterfly exhibit scales with a morphological structure that has a characteristic size on the order of micrometers. This unique micro-patterning results in a surface drag alteration, and leads to an increase in thrust and lift during flapping and gliding flight at high Reynolds numbers (Re ~= 10e3- 10e4). This reduction in energy expended would be important to the Monarch which has the longest migration of any insect. Preliminary results performed by the PIs indicate: (1) flow passing transverse to the rows of scales can decrease the local surface drag by 40% at low Re via a roller bearing effect, (2) flow passing parallel to the rows of scales can increase local surface drag by over 100%, (3) higher drag differences occur in the very low Re regime (Re ~ 5), (4) leading edge vortex strength may vary based on surface drag alteration, and (5) initial flight tests of Monarch butterflies indicate a 10% increase in flapping frequency for those without scales to maintain similar energetic free flight. Proposed work will statistically determine the increased aerodynamic efficiency of butterfly wings with scales through flight testing of live Monarch specimens in a state-of-the-art autonomous tracking facility at the University of Alabama Huntsville; preliminary results have already shown the capability to obtain mm level tracking of body and wing motion at 370 fps. Autorotating drop tests of single Monarch forewings will also be performed by a REU student to measure increased aerodynamic performance with the presence of scales. A series of dynamically scaled tests carried out in high viscosity silicone oil at the University of Alabama will allow for models of butterfly-inspired geometries with an increase in 10 to 100 times in sizing from real scales. The proposed studies will (1) measure variation in the drag coefficient over streamlined models in drop tests with butterfly-inspired surface patterning, (2) utilize DPIV measurements of boundary layer formation in tow tank studies over flat plate models with butterfly-inspired surface patterning, and (3) evaluate leading edge vortex strength variation based on surface patterning inspired by butterfly scales in pitching plate experiments. The third set of experiments will utilize the TSI V3V system for full 3-D volumetric velocity flow measurements recently acquired by the PI through a NSF MRI-R2 award.Intellectual Merit :The proposed collaborative effort will result in the potentially transformative discovery of a new and unique passive surface drag control methodology derived from butterfly scales functioning at the micro-scale level. Proposed work will test our working hypothesis that local surface drag alteration results in reduced energy requirements for butterflies in flapping and gliding flight. Additional work will better elucidate the surface drag alteration and corresponding vortex control for fluid dynamic confirmation of the hypothesized mechanisms for increased aerodynamic efficiency. This fundamental understanding will advance knowledge for the ultimate use of a butterfly-inspired surface patterning for other engineering applications.Broader Impacts :Innovations in the field of boundary layer control are needed to provide efficient methodologies to decrease drag (resulting in increased payload, range or fuel savings) for MAVs as well as higher Re applications. A unique, bioinspired technology in the form of a passive microgeometry leading to drag reduction has the potential to impact this area of research with future applications with increased energy conservation and flow control. The discovery of the biological aerodynamic function of butterfly scales would also result. In addition, the proposed study involves a number of other beneficial outcomes including the training of students at all levels and broad dissemination of results in journals/conference proceedings and the public media (e.g. National Geographic Online). Undergraduate student involvement will take place through REU participation with a focus on involving underrepresented groups. Bio-inspired engineering is an excellent topic for public outreach, and butterflies generate a high level of interest.

黑脉金斑蝶的翅膀上有鳞片，其形态结构特征尺寸在微米量级。这种独特的微模式导致了表面阻力的改变，并导致了高雷诺数（Re ~= 10e3- 10e4）下扑翼和滑翔飞行时推力和升力的增加。这种能量消耗的减少对于迁徙时间最长的黑脉金斑蝶来说是很重要的。初步调查结果显示：(1)低Re时，横向经过鳞片排的气流通过滚子轴承效应可使局部表面阻力降低40%；(2)平行经过鳞片排的气流可使局部表面阻力增加100%以上；(3)极低Re区（Re ~ 5）阻力差异较大；(4)前缘涡强度可能随表面阻力变化而变化。(5)黑脉金斑蝶的初步飞行试验表明，没有鳞片的黑脉金斑蝶为了保持类似的能量自由飞行，拍打频率增加了10%。拟议的工作将通过在阿拉巴马大学亨茨维尔分校最先进的自主跟踪设施中对活的帝王蝶标本进行飞行测试，统计确定带鳞片的蝴蝶翅膀增加的空气动力学效率；初步结果已经表明，该系统能够以370帧/秒的速度获得毫米级的身体和翅膀运动跟踪。此外，一名REU学生还将对单个君主前翼进行自旋跌落测试，以测量配重后增加的气动性能。阿拉巴马大学在高粘度硅油中进行的一系列动态缩放测试将使蝴蝶几何模型的尺寸比实际尺寸增加10到100倍。拟开展的研究将(1)利用蝴蝶启发的表面图案测量流线型模型的下降试验中阻力系数的变化，(2)利用DPIV测量蝴蝶启发的表面图案在平板模型的拖曳槽研究中边界层形成，以及(3)在俯仰板实验中基于蝴蝶鳞片启发的表面图案评估前缘涡强度的变化。第三组实验将利用TSI V3V系统进行全三维体积速度流测量，该系统是PI最近通过NSF MRI-R2奖获得的。知识价值：本次合作将带来一种新的、独特的被动表面阻力控制方法的潜在变革，该方法来源于蝴蝶鳞片在微观尺度上的作用。拟议的工作将验证我们的工作假设，即局部表面阻力改变导致蝴蝶在拍打和滑翔飞行中减少能量需求。进一步的工作将更好地阐明表面阻力变化和相应的涡流控制，从而在流体动力学上证实提高气动效率的假设机制。这种基本的理解将推进知识的蝴蝶启发的表面图案的其他工程应用的最终使用。更广泛的影响：边界层控制领域需要创新，以提供有效的方法来减少mav的阻力（从而增加有效载荷、航程或节省燃料）以及更高的Re应用。一种独特的、受生物启发的技术，以被动微几何形状的形式减少阻力，有可能影响这一领域的研究，并在未来的应用中增加节能和流动控制。蝴蝶鳞片的生物气动功能的发现也将随之产生。此外，拟议的研究还涉及一些其他有益的成果，包括对各级学生的培训，以及在期刊/会议论文集和公共媒体（例如国家地理在线）上广泛传播研究结果。本科学生的参与将通过REU的参与进行，重点是涉及代表性不足的群体。生物工程是公众宣传的一个极好的话题，蝴蝶产生了高度的兴趣。