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.

Lang/Slegers1335848/1335572帝王蝶的翅膀呈现出具有微米量级特征尺寸的形态结构的鳞片。 这种独特的微图案会导致表面阻力的变化，并导致在高雷诺数 (Re ~= 10e3- 10e4) 扑动和滑翔飞行期间推力和升力增加。能量消耗的减少对于帝王蝶来说非常重要，因为帝王蝶是所有昆虫中迁徙时间最长的。 PI 进行的初步结果表明：(1) 横向穿过鳞片行的流动可通过滚子轴承效应在低 Re 下将局部表面阻力降低 40%，(2) 平行于鳞片行流动的流动可增加局部表面阻力超过 100%，(3) 在非常低的 Re 状态（Re ~ 5）中出现较高的阻力差异，(4) 前缘涡强度可能会根据表面阻力的变化而变化，以及 (5) 初始飞行测试君主对于那些没有鳞片的蝴蝶来说，为了保持类似的精力充沛的自由飞行，其扑动频率要增加 10%。拟议的工作将通过在阿拉巴马州亨茨维尔大学最先进的自动跟踪设施中对活体帝王蝶标本进行飞行测试，统计确定有鳞蝴蝶翅膀的空气动力学效率的提高；初步结果已经表明能够以 370 fps 的速度获得毫米级的机身和机翼运动跟踪。 REU 学生还将对单个 Monarch 前翼进行自动旋转跌落测试，以测量鳞片存在下增加的空气动力学性能。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允许蝴蝶启发的几何模型的尺寸比实际尺寸增加 10 至 100 倍。拟议的研究将（1）测量具有蝴蝶启发表面图案的跌落测试中流线型模型的阻力系数的变化，（2）在具有蝴蝶启发表面图案的平板模型上的拖车研究中利用边界层形成的 DPIV 测量，（3）根据受俯仰板实验中蝴蝶鳞片启发的表面图案评估前缘涡强度变化。第三组实验将利用 TSI V3V 系统进行完整的 3D 体积速度流量测量，PI 最近通过 NSF MRI-R2 奖项获得了该系统。 智力优点：拟议的合作努力将带来潜在的变革性新发现以及源自微尺度水平蝴蝶鳞片的独特被动表面阻力控制方法。拟议的工作将检验我们的工作假设，即局部表面阻力的变化会导致蝴蝶扑动和滑翔飞行时的能量需求减少。额外的工作将更好地阐明表面阻力的变化和相应的涡流控制，以流体动力学确认提高空气动力学效率的假设机制。这一基本理解将增进对蝴蝶启发的表面图案在其他工程应用中的最终使用的认识。更广泛的影响：需要边界层控制领域的创新来提供有效的方法来减少阻力（从而增加有效载荷、范围或节省燃料）适用于 MAV 以及更高 Re 的应用。一种独特的、受生物启发的被动微观几何技术，可以减少阻力，有可能通过增强节能和流量控制来影响这一研究领域的未来应用。蝴蝶鳞片的生物空气动力学功能的发现也将随之而来。此外，拟议的研究还涉及许多其他有益成果，包括对各级学生的培训以及在期刊/会议记录和公共媒体（例如国家地理在线）上广泛传播结果。本科生的参与将通过 REU 进行，重点关注代表性不足的群体。仿生工程是公众宣传的一个很好的话题，蝴蝶引起了人们的高度兴趣。