羽毛表面沟槽结构对减小鸟类飞行阻力的影响

Flow drag reduction technology, with significant impact on energy saving and wide engineering applications, has been investigated for decades. Making decrease in drag component would lead to saving large amount of energy and decrease environmental pollution as a second result. The objective of present project is to propose a novel aspect of drag reduction technology based on the riblet structure of birds' feather and most probably offer a high level of drag reduction technology from the aspect of bionics. Birds are endowed with excellent flying performance after a long-term evolution and the flight drag is considered generated from the interaction force of air acting on birds' feather. So, in a basis of the project is to study the surface morphology of birds' feather and to explore the drag reducing mechanism of bionic riblet surface. Based on the understanding of drag reduction mechanism, a concrete strategy in the application of aircraft design is presented with the use of bionic riblet film. The first detailed study of the project is to investigate the characteristics of non-smooth surface of several type birds' feather. Influence of riblets on the near-wall flow is carried out through computational fluid dynamics(CFD). A criteria of riblet geometrical parametres will be given for high level of drag reduction. Roll hot pressing technology will be adopted in the project to manufacture feather-like riblet film and experimental investigation of effect of riblet film on drag reduction is planned to be conducted in a wind tunnel.. This project will develop a novel method to reduce flow drag reduction from the aspect of bionics with high level of drag reduction and promote the development of both drag reduction technology and bionics.

鸟类经过长期进化具有优良的飞行特性，飞行时所受阻力来源于翅膀翼型和羽毛形态结构与空气间的相互作用。因此，探究羽毛表面因羽小枝相互钩连形成的沟槽结构对鸟类飞行阻力的影响，有利于揭示羽毛非光滑表面的减阻特性，既而可应用于飞行器仿生减阻技术的开发上。本项目从研究典型鸟类飞羽和尾羽的非光滑表面特征入手，分析沟槽结构对羽毛表面空气流动的影响，揭示羽毛非光滑表面减小飞行阻力的机理。进而，采用对辊热压工艺开发设计仿生减阻沟槽薄膜，贴敷于飞行器表面实现减小飞行阻力的目的。本项目研究成果不仅可以在理论上取得创新性成果，补充和促进仿生学及减阻理论的发展；而且，可广泛应用于各类型飞行器，有利于提高飞行器航程航速，降低能源消耗和环境污染。本项目有望以羽毛表面沟槽结构为基础，提出降低飞行器阻力的新思路和新方法。

摘要：鸟类经过长期进化具有优良的飞行特性，飞行时所受阻力来源于翅膀翼型和羽毛形态结构与空气间的相互作用。本课题从研究典型鸟类飞羽和尾羽的非光滑表面形貌特征入手，揭示了沟槽内微旋涡的生成与扩展是羽毛表面沟槽降低飞行阻力的主要原因，通过系统研究沟槽对微旋涡的生成、壁面剪切率、粘性摩擦力以及压力分布、压差阻力的影响发现存在最优的沟槽形貌使沟槽表面受力最小。基于动态网格技术，确定沟槽形貌构型参量的取值准则并研制出制备仿羽毛沟槽薄膜的覆膜机，通过对辊热压技术制备出仿羽毛表面沟槽结构的微米级沟槽薄膜，沟槽形貌由热压模具表面形貌决定。将仿生沟槽薄膜贴敷于风洞模型的表面进行试验，结果表明：研制出的仿羽毛沟槽薄膜具有显著的降低飞行阻力的作用，并获得了最大45%的减阻效果。本课题研究成果不仅在理论上取得了创新性成果，补充和促进仿生学及减阻理论的发展，而且可广泛应用于各类型飞行器，有利于提高飞行器航程和航速，降低能源消耗和环境污染。本课题以羽毛表面沟槽结构为基础，提出降低飞行器阻力的新思路和新方法，完成了项目立项时所立下的各项科研任务。