三维仿生悬停扑翼的时间非对称扑动及柔性变形耦合气动机理研究

In order to improve the loading capacity and flapping efficiency of the bionic hovering wing, the aerodynamic characteristics of the hovering humblebee is investigated in this project. The investigation of some special wing motion of the hovering insect on the aerodynamic characteristics and vortex transport of flapping wing is carried out by using numerical and prototype flight test method for the basic scientific research. The research involves: firstly, the improvement of the existing studying hovering humblebee characteristics of symmetric flapping model is carried out, and the asymmetric flapping model is established. Secondly, Through the analysis of the mechanical properties of the insect wing, three-dimensional numerical model of the bionic flexible wing is established, and the self-developed coupling algorithm is employed to achieve the aerodynamic characteristics of the hovering bionic wing with asymmetric flapping, flexibility and fluid flow coupling analyzing. Finally, the response surface methodology is employed to optimize the aerodynamic parameters of the hovering wing, and the prototype is designed for the validation. The object of this research is to reveal the effect of time asymmetric flapping and flexibility of wing on the aerodynamic characteristics and vortex transport of flapping wing, and it is hoped to provide new ideas and theoretical basis for the development of a stronger loading capacity and a higher flight efficiency of flapping micro air vehicle (FMAV).

本项目以黄蜂悬停时扑翼的气动特性为研究对象，以提高仿生悬停扑翼的负载能力和飞行效率为研究目标，采用数值计算和样机飞行实验相结合的方法，对昆虫悬停时涉及到的一些特殊的扑翼运动方式和流体相互作用机制及流场中涡的运动特性进行基础科学研究。具体研究内容包括：首先改进现有研究仿黄蜂悬停扑翼气动机理的对称扑动模型，构建悬停扑翼的时间非对称扑动轨迹模型；然后通过对黄蜂翅膀力学特性分析，构建三维仿生扑翼柔性变形的数值计算模型，并采用自编的耦合算法实现对扑翼的时间非对称扑动、柔性变形和流体流动相互耦合气动特性的数值研究；最后采用响应面法对扑翼的气动参数进行优化，并设计扑翼样机，进行飞行验证。本项目旨在揭示时间非对称扑动及柔性变形耦合对三维仿生悬停扑翼负载能力和飞行效率及流场中涡运动机制的影响规律，为研制负载能力更强和飞行效率更高的微型扑翼飞行器提供理论和技术基础。

负载能力和飞行效率问题限制了扑翼飞行器的发展和广泛应用。本项目依照申请时的研究计划，采用数值计算和样机飞行实验相结合的方法，研究了时间非对称扑动和柔性变形对三维仿黄蜂悬停扑翼气动特性产生的影响。开发了一套可有效求解三维仿生扑翼的时间非对称扑动和柔性变形数值计算程序，并对程序的正确性和有效性进行了验证。得到了扑翼升力系数均值和悬停效率随下扑时间比变化的性能曲线，并通过流场分析发现，采用时间非对称扑动可增强使扑翼产生高升力的旋转环流机制及扑翼表面涡流和展向流强度的结论；得到了扑翼升力系数均值和悬停效率随扑翼柔性尺度变化的性能曲线，并指出扑翼扑动频率和系统固有频率相同，且扑翼密度和黄蜂翅膀密度相同时，柔性变形可抑制前缘涡的脱落，并增强使扑翼产生高升力的尾迹捕捉机制的结论。最后基于数值分析结果，研制了一款具有一定悬停能力的两自由度扑翼样机，该样机理论最大负载可达5g。