羽翅仿生扑翼系统多体模型及其多涡干扰机理研究

Inspired by the flutter and deformation patterns of the bird's wing during the real flight, the new multi-body bio-inspired ventilated flapping wing design concept has been proposed. It will focus on “ventilating” the wings during the upstroke motion in order to reduce any negative lift，drag and thereby produce a net positive lift at each flapping cycle. The concept of using the wing’s own air pressure from the flapping motion to open and close the small moving flaps has been introduced as a possible passive control system. This design not only can improve the lift and reduce the drag characteristics respectively, it also can reduce the energy loss, improve the flutter and flight efficiency and then further provide a new idea for the micro flapping wing design. However, the present awareness on the ventilated flapping wing system especially in the flow field structure, the mean lift and thrust coefficients of the entire flapping wing influenced by different parameters (flapping and inclination angles etc.) are still not very clear. In addition, the aerodynamic interference and influence mechanism between the small moving flaps and main wing are also needed to investigate urgently. In this project, we will strongly keep the ventilated design concept in mind. The vortical structures in the chordwise and spanwise directions at different positions together with the pressure distribution around the wing will be obtained computationally and analyzed in details by adopting the simulation and experiment methods. The aerodynamic characteristics and vortex interferences between the main wing and small moving flaps at different shapes and flapping modes will be deeply analyzed.

仿生通风扑翼是模仿飞行中鸟类翅膀扑动变形及其飞羽适时地打开和闭合的运动规律而提出的一种新概念扑翼模型。通过主翼面开槽，形成若干随翼面压强变化而实现自行开闭的运动小翼。这种设计不仅可显著减小扑翼上扑时的空气阻滞，从而减小负升力、改善其升力特性，而且还可减小扑翼系统自身能量损耗，提高扑动和飞行效率。为实现高升阻比、低能耗特性的微型扑翼飞行器设计提供了新思路。然而，现阶段对于仿生通风扑翼系统的研究尤其是扑动角、倾斜角等各个参数变化会给整个扑翼的流场结构以及平均升力系数和推力系数等气动特性带来哪些影响尚不明确。自行开闭的翼面小翼的动态运动与主扑翼之间的气动力和涡干扰机理亟待研究。本项目将紧密围绕通风扑翼的新型概念设计，采用实验和数值模拟相结合的方法，通过分析翼面周围的弦向和展向的压强及动态涡分布，对不同气动外形和扑动方案的通风扑翼流场的动态气动特性以及双翼之间的气动力、涡干扰等问题进行深入的研究。

本项目以新型通风扑翼外形设计及气动特性为主要研究对象，紧紧围绕新型通风扑翼的仿生设计理念，通过主翼面开槽，形成若干随翼面压强变化而实现自行开闭的运动小翼。这种设计不仅可显著减小扑翼上扑时的空气阻滞，从而减小负升力、改善其升力特性，而且还可减小扑翼系统自身能量损耗，提高扑动和飞行效率。结合空气动力学和计算流体力学建立仿生通风扑翼系统的多体模型，并辅以实验验证。针对仿生通风扑翼的气动外形设计及扑动方案确定、推导和描述了运动方程组和涡运动轨迹，进而进行了三维模型的动态数值模拟。通过采用PIV切片技术显示了通风扑翼在不同扑动状态、扑动参数以及展弦向位置下的动态流场结构、前缘涡和尾涡等的形成、合并和脱落的全过程。通过研究通风扑翼的动态气动力特性和捕捉动态尾涡的运动轨迹，阐明了翼面小翼的动态运动对整个通风扑翼系统气动特性的影响机理。归纳总结出了通风扑翼系统的动态气动力特性、流动规律、动态涡结构及涡干扰特性在不同扑动频率、扑动角和扑动倾角等参数变化下的变化规律。本项目的研究无论在理论上还是工程上都可以让我们对新型仿生通风扑翼布局的设计理念和气动特性方面有一个较为深刻的理解，并为今后设计和研发提供相应的理论依据。这些研究成果对微型扑翼飞行器的设计和改进都具有重要的科学指导意义和工程应用前景。