柔性翼气动力和变形特性的实验研究

微型飞行器在军、民用领域具有广阔的应用前景，柔性翼是提升微型飞行器的气动性能的有效方法。为了更好地对柔性翼进行控制，对柔性翼变形和振动特性及其对气动力的影响进行了同步测量。研究结果表明，相比于刚性翼，柔性翼使失速迎角推迟了6°，最大升力系数提升了47.4%，升阻比提高了17.8%。柔性翼的周期性振动除了迎角0°~2°呈现大振幅、小静变形特征外，振动的振幅随着迎角增加经历无明显波峰、三波峰到单波峰的转换。升力系数最大时对应的薄膜变形、振动振幅均达到最大。此外，变形最大的弦向位置随迎角的变化决定了俯仰力矩的特性。据此提出了施加弯度和特定频率的振动激励来提升气动性能的主动控制策略。 

Experimental study on aerodynamic and deformation characteristics of flexible membrane wing

Micro air vehicles (MAV) have wide appications in both miltary and civilian fields, and flexible membrane wings are an effective method to improve the aerodynamic of MAV. In order to better control the flexible wing, the vibration and deformation characteristics of the flexible membrane wing and their impact on aerodynamic force are measured synchronously. Compared with the rigid wing, for the flexible membrane wing, the stall angle of attack is delayed by 6°, the maximum lift coefficient is increased by 47.4%, and the lift-drag ratio is increased by 17.8%. In addition to the characteristics of large amplitude and small static deformation at α=0°~2°, the amplitude of the periodic vibration of the flexible membrane wing undergoes a transition from no obvious crest, three crests to one crest as the angle of attack increases. When the lift coefficient is maximum, the corresponding membrane deformation and vibration amplitude both reach their maxima. Besides, the chordwise position of the maximum deformation changes with the angle of attack, which determines the pitching moment characteristics. Based on these results, an active control method of improving aerodynamic performance by applying deformation and vibration excitation with specific frequency is proposed.