扑翼飞行器转弯机动非定常气动特性与流场演化研究

Study on Unsteady Aerodynamic Characteristics and Flow Field Evolution of a Flapping-Wing Vehicle during Turning Maneuvers

摘要: 为揭示仿生扑翼飞行器在复杂机动中的非定常气动与流场重构机理，本文以空间曲柄摇杆传动的扑翼飞行器为对象，利用ANSYS Fluent结合UDF与重叠网格技术，模拟了其由平飞向90˚侧风大角度转弯的时空耦合过程。分析连续6个扑动周期内的气动载荷与Q准则三维涡系拓扑表明：转向启动期，外侧翼维持强附着前缘涡(LEV)，左右翼压差失衡产生向心滚转与偏航力矩；持续转弯期，曲线轨迹诱导尾迹涡侧向弯曲，大侧滑角导致迎/背风翼解耦，背风翼因机身遮挡引发前缘涡剥离；至90˚侧风极限工况，横向气流使双翼上表面被高压覆盖($\Delta P<0$ )并产生剧烈负升力，规则展向涡瓦解为大尺度钝体分离与深度失速。研究揭示了极限横风对扑翼气动特性的破坏机制，可为扑翼飞行器控制律设计与外形优化提供新思路。

Abstract: To reveal the unsteady aerodynamic responses and flow field reconstruction of bionic flapping-wing vehicles during complex maneuvers, a vehicle driven by a spatial crank-rocker mechanism was investigated. Using ANSYS Fluent integrated with UDF and overset grid techniques, the spatiotemporal coupled flight transition from level flight to a 90˚ crosswind sharp turn was simulated. Analysis of the aerodynamic loads and three-dimensional vortex topology visualized using the Q-criterion over six consecutive flapping cycles reveals that, during turn initiation, the outer wing maintains a strong attached leading-edge vortex (LEV), while the pressure imbalance between the two wings generates rolling and yawing moments toward the turn center. During sustained turning, the curved flight trajectory induces lateral bending of the wake vortices. A large sideslip angle leads to aerodynamic decoupling between the windward and leeward wings, with fuselage shielding causing LEV detachment from the leeward wing. Under the limiting condition of a 90˚ sideslip angle, crossflow produces high-pressure regions over the upper surfaces of both wings ($\Delta P<0$ ), resulting in substantial negative lift. The organized spanwise vortices break down, giving way to large-scale bluff-body separation and deep stall. These findings elucidate how extreme crosswinds degrade flapping-wing aerodynamic performance and provide insights into control-law design and aerodynamic shape optimization for flapping-wing aircraft.