This study considers the effect of kinematics on the aerodynamic loads and flow structure around moving blades of micro air vehicles (MAVs) in deep dynamic stall. The transversal (pure heaving) and rotational (pure pitching) motions are considered distinctly to investigate the dynamic stall. An equivalent effective angle of the attack profile is given to both motions. This method helps to figure out the influence of kinematics on flow structures when all boundary conditions and effective angles of attack profiles are the same. An experiment is conducted in fully turbulent flow at Re = 1.5×10⁴ to avoid any transition regime in the boundary layer, and make the results relatively independent of the flow characteristics. A NACA 0012 airfoil is chosen at high reduced frequencies (k = 0.25 and 0.375) and high angles of attack to reach deep dynamic stall conditions. Additionally, time-resolved particle image velocimetry (PIV) and post-processing are used to compute the aerodynamic loads using a control-volume approach. The flow field is also reconstructed using proper orthogonal decomposition (POD) to separate the flow structures in different modes. It is shown that the kinematics can significantly influence the flow structure and aerodynamic loads. In the pre-stall region, the pure pitching motion usually produces higher lift force, while the pure heaving motion has a higher lift peak. However, in the post-stall region, the pure heaving motion usually has higher lift than the pure pitching motion. The pure heaving motion produced lower drag force than the pure pitching motion. For pure heaving motion, the POD analysis reveals there is a high-energy mode in the flow structure that helps to make the vortices more stable compared to pure pitching motion. Furthermore, the pure heaving motion adds extra kinetic energy to the boundary layer, which decelerates the reversal flow and the transfer of the separation point on suction side of the airfoil.

本研究考虑了运动学对深动态失速中微型飞行器（MAV）的动叶片周围的空气动力学负载和流动结构的影响。横向（纯粹起伏）和旋转（纯粹俯仰）运动被认为是用来研究动态失速的。两种运动都具有等效的有效攻角。当所有边界条件和有效攻角均相同时，该方法有助于找出运动学对流动结构的影响。在Re = 1.5×10 ^4的全湍流中进行实验，以避免边界层出现任何过渡状态，并使结果相对独立于流动特性。选择NACA 0012机翼的高降低频率（k= 0.25和0.375）和高攻角以达到深动态失速条件。此外，时间分辨粒子图像测速（PIV）和后处理用于使用控制量方法来计算空气动力学负荷。还使用适当的正交分解（POD）重构流场，以分离不同模式的流结构。结果表明，运动学可以显着影响流动结构和空气动力负荷。在失速前区域，纯俯仰运动通常会产生较高的升力，而纯升沉运动则具有较高的升力峰值。然而，在失速后区域中，纯粹的起伏运动通常具有比纯粹的俯仰运动更高的升力。纯的起伏运动产生的拖曳力低于纯的俯仰运动。为了获得纯粹的起伏运动，POD分析表明，与纯俯仰运动相比，流动结构中存在高能模式，有助于使旋涡更稳定。此外，纯粹的起伏运动为边界层增加了额外的动能，从而降低了反向流动和翼型吸力侧分离点的转移。