Ahnn Sangwoo, Kim Hyeongmin, Choi Haecheon
Department of Mechanical Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Institute of Advanced Machines and Design, Seoul National University, Seoul 08826, Republic of Korea.
Bioinspir Biomim. 2024 Dec 16;20(1). doi: 10.1088/1748-3190/ad9a45.
We improve the aerodynamic performance of a simplified vertical-axis wind turbine (VAWT) using a biomimetic flap, inspired by the movement of secondary feathers of a bird's wing at landing (Liebe 197954). The VAWT considered has three NACA0018 straight blades at the Reynolds number of80000based on the turbine diameter and free-stream velocity. The biomimetic flap is made of a rigid rectangular curved plate, and its streamwise length is 0.2and axial (spanwise) length is the same as that of blade, whereis the blade chord length. This device is installed on the inner surface of each blade. Its one side is attached near the blade leading edge (pivot point), and the other side automatically rotates around the pivot point (without external power input) in response to the surrounding flow field during blade rotation. The flap increases the time-averaged power coefficient by 88% at the tip-speed ratio of 0.8, when its pivot point is at 0.1downstream from the blade leading edge. While the torque on the blade itself does not change even in the presence of the flap, the flap itself generates additional torque, thus increasing the overall power coefficient. The phase analysis indicates that the power coefficient of VAWT significantly increases during flap opening to full deployment through the interaction with vortices separated from the blade leading edge. When the pivot point of flap is farther downstream from the leading edge or the flap operates at a high tip-speed ratio, the performance of the flap diminishes due to its weaker interaction with the separating vortices.
我们受鸟类翅膀着陆时次级羽毛运动的启发（Liebe，197954），使用仿生襟翼来改善简化的垂直轴风力涡轮机（VAWT）的空气动力学性能。所考虑的垂直轴风力涡轮机基于涡轮机直径和自由流速度，在雷诺数为80000时具有三个NACA0018直叶片。仿生襟翼由刚性矩形弯曲板制成，其流向长度为0.2，轴向（展向）长度与叶片相同，其中为叶片弦长。该装置安装在每个叶片的内表面。其一侧附着在叶片前缘（枢轴点）附近，另一侧在叶片旋转过程中响应周围流场自动绕枢轴点旋转（无需外部动力输入）。当襟翼的枢轴点位于叶片前缘下游0.1处时，在叶尖速比为0.8时，襟翼可将时间平均功率系数提高88%。虽然即使存在襟翼，叶片自身的扭矩也不会改变，但襟翼本身会产生额外的扭矩，从而提高整体功率系数。相位分析表明，通过与从叶片前缘分离的涡旋相互作用，垂直轴风力涡轮机的功率系数在襟翼打开至完全展开期间显著增加。当襟翼的枢轴点离前缘更远或襟翼在高叶尖速比下运行时，由于其与分离涡旋的相互作用较弱，襟翼的性能会下降。
