Seagull's wing blade design(bio-inspiration)

What it does

This vertical-axis micro wind turbine blade is inspired by seagull wing morphology. An internal air dam aids self-start and rotation at low wind speeds. Tests showed startup time cut from 80 to 30 seconds, making it ideal for compact, low-wind urban areas.

Your inspiration

While using the subway in Korea, I noticed that wind from passing trains occurs regularly. A study (Kim, 2008) showed wind speeds near platform screen doors reaching 15.55–16.17 m/s, suitable for micro wind energy. Savonius blades showed strong self-start, while H-Darrieus blades offered better high-speed efficiency. I aimed to combine both traits. To suit confined spaces like tunnels, I turned to biomimicry. Seagulls, adapted to coastal winds, inspired my design. Based on Teruaki et al., I created a vertical-axis blade reflecting both the sweptback and dihedral angles of seagull wings.

How it works

1. Drag characteristics are essential for self-starting. To achieve this, an air dam was integrated into the blade design, allowing wind to push from behind and initiate rotation. The opposite blade features a lift-type airfoil, enabling it to slice through air and assist in the startup. The air-dam was inspired by the challenge of enabling self-starting in lift-type blades. Based on the cross-sectional structure of shark skin, the design channels airflow to generate necessary drag during initial rotation. 2. Once the drag-driven blade accelerates and its tip speed exceeds the wind speed, the groove (air-dam) no longer receives direct wind but instead creates a localized vacuum. This draws part of the surface airflow into the groove, generating a vortex within the air dam. This dynamic supports sustained high-speed rotation.

Design process

1. Understanding Lift and Drag Blades ∎ Through experiments with Savonius (drag-type) and H-Darrieus (lift-type) blades, their respective characteristics in startup and rotational efficiency were identified. 2. Setting Design Goals ∎ The design aimed to achieve self-starting capability, rapid acceleration in rotational speed, and performance exceeding the ambient wind speed. 3. Biomimicry Research – Finding Inspiration Various biological forms were explored as inspiration, including humpback whale flippers, shark skin cross-sections, streamlined fish bodies, and seagull wings. 4. Initial Testing – Identifying the Problem ∎ The blade successfully self-started and exceeded wind speed, but post-startup acceleration was slow, indicating a need for improvement. 5. Problem Solving – Addressing Slow Acceleration ∎ To enhance acceleration, an air-dam was added to the seagull wing-inspired blade design, which improved early-stage rotational speed. 6. New Issue – Low Maximum Speed ∎ While the air-dam improved self-starting and acceleration, it also caused a decrease in the blade’s maximum rotational speed. ∎ A potential solution to the new issue was identified, but it was excluded due to the lack of specific experimental validation

How it is different

1. The central pillars in subway tunnels are approximately 400 mm deep, and motorway central reservations are around 600 ± α mm. To utilize these narrow spaces, the blade is designed with a compact diameter (⌀400 mm) while still generating strong rotational torque. 2. By adjusting the scale, the system can be applied in broader urban areas such as building rooftops, parks, streetlights, and under bridges. 3. The dihedral-shaped blades, angled by design, enable the turbine to respond to wind coming from various directions, not just from the side.

Future plans

1. Identifying Potential This design shows promise, but further testing in various environments is needed. The first step is to build a prototype for real-world observation. Field tests can reveal unseen performance factors and guide improvements. 2. Real-Life Application If effective, it can be installed in subway tunnels, highway medians, parks, and under bridges—urban spaces with untapped wind energy. It may also serve as temporary or emergency power in off-grid, disaster, or war-affected areas. Mobile deployment by truck enables flexible energy delivery.

Awards

Although not the same design, I submitted related projects to national design competitions and received awards: ∎ 2020: Special Prize, 55th Korea Design Exhibition – “Wind Power Blade Using Subway Wind” ∎ 2023: Special Prize, 58th Korea Design Exhibition – “Variable Blade for Micro Wind Power Generation”