Bio-inspired grooves delay airplane wing stalls: Nature’s solution to safer flight

For decades, aerospace engineers have grappled with the challenge of delaying airfoil stall—a critical safety hazard in aviation where abrupt lift loss occurs at high angles of attack. Traditional vortex generators (VGs), while effective, introduce significant drag penalties during the cruise, increasing fuel consumption. Although reducing the size of VGs can decrease additional loss, it simultaneously weakens the intensity of their induced vortices, losing the ability to control boundary layer separation. Thus, there is an urgent need for a novel VG structure that can uphold the control effect while further mitigating the additional loss.

Recently, a research team led by Associate Professor Peng Zhang from the Civil Aviation University of China first reported a novel passive control method inspired by bird feathers (bio-inspired herringbone groove array). This method offers a transformative solution that achieves minimal additional losses while maintaining the strength of induced vortices. Their work not only elucidates the key factors influencing the control effectiveness of this bionic structure, but also reveals the physical mechanisms by which it effectively delays stall.

The team published their work in Chinese Journal of Aeronautics on April 4, 2025.

The characteristics of bio-inspired herringbone groove array are as follows: multiple grooves are arranged in parallel along the flow direction, and the grooves are oriented at a specific angle relative to the flow direction; the left-tilted and right-tilted micro-grooves are placed side by side in an alternating manner along the span-wise direction forming a herringbone array. “The herringbone groove array can be conceptualized as a series of ribbed micro VGs aligned in the direction of flow. Despite being smaller in size compared to traditional VGs, the vortices generated by the herringbone groove array maintain strength due to the accumulation effect of the micro-scale grooves, while the smaller size results in fewer flow losses.” said Peng Zhang, Associate professor at the College of Aeronautical Engineering at Civil Aviation University of China, a senior expert whose research interests focus on the field of aerothermodynamics.

The researchers elucidated the key parameters influencing the control effectiveness of bionic structures through numerical simulation methods. As the groove depth/yaw angle increases, the broadening amount of the stable working range first increases and then decreases. When the groove depth is 0.00135 times of chord length and the yaw angle is 45 degrees, the best control effect can be obtained, and the broadening amount of the stable working range can reach 28.57%. Compared with traditional VGs, the herringbone groove array has fewer negative impacts on the aerodynamic performance of the airfoil under small angle-of-attack conditions.

In addition, the researchers explained the mechanism behind the delay of the airfoil stall. Due to the pressure difference, several small-scale induced vortices are created within the grooves and ultimately develop together into a pair of large-scale induced vortexes with high strength by the accumulation effect. Under the induction of the fluid in the grooves, the fluid adjacent to the upper surface of the groove array generates a spanwise velocity component and eventually becomes a part of the downstream large-scale induced vortices, which further enhances the strength of the induced vortices. The induced vortices of the groove array strengthen the mixing between the mainstream and the boundary layer, so that the boundary layer can obtain enough energy to resist the reverse pressure gradient under the large angle-of-attack conditions, and effectively delay the airfoil stall.

While simulations validate the concept, wind tunnel testing is underway. The team aims to optimize groove layouts for commercial wings and drones. “We’re exploring 3D-printed integrations for existing fleets,” Peng Zhang noted. “The ultimate goal? Making stall-resistant wings as commonplace as bird flight.”

Other contributors include Junping Du and Yonghong Li from the College of Aeronautical Engineering at Civil Aviation University of China in Tianjin, China.

Original Source

Peng ZHANG, Junping DU, Yonghong LI. Delay of airfoil stall via bio-inspired herringbone groove array [J]. Chinese Journal of Aeronautics, 2025, https://doi.org/10.1016/j.cja.2025.103527.

About Chinese Journal of Aeronautics 

Chinese Journal of Aeronautics (CJA) is an open access, peer-reviewed international journal covering all aspects of aerospace engineering, monthly published by Elsevier. The Journal reports the scientific and technological achievements and frontiers in aeronautic engineering and astronautic engineering, in both theory and practice. CJA is indexed in SCI (IF = 5.3, top 4/52, Q1), EI, IAA, AJ, CSA, Scopus.