Journal of Technology in Aerospace Engineering

Journal of Technology in Aerospace Engineering

Experimental flow field investigation of swept bird-like rigid wing by flow visualization technique

Document Type : Technical Note

Authors
Hamzeh Eshraghi 1
Mojtaba Ramezani voloojerdi 2
Mahmoud Mani 1
1 Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran
2 Department of Aerospace Engineering, Amirkabir University of Technology
10.22034/jtae.2025.9.4.5
Abstract
Gliding flight represents one of the most critical phases in both natural avian locomotion and the operation of bio-inspired aerial models. This study investigates the surface flow field over three static wing configurations. To examine the influence of sweep-back on flow structures, three wings with the S1223 airfoil were tested: one without sweep-back, one with a conventional 30° sweep-back, and one with a 30° bird-inspired sweep-back incorporating a curved junction. While all models had identical chord lengths and wing areas, differences in sweep-back geometry led to slight variations in span. The models were evaluated in a wind tunnel under various angles of attack and flow velocities. To visualize the flow patterns, fluorescent powder and paraffin were applied to the wing surfaces, capturing the flow structure through surface imprinting. Ultraviolet illumination highlighted the flow patterns and their effects across the wing surfaces. The angle of attack was a controlled variable used to examine its role in shaping vortex formation and flow behavior across distinct sweep-back configurations. Findings indicate that at low angles of attack and prior to static stall, the separation bubble region was smallest in the bird-inspired model with a curved sweep-back, compared to both the non-swept and conventionally swept wings.
Keywords
Experimental method
Flow visualization
Sweep angle
Rigid wing
Bird-like
Subjects
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  • Receive Date 22 November 2024
  • Revise Date 30 March 2025
  • Accept Date 07 May 2025
  • First Publish Date 10 June 2025