Wake transition and aerodynamics of a dragonfly-inspired airfoil
Fuente:
arXiv
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866908319758680064 |
|---|---|
| author | Chiarini, Alessandro Nastro, Gabriele |
| author_facet | Chiarini, Alessandro Nastro, Gabriele |
| contents | We investigate the dynamics and the stability of the incompressible flow past a corrugated dragonfly-inspired airfoil in the two-dimensional (2D) $α-Re$ parameter space, where $α$ is the angle of attack and $Re$ is the Reynolds number. The angle of attack is varied between $-5^\circ \le α\le 10^\circ$, and $Re$ (based on the free-stream velocity and the airfoil chord) is increased up to $Re=6000$. The study relies on linear stability analyses and three-dimensional (3D) nonlinear direct numerical simulations. For all $α$ the primary instability consists of a Hopf bifurcation towards a periodic regime. The linear stability analysis reveals that two distinct modes drive the flow bifurcation for positive and negative $α$, being characterised by a different frequency and a distinct triggering mechanism. The critical $Re$ decreases as $|α|$ increases, and scales as a power law for large positive/negative $α$. At intermediate $Re$, different limit cycles arise depending on $α$, each one characterised by a distinctive vortex interaction, leading thus to secondary instabilities of different nature. For intermediate positive/negative $α$ vortices are shed from both the top/bottom leading- and trailing-edge shear layers, and the two phenomena are frequency locked. By means of Floquet stability analysis, we show that the secondary instability consists of a 2D subharmonic bifurcation for large negative $α$, of a 2D Neimark--Sacker bifurcation for small negative $α$, of a 3D pitchfork bifurcation for small positive $α$, and of a 3D subharmonic bifurcation for large positive $α$. The aerodynamic performance of the dragonfly-inspired airfoil is discussed in relation to the different flow regimes emerging in the $α-Re$ space of parameters. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_11309 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Wake transition and aerodynamics of a dragonfly-inspired airfoil Chiarini, Alessandro Nastro, Gabriele Fluid Dynamics We investigate the dynamics and the stability of the incompressible flow past a corrugated dragonfly-inspired airfoil in the two-dimensional (2D) $α-Re$ parameter space, where $α$ is the angle of attack and $Re$ is the Reynolds number. The angle of attack is varied between $-5^\circ \le α\le 10^\circ$, and $Re$ (based on the free-stream velocity and the airfoil chord) is increased up to $Re=6000$. The study relies on linear stability analyses and three-dimensional (3D) nonlinear direct numerical simulations. For all $α$ the primary instability consists of a Hopf bifurcation towards a periodic regime. The linear stability analysis reveals that two distinct modes drive the flow bifurcation for positive and negative $α$, being characterised by a different frequency and a distinct triggering mechanism. The critical $Re$ decreases as $|α|$ increases, and scales as a power law for large positive/negative $α$. At intermediate $Re$, different limit cycles arise depending on $α$, each one characterised by a distinctive vortex interaction, leading thus to secondary instabilities of different nature. For intermediate positive/negative $α$ vortices are shed from both the top/bottom leading- and trailing-edge shear layers, and the two phenomena are frequency locked. By means of Floquet stability analysis, we show that the secondary instability consists of a 2D subharmonic bifurcation for large negative $α$, of a 2D Neimark--Sacker bifurcation for small negative $α$, of a 3D pitchfork bifurcation for small positive $α$, and of a 3D subharmonic bifurcation for large positive $α$. The aerodynamic performance of the dragonfly-inspired airfoil is discussed in relation to the different flow regimes emerging in the $α-Re$ space of parameters. |
| title | Wake transition and aerodynamics of a dragonfly-inspired airfoil |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2502.11309 |