A Deeper Insight into Dynamic Stall of Vertical Axis Wind Turbines: Parametric Study of Symmetric Airfoils
Tirandaz, R.; Rezaeiha, A.; Micallef, D. (2026). A Deeper Insight into Dynamic Stall of Vertical Axis Wind Turbines: Parametric Study of Symmetric Airfoils. Energies (Basel) 19(7): 1615. https://dx.doi.org/10.3390/en19071615
In: Energies (Basel). Molecular Diversity Preservation International (MDPI): Basel. ISSN 1996-1073; e-ISSN 1996-1073, more
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| Author keywords |
unsteady aerodynamics;dynamic stall;morphing blade;floating offshore wind turbine (FOWT);computational fluid dynamics (CFD);adaptive simulation sas;aerodynamic performance;cfd simulations;domain size;speed;guidelines;thickness;blades;impact;shape |
| Authors | | Top |
- Tirandaz, R.
- Rezaeiha, A., more
- Micallef, D.
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| Abstract |
Vertical axis wind turbines (VAWTs) suffer from dynamic stall (DS) at low tip-speed ratios (lambda), where cyclic variations in angle of attack (alpha) dominate the blade aerodynamics, severely undermining aerodynamic performance and power extraction. The coupled influence of airfoil parameters on DS remains unexplored. To address this gap, a fully coupled parametric study using 126 incompressible URANS simulations is conducted, examining three geometric parameters of symmetric airfoils: maximum thickness (t/c), chordwise position of maximum thickness (xt/c), and leading-edge (LE) radius index (I). The results show that coupled geometric modification fundamentally alters the stall mechanism, shifting it from abrupt, LE-driven separation toward a gradual, trailing-edge (TE)-controlled process as airfoils transition from thin, forward-xt/c profiles to thicker configurations with aft xt/c and reduced I. This transition enhances boundary-layer (BL) stability, delays DS onset, weakens dynamic stall vortex (DSV) formation, and mitigates unsteady aerodynamic loading. Within the investigated design space, the best-performing configuration (NACA0024-4.5/3.5) achieves a 73% increase in turbine power coefficient (CP) relative to the baseline airfoil (NACA0018-6.0/3.0), mainly through passive control of BL separation and vortex development. These findings highlight the limitations of single-parameter optimization and establish a physics-based, coupled-design framework for mitigating DS-induced performance losses in VAWTs. |
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