Table 4 Summary of recent performance improvement strategies for Savonius and Darrieus turbines, highlighting modification methods, reported gains, and practical advantages.
From: Advanced blade profiles for improved efficiency in Savonius wind turbines: the aeroleaf case study
Study/references | Modification/method | Reported improvement | Advantage |
|---|---|---|---|
Adjoint-based NACA 0012 optimization28 | Airfoil optimization (transonic) | 62% reduction in drag coefficient | Improved lift-to-drag balance |
J-Blade H-Darrieus27 | J-foil blade geometry | 12.3% reduction in wake turbulence, improved torque uniformity | Enhanced stability and reduced stresses |
NACA-0022 evaluation14 | Dynamic pitch oscillations | Stall angle shifted (11° → 14° at higher Re) | Delayed stall improves efficiency |
Gurney flap integration66 | Flap/mini-flap devices | Cp = 0.46 at TSR 2.5 (≈ 9.8% gain) | Significant improvement for Darrieus |
Blade height impact13 | Embossed blade NACA0015-Opt | 9–52% reduction in self-starting torque across U ∞ = 1–9.5 m/s | Better startup characteristics |
Inertia effects26 | Modified inertia distribution | 30% higher rotational speed, ~ 70% Cp gain | Increased energy capture |
Darrieus start-up67 | Numerical + experimental mods | Improved low-speed startup | Enhanced practicality in urban flows |
H-rotor simulation68 | Aerodynamic shape optimization | CL/CD ↑ 34% and 18% at Re = 35,780 and 53,670 | Better low-Re performance |
Vortex cavity + deflectors6 | Passive flow control | ~ 25% Cp increase | Reduced wake losses |
Leading-edge protuberances25 | Passive stall control | Cp increase between 20–46% at U ∞ = 5.5–9 m/s | Improved stall resilience |
