CFD modeling of actual eroded wind turbine blade

Abstract

Abstract. Leading edge erosion (LEE) is one of the most critical degradation mechanisms that occur with wind turbine blades (WTBs), generally starting from the tip section of the blade. A detailed understanding of the LEE process and the impact on aerodynamic performance due to the damaged leading edge (LE) is required to select the most appropriate Leading Edge Protection (LEP) system and optimize blade maintenance. Providing accurate modeling tools is therefore essential. This paper presents a two-part study investigating Computational Fluid Dynamics (CFD) modeling approaches for different orders of magnitudes in erosion damage. The first part details the flow transition modeling for eroded surfaces with roughness in the order of 0.1–0.2 mm, while the second part focuses on a novel study modeling high-resolution scanned LE surfaces from an actual blade with LEE damage in the order of 10–20 mm (approx. 1 % chord). 2D and 3D surface resolved Reynolds Average Navier Stokes (RANS) CFD models have been applied to investigate wind turbine blade section in the Reynolds number range of 3–6 million. From the first part, the calibrated CFD model for modeling flow transition accounting roughness shows good agreement of the aerodynamic forces for airfoils with leading-edge roughness heights in the order of 140–200 μm, while showing poor agreement for smaller roughness heights in the order of 100 μm. Results from the second part of the study indicate that up to 3.3 % reduction in AEP can be expected when the LE shape is degraded by 0.8 % of the chord, based on the NREL 5MW turbine. The results also suggest that under fully turbulent condition the eroded LE shapes show the least amount of influence on the aerodynamic performances and results in negligible difference to AEP.

Study of implicit CFD modeling of riblets on wind turbine airfoil in transitional flow

“…Based on in-house experience/sensitivity study, the 2D RANS CFD simulations were all performed with an o-grid domain with an extent of 90 chords. Previous results [19] from the grid refinement study showed that a minimum of 350 points on the airfoil boundary are required to resolve the transitional flow around the airfoil section which achieves a grid-independent solution, thus it was also adapted for this work. The computational grid consists of approximately 200,000 purely hexahedral elements and was generated using the Pointwise software.…”

Aerodynamic simulation of rough and eroded blades, AEP effect and mitigation using low drag vortex generators

“…The conclusion was that as closer to the leading edges and as sharper the erosion corners the most harmful effect over AEP was obtained and quatified as 3% reduction. Vimalakanthan et al (2022) presented combined transition and rough CFD simulations of NACA 63 3 418 airfoil and the CFD modelling of an actual eroded blade. The conclusion of the study was that the calibrated CFD model for modeling flow transition accounting roughness shows good agreement of the aerodynamic forces for airfoils with leading-edge roughness heights in the order of 140-200 µm when comparing with the experiments, while showing poor agreement for smaller roughness heights in the order of 100 µm.…”