Unsteady Aerodynamic Errors in BEM Predictions Under Yawed Flow: CFD-Based Insights into Flow Structures for the NREL Phase VI Rotor

Jiahong Hu, Hui Yang () and Jiaxin Yuan
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Jiahong Hu: School of Transportation Engineering, Shanghai University of Engineering Science, Songjiang Campus, Shanghai 201620, China
Hui Yang: School of Transportation Engineering, Shanghai University of Engineering Science, Songjiang Campus, Shanghai 201620, China
Jiaxin Yuan: School of Transportation Engineering, Shanghai University of Engineering Science, Songjiang Campus, Shanghai 201620, China

Energies, 2025, vol. 18, issue 18, 1-24

Abstract: Efficient prediction of aerodynamic loads on wind turbine blades under yawed inflow remains challenging due to the complexity of three-dimensional unsteady flow phenomena. In this work, a modified blade element momentum (BEM) method, incorporating multiple correction models, is systematically compared with high-fidelity computational fluid dynamics (CFD) simulations for the NREL Phase VI wind turbine across a range of inflow velocities (7–15 m/s) and yaw angles ( 0 ° – 60 ° ). A normalized absolute error metric, referenced to experimental measurements, is employed to quantify prediction discrepancies at different yaw conditions, wind speeds, and spanwise blade locations. Results indicate that the corrected BEM method maintains good agreement with measurements under non-yawed attached flow, with errors within 2%, but its accuracy declines substantially in separated and yawed flow regimes, where errors can exceed 20% at high yaw angles (e.g., 60 ° ) and low tip-speed ratios. CFD flow-field visualizations, including vorticity and Q-criterion iso-surfaces, reveal that yawed inflow strengthens vortex interactions on the leeward side and generates Coriolis-driven spanwise vortex structures, promoting stall progression from tip to root. These unsteady phenomena induce load fluctuations that are not captured by steady-state BEM formulations. Based on these insights, future studies could incorporate vortex structure and spanwise flow features extracted from CFD into unsteady correction models for BEM, enhancing prediction robustness under complex operating conditions.

Keywords: yawed inflow; blade element momentum (BEM); computational fluid dynamics (CFD); unsteady aerodynamics; wind turbine; stall vortex (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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