Storm A. Mata | Searcharxiv

arXiv2026

Influence of wind shear and veer on power, thrust, and induction of an actuator disk

Wind shear and wind veer (gradients of wind speed and direction, respectively) are ubiquitous in the atmospheric boundary layer (ABL), and wind turbines therefore routinely operate in sheared and veered conditions. Previous field campaigns have observed statistically significant variations in power production efficiency (quantified by a power coefficient) upwards of 15% due to shear and veer. However, it is not yet clear how non-uniform inflow conditions alter rotor aerodynamics and drive these efficiency variations. In this study, we perform concurrent-precursor large-eddy simulations (LES) of an actuator disk-modeled wind turbine across stratified ABL conditions to demonstrate that shear and veer can reduce wind power efficiency by more than 20%. To support these ABL simulations, we perform simplified inflow LES where shear and veer are controlled independently. Using these controlled simulations, we demonstrate that shear and veer effects can be decomposed into: (1) geometric effects, due to changes in rotor-equivalent wind speed, and (2) inductive effects, which change the rotor aerodynamics and induced velocities. Inductive effects of wind shear modulate the power coefficient through changes to the local induction, while inductive effects of wind veer reduce the power coefficient by generating an adverse pressure gradient at the rotor scale. The geometric and inductive effects of shear and veer approximately linearly superimpose, with increasing losses as shear and veer magnitudes increase. Inductive effects account for a significant fraction of the observed losses, and the induction of a turbine is affected by shear, veer, and wall proximity through processes that are neglected in existing engineering models. Revealing the mechanisms through which shear and veer affect rotor performance establishes a framework that can enable improved power prediction in realistic ABL conditions.

physics.flu-dyn↗

arXiv2023

Modeling the effect of wind speed and direction shear on utility-scale wind turbine power production

Wind speed and direction variations across the rotor affect power production. As utility-scale turbines extend higher into the atmospheric boundary layer (ABL) with larger rotor diameters and hub heights, they increasingly encounter more complex wind speed and direction variations. We assess three models for power production that account for wind speed and direction shear. Two are based on actuator disc representations and the third is a blade element representation. We also evaluate the predictions from a standard power curve model that has no knowledge of wind shear. The predictions from each model, driven by wind profile measurements from a profiling LiDAR, are compared to concurrent power measurements from an adjacent utility-scale wind turbine. In the field measurements of the utility-scale turbine, discrete combinations of speed and direction shear induce changes in power production of -19% to +34% relative to the turbine power curve for a given hub height wind speed. Positive speed shear generally corresponds to over-performance and positive direction shear to under-performance, relative to the power curve. Overall, the blade element model produces both higher correlation and lower error relative to the other models, but its quantitative accuracy depends on induction and controller sub-models. To further assess the influence of complex, non-monotonic wind profiles, we also drive the models with best-fit power law wind speed profiles and linear wind direction profiles. These idealized inputs produce qualitative and quantitative differences in power predictions from each model, demonstrating that time-varying, non-monotonic wind shear affects wind power production.

physics.flu-dyn↗