Assessing the reliability of current stall delay models using NREL phase VI and MEXICO Data

What is it about?

The Blade Element Momentum (BEM) theory is widely used in the preliminary design and optimization of horizontal axis wind turbines. However, its accuracy is largely determined by the three-dimensional airfoil polars. In the last 30 years, various stall delay models were proposed to correct the two-dimensional airfoil polars based on the centrifugal pumping mechanism, which is widely claimed to explain the forces augmentation on a rotating wind turbine blade. The generality of these models was evaluated in this work by applying the well-known verification, calibration, and validation approach and using the NREL and MEXICO wind turbines data.

Featured Image

Photo by Artur Zudin on Unsplash

Photo by Artur Zudin on Unsplash

Why is it important?

We found that the centrifugal pumping mechanism produced a small force augmentation, in contrast to experimental data that shows a large force augmentation. Thus, the lack of generality of current stall delay models is due to the centrifugal pumping assumption. Consequently, future models need to go beyond modeling the centrifugal pumping mechanism and account for the contribution of the complex three-dimensional vortical flow near the hub.