Servo-aero-gravo-elastic (SAGE) scaling and its application to a 13-MW downwind turbine

Journal Article · Wed Nov 04 00:00:00 EST 2020 · Journal of Renewable and Sustainable Energy

DOI:https://doi.org/10.1063/5.0021171· OSTI ID:1703880

Kaminski, Meghan ; Loth, Eric; Zalkind, Daniel; Pao, Lucy; Selig, Michael; Johnson, Kathryn

Reduced scale wind turbines can be extremely cost-effective to test new rotor concepts since prototype costs are heavily dependent on the rotor diameter. Ideally, the scaled model would have the same non-dimensional deflections, dynamics, and control behavior as the full-scale model. This would provide a high-fidelity demonstration of the full-scale performance, which is ideal if the full-scale turbine has significant aeroelastic interactions. To this end, servo-aero-gravo-elastic (SAGE) scaling is developed and applied to a 13-MW turbine that is scaled to a 20% scale model. The scaling preserves the tip-speed ratio, the rotor speed normalized by the flapping frequency, and the tip deflections normalized by the blade length. In addition, the controller employs the same control structure (gain-scheduled pitch control and variable speed torque control) and is scaled dynamically (e.g., matching non-dimensional time constant of the pitch angle, etc.). Furthermore, the thrust, gravity, and centrifugal moments are scaled such that the load angles are preserved as a function of a non-dimensional wind speed. However, the environmental scaling must consider differences in Reynolds number (since this parameter cannot be held constant) and subsequent changes in the axial induction factor. While the presented results showcase these differences during operational conditions, the non-dimensional tip deflections remain comparable through all wind speed ranges, indicating the viability of the SAGE scaling method in matching full-scale aeroelastic responses.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AR0000667
• OSTI ID: 1703880
• Journal Information: Journal of Renewable and Sustainable Energy, Journal Name: Journal of Renewable and Sustainable Energy Vol. 12 Journal Issue: 6; ISSN 1941-7012
• Publisher: American Institute of Physics
• Country of Publication: United States
• Language: English