Design and Testing of a Scaled Demonstrator Turbine at the National Wind Technology Center

Bay, Christopher J.; Damiani, Rick; Fingersh, Lee; Hughes, Scott; Chetan, Mayank; Yao, Shulong; Griffith, D. Todd; Ananda, Gavin K.; Selig, Michael S.; Zalkind, Daniel; Pao, Lucy Y.; Martin, Dana; Johnson, Kathryn; Kaminski, Meghan; Loth, Eric

doi:10.2514/6.2019-1068

Cited by 15 publications

(23 citation statements)

References 15 publications

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“…When referencing the predicted turbulent dynamics of Figure 10B, the above‐rated conditions of the demonstrator are projected to have similar nondimensional tip deflections as that of the SUMR‐13 model. Conversely, the above‐ and below‐rated deflections of the SUMR‐D blades are predicted to fall below the SUMR‐13 predictions, which is partially a result of pitch setting limitations deriving from retrofitting the CART2 as a downwind machine 17 . Due to the system primarily being tested in above‐rated conditions, the trade‐off between matching above‐ and below‐rated conditions was deemed adequate.…”

Section: Resultsmentioning

confidence: 97%

“…The fabricated SUMR‐D blade contains two shear webs that do not twist throughout the length of the blade 18 . A root adapter is included for SUMR‐D to both allow for a transition to the oval root of the CART2 hub, as well as to create the sought 12.5° precone angle since the CART2 had no such coning 17 …”

Section: Resultsmentioning

confidence: 99%

“…With the blade root fixed to a test stand, loads were applied at three stations along the span (28%, 50%, and 74.5%) and ramped from 0 N up to the target loads, held at the target load for at least 10 seconds, then gradually removed. The maximum blade loads at these locations were calibrated to render the scaled moment distribution calculated for Design Load Case (DLC) 6.2 based on FAST simulations 17 and IEC 61400‐1 prescriptions 28 . Load simulations proved that DLC 6.2 is the main ultimate limit‐state design driver.…”

Section: Methodsmentioning

confidence: 99%

“…The 20.87‐m‐long demonstrator blade made use of the same airfoils as the full‐scale blade in order to preserve aeroelastic characteristics. Ground testing and numerical simulation of operational conditions are used to investigate the blade scaling methodology 17,18 . The scaled rotor is denoted the SUMR‐Demonstrator (SUMR‐D) 19 and was designed for operational field testing on a research turbine and employs the GAS method previously employed for a 1% model 13 but with modifications due to safety constraints for operational testing at the National Wind Technology Center (NWTC) at the Flatirons Campus on the two‐bladed Controls Advanced Research Turbine (CART2) 20,21 .…”

Section: Introductionmentioning

confidence: 99%

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Gravo‐aeroelastic scaling of a 13‐MW downwind rotor for 20% scale blades

et al. 2020

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A 105‐m, 13‐MW two‐bladed downwind Segmented Ultralight Morphing Rotor (SUMR‐13) blade was gravo‐aeroelastically scaled by 20% to a 20.87‐m‐long demonstrator blade and confirmed through structural ground testing. The subscale model was achieved through geometric scaling and by aeroelastic scaling principles based on operational flapwise deflections combined with rotational and structural frequencies while retaining the turbine tip‐speed ratio. In particular, the subscale demonstrator was designed to replicate, as closely as possible, the nondimensional geometry, the ratio of centrifugal to gravitational moments, the tip‐speed ratio, and the nondimensional rotation rate. The intent for this demonstrator was to achieve the same nondimensional flapwise blade deflections and dynamics of the full‐scale 13‐MW rotor. The manufactured SUMR‐D blade resulted in less than half of the mass of the conventional two‐bladed Controls Advanced Research Turbine (CART2) rotor blade based on scaling and a lower power rating, though with some differences in mass and stiffness from the ideal scaled‐down design to meet safety requirements at the test site. To achieve proper scaling, operational pitch control set points were altered to account for the differences by evaluating simulated operation of both the SUMR‐13 and SUMR‐D rotors. Structural testing of the SUMR‐D blade investigated the response to well‐defined flapwise loads and indicated that the subscale blade had the appropriate elastic properties needed for both scaling and for safe operational field testing.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravo‐aeroelastic scaling of a 13‐MW downwind rotor for 20% scale blades

et al. 2020

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“…This paper presents the development of a structural digital twin model of the SUMR-D blades. 11,18 Specific to SUMR-D and its fieldtesting campaign, the digital twin model offers key information for the following objectives: (1) an updated blade model to provide confidence in control system development and stable rotor operation for the field experiment, (2) validation of GAS objectives of the as-built blade prior to field-testing, (3) verification of aeroelastic performance and codes used in design (such as NuMAD, ANSYS, and OpenFAST), and (4) further evaluation of GAS scaling objectives for SUMR-D during field-testing. The SUMR-D blades are non-traditional, highly coned, and flexible structures.…”

mentioning

confidence: 99%

Multi‐fidelity digital twin structural model for a sub‐scale downwind wind turbine rotor blade

2021

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This paper presents the development of a multi-fidelity digital twin structural model (virtual model) of an as-built wind turbine blade. The goal is to develop and demonstrate an approach to produce an accurate and detailed model of the as-built blade for use in verifying the performance of the operating two-bladed, downwind rotor.The digital twin model development methodology, presented herein, involves a novel calibration process to integrate a wide range of information including design specifications, manufacturing information, and structural testing data (modal and static) to produce a multi-fidelity digital twin structural model: a detailed high-fidelity model (i.e., 3D finite element analysis [FEA]) and consistent beam-type models for aeroelastic simulation. A key element is that the multi-fidelity structural digital twin method follows the rotor from the stages of design, to manufacturing, then to the ground testing and field operation. The result of this comprehensive approach is an accurate multi-fidelity digital twin structural model for the geometric, structural, and structural dynamic properties of the as-built blade within a 1% match in mass properties, 3.2% in blade frequencies, and 6% in deflection. The different stages of processing this information within the methodology are discussed. The rotor examined is the SUMR-Demonstrator (SUMR-D), which was installed on the Controls Advanced Research Testbed (CART-2) wind turbine at the National Wind Technology Center. The digital twin model developed here was utilized to design controllers to safely operate SUMR-D in field tests, which are providing additional data for further evaluation and development of the multi-fidelity digital twin structural model.digital twin, downwind, extreme-scale wind turbine, field-testing, multi-fidelity model | INTRODUCTIONA numerical model that represents a physical system (i.e., "Digital Twin" as it's commonly known) has a wide variety of uses specifically to understand the behavior of a system under varying environmental or operating conditions without the cost of experimental operation time. Digital twins can aid in troubleshooting and remediation of performance issues, assist in prediction of failure of a real-world system, and help understand systems in extreme conditions that are difficult or risky to replicate physically. Digital twins can also provide estimates of system response (i.e., sensing) that are difficult or costly to measure. The low cost of digital twin models provides an abundance of opportunities for industry and

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Influence of tower shadow on downwind flexible rotors: Field tests and simulations

2021

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As wind turbine rotors become larger, the blades become more flexible, requiring extra stiffness and cost to avoid the risk of tower strike. Wind turbines in a downwind configuration have a reduced risk of tower strike because the rotor thrust acts away from the tower. However, downwind blades pass through the wake of the tower, and the resulting load variation may contribute to blade fatigue. To date, there have been no field tests to quantify this tower shadow effect on unsteady blade moments. The present study reports on the first field testing of a flexible, downwind, coned rotor and compares the experimental data against simulations run in Open-FAST. The tower shadow effect is simulated using the conventional Powles model and a new Eames model (developed herein), which includes the influence of upstream turbulence. Both models reasonably predict the blade root out-of-plane bending moment data and the tower shadow dip magnitude when compared to field test data in Region 3. Tower shadow was found to increase the short-term Damage Equivalent Loads (DELs) by less than 10% compared to other effects (gravity, shear, and turbulence), and the predictions were consistent with experiments. These results indicate that the tower shadow effect can be reasonably modeled with the simpler Powles model and that the tower shadow effect can be small compared to the effect of turbulence. However, long-term fatigue due to tower shadow should be included in detailed structural analysis and design of the rotor and the tower.

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Design and Testing of a Scaled Demonstrator Turbine at the National Wind Technology Center

Abstract: This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. U.S. Department of Energy (DOE) reports produced after 1991 and a growing number of pre-1991 documents are available free via www.OSTI.gov.

Cited by 15 publications

References 15 publications

Gravo‐aeroelastic scaling of a 13‐MW downwind rotor for 20% scale blades

Gravo‐aeroelastic scaling of a 13‐MW downwind rotor for 20% scale blades

Multi‐fidelity digital twin structural model for a sub‐scale downwind wind turbine rotor blade

Influence of tower shadow on downwind flexible rotors: Field tests and simulations

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