Attachment 2 - Statement of Work (Topic Area 2).pdf

Attachment No. 2

APPENDIX A

STATEMENT OF WORK

Topic Area 2. Aerodynamic Characterization of Nonoperational Loads Phenomena

January 7, 2025

1.0 BACKGROUND

Modern wind turbines are the largest rotating machines ever built by humankind,1 and continued innovation for lower energy cost and enhanced plant power production requires validated modeling and simulation capabilities that mitigate the financial risk of technology innovation and deployment barriers.

A wind turbine blade is exposed to high loads not only during operation but also when it is stopped for installation, maintenance, or idling (during the passage of extreme weather); in these situations, the wind may come from any direction, be highly unsteady, and/or vary in space and time, and the loads response from the wind turbine blades could result in vibrations (usually called stall- or vortex-induced vibrations).

The design tools used today for calculating wind blade aerodynamic loads and vibrations can represent unsteady behavior reasonably well when the turbine is in operation. But these tools often make fewer representative assumptions for conditions when the rotor is idling slowly or parked, leading to overly conservative designs or a risk of damage in certain wind conditions, depending on the assumptions made.2 Recent research using high-fidelity modeling3 and low-order surrogates shows promise on how to improve capabilities,4 but the computational costs remain high, and the methods lack robust validation to generate sufficient confidence.

During extreme wind events, when wind turbines are typically idling with the generator disconnected, the blades are feathered; similarly, in other situations (lower/moderate wind speeds below cutout) with high pitch/yaw angles, the attitude of the blades creates deep-stall aerodynamic behavior. Similarly significant (~30°–70°) inclination and blade lean angles lead to fully three-dimensional flow with a substantial spanwise flow that can promote lock-in behaviors. These complex aerodynamics in combination with blade edgewise vibrations, can lead to blade damage and dangerous failure events. Furthermore, rapid changes in the magnitude and direction of the flow and blade/airfoil motion (e.g., in edgewise vibration states) can generate additional dynamic phenomena, further complicating the aerodynamic characterization.

1 Veers, P., K. Dykes, E. Lantz, S. Barth, C.L. Bottasso, O. Carlson, A. Clifton, et al. 2019. “Grand Challenges in the Science of Wind Energy.” Science 366(6464): eaau2027. https://doi.org/10.1126/science.aau2027.

2 Bangga, G., M. Carrion, W. Collier, and S. Parkinson. 2023. “Technical Modeling Challenges for Large Idling Wind Turbines.” Journal of Physics: Conference Series 2626: 012026. https://doi.org/10.1088/1742-6596/2626/1/012026.

3 Horcas, S.G., N.N. Sørensen, F. Zahle, G.R. Pirrung, and T. Barlas. 2022. “Vibrations of Wind Turbine Blades in Standstill: Mapping the Influence of Inflow Angles. Physics of Fluids 34(5):

054105. https://doi.org/10.1063/5.0088036.

4 Santhanam, C., R. Riccardo, and T. Knudsen.2023. “A Study of Stall-Induced Vibrations Using Surrogate-Based Optimization.” Renewable Energy 214: 201–215. https://doi.org/10.1016/j.renene.2023.05.054.

https://doi.org/10.1126/science.aau2027 https://doi.org/10.1088/1742-6596/2626/1/012026 https://doi.org/10.1063/5.0088036 https://www.sciencedirect.com/journal/renewable-energy https://doi.org/10.1016/j.renene.2023.05.054

Figure 1. Flow inclination angle definition to characterize S-VIV sensitive blade states (Horcas et al. 2022)

2.0 OBJECTIVE

This work will provide the necessary data to develop and validate tools used in the design and development of very large commercial wind turbine rotors and facilitate the accelerated development and deployment of cost-effective wind technology. As such, please be aware that all data delivered and/or generated under this project, including airfoil shapes, will be made publicly available by DOE’s Wind Energy Technologies Office (WETO) and/or NREL. For proprietary airfoil/blade shapes (I.e., those not generated under this Subcontract or with other public funding) proposed as test articles by the Subcontractor and related data, NREL will work with selected awardees to limit their availability to the public to non-commercial, research purposes only. The specific objectives are to:

• Collect and disseminate benchmark aerodynamic data to validate and improve modeling and simulation tools that are used to predict the behavior of nonoperational wind turbine rotors e.g., idling or parked or storm conditions.

• Inform the wind industry with physical insights that advance modeling capabilities to minimize the risks and costs of next-generation wind turbines.

3.0 SCOPE, EXPECTATIONS AND REQUIREMENTS

To meet the above objectives, experimental test plans will be prepared by the Subcontractor (tests will be conducted at a facility selected by the Subcontractor). The test plans could include, but are not limited to:

• Wind tunnel experiments to characterize the 3D unsteady aerodynamics (and resultant loads) of a fully instrumented blade test article in a state (pitch, inclination, yaw, etc.) representative of conditions that drive wind turbine nonoperational loads, e.g., standstill/stall- or vortex-induced vibrations. The blades could be aero-elastically scaled, tailored for a specific structural response, or rigid.

• Instrumented blade article testing with inflow variations—spatial and temporal—that would simulate variations from gusts or other severe weather operating environments.

• Unsteady airfoil tests with complex motion tailored to represent motion seen in blades undergoing stall- or vortex-induced vibrations; a broad range of angles of attack to encompass various separated flow states is desired viz., the deep-stall states previously referred to.

• Experiments with compliant or dynamic support structures, if and as necessary tailored to characterize the effect of such boundary conditions on aeroelastic responses in deep stall conditions are also of interest.

• A combination of tailored airfoil and 3D blade tests to test hypothesis on correlations of aerodynamic behaviors.

Test plans delivering data for 3D blade validation are preferred; adjacent or integrated computational modeling efforts are welcome but must include evidence of relevant and quality validation of the base computational fluid dynamics platforms (if proposed), including the source(s) of data.

Other key expectations from the test plans are that they:

• Should describe the facility or facilities chosen to test, observations to be made and instruments to be used, the rationale for that selection, and the modeling effort that will accompany the test, both to inform the experimental design and enhance the quality and the physical understanding of the experimental results.

• Achieve a chord Reynolds number >1 million at midspan of the test article if a blade test is being proposed, or >2 million for airfoil testing; or substantial justification must be provided of the validity of the scaling approach’s ability to capture the right aerodynamic effects.

• Meet expected criteria for test section inflow quality (including turbulence, relevant profiling) and avoidance/correction of tunnel blockage effects, and their impact on experimental results.

• Support the instrumentation and data collection requirements for high-fidelity validation. For example, the instrumentation must have the capability to capture both the static and dynamic loading behavior expected from flow separation from blades operating under stalled conditions, as well as visualize and measure the flow features that lead to those loads.

4.0 TASKS

Subcontractors are expected to provide a preparatory phase leading up to a Go/No-Go Pre-Test Readiness Review; a notional schedule/task list with minimum expected critical reviews and workshops is included below for guidance.

5.0 REVIEW MEETINGS AND TRAVEL REQUIREMENTS

• A project kickoff meeting is to be planned (TBD in person or virtual).

• There will be virtual (monthly, quarterly) and in-person meetings where necessary (e.g., annual) throughout the duration of the project, which will include subcontractor and technical management (NREL, WETO) teams.

• Key technical reviews, e.g., the Critical Design Review, will preferably be held at the identified test facility.

• Domestic and international travel should be planned to present results at conferences and may include DOE, lab technical representatives, and participants.

• One technical workshop for sharing knowledge and results should be planned by the subcontractor during project execution; this would ideally be co-located with R&D community events like NAWEA, Torque, or other AIAA/ASME conferences

6.0 DELIVERABLES

Key deliverables and milestones that the subcontractor must incorporate in their project proposal include:

No. Deliverable Description Due Date

6.1 Quarterly progress report/summaries Throughout the project’s period of performance

6.2 Test article design/selection and science plan (for review and approval)

Before completion of Q4 of project execution

6.3 Delivery of fabricated and instrumented test articles to test facility

TBD

6.4 Pre-Test Readiness Review material for Go/No-Go milestone (for joint review and approval)

TBD

6.5 Minimum Test Matrix Before completion of Q8 of

project execution

6.6 Calibration and Initial Result Quality Assessments (report) TBD

6.7 Results/analysis and lessons learned workshop Final quarter of the period of performance

6.8 Validation data documentation and delivery to WETO data

hub (see more details below)

Continuous, to be completed by final quarter of project

6.9 Final technical reports Completion of the period of

performance

Validation Data Delivery: The Subcontractor shall develop a complete data documentation and metadata structure in coordination with the NREL and WETO Wind Data Hub5 management teams. The data archive is expected to include:

• All experimental design and analysis documentation (drawings, specifications, test protocols, analysis methods, etc.), including wind tunnel test article CAD files.

• Quality-controlled experimental data—raw and corrected—and associated post-processing/analysis codes (if developed under this project)

5 Pacific Northwest National Laboratory. No date. “Wind Data Hub.” https://wdh.energy.gov .

• Documentation of quality assurance throughout the program, including scans and analysis of as-built test articles used to ensure design intent was met in fabrication and experimental assurance of intended flow quality/state (e.g., two-dimensionality of flow for airfoil performance, correction methods accuracy).

All data will be publicly available and accessible to enable the maximum benefit for the wind industry and the research community.

DELIVERABLE ADDRESS:

The Subcontractor shall clearly label all deliverables to include:

• The subcontractor’s name

• NREL’s subcontract number

• NREL Technical Monitor’s name

• Deliverable date, and

• Deliverable description.

Electronic deliverables (one master electronic version, including graphics) shall be sent via email to the NREL personnel as follows:

*, Technical Monitor *, Project Managers e-mail: *.*@nrel.gov email: *.*@nrel.gov

Deliverable(s) shall be shipped to:

National Renewable Energy Laboratory

Attn: Recipients’ Name *, Building * / Room * / Lab *

16253 Denver West Parkway

Golden, CO 80401

DELIVERY OF DATA

A copy of all data (as that term is defined in this Subcontract) first produced in the performance of this Subcontract is an additional deliverable of this Subcontract and shall be provided to the technical monitor as a condition of final payment, in accordance with the Subcontract. For all deliverables, make particular note of the requirements provided in the Rights in Data clause of this Subcontract regarding data not first produced in the performance of this Subcontract.

Rights in Technical Data

• All data generated under this project, including airfoil shapes, will be made publicly available by NREL/WETO.

• For proprietary airfoil/blade shapes (I.e., those not generated under this project or with other public funding) proposed as test articles by the Subcontractor and related data, NREL will work with selected awardees during the contracting phase to limit their access to the public for non-commercial, research purposes only.

mailto:*.*@nrel.gov mailto:*.*@nrel.gov

7.0 ELECTRONIC REPORTING REQUIREMENTS FOR SUBCONTRACT REPORT DELIVERABLES

It is NREL’s intention to publish subcontract report deliverables containing publicly available information (e.g. non-confidential, non-protected, non-proprietary information) for distribution on the internet.

The subcontractor shall provide the final approved version of report deliverables in accordance with the electronic reporting requirements described below.

The technical monitor may specifically direct the subcontractor to provide reports in one or more of the file format standards provided below:

7.1 The subcontractor shall submit all report deliverables (including status, annual, or final reports) as electronic files in Adobe .pdf format, preferably with all graphics and images embedded within the document.

7.2 All final approved version submissions shall be delivered to NREL via e-mail to the NREL Technical Monitor.

7.3 If it is not possible to include all of the graphics and images (figures, illustrations, and photographs) in the same file as the text, NREL will accept the text in Adobe .pdf formats and the graphics and images as separate electronic graphic or image files*.

The accepted standard for page layout and graphics is the Adobe Creative Suite of programs.

*The acceptable graphic or image file formats are: .eps, .tif, .gif, .jpg, .wmf, .emf, .pct, .png, .bmp, .psd, .ai, .fh, .qif, .fpx, cdr. The preferred resolution for graphics or images is 300 dpi. Include all fonts used in creating the file.

7.4 For animation, video, or multi-media elements, CD-ROM, DVR and thumb drive are acceptable technical deliverable media.

7.5 For all calculations in support of subcontract reports that are conducted in ASPEN+, an electronic copy of INPUT, REPORT and BACKUP (if Model Manager is used) must be submitted with all reports. Additionally, if costing or sizing calculations are conducted in a spreadsheet [no process calculations (heat and material balances) in spreadsheet format are permitted], a copy of the fully documented MS Excel file shall be supplied.

7.6 A fully executed model release shall be supplied to NREL with all photographs and images, regardless of whether such photographs or images are delivered to NREL electronically or in hard copy. Such model release shall certify that the Alliance for Sustainable Energy, LLC, Management and Operating Contractor for the National Renewable Energy Laboratory for the U.S. Department of Energy is granted a non-exclusive, paid-up, irrevocable, worldwide license to publish such photographs in any medium or reproduce such photographs or allow others to do so for United States Government purposes. Model releases are required in all situations in which a reasonable person would respond in the affirmative to the question – could someone, other than the model himself/herself, recognize the person in this photograph or image? All model releases shall be provided to the subcontract associate as a condition of final payment, in accordance with the subcontract. To obtain a Subcontractor Model Release form, please contact images@nrel.gov.

mailto:images@nrel.gov

8.0 ACKNOWLEDGEMENTS IN SUBCONTRACTOR PUBLICATIONS

In any scientific or technical report or article, conference paper, journal article, etc. based on or containing data first produced in the performance of this subcontract and published in academic, technical or professional journals, symposia proceedings or similar works, the subcontractor shall use this acknowledgement stating, “This [article, conference paper, journal article, etc.] was developed based upon funding from the Alliance for Sustainable Energy, LLC, Managing and Operating Contractor for the National Renewable Energy Laboratory for the U.S. Department of Energy.”

9.0 COPYRIGHT PERMISSION/AUTHORIZATIONS

The subcontractor is responsible for obtaining copyright permissions and/or authorizations for all information and/or data, as applicable that is incorporated into all final technical reports.

Electronic copies of these copyright permissions and/or authorizations shall be provided to the at the email address provided below. The subcontractor shall also provide a written certification to the Technical Monitor as to such permissions and/or authorizations as a condition of final payment. The subcontractor’s (including all lower tier subcontractors, as applicable) certification shall specify that “I have obtained all necessary and legally required copyright permissions and/or authorizations for any and all information, data, graphs, images, etc., as applicable, that is incorporated into the final Technical Report titled __________________________, delivered under this Subcontract No.__________. Copies of these permissions and/or authorizations are attached.”