Appendix 1.D - Open Source Airfoils Candidates.pdf
PDF 185 KB Posted
- Attached to
- Fundamental Aerodynamics for Large Wind Turbine Performance and Reliability Federal contract opportunity
- Solicitation number
- RFX-2025-10021
- Issued by
- Department of Energy Office of Science
About this file
This is an appendix document describing two Open-Source Offshore (OSO) airfoils developed by Sandia National Laboratories and NREL for research purposes in offshore wind turbines. The airfoils (OSO-21-WT1 and OSO-30-WT1) are designed to meet modern turbine requirements while being free of proprietary constraints, targeting the IEA 22 MW wind turbine project.
The document provides detailed technical specifications and performance metrics for both airfoils, including thickness ratios (21% and 30%), Reynolds numbers (Re=12e6 and Re=18e6), and lift coefficients (1.4 and 1.5). The airfoils mostly meet design criteria with two exceptions: the OSO-21-WT1 exceeds the L/D Roughness Loss metric (43% vs 40% target), and both airfoils exceed the desired lift coefficient margin (0.5 and 0.4 vs 0.3 target). The airfoil coordinates will be publicly available on SNL's Github repositories. The development involved collaboration between Sandia National Laboratories, California State Long Beach University, NREL, and was supported by the DOE Wind Energy Technologies Office.
View the file
Other files for this federal contract opportunity
| File | Type | Posted |
|---|---|---|
| Revised Attachment 1.A - NFAC Test Planning Additional Information.pdf | ||
| Revised Attachment 1 - Statement of Work (Topic Area 1)-2.pdf | ||
| Amendment No. 1 to RFX-2025-10021 - Fundamental Aerodynamics for Large Wind Turbine Performance and Reliability.pdf | ||
| Attachment 3 - Sample Subcontract Schedule.pdf | ||
| Request for Proposal RFX-2025-10021.pdf | ||
| Attachment 1.A - NFAC Test Planning Additional Information.pdf | ||
| Attachment 1.B - NFAC Testing Cost Estimates.pdf | ||
| Attachment 2 - Statement of Work (Topic Area 2).pdf | ||
| Attachment 1.C - NFAC Test Planning Guide.pdf | ||
| Attachment 1 - Statement of Work (Topic Area 1).pdf | ||
| Attachment No. 4 - Sample Deliverable Summary Table.xlsx | XLSX spreadsheet |
Show all 11
On GovTribe
Work with this file on GovTribe
- Download the original file
- Contacts named in this file
- Similar government files
- Ask GovTribe AI about this file
Text version
APPENDIX 1-D. Open-Source Airfoil Candidates
Description and Characteristics of the Open-Source Airfoils designed at SNL/NREL
The Open-Source Offshore (OSO) airfoils have been developed for research purposes for offshore wind turbines, offering a set of airfoils that captures modern turbine design requirements and industry design practices without the proprietary constraints on research use. The eventual airfoil family will target the IEA 22 MW wind turbine [Zahle et al. 2024], which was originally developed with the FFA airfoils. The two airfoils summarized in Table 1 (OSO-21-WT1 and OSO-30-WT1) started development as part of a family of airfoils being developed targeting the IEA 22 MW wind turbine.
The criteria used to design these airfoils are re-iterated from the SOW in Table 1, aim to encapsulate requirements of modern airfoils for offshore wind turbine applications, and were developed with feedback form industry and research experts. The airfoils were designed using XFOIL and candidate airfoils were then analyzed in RFOIL, which is considered more accurate than XFoil for high lift predictions of thicker airfoils. The design process for a preliminary family of airfoils is available for a more detailed explanation of the design requirements and metrics [Karcher et al. 2025].
Most of the design criteria are met for these two airfoils, with two exceptions. For the OSO-21-WT1 airfoil, the L/D Roughness Loss metric is exceeded (43% > 40% goal); for both airfoils the desired lift coefficient travel beyond design value (“CL_Margin”) was moderately exceeded (0.5 > 0.3) while smooth-stall (computed) were achieved. Note that all of the metrics are computed using RFOIL, and like other new airfoils, these will need to be experimented validated before high-Reynolds number testing. The airfoil coordinates will be shared publicly on SNL’s public Github repositories:
(https://github.com/sandialabs/released-oso-airfoils).
Table 1. Open-Source Offshore airfoil design criteria and performance summary (computed metrics)
Design Criteria
Modern Airfoil tip region Modern Airfoil mid-span
OSO-21-WT1
Airfoil, tip region
OSO-30-WT1
Airfoil, mid-span Thickness - t/c 21% 30% 21% 30% Reynolds Number, Chordwise, design target Re=12e6+ Re=15e6+ Re=12e6 Re=18e6 CL_Design 1.2-1.6 1.2-1.6 1.4 1.5 L/D clean >200 >160 206 172 L/D rough >115 >95 117 102 L/D Roughness Loss % <40% <40% 43% 40% Stall Margin - Clean >3 deg. 7.0 6 Stall Margin - Rough >3 deg. 7.0 4.2 CL Margin Cl_Max - Cl_Des < 0.3 0.5 0.4
Post Stall Slope - Clean (dCL/dAlpha < -0.17/deg. over 2 deg.
post stall) -0.132
-0.076
Post stall slope - Rough (dCL/dAlpha < -0.17/deg. over 2 deg.
post stall) -0.135
-0.085 https://github.com/sandialabs/released-oso-airfoils
L/D robustness - Clean +/- 15% from peak L/D at +/- 15% from design AoA -5.7% -1.5%
L/D robustness - Rough +/- 15% from peak L/D at +/- 15% from design AoA -3.3% -2.5%
CM Magnitude ~Equal or less than existing open airfoils
(FFA , S-series) -0.15 -0.135
Structures - TE angle Last 2% of chord must have a wedge angle of at least 10 degrees ü ü Structures - Leading Edge Curvature - Shaped for robust performance, manufacturing, and erosion resistance
LE Radius > 0.01 LE Radius > 0.04 ü ü
Structures - Aft section upper surface curvature
Limit concave curvature on aft airfoil upper surface for buckling resistance ü ü
Structures - Spar location and thickness
Maximum thickness of airfoil measured perpendicular to chord line and located aft of 25% normalized chord ü ü
Structures - Bending Stiffness
Quantify that structural performance is at least as good as existing open airfoils, for example by comparing area moment of inertia. ü ü
The Open-Source Offshore (OSO) airfoils have been developed by Sandia National Laboratories in collaboration with the university of California State Long Beach, the National Renewable Energy laboratory, as well as through the advisement of many experts and the support of the DOE Wind Energy Technologies Office.
References Zahle, F., Barlas, A., Loenbaek, K., Bortolotti, P., Zalkind, D., Wang, L., Labuschagne, C., Sethuraman, L., and Barter, G., “Definition of the IEA Wind 22-Megawatt Offshore Reference Wind Turbine,” Technical University of Denmark, 2024.
https://doi.org/10.11581/dtu.00000317.
Cody J. Karcher, David C. Maniaci, Chris Kelley, Alan Hsieh, Nathaniel deVelder and Anurag Gupta. "Design of a Preliminary Family of Airfoils for High Reynolds Number Wind Turbine Applications," AIAA 2025-0840. AIAA SCITECH 2025 Forum.
January 202 https://doi.org/10.11581/dtu.00000317 https://arc.aiaa.org/doi/10.2514/6.2025-0840 https://arc.aiaa.org/doi/10.2514/6.2025-0840
File details come from the government source that posted it. Updated .