Aero-Structural Analysis and Dimensional Optimization of a Prototype Hybrid Wind–Photovoltaic Rotor with 12 Pivoting Flat Blades and a Peripheral Stiffening Ring
Source abstract
Abstract
We present the first aero-structural evaluation of a 3 m-diameter hybrid wind-PV rotor employing flat-plate blades stiffened by a peripheral ring. Owing to the lack of prior data, we combine low-Reynolds BEM, elastic FEM sizing, and steady-state CFD (k-ω SST) to build a coherent preliminary load and performance dataset. After upsizing the hub pins (Ø 30 mm), ring (50 × 50 mm) and spokes (Ø 40 mm), von Mises stresses stay below 25% of the 6061-T6 yield limit and tip deflection remains within 0.5% R across Cut-in (3 m/s), Nominal (5 m/s) and Extreme (25 m/s) wind cases. CFD confirms a flat efficiency plateau at λ = 2.4–2.8 (β = 10°) and zero braking torque at β = 90°, validating a three-step pitch schedule (20° start-up → 10° nominal → 90° storm). The study addresses only the rotor; off-the-shelf generator, brake, screw-pitch and azimuth/tilt drives will be integrated later. These findings set a solid baseline for full-scale testing and future transient CFD/FEM iterations.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Wind Energy Research and Development · Biomimetic flight and propulsion mechanisms · Wave and Wind Energy Systems
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Doctoral School of Engineering, Valahia University of Targoviste, 130004 Targoviste, Romania
Mechanical Department, Materials and Mechanical Faculty, ‘Valahia’ University, 130004 Targoviste, Romania
References (44)
Show source-provided references
1. International Energy Agency (2024). Renewables 2024: Analysis and Forecasts to 2030, IEA. Available online: https://www.iea.org/reports/renewables-2024.
2. Gorman, W., Rand, J., Manderlink, N., Cheyette, A., Bolinger, M., Seel, J., Jeong, S., and Wiser, R.H. (2025, July 15). Hybrid Power Plants: Status of Operating and Proposed Plants, 2024 Edition, Available online: https://emp.lbl.gov/hybrid-power-plants-status-operating-and-proposed-plants-2024-edition.10.2172/2440851 ↗
3. Hassan, Q., Algburi, S., Sameen, A.Z., Salman, H.M., and Jaszczur, M. (2023). A Review of Hybrid Renewable Energy Systems: Solar and Wind-Powered Solutions: Challenges, Opportunities, and Policy Implications. Results Eng., 20.10.1016/j.rineng.2023.101621 ↗
4. Alnaimi, F.B.I., Kazem, H.A., Alzakri, A.B., and Alatir, A.M. (2024). Design and Implementation of Smart Integrated Hybrid Solar-Darrieus Wind Turbine System for In-House Power Generation. Renew. Energy Environ. Sustain., 9.10.1051/rees/2023019 ↗
5. (2025, August 05). 24th International Wind & Solar Integration Workshop 2025—Preliminary Program. Berlin, Germany, 7–10 October 2025. Available online: https://windintegrationworkshop.org/program-overview-preliminary/.
6. Ministry of New and Renewable Energy (MNRE), Government of India (2025, July 23). Amendment in the Guidelines for Tariff-Based Competitive Bidding Process for Procurement of Power from Grid-Connected Wind–Solar Hybrid Projects, Available online: https://mnre.gov.in/en/notices/amendment-in-the-guidelines-for-tariff-based-competitive-bidding-process-for-procurement-of-power-from-grid-connected-wind-solar-hybrid-projects.
7. Meister, R., Yaïci, W., Moezzi, R., Gheibi, M., Hovi, K., and Annuk, A. (2025). Evaluating the Balancing Properties of Wind and Solar Photovoltaic System Production. Energies, 18.10.20944/preprints202503.0691.v1 ↗
8. U.S. Energy Information Administration (2025, July 27). Solar and Wind Power Curtailments Are Increasing in California. Today in Energy, 28 May 2025, Available online: https://www.eia.gov/todayinenergy/detail.php?id=65364.
9. Low Reynolds Number Aerodynamics of Low-Aspect-Ratio, Thin/Flat/Cambered-Plate Wings10.2514/2.2676 ↗
10. (2019). Wind Energy Generation Systems—Part 2: Small Wind Turbines (Standard No. IEC 61400-2:2019).
11. Burton, T., Jenkins, N., Sharpe, D., and Bossanyi, E. (2021). Design Loads for HAWTs. Wind Energy Handbook, Wiley. [3rd ed.].10.1002/9781119451143 ↗
12. Progress in the Validation of Rotor Aerodynamic Codes Using Field Data10.5194/wes-8-211-2023 ↗
13. AIAA (2002). Guide for the Verification and Validation of Computational Fluid Dynamics SimulationsAIAA G-077-1998 (Reaffirmed 2002).
14. Monitoring the Wake of Low Reynolds Number Airfoils for Their Aerodynamic Loads Assessment
15. Traub, L.W. (2024). Wing Efficiency Enhancement at Low Reynolds Number. Aerospace, 11.10.3390/aerospace11040320 ↗
16. Gutiérrez-Castillo, P., Aguilar-Cabello, J., Alcalde-Morales, S., Parras, L., and del Pino, C. (2021). On the lift curve slope for rectangular flat plate wings at moderate Reynolds number. J. Wind Eng. Ind. Aerodyn., 208.10.1016/j.jweia.2020.104459 ↗
17. Zahle, F., Li, A., Lønbæk, K., Sørensen, N.N., and Riva, R. (2024). Multi-fidelity, steady-state aeroelastic modelling of a 22-megawatt wind turbine. J. Phys. Conf. Ser., 2767.10.1088/1742-6596/2767/2/022065 ↗
18. Hybrid-Lambda: A Low-Specific-Rating Rotor Concept for Offshore Wind Turbines10.5194/wes-9-359-2024 ↗
19. A Scaling Methodology for the Hybrid-Lambda Rotor—Characterization and Validation in Wind Tunnel Experiments10.5194/wes-10-1329-2025 ↗
20. Multipoint High-Fidelity CFD-Based Aerodynamic Shape Optimization of a 10 MW Wind Turbine10.5194/wes-4-163-2019 ↗
21. Du, B., Shen, E., Wu, J., Guo, T., Lu, Z., and Zhou, D. (2025). Aerodynamic Prediction and Design Optimization Using Multi-Fidelity Deep Neural Network. Aerospace, 12.10.3390/aerospace12040292 ↗
22. Jiang, J., Zhang, Z., Han, Z., Li, Y., Zhang, L., Chen, Z., Fan, X., Xu, S., and Li, B. (2024). Study on the Structural Strength Assessment of Mega Offshore Wind Turbine Tower. Energies, 18.10.3390/en18010069 ↗
23. Nonlinear Finite Element Analysis of Tubular Steel Wind Turbine Towers near Man Door and Ventilation Openings to Optimize Design against Buckling10.3390/vibration7010012 ↗
24. Hu, Y., Yang, J., and Baniotopoulos, C.C. (2020). Repowering Steel Tubular Wind Turbine Towers Enhancing Them by Internal Stiffening Rings. Energies, 13.10.3390/en13071538 ↗
25. (2025, September 08). General Electric Renovables España, S.L. Rotor Assembly Having a Pitch Bearing with a Stiffener Ring. EP Patent EP 3 736 438 B1. Available online: https://patents.google.com/patent/EP3736438B1/en.
26. Alternative Ring Flange Models for Buckling Verification of Tubular Steel Wind Turbine Towers via Advanced Numerical Analyses and Comparison to Code Provisions10.1016/j.istruc.2022.11.090 ↗
27. Burton, T., Jenkins, N., Sharpe, D., Bossanyi, E., and Graham, M. (2021). Further Aerodynamic Topics for Wind Turbines. Wind Energy Handbook, Wiley. [3rd ed.]. Available online: https://onlinelibrary.wiley.com/doi/10.1002/9781119451143.ch4.10.1002/9781119451143 ↗
28. (2013). Wind Turbines—Part 2: Small Wind Turbines (Standard No. IEC 61400-2:2013).
29. Schepers, J.G., Boorsma, K., Aagaard Madsen, H., Pirrung, G., Bangga, G., Sørensen, N.N., Grinderslev, C., Forsting, A.M., Imiela, M., and Ramos-García, N. (2022). Final Report of IEA Wind Task 29, Phase IV: Validation of Aerodynamic Models, International Energy Agency, IEA Wind. Available online: https://iea-wind.org/task-29.
30. Cardamone, R., Broglia, R., Papi, F., Rispoli, F., Corsini, A., Bianchini, A., and Castorrini, A. (2025). Aerodynamic Design of Wind Turbine Blades Using Multi-Fidelity Analysis and Surrogate Models. Int. J. Turbomach. Propuls. Power, 10.10.3390/ijtpp10030016 ↗
31. Schepers, J.G., Boorsma, K., Madsen, H., Pirrung, G., Özçakmak, Ö.S., Bangga, G., Guma, G., Lutz, T., Potentier, T., and Braud, C. (2021). IEA Wind TCP Task 29, Phase IV: Detailed Aerodynamics of Wind Turbines, IEA Wind.
32. Celik, I.B., Ghia, U., Roache, P.J., Freitas, C.J., Coleman, H., and Raad, P.E. (2008). Procedure for Estimation and Reporting of Uncertainty Due to Discretization in CFD Applications. J. Fluids Eng., 130.10.1115/1.2960953 ↗
33. Hau, E., and Siegfriedsen, S. (2025). Wind Turbines: Fundamentals, Technologies, Application, Economics, Springer. [4th ed.].10.1007/978-3-031-87795-7 ↗
34. Effect of Internal Stiffening Rings and Wall Thickness on the Structural Response of Steel Wind Turbine Towers10.1016/j.engstruct.2014.09.015 ↗
35. Shiomitsu, D., and Yanagihara, D. (2021). Estimation of Ultimate Strength of Ring-Stiffened Cylindrical Shells under External Pressure with Local Shell Buckling or Torsional Buckling of Stiffeners. Thin-Walled Struct., 161.10.1016/j.tws.2020.107416 ↗
36. Implementation of the Blade Element Momentum Model on a Polar Grid and Its Aeroelastic Load Impact10.5194/wes-5-1-2020 ↗
37. Investigations on Self-Starting and Performance Characteristics of Simple H and Hybrid H-Savonius Vertical Axis Wind Rotors10.1016/j.enconman.2014.07.056 ↗
38. Jonkman, J., Butterfield, S., Musial, W., and Scott, G. (2009). Definition of a 5-MW Reference Wind Turbine for Offshore System DevelopmentNREL/TP-500-38060.10.2172/947422 ↗
39. Full-Scale Test of Trailing Edge Flaps on a Vestas V27 Wind Turbine: Active Load Reduction and System Identification10.1002/we.1589 ↗
40. The Potential of Agrivoltaic Systems10.1016/j.rser.2015.10.024 ↗
41. Damiani, R., and Davis, D. (2025, August 05). Design Load Basis Guidance for Distributed Wind Turbines; SR-5000-91458; National Renewable Energy Laboratory (NREL), Golden, CO, USA, 2024, Available online: https://www.nrel.gov/docs/fy25osti/91458.pdf.
42. A Simple Method for Modelling Fatigue Spectra of Small Wind Turbine Blades10.1002/we.2588 ↗
43. Sutherland, H.J. (1999). On the Fatigue Analysis of Wind TurbinesSAND99-0089.10.2172/9460 ↗
44. Schaarup, J. Guidelines for Design of Wind Turbines, 253p. Available online: https://orbit.dtu.dk/en/publications/guidelines-for-design-of-wind-turbines.