Vertical Axis Tidal Turbine Behaviour under Sheared Flow Effects

Abstract

Tidal turbines are often subjected to complex flow conditions that can affect their power output and the risk of failure. In this article, an experimental study on a vertical axis tidal turbine with twin counter-rotating rotors is carried out at 1/20 scale, submitted to a sheared turbulent (ST) flow and a sheared weakly turbulent (SWT) flow. The performance and wake development comparison indicates that the turbine behaves differently depending on the shear rate considered. A 7% decrease in performance is observed at the turbine’s nominal operating point between uniform and ST conditions. The asymmetry of the flow along the vertical axis is reflected in the angular and frequency distributions of the rotor torque, indicating a production asymmetry between the lower and the upper rotors. Analysis of wake development reveals that transport terms constitute the main mechanism of wake dissipation. In the case of SWT and uniform flow, vertical advection largely dominates the other terms, whereas in ST flow, transverse advection is initially predominant. This results in a higher average wake height and a lower average wake width in the ST case compared to the other flow conditions, and a faster wake recovery.

Keywords

Sheared flow / Wake recovery / Tidal turbines / Turbulence / Performance / Momentum balance

Acknowledgments

The authors acknowledge Benoit Gomez for his help during the tests and the data analysis.

Author Contributions

Conceptualization, R.L., G.G. and G.M.; Methodology, R.L., B.G., J.-V.F., C.P. and G.G.; Validation, R.L., Y.S. and B.G.; Formal Analysis, R.L.; Investigation, R.L., Y.S., J.-V.F. and G.G.; Data Curation, R.L.; Writing—Original Draft Preparation, R.L.; Writing—Review & Editing, R.L., Y.S. and G.G.; Visualization, R.L.; Supervision, C.P., G.G. and G.M.; Project Administration, G.G. and G.M.; Funding Acquisition, G.G. and G.M.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data supporting the findings of this study are available from the corresponding author, upon reasonable request.

Funding

This research was funded by the French Agence Nationale de la Recherche through the Verti-Lab project (ANR-23-LCV1-0009-01), the French Research and Technology National Association (ANRT) under the convention Cifre n◦ 2023/0217 and the CPER IDEAL.

Declaration of Competing Interest

The authors declare that they have potential conflicts of interest, some of them being employed by HydroQuest and all working together on the Verti-Lab project.

References

[1] Maka AOM, Ghalut T, Elsaye E. The pathway towards decarbonisation and net-zero emissions by 2050: The role of solar energy technology. Green Technol. Sustain. 2024, 2, 100107. doi:10.1016/j.grets.2024.100107.

[2] Copping A, Wood D, Rumes B, Ong EZ, Golmen L, Mulholland R, et al. Effects and management implications of emerging marine renewable energy technologies. Ocean Coast. Manag. 2025, 264, 107598. doi:10.1016/j.ocecoaman.2025.107598.

[3] Jin S, Greaves D. Wave energy in the UK: Status review and future perspectives. Renew. Sustain. Energy Rev. 2021, 143, 110932. doi:10.1016/j.rser.2021.110932.

[4] Suarez L, Guerra M, Williams ME, Escauriaza C. Tidal energy resource assessment in the Strait of Magellan in the Chilean Patagonia. Renew. Energy 2025, 252, 123430. doi:10.1016/j.renene.2025.123430.

[5] Lamy JV, Azevedo IL. Do tidal stream energy projects offer more value than offshore wind farms? A case study in the United Kingdom. Energy Policy 2018, 113, 28-40. doi:10.1016/j.enpol.2017.10.030.

[6] Benelghali S, Benbouzid M, Charpentier J-F. Marine Tidal Current Electric Power Generation Technology: State of the Art and Current Status. In Proceedings of the 2007 IEEE International Electric Machines & Drives Conference, IEMDC 2007, Antalya, Turkey, 3-5 May 2007. doi:10.1109/IEMDC.2007.383635.

[7] Mullings H, Draycott S, Thiébot J, Guillou S, Mercier P, Hardwick J, et al. Evaluation of Model Predictions of the Unsteady Tidal Stream Resource and Turbine Fatigue Loads Relative to Multi-Point Flow Measurements at Raz Blanchard. Energies 2023, 16, 7057. doi:10.3390/en16207057.

[8] Zhou Z, Benbouzid M, Charpentier J-F, Scuiller F, Tang T. Developments in large marine current turbine technologies—A review. Renew. Sustain. Energy Rev. 2017, 71, 852-858. doi:10.1016/j.rser.2016.12.113.

[9] Ouro P, Runge S, Luo Q, Stoesser T. Three-dimensionality of the wake recovery behind a vertical axis turbine. Renew. Energy 2019, 133, 1066-1077. doi:10.1016/j.renene.2018.10.111.

[10] Satrio D, Utama IK, Mukhtasor M. Vertical Axis Tidal Current Turbine: Advantages and Challenges Review. In Proceedings of the Ocean, Mechanical and Aerospace—Scientits and Engineers, Terengganu, Malaysia, 7-8 November 2016.

[11] Eriksson S, Bernhoff H, Leijon M. Evaluation of different turbine concepts for wind power. Renew. Sustain. Energy Rev. 2008, 12, 1419-1434. doi:10.1016/j.rser.2006.05.017.

[12] Milne IA, Sharma RN, Flay RGJ, Bickerton S. Characteristics of the turbulence in the flow at a tidal stream power site. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 2013, 371, 20120196. doi:10.1098/rsta.2012.0196.

[13] Moreau M, Germain G, Maurice G. Experimental performance and wake study of a ducted twin vertical axis turbine in ebb and flood tide currents at a 1/20th scale. Renew. Energy 2023, 214, 318-333. doi:10.1016/j.renene.2023.05.125.

[14] Linant R, Saouli Y, Germain G, Maurice G. Experimental Study of the Wave Effects on a Ducted Twin Vertical Axis Tidal Turbine Wake Development. J. Mar. Sci. Eng. 2025, 13, 375. doi:10.3390/jmse13020375.

[15] Sezer-Uzol N, Uzol O. Effect of steady and transient wind shear on the wake structure and performance of a horizontal axis wind turbine rotor. Wind Energy 2025, 16, 1-17. doi:10.1002/we.514.

[16] Khan M, Odemark Y, Fransson J. Effects of Inflow Conditions on Wind Turbine Performance and near Wake Structure. Open J. Fluid Dyn. 2017, 7, 105-129. doi:10.4236/ojfd.2017.71008.

[17] Li L, Liu Y, Yuan Z, Gao Y. Wind field effect on the power generation and aerodynamic performance of offshore floating wind turbines. Energy 2018, 157, 379-390. doi:10.1016/j.energy.2018.05.183.

[18] Badshah M, Badshah S, VanZwieten J, Jan S, Amir M, Malik SA. Coupled Fluid-Structure Interaction Modelling of Loads Variation and Fatigue Life of a Full-Scale Tidal Turbine under the Effect of Velocity Profile. Energies 2019, 12, 2217. doi:10.3390/en12112217.

[19] Moreau M, Germain G, Maurice G. Misaligned sheared flow effects on a ducted twin vertical axis tidal turbine. Appl. Ocean. Res. 2023, 138, 103626. doi:10.1016/j.apor.2023.103626.

[20] Mendoza V, Chaudhari A, Goude A. Performance and wake comparison of horizontal and vertical axis wind turbines under varying surface roughness conditions. Wind Energy 2019, 22, 458-472. doi:10.1002/we.2299.

[21] Gaurier B, Germain G, Facq J-V, Bacchetti T. Wave and Current Flume Tank of IFREMER at Boulogne-sur-Mer. Description of the Facility and Its Equipment; Ifremer: Boulogne-sur-Mer, France, 2018. doi:10.13155/58163.

[22] Owen PR, Zienkiewicz HK. The production of uniform shear flow in a wind tunnel. J. Fluid Mech. 1957, 2, 521-531. doi:10.1017/S0022112057000336.

[23] Magnier M, Germain G, Gaurier B, Druault P, Gaurier B, Druault P. Velocity Profile Effects on a Bottom-Mounted Square Cylinder Wake and Load Variations. In Proceedings of the 14th European Wave and Tidal Energy Conference, Plymouth, UK, 5-9 September 2021.

[24] Sellar B, Wakelam G, Sutherland D, Ingram D, Venugopal V. Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves. Energies 2018, 11, 176. doi:10.3390/en11010176.

[25] Gooch S, Thomson J, Polagye B, Meggitt D. Site Characterization for Tidal Power. In Proceedings of the OCEANS 2009, Biloxi, MS, USA, 26-29 October 2009; pp. 1-10. doi:10.23919/OCEANS.2009.5422134.

[26] Lewis M, Neill SP, Robins P, Hashemi MR, Ward S. Characteristics of the velocity profile at tidal-stream energy sites. Renew. Energy 2017, 114, 258-272. doi:10.1016/j.renene.2017.03.096.

[27] Furgerot L, Bois PBD, Méar Y, Morillon M, Poizot E, Bennis A-C. Velocity Profile Variability at a Tidal-Stream Energy Site: From Short to Yearly Time Scales. In Proceedings of the 2018 OCEANS—MTS/IEEE Kobe Techno-Oceans (OTO), Kobe, Japan, 28-31 May 2018; pp. 1-8. doi:10.1109/OCEANSKOBE.2018.8559326.

[28] Blackmore T, Myers LE, Bahaj AS. Effects of turbulence on tidal turbines: Implications to performance, blade loads, and condition monitoring. Int. J. Mar. Energy 2016, 14, 1-26. doi:10.1016/j.ijome.2016.04.017.

[29] Allmark M, Mason-Jones A, Facq J-V, Gaurier B, Germain G, O’Doherty T. Combined effects of yaw misalignment and inflow turbulence on tidal turbine wake development. Energy 2025, 324, 135728. doi:10.1016/j.energy.2025.135728.

[30] Bossard J. Caractérisation Expérimentale du Décrochage Dynamique dans les Hydroliennes à Flux Transverse par la Méthode PIV. Comparaison avec les Résultats Issus des Simulations Numériques. Ph.D. Thesis, Université de Grenoble, Saint-Martin-d'Hères, France, 2012.

[31] Saouli Y, Gaurier B, Germain G, Linant R, Maurice G. Experimental investigation of the flow direction effects on a quadrirotor vertical axis tidal turbine. Ocean Eng. 2025, 341, 122519. doi:10.1016/j.oceaneng.2025.122519.

[32] Talamalek A, Runacres MC, De Troyer T. Experimental investigation of the wake replenishment mechanisms of paired counter-rotating vertical-axis wind turbines. J. Wind Eng. Ind. Aerodyn. 2024, 252, 105830. doi:10.1016/j.jweia.2024.105830.

[33] Magnier M, Delette N, Druault P, Gaurier B, Germain G. Experimental study of the shear flow effect on tidal turbine blade loading variation. Renew. Energy 2022, 193, 744-757. doi:10.1016/j.renene.2022.05.042.

[34] Linant R, Germain G, Facq J-V, Penisson C, Maurice G. Vertical Axis Tidal Turbine Behaviour in a Non-Uniform Velocity Profile. In Proceedings of the 19e Journées de l’Hydrodynamique, Nantes, France, 26-28 November 2024.

[35] Peng HY, Lam HF. Turbulence effects on the wake characteristics and aerodynamic performance of a straight-bladed vertical axis wind turbine by wind tunnel tests and large eddy simulations. Energy 2016, 109, 557-568. doi:10.1016/j.energy.2016.04.100.

[36] Grondeau M, Guillou S, Mercier P, Poizot E. Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach. Energies 2019, 12, 4273. doi:10.3390/en12224273.

[37] Högström U, Asimakopoulos DN, Kambezidis H, Helmis CG, Smedman A. A field study of the wake behind a 2 MW wind turbine. Atmos. Environ. 1988, 22, 803-820. doi:10.1016/0004-6981(88)90020-0.

[38] Zhang W, Markfort CD, Porté-Agel F. Wind-Turbine Wakes in a Convective Boundary Layer: A Wind-Tunnel Study. Bound.-Layer Meteorol. 2013, 146, 161-179. doi:10.1007/s10546-012-9751-4.

[39] Vermeer LJ, Sørensen JN, Crespo A. Wind turbine wake aerodynamics. Prog. Aerosp. Sci. 2003, 39, 467-510. doi:10.1016/S0376-0421(03)00078-2.

[40] Araya DB, Colonius T, Dabiri JO. Transition to bluff-body dynamics in the wake of vertical-axis wind turbines. J. Fluid Mech. 2017, 813, 346-381. doi:10.1017/jfm.2016.862.

[41] Bachant P, Wosnik M. Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine. Energies 2016, 9, 73. doi:10.3390/en9020073.

[42] Shen X, Zhu X, Du Z. Wind turbine aerodynamics and loads control in wind shear flow. Energy 2011, 36, 1424-1434. doi:10.1016/j.energy.2011.01.028.

[43] Wen J, Liu C, Zhang S, Zhou L, Tang H, Xia Y, et al. Wake dynamics and coherence modes of vertical-axis wind turbines: The role of atmospheric boundary layer. Phys. Fluids 2025, 37, 067123. doi:10.1063/5.0271326.

[44] Dhalwala M, Bayram A, Oshkai P, Korobenko A. Performance and near-wake analysis of a vertical-axis hydrokinetic turbine under a turbulent inflow. Ocean Eng. 2022, 257, 111703. doi:10.1016/j.oceaneng.2022.111703.