Articles | Volume 11, issue 3
https://doi.org/10.5194/wes-11-911-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-11-911-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
23 Mar 2026
Research article |
| 23 Mar 2026
| 23 Mar 2026
Wind tunnel load measurements of a leading-edge inflatable kite rigid-scale model
Jelle Agatho Wilhelm Poland
CORRESPONDING AUTHOR
Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, the Netherlands
Johannes Marinus van Spronsen
Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, the Netherlands
Mac Gaunaa
Department of Wind and Energy Systems, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark
Roland Schmehl
Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, the Netherlands
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Jelle Agatho Wilhelm Poland, Kasper Raphaël G. Masure, Oriol Cayon, and Roland Schmehl
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2026-46, https://doi.org/10.5194/wes-2026-46, 2026
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Soft inflatable kites are promising tools for renewable applications, but their unusual shape makes them difficult to analyse with conventional aerodynamic methods. A fast, accurate computer model is presented based on detailed airflow simulations and wind-tunnel measurements. Aerodynamic forces are predicted within about 10 % of experimental values while requiring far less computing time. It also helps designers balance efficiency and stability, enabling faster, more reliable kite development.
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We studied how air flows around a rigid scale model of a soft kite wing used for harvesting airborne wind energy and wind-assisted ship propulsion. Using a wind tunnel and a laser-based imaging method, we measured the airflow at different angles to compare with computer simulations. Results confirm key aerodynamic trends such as stall onset and spanwise lift variation, and highlight the influence of struts and recirculation zones on kite aerodynamics.
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Soft inflatable kites are promising tools for renewable applications, but their unusual shape makes them difficult to analyse with conventional aerodynamic methods. A fast, accurate computer model is presented based on detailed airflow simulations and wind-tunnel measurements. Aerodynamic forces are predicted within about 10 % of experimental values while requiring far less computing time. It also helps designers balance efficiency and stability, enabling faster, more reliable kite development.
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Wind Energ. Sci., 11, 195–216, https://doi.org/10.5194/wes-11-195-2026, https://doi.org/10.5194/wes-11-195-2026, 2026
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Wind Energ. Sci., 10, 2299–2349, https://doi.org/10.5194/wes-10-2299-2025, https://doi.org/10.5194/wes-10-2299-2025, 2025
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Oriol Cayon, Vince van Deursen, and Roland Schmehl
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-205, https://doi.org/10.5194/wes-2025-205, 2025
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Oriol Cayon, Simon Watson, and Roland Schmehl
Wind Energ. Sci., 10, 2161–2188, https://doi.org/10.5194/wes-10-2161-2025, https://doi.org/10.5194/wes-10-2161-2025, 2025
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Clemens Paul Zengler, Niels Troldborg, and Mac Gaunaa
Wind Energ. Sci., 10, 1485–1497, https://doi.org/10.5194/wes-10-1485-2025, https://doi.org/10.5194/wes-10-1485-2025, 2025
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Rishikesh Joshi, Dominic von Terzi, and Roland Schmehl
Wind Energ. Sci., 10, 695–718, https://doi.org/10.5194/wes-10-695-2025, https://doi.org/10.5194/wes-10-695-2025, 2025
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Wind Energ. Sci., 9, 2261–2282, https://doi.org/10.5194/wes-9-2261-2024, https://doi.org/10.5194/wes-9-2261-2024, 2024
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Rishikesh Joshi, Roland Schmehl, and Michiel Kruijff
Wind Energ. Sci., 9, 2195–2215, https://doi.org/10.5194/wes-9-2195-2024, https://doi.org/10.5194/wes-9-2195-2024, 2024
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Mark Schelbergen and Roland Schmehl
Wind Energ. Sci., 9, 1323–1344, https://doi.org/10.5194/wes-9-1323-2024, https://doi.org/10.5194/wes-9-1323-2024, 2024
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We present a novel two-point model of a kite with a suspended control unit to describe the characteristic swinging motion of this assembly during turning manoeuvres. Quasi-steady and dynamic model variants are combined with a discretised tether model, and simulation results are compared with measurement data of an instrumented kite system. By resolving the pitch of the kite, the model allows for computing the angle of attack, which is essential for estimating the generated aerodynamic forces.
Maaike Sickler, Bart Ummels, Michiel Zaaijer, Roland Schmehl, and Katherine Dykes
Wind Energ. Sci., 8, 1225–1233, https://doi.org/10.5194/wes-8-1225-2023, https://doi.org/10.5194/wes-8-1225-2023, 2023
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This paper investigates the effect of wind farm layout on the performance of offshore wind farms. A regular farm layout is compared to optimised irregular layouts. The irregular layouts have higher annual energy production, and the power production is less sensitive to wind direction. However, turbine towers require thicker walls to counteract increased fatigue due to increased turbulence levels in the farm. The study shows that layout optimisation can be used to maintain high-yield performance.
Mac Gaunaa, Niels Troldborg, and Emmanuel Branlard
Wind Energ. Sci., 8, 503–513, https://doi.org/10.5194/wes-8-503-2023, https://doi.org/10.5194/wes-8-503-2023, 2023
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We present an analytical vortex model. Despite its simplicity, the model is fully consistent with 1D momentum theory. It shows that the flow through a non-uniformly loaded rotor operating in non-uniform inflow behaves locally as predicted by 1D momentum theory. As a consequence, the local power coefficient (based on local inflow) of an ideal rotor is unaltered by the presence of shear. Finally, the model shows that there is no cross-shear deflection of the wake of a rotor in sheared inflow.
Ang Li, Mac Gaunaa, Georg Raimund Pirrung, Alexander Meyer Forsting, and Sergio González Horcas
Wind Energ. Sci., 7, 1341–1365, https://doi.org/10.5194/wes-7-1341-2022, https://doi.org/10.5194/wes-7-1341-2022, 2022
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A consistent method of using two-dimensional airfoil data when using generalized lifting-line methods for the aerodynamic load calculation of non-planar horizontal-axis wind turbines is described. The important conclusions from the unsteady two-dimensional airfoil aerodynamics are highlighted. The impact of using a simplified approach instead of using the full model on the prediction of the aerodynamic performance of non-planar rotors is shown numerically for different aerodynamic models.
Ang Li, Georg Raimund Pirrung, Mac Gaunaa, Helge Aagaard Madsen, and Sergio González Horcas
Wind Energ. Sci., 7, 129–160, https://doi.org/10.5194/wes-7-129-2022, https://doi.org/10.5194/wes-7-129-2022, 2022
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An engineering aerodynamic model for the swept horizontal-axis wind turbine blades is proposed. It uses a combination of analytical results and engineering approximations. The performance of the model is comparable with heavier high-fidelity models but has similarly low computational cost as currently used low-fidelity models. The model could be used for an efficient and accurate load calculation of swept wind turbine blades and could eventually be integrated in a design optimization framework.
Ang Li, Mac Gaunaa, Georg Raimund Pirrung, and Sergio González Horcas
Wind Energ. Sci., 7, 75–104, https://doi.org/10.5194/wes-7-75-2022, https://doi.org/10.5194/wes-7-75-2022, 2022
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An engineering aerodynamic model for non-planar horizontal-axis wind turbines is proposed. The performance of the model is comparable with high-fidelity models but has similarly low computational cost as currently used low-fidelity models, which do not have the capability to model non-planar rotors. The developed model could be used for an efficient and accurate load calculation of non-planar wind turbines and eventually be integrated in a design optimization framework.
Thanasis Barlas, Georg Raimund Pirrung, Néstor Ramos-García, Sergio González Horcas, Robert Flemming Mikkelsen, Anders Smærup Olsen, and Mac Gaunaa
Wind Energ. Sci., 6, 1311–1324, https://doi.org/10.5194/wes-6-1311-2021, https://doi.org/10.5194/wes-6-1311-2021, 2021
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Curved blade tips can potentially have a significant impact on wind turbine performance and loads. A swept tip shape optimized for wind turbine applications is tested in a wind tunnel. A range of numerical aerodynamic simulation tools with various levels of fidelity are compared. We show that all numerical tools except for the simplest blade element momentum based are in good agreement with the measurements, suggesting the required level of model fidelity necessary for the design of such tips.
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Short summary
We tested a small model of an energy-generating kite in a wind tunnel to study its aerodynamic behaviour. By comparing measurements to computer simulations, we validated the models and identified where they match the real performance and where they fall short. These insights will guide more accurate aerodynamic modelling and inform design choices for kites used in airborne wind energy systems.
We tested a small model of an energy-generating kite in a wind tunnel to study its aerodynamic...
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