Flow Curvature Effects for VAWT: a Review of Virtual Airfoil Transformations and Implementation in XFOIL

Sander van der Horst, Jelmer E. van de Wiel, Carlos Simao Ferreira, Néstor Ramos García

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


Blades on a Vertical Axis Wind Turbine (VAWT) experience curved streamlines, caused by the rotation of the turbine. This phenomenon is known as flow curvature and has effects on the aerodynamic loading of the blades. Several authors have proposed methods to account for flow curvature, resulting in methods to transform the original airfoil in curved flow to a virtual airfoil, which can be analysed in straight flow. This paper reviews multiple of such virtual airfoil transformations and compares the outcomes. All methods show good correspondence to the curved flow press ure distribution, but small errors remain that are intrinsic to the conformal methods used. It is shown that VAWT rotation is equivalent to an eternal pitching motion. Using this similarity, flow curvature modeling has been added to the airfoil analysis tool XFOIL. The various changes have been made in the inviscid solver, in a way that the viscous solver need not to be changed.
Original languageEnglish
Title of host publicationProceedings of the 34th Wind Energy Symposium
PublisherAmerican Institute of Aeronautics and Astronautics
Publication date2016
Article numberAIAA 2016-1734
Publication statusPublished - 2016
Event34th Wind Energy Symposium - San Diego, CA, United States
Duration: 4 Jan 20168 Jan 2016
Conference number: 34


Conference34th Wind Energy Symposium
CountryUnited States
CitySan Diego, CA
Internet address

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