Appropriate dynamic-stall models for performance predictions of VAWTs with NLF blades

摘要

This paper illustrates the relative merits of using Natural Laminar Flow (NLF) airfoils in the design ofVertical Axis Wind Turbines (VAWT). This is achieved by the application of the double-multiple-streamtube model of Paraschivoiu to the performance predictions of VAWTs equipped withconventional and NLF blades. Furthermore, in order to clearly illustrate the potential benefit ofreducing the drag, the individual contributions of lift and drag to power are presented. Thedynamic-stall phenomena are modelled using the method of Gormont as modified by severalresearchers. Among the various implementations of this dynamic-stall model available in the literature,the most appropriate and general for NLF applications has been identified through detailedcomparisons between predicted performances and experimental data. This selection process ispresented in the paper. It has been demonstrated that the use of NLF airfoils in VAWT applicationscan lead to significant improvements with respect to conventional design only in a very low windspeed range, the extent of which is negligible with respect to the VAWT operational wind speeds.