Peter Bjørn Andersen

Wind Tunnel Test on Wind Turbine Airfoil with Adaptive Trailing Edge Geometry

,A wind tunnel test of the wind turbine airfoil Ris oe-B1-18 airfoil equipped with an Adaptive Trailing Edge Geometry (ATEG) was carried out. The ATEG was made by piezo electric actuators attached to the trailing edge of a non-deformable airfoil and controlled by an amplifier. The airfoil was tested at Re = 1.66x10 6 . Steady state and dynamic tests were carried out with prescribed deflections of the ATEG. The steady state tests showed that deflecting the ATEG towards the pressure side (posi tive β) translated the lift curve to higher lift values and deflecting the ATEG towards the suc tion side (negative β β β β) translated the lift curve to lower lift values. Furthermore, cd was almost unaffected by the ATEG actuation. Testing the airfoil for a step change of the ATEG f rom β=-3.0 to +1.8 showed that the obtainable Δcl was 0.10 to 0.13 in the linear part of the lift cu rve. Modeling the step response with an indicial function formulation showed that t he time constant in the step change and in sinusoidal deflections in dimensionless terms was T0* =0.6. Testing the ability of the ATEG to cancel out the load variations for an airfoil in si nusoidal pitch motion showed that it was possible to reduce the amplitude with around 80% from Δ Δ Δ Δcl=0.148 to Δcl=0.032.

Design and verification of airfoils resistant to surface contamination and turbulence intensity

This paper presents the design of high performance airfoils for incompressible ∞ow and for Reynolds numbers at 6mio with a lift performance which is resistant to surface contamination and turbulence intensity. The Ris?-C2 airfoil family is dedicated for MW-size wind turbines, which are exposed to varying in∞ow conditions and surface contamination from bugs and dust. The airfoils were designed to have high maximum lift coe‐cient, while maintaining high aerodynamic e‐ciency. Given these characteristics the airfoils were designed with maximum stifiness. The design was carried out with a quasi 3D multi disciplinary optimization tool to take into account the complete blade shape. The design of the Ris?-C2-18 airfoil was verifled in the LM Glasflber wind tunnel, Denmark and showed good agreement with predicted characteristics.

A Dynamic Stall Model for Airfoils with Deformable Trailing Edges

The present work contains an extension of the Beddoes-Leishman (B-L) type dynamic stall model, as described by Hansen et al. In this work a Deformable Trailing Edge Geometry (DTEG) has been added to the dynamic stall model. The model predicts the unsteady aerodynamic forces and moments on an airfoil section undergoing arbitrary motion in heave, lead-lag, pitch, Trailing Edge (TE) flapping. In the linear region, the model reduces to the inviscid model of Gaunaa, which includes the aerodynamic effect of a thin airfoil with a deformable camberline in inviscid flow. Therefore, the proposed model can be considered a crossover between the work of Gaunaa for the attached flow region and Hansen et al. The model will be compared to wind tunnel measurements from Velux described by Bak et al.