Results of the AVATAR project for the validation of 2D aerodynamic models with experimental data of the DU95W180 airfoil with unsteady flap

C Ferreira,N.R Garcia,D Baldacchino,A Gonzalez,S Knecht,P Chassapogiannis,M Aparicio,T Lutz,A Van Zuijlen,J Prospathopoulos,S Voutsinas,S Gómez,T Gillebaart,G Papadakis,X Munduate,K Diakakis,J.N Sørensen,E Jost

doi:10.1088/1742-6596/753/2/022006

Abstract

The FP7 AdVanced Aerodynamic Tools for lArge Rotors - Avatar project aims to develop and validate advanced aerodynamic models, to be used in integral design codes for the next generation of large scale wind turbines (10-20MW). One of the approaches towards reaching rotors for 10-20MW size is the application of flow control devices, such as flaps. In Task 3.2: Development of aerodynamic codes for modelling of flow devices on aerofoils and, rotors of the Avatar project, aerodynamic codes are benchmarked and validated against the experimental data of a DU95W180 airfoil in steady and unsteady flow, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, carried out within the framework of WP3: Models for Flow Devices and Flow Control, Task 3.1: CFD and Experimental Database. The aerodynamics codes are: AdaptFoil2D, Foil2W, FLOWer, MaPFlow, OpenFOAM, Q3UIC, ATEFlap. The codes include unsteady Eulerian CFD simulations with grid deformation, panel models and indicial engineering models. The validation cases correspond to 18 steady flow cases, and 42 unsteady flow cases, for varying angle of attack, flap deflection and reduced frequency, with free and forced transition. The validation of the models show varying degrees of agreement, varying between models and flow cases.

Highlights

The pursuit for lower Cost of Energy (CoE) for wind turbines has resulted in new concepts with active and passive flow control devices ([1])
This paper presents the validation of seven numerical models against the collected data for measurements on a DU95W180 airfoil equipped with an actuated rigid trailing edge flap with 20% chord in steady and unsteady flow, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, in free and forced laminar-turbulent transition
The sub-set of results presented4 shows that the difference between experimental and numerical results has two sources: an error in the prediction of average steady results; and an error in the prediction of unsteady flow effects

Summary

Introduction

The pursuit for lower Cost of Energy (CoE) for wind turbines has resulted in new concepts with active and passive flow control devices ([1]). Published under licence by IOP Publishing Ltd boundary layer control and trailing edge flaps. A review of different actively controlled smart rotor concepts was presented in [2], concluding that trailing edge flaps are among the most promising concepts. The work by ([6]) studied the concept of controlling the flap based on a pressure difference over the airfoil at different chord-wise positions using potential flow. The work in [9] studied three state-of-the-art numerical models (Reynolds Averaged Navier Stokes, inviscid-viscid interaction model and a dynamic stall model) for a pitching and a flapping airfoil

Methods

Results

Conclusion