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Wind turbine blade airfoil section test

Objective

To investigate the behaviour of airfoils currently used in wind turbine blades.
Within the framework of the JOULE 1 programme, two aerofoils of 21% and 25% rela
tive thickness were designed and tested in the low speed turbulence wind tunnel of Delft University of Technology. During the wind tunnel measurements the standard tests were performed to establish the low speed aerodynamic characteristics of the aerofoils both in the clean configuration and in the tripped pper surface boundary layer condition for Reynolds numbers between 1 (10{6}) and 3(10{6}). I addition the effects on the airfoil performance of vortex generators at different chord locations and Gurney flaps were studied.

During the project in fact two 25% thick aerofoils were designed, one with a high and another with a moderateCi,max. In view of the applicability of the airfoil halfway the blade, the design with moderate peak lift coefficient was chosen to investigate experimentally. The thick airfoil was shown to have a higher lift to drag ratio, a higher maximum lift coefficient and a better behaviour in the turbulent upper surface condition than an equivalent from the NACA six digit series. The 21% thick airfoil showed to be a good intermediate between the thick and highly cambered outboard airfoils with moderate thickness such as the NACA 63-6xx series.
This project is the follow-up of the work by ENEA and Politecnico di Torino on wind tunnel tests of airfoil sections extended to high angles of attack. The main result of it was determination of principal aerodynamic parameters (lift, drag and moment coefficients and pressure distribution) of six important airfoil sections (NACA 8 digits, Wortmann, NASA LS) at two Reynolds numbers (0.95 and 1.3 millions) and at angles of attack from -90 to +90 degrees.

The general objective of the project is to gain further insight on the behaviour airfoils whose aerodynamic properties are well known only for those conditions which are of interest to the aeronautical industry, e.g. low angles of attack and non-stall behaviour. These are far from the actual conditions to which wind turbine blades are subject under normal operation With respect to the previous work, which mainly dealt with the effects caused by large angle of attack, this proposal will extend it to investigate the effect of Reynolds numbers, roughness, wear, etc., as well as to test further types of commonly used airfoils.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

ITALIAN AGENCY FOR NEW TECHNOLOGY, ENERGY AND THE ENVIRONMENT
Address
Via Angullarese 301
00060 Roma
Italy

Participants (2)

POLITECNICO DI TORINO
Italy
Address
Corso Duca Degli Abruzzi 24
10129 Torino (Turin)
Technische Universiteit Delft
Netherlands
Address
4,Mekelweg
2628 CD Delft