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Soft rotor design for flexible turbines



The ultimate objectives of the project are to improve the performance and show the cost effectiveness of flexible wind turbine designs. This will be achieved by bringing new advanced technological know-how to the design of optimal soft rotors for stall regulated, free yawing, free-tilting, teetered two-bladed wind turbines. A demonstration will be made on an existing "flexible" wind turbine.

Technical Approach

The project will result in the design and manufacture of a soft rotor, that takes advantage of structural coupling between different component deflections, bending/torsion in particular, in order to obtain optimal aerodynamic and dynamic characteristics under load. The measurement of its performance and the turbine's overall unsteady behaviour as compared to the use of present "stiff" rotors will show to what extent the target objectives have been attained.

The project consists in development of the Risø 15 kw, stall regulated, two bladed, downwind turbine with free yaw and tilt from a relatively stiff teetering rotor to a flexible rotor. This involves the aerodynamic and structural design of the rotor, the manufacture and the testing of the rotor on an existing flexible turbine.

Expected Achievements and Exploitation

The practical result of the project is an advanced two bladed flexible rotor, which takes advantage of structural couplings and has a diameter of 12-14 m. This might be seen as a scale rotor, as all conceptual design principles and calculation methods are focused on application to large turbines (> 500 kw). Thus, even though the resulting turbine design can be used directly for a small scale turbine, the main spin-off of the project is the use of design tools for prediction of structural and aeroelastic stability and verification/ demonstration of their potential capabilities. The study is parametric and is accompanied by a demonstration to show which potentially favourable degrees of freedom can be accounted for in the design in order to obtain a light weight, simple and stable turbine. The demonstration turbine will be regarded as a prototype for the development of a 300-500 kW machine.

Funding Scheme

CSC - Cost-sharing contracts


Risø National Laboratory
399,Frederiksborgvej 399
4000 Roskilde

Participants (2)

LM Glasfiber A/S
1,Rolles Moellevej
6640 Lunderskov
Office National d'Etudes et de Recherches A?rospatiales
29 Avenue De La Division Leclerc
92322 Châtillon