Aeroelastic research programme 2000-2001
The project has comprised the following six milestones: a) status on 2D and 3D CFD computations, b) implementation of improved aerodynamic and structural sub models in the aeroelastic codes FLEX4 and HAWC, c) design of an airfoil family with high maximum lift, d) determination of the potential in prediction of dynamic stability, e) analysis of the uncertainty in computation of design loads, f) guidelines for optimised blade dynamics.
The project covers a one year period from mid 2000 to mid 2001 of a continuously running 5 years research programme on aeroelasticity. The overall objectives of the project are to improve the load and design basis for wind turbines and to ensure in collaboration with industry a continuously running process on development of new designs and solution of actual problems. Specifically the main goals for the present period are the following: a) Derivation of 3D airfoil data for a MW turbine for use in aeroelastic calculations. b) Implementation and improvement of sub models for structural and aerodynamic modelling in the aeroelastic codes FLEX4 and HawC. c) Design of an airfoil series with high maximum lift coefficient for blades on off-shore wind turbines. d) Investigation of possible methods for determination of dynamic stability. e) Uncertainties in derivation of design loads. f) Derivation of guide lines for optimised blade dynamics. The research work is carried out within close contact to the industry and in parallel to these main research areas a number of subjects representing problems and potentials for the industry will be taken up
The project 'Program for forskning i aeroelasticitet EFP-2000', has been carried out in collaboration between Risø, DTU and the wind turbine industry. The project period has been 2000-2001 and it is the fourth period of a five years research program on aeroelasticity initiated in 1997. Within the present period the project has comprised the following six milestones: a) status on 2D and 3D CFD computations, b) implementation of improved aerodynamic and structural sub models in the aeroelastic codes FLEX4 and HAWC, c) design of an airfoil family with high maximum lift, d) determination of the potential in prediction of dynamic stability, e) analysis of the uncertainty in computation of design loads, f) guidelines for optimised blade dynamics. Within the project important results have been obtained and in particular within the following three main areas: 1) verification, development and application of 2D and 3D CFD computation on airfoils and rotors; 2) dynamic stabiblity of a complete wind turbine structure; 3) importance of non-linearity's related to big blade deflections. The development of rotor computations with the 3D CFD code EllipSys3D has been an important research area since the start of the aeroelastic research programme in 1997, where initial results of 3D computations on a rotor were presented. However, first within the present project a verification of these 3D rotor computations has been possible. A blind test of rotor codes was carried out by NREL in USA using experimental data from a comprehensive wind tunnel experiment on a 10 m rotor. Out of about 20 different codes EllipSys3D gave results with the best correlation with the experimental data and in particular the 3D effect on the airfoil characteristics was well predicted. Within the research areas on dynamic stability a simple, linear structural model has been developed enabling the computation of a Campbell diagram within a few seconds. Such a diagram illustrates the rotor modes during operation and is an important input to a complete dynamic stability analysis. A new structural model has been developed in order to investigate the importance of non-linearity's caused by big blade deflections. Initial results show that a blade loaded flapwise has a slightly higher flapwise stiffness compared with the stiffness computed by a linear model. Besides the results within the three main research areas mentioned above important results have been obtained within other areas as e.g. airfoil design. The models for airfoil optimisation and design have been further developed and using these tools three new airfoils with a thickness of 18%, 24% and 30% have been designed. They all show improved characteristics compared with typical used airfoils for wind turbine blades such as NACA and FFA airfoils
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Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| Danmarks Tekniske Universitet (DTU) | 3,55 mio. DKK |
Contact
P.O. Box 49
DK-4000 Roskilde, Denmark
Aagaard Madsen, Helge (forskningsspecialist), 46775047, helge.aagaard.madsen@risoe.dk
Øvr. Partnere: Danmarks Tekniske Universitet. Afdeling for Energiteknik