Program for research in applied aeroelasticity
The overall objective of the project is to ensure the development of an aetoelastic design complex, which can create the basis for the nest generation of wind turbines and make new design trends possible. The project constitutes a strategic cooperation between Risø and DTU and the wind turbine manufacturers with emphasis on obtaining a proper relation between long term strategic research, applied research and technological development
Within the Aeroelastic Research Program (EFP-97 to EFP-01) methods and models were developed, which were gathered and coordinated to a design complex in a EFP-02 project applying and demonstrating the models on Danish MW turbines. The development of the present multi MW turbines has only been possible with application of such methods. The application has lead to a bigger boldness in upscaling and application of new principles. Thus, the new designs operates on the limit of the validity of the aeroelastic computations. Activities: The project is aiming at a continued development and generalization of the aeroelastic computational methods in cooperation betwen Risø, DTU and the wind turbine industry. The main contribution is defined in the milestones below, which are planned to ensure continuity in the aeroelastic research and to consider the trends in the development and future possibilities for the wind turbine industry. 1) A method for 3D correction of airfoil characteristics. 2) Development of a model for 3D induction and stall modeling. 3) Design tool for 3D blade and airfoil design. 4) Clarification of uncertainties for computations of tower loads. 5) Modeling of pitch moments on flexible blades with large. deflections 6) Further development of a stability model - periodic loads
The project 'Program for Research in Applied Aeroelasticity' was carried out from 1. April 2004 to 31. March 2005. The partners in the project are Risø National Labortory(Risø) and the Technical University of Denmark (DTU). The overall objective of the project is to ensure the development of an aetoelastic design complex, which can create the basis for the nest generation of wind turbines and make new design trends possible. The project constitutes a strategic cooperation between Risø and DTU and the wind turbine manufacturers with emphasis on obtaining a proper relation between long term strategic research, applied research and technological development. The results from the project are obtained by focusing on several pre-defined milestones, but other topics and problems have as well been investigated and published scparately. Furthermore, concerning the six milestones the order of priorities have been changed, where the results are described below. 1) Method for 3D correction of airfoil characteristics: A new model for 3D correction of airfoil characteristics for use in aeroelastic codes has been establislied, Application of the model on three rotors indicated that the load distribution compared to measurements are determined better compared to existing 3D correction models. 2) Development of a model for 3D induction and stall modelling: A near wake model is implemented for calculation of the dynamic induction on wind turbin rotors. It is expected that e.g. the aerodynamic damping will be computed more precise when using the new model compared to the BEM model. 3) Clarification of uncertainties onthe calculation of tower laods: A detailed comparison of the aeroelastic models FLEX5 and HAWC has shown, that there is no differences in the models that can cause big differences in the computed loads. The comparison has shown that it is more likely that it depends on the user if the differences arise. 4) Modelingo pitch moment on flexible blades with large deflections: A model for the pitch servo dynamics on a modern wind turbine has been established and implemented in HAWC2. The conclusion of the investigation of the consequences of the pitch servo characteristics was among other things that the coupling between the structure/aerodynamics with the pitch actuator can be of significance. 5) Further development of stabilily model - periodic loadls: A non-linear stability analysis is carried out, where periodic loads are included and compared to a linear stability analysis, which is used in HAWCStab. For an airfoil with an aerodynamically damping close to zero in the direction of vibration, the aerodynamic force in that direction depends mostly on the square of the velocity of the airfoil. The linear damping is only changed slightly by the forced vibration of the airfoil. The present HAWCStab is assumed to predict the mean aeroelastic damping for the modal shapes of a wind turbine in normal operation. The milestone Design tool for 3D blade and airfoil design has changed its order of priority in the project and the subject will be a part of the EFP-2005 project 'Program for Research in Applied Aeroelasticity'
Key figures
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| Danmarks Tekniske Universitet (DTU) |
Contact
P.O. Box 49
DK-4000 Roskilde, Denmark
www.risoe.dtu.dk
Bak, Christian , 46775091, christian.bak@risoe.dk
Øvr. Partnere: DTU
