Taming the inevitable: significant parameters of teeter end impacts

The Science of Making Torque from Wind 2014

Schorbach, V.^1 ; Dalhoff, P.^1 ; Gust, P.^2

Hamburg University of Applied Sciences, Berliner Tor 21, 20099 Hamburg, Germany^1

University of Wuppertal, Gauss Strasse 20, 42119 Wuppertal, Germany^2

关键词: Blade loading;    Dimensional analysis;    Extreme loads;    Influencing parameters;    Normal operations;    Out-of-plane bending;    Restraint systems;    Turbine parameters;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/524/1/012070/pdf
DOI  :  10.1088/1742-6596/524/1/012070

来源: IOP

【 摘 要 】

Two bladed wind turbines are recently discussed more often as the question arises for the most suitable offshore turbine concept. Regarding this turbine concept, a solution for the more challenging dynamics is required. A teetered hub has been a solution for quite an amount of the former two bladed turbines. During normal operation this is an efficient possibility to eliminate the hub bending moment coming from unequal blade loading. But looking at extreme load cases the teeter end impact is a major problem. The teeter end impact is quite often described as the occasion which destroys the load reducing advantage of the teeter mechanism. However, a more detailed analysis of the intensity of the hub out of plane bending moment of the teeter end impact including influencing parameters is not given in literature. For this study, the teetered turbine CART2 from NREL is simulated with the aeroelastic tool Bladed 4.5. Design load cases leading to teeter end impacts have been identified for the CART2. The influence of different parameters of teeter end impacts will be analysed. A distinction of these parameters can be made between turbine parameters and teeter system parameters. Rotor mass and speed are turbine parameters. Pitch-teeter-coupling, the free teeter angle and the damping or stiffness of the restraint system belong to the teeter system parameters. The importance of these parameters will be investigated on three different IEC 61400-1-ed. 2 load cases leading to teeter end impacts. The simulation results will be compared with a dimensional analysis of the analytical teeter equations. Results of this study show which parameters have the most significant influence on teeter end impacts. In short, this paper will contribute to a better understanding of teeter end impacts, which are widely regarded as a severe problem but whose nature has not been the subject of a detailed analysis so far.