Two bladed wind turbines are discussed as a possible turbine alternative for offshore use as they show a potential to save cost of energy. But compared to three-bladed turbines, their dynamic behavior is much more challenging. A possible solution to handle these larger dynamic loads is the use of a teeter hinge, which can significantly reduce fatigue loads. In contrast to that, extreme loads, coming from teeter end impacts, are often described as a problem for teetered turbines.There are different design parameters of the teeter system of a turbine, which have an influence on extreme loads during teeter end impacts. Despite numerous studies on teeter movement and load reduction potentials of operational loads, scientific literature does not give information about suitable load-reducing combinations of teeter design parameters and their influence on extreme loads. This paper, which is a summary of a PhD thesis, 1 analyses which combination of teeter parameters has the largest load-reducing influence on extreme loads. Aeroelastic load simulations of the teetered turbine CART2 from the NREL test site and one of today's commercial two-bladed turbines, the SCD3MW from aerodyn (both pitch controlled upwind turbines), will be used.
KEYWORDSCART2, extreme loads, SCD3MW, teeter, two bladed
INTRODUCTIONIn today's literature, teeter end impacts are often described as situations that lead to critical loads. 2-8 Some of these studies even come to the conclusion that teeter end impacts make the load-reducing advantage of the teeter hinge obsolete. However, an overview of turbine design parameters influencing these loads is not given. A summary of research on teeter behaviour and a first approach of influences on teeter extreme loads has been done in Schorbach et al. 9 Closing this research gap is the aim of this study.