Single-step versus coupled-aero-structure simulation of a wind turbine with bend-twist adaptive blades

In wind turbines with bend-twist adaptive blades there is an interaction between the induced twist due to elastic coupling and the blade loading as the source load of induced twist. This interaction makes the simulation of these types of wind turbines a coupled aero-structure process that needs an internal correction loop. In each run of the correction loop a finite element analysis of the blade is necessary to find the induced twist and this makes the simulation process very time consuming and cumbersome. On the other hand, in wind turbines with stretchtwist adaptive blades the centrifugal force, as the source load, produces the induced twist but it is not affected by the induced twist directly. Therefore, a single-step simulation can be carried out with no need for a correction loop. A single step simulation is more time efficient than a coupled aero-structure one. This study compares the results of simulations of a modelled wind turbine with bend-twist adaptive blades both by a single step approach and by a coupled aero-structure approach. In this way the question of how accurate can be a single step simulation of a wind turbine with bend-twist adaptive blades, can be answered. Comparison of the results shows that even for small amounts of induced twist and low wind velocities a single step simulation approach gives unrealistic results and cannot be used for simulation of a wind turbine with bend-twist adaptive blades.