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This paper presents an experimental aeroservoelastic investigation of a novel load al-leviation concept using trailing edge aps. These aps are autonomous units, which are self-powered and self-actuated, using trailing edge tabs, thereby demonstrating advantages in comparison with conventional ap systems in terms of wiring and structural integration. The aps are free-oating and mass underbalanced, such that they may utter at operation velocities unless suppressed by their own control system. This makes the system very re-sponsive for turbulence and control action. In the wind tunnel campaign presented in this paper, the limit cycle behavior of autonomous, free-oating aps was investigated. It has been shown that limit cycle oscillation can be reached either through structural limiters or by control actions of the trailing edge tabs. In the latter case, the amplitude of the limit cycle oscillation is adjustable to the required energy output. An energy balance of har-vested power and power consumption for actuators and sensing system was made showing that the vibration energy of limit cycle oscillations can be used to keep the amplitude of the limit cycle constant, while the electric batteries that power the load alleviation system are being charged.
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This paper presents an experimental aeroservoelastic investigation of a novel load al-leviation concept using trailing edge aps. These aps are autonomous units, which are self-powered and self-actuated, using trailing edge tabs, thereby demonstrating advantages in comparison with conventional ap systems in terms of wiring and structural integration. The aps are free-oating and mass underbalanced, such that they may utter at operation velocities unless suppressed by their own control system. This makes the system very re-sponsive for turbulence and control action. In the wind tunnel campaign presented in this paper, the limit cycle behavior of autonomous, free-oating aps was investigated. It has been shown that limit cycle oscillation can be reached either through structural limiters or by control actions of the trailing edge tabs. In the latter case, the amplitude of the limit cycle oscillation is adjustable to the required energy output. An energy balance of har-vested power and power consumption for actuators and sensing system was made showing that the vibration energy of limit cycle oscillations can be used to keep the amplitude of the limit cycle constant, while the electric batteries that power the load alleviation system are being charged.
In this paper a new method to obtain a geometrically non-linear wind turbine structural model based on the full linear finite element model is presented. For this purpose, the wind turbine model is divided into multiple segments, i.e. tower, drive train and blades. For each segment a modal analysis is carried out. Boundary grid points are defined on each segment and loaded by ficticious masses. The modal analysis produces a set of 6 rigid-body modes and elastic modes close to fixed-fixed analysis. For the aeroelastic turbine simulation, the ficticious masses are removed. The elastic modes are used as master modes that describe the deformation, while the rigid-body modes are used as slaves to establish compatibility between the segments. A modal analysis is carried out in the local segment attached reference frame, yielding a local linear solution that is part of a global non-linear analysis. Large rotations and displacements are provided by rigid-body modes in a co-rotational framework.
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In this paper a new method to obtain a geometrically non-linear wind turbine structural model based on the full linear finite element model is presented. For this purpose, the wind turbine model is divided into multiple segments, i.e. tower, drive train and blades. For each segment a modal analysis is carried out. Boundary grid points are defined on each segment and loaded by ficticious masses. The modal analysis produces a set of 6 rigid-body modes and elastic modes close to fixed-fixed analysis. For the aeroelastic turbine simulation, the ficticious masses are removed. The elastic modes are used as master modes that describe the deformation, while the rigid-body modes are used as slaves to establish compatibility between the segments. A modal analysis is carried out in the local segment attached reference frame, yielding a local linear solution that is part of a global non-linear analysis. Large rotations and displacements are provided by rigid-body modes in a co-rotational framework.
