The rotor design of the horizontal axis fixedpitch SCHOTTEL Instream Turbine SIT250 aims for a passive-adaptive deformation – in particular torsion – to reduce the thrust loads in off-design conditions. To realize the demanded passive-adaptive behaviour, the blades are designed as a composite blade with exact tuned structural stiffness properties. Experimental verification of the blades are an essential part of a development process to proof the passive-adaptive property of the new design as well as its strength against the design loads before operating in the harsh marine environment of tidal currents. The objectives of this work are:
* To describe a design procedure for a passive-adaptive tidal turbine blade
*To present a unique test rig for full-scale passiveadaptive tidal turbine blades
*Present the result from a full-scale testing
The structural design is obtained in an iterative process accounting for the coupling between structural properties and loading of the blade. Therefore, the laminate layup is adapted based on results from dynamic load simulations, taking into account the changed structural properties, until the design is numerically verified. To enable the experimental verification of the structural properties in terms of static strength against extreme loads and passive-adaptive pitch behaviour a unique test rig was designed and built. Eventually, a prototype of the newly developed blades was tested on the novel test rig. The recorded deformation has been compared to the results of the FEM simulations. While the flapwise and torsional deflection was underpredicted, the general passive-adaptive pitch behaviour was verified experimentally.