Smalls drops, big impact: Even just minor rain erosion damage on rotor blade surfaces can impair performance and shorten the service life of wind turbines. Fraunhofer IWES has been operating a rain erosion test bench since 2015 in order to achieve a better understanding of how damage progresses and derive effective preventative measures. Within the scope of the newly started “BeLeB” research project the aim is to contribute to the development of reliable forecasting models for erosion damage and apply them to turbine operation. In particular, this also encompasses the assessment of practice-relevant repair concepts. To achieve these goals, the test bench is set up to enable continuous testing and precise damage documentation by means of high-resolution 3D images. Offshore operating data are used by way of comparison for validation purposes.
When operating, the wing tip of a wind turbine can reach speeds of 300 to 350 km/h and, as a result, rain drops and pollution in the air act like sandpaper on the surface of the material. Parts which are subjected to particular stresses, such as the leading edge of blades, are therefore finished with protective systems such as paint and coatings. The development and validation of a method for the accelerated service life analysis of coating systems helps to prevent turbine downtimes and loss of profits.
To this end, as part of the BeLeB research project (development of a method for determining the service life of rotor blade coatings), tests are performed on the Fraunhofer IWES test bench. These are compared against the measurement data from a long-term study of selected turbines on which a certain coating material is used. The comparison of damage progression on the test bench and damage documentation from operational offshore turbines guarantees that the test bench reproduces the most realistic conditions possible and that the effectiveness of protective mechanisms can be simulated reliably over accelerated time periods. This allows the development of practical preventative measures.
