Fraunhofer IWES Making Room for XXL Blades

German research institute Fraunhofer IWES has received funding to build a test bench for rotor blades measuring up to 115 meters in length.

Fraunhofer IWES received funding to the tune of around EUR 12 million for the `Future Concept Operational Stability Rotor Blades Phase II` project.

To this end, a new test bench is set to be constructed in Bremerhaven as of the end of 2019. It encompasses a very large test bed for full-scale blade testing and benches for segment and component tests, Fraunhofer IWES said. The predecessor project investigated the viability of new test procedures and tested them out in small-scale test runs; the second phase will now see them employed on a larger scale.

Ground will be broken on the new test bench in Bremerhaven by the end of the year, and the facility is expected to start operation in 2021. The core of the planned test bench will be a new test block measuring 11×11 meters and with the option of being extended to suit higher blade lengths in the future if and when required. Moreover, the test bench will comprise the possibility to offer component and segment testing – which is a novelty for the wind industry, Fraunhofer IWES said.

In addition to the higher loads encountered in full-scale blade testing, the duration of the test, indirectly related to the size, represents a further challenge. Moreover, it is not possible to assess all areas of the rotor blade in detail and model them with statistical reliability in full-scale blade testing. Testing facilities for components and segments as well as the use of new methods can close this gap. They should provide more detailed information on critical rotor blade sections in this respect.

”Large independent test facilities are a major enabler for our upcoming developments of large offshore turbines. New concepts such as component testing and segment testing of blades are extremely interesting for us,” Flemming Kløcker Grove, Senior Project Manager at MHI Vestas Offshore Wind, said.

As the investigation of segments such as the trailing edge of a blade is more cost-effective than full-scale blade testing, it will be possible for manufacturers to perform a number of tests on one component in the future and increase the statistical relevance of the results. In addition, it is possible to induce and understand specific damage mechanisms.

”It’s not just about testing longer blades – we also want to test more intelligently and expand our position as a leading institute for rotor blade tests,” said Steffen Czichon, Head of Fraunhofer´s Department for Rotor Blades.

The aim of the ´Future Concept Operational Stability Rotor Blades Phase II´ project is to ensure that experimental testing of very long rotor blades remains economically viable for manufacturers. New testing procedures for the investigation of segments and components will offer a better understanding of critical areas and thus increase the informative value of the tests considerably. This information can be employed to design rotor blades even more precisely in the future, thereby saving on both weight and costs.

The project is funded by German Federal Ministry of Education and Research (BMBF) and the State of Bremen/ERDF, which will participate with EUR 3.65 million altogether; with EUR 8 million coming from German Federal Ministry for Economic Affairs and Energy (BMWi).