Innovative tip design reduces costs

In a challenging experiment, ECN and LM Wind Power have successfully extended blades with an add-on tip extension to test new blade tip designs in the InnoTip research project. With the project now coming to a close, these innovation tip designs could significantly reduce the cost of energy.

‘Shark fins’, ‘winglets’ and ‘turbulators’ all refer to types of tip designs for wind turbine blades—part of an innovative research project called ‘InnoTip.’ The blade tip is the primary source of noise, loads and power output from a wind turbine, so there are significant potential gains from further optimizing this part of the blade.

The winglet tip consists of a bend on the tip and the turbulator tip involves wake reduction geometry that improves efficiency. The shark fin improves flow characteristics around the tip area which has a significant effect on blade performance (photos courtesy of Skysurvey BV).

With the ultimate goal of reducing the Levelized cost of energy (LCoE) through optimized tip design, the InnoTip research project started as a collaboration between LM Wind Power’s aerodynamics team and ECN. During this project, three new tip designs were delivered and two were tested by extending blades with a temporary add-on tip extension—a unique process.

The project showed that power increase from the new tip designs was even better than expected—up to six percent in the initial tests—proving that these new geometries, as well as the field tests, were successful.

Once the three new tips were designed, it was time to put them to the test at ECN’s test site in the Dutch Wieringermeer. Instead of building new blades, the team would replace only the tips on blades already in operation – almost like putting a “sock” on the end of a blade. This was a unique and complex challenge.

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