Turbines of the year - Rotor blades

WORLDWIDE: Designers look to efficiency of manufacture and ease of transport as blades continue to grow in size

Longer blades… The E-115 prototype has now been installed in Germany
Longer blades… The E-115 prototype has now been installed in Germany


GOLD Enercon E-115 segmented rotor blade

Enercon's 2.5MW E-115 turbine features new-generation slender (load-reducing) segmented rotor blades comprising two glass-fibre reinforced epoxy sections joined by cross-sectional and longitudinal bolts.

Traditional blade manufacture is labour intensive, which poses an increasing challenge as blades grow ever longer. The E-115's blades comprise an inner section of about 12 metres, and an outer sector of 44 metres, a design solution aimed to facilitate transport and installation especially at space constrained inland and forested sites.

Enercon's novel technique for manufacturing the inner segments involves machine wrapping pre-soaked fibreglass fabric around a positive cylindrical core that in ready form constitutes the load-bearing structure. In the second step the aerodynamic trailing edge — with Enercon's characteristic integrated spoiler — is bonded with this blank to produce the final airfoil structure and shape. Automation of the wrapping process provides time saving and cost benefits, plus higher manufacturing quality and better working ergonomics.

The blade incorporates a factory-assembled trailing-edge integrated spoiler that is much longer than the separate site-assembled wide spoiler of a traditional E-101 blade. It also flattens towards the blade foot creating the "flat-back" profile that has become increasingly common.

The outer segment is built from standard half shells with state-of-the-art vacuum-infusion technology.

Enercon's E-126 turbines are fitted with segmented blades but with the inner sections in steel. However, it sounds not unlikely that the slender composite segmented blade technology pioneered on the E-115 turbine might well serve as the blueprint for an E-126 successor blade design of the future.

Click here for more on the Turbines of the Year 2013

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