Turbines of the year: Rotor blades

WORLDWIDE: Blade development reached new lengths in 2016 in both the onshore and offshore sectors

LM 88.4 P… Current holder of the world’s longest blade record


GOLD LM 88.4 P rotor blade

LM’s 88.4 P blade for the 8MW Adwen AD 8-180 is the longest ever developed, for the world’s largest rotor diameter at 180 metres.

Blade mass of below 34 tonnes has been enabled by LM’s "hybrid carbon" technology, which has been field-tested and validated on blades of about 60 metres.

A new resin allows combined use of glass and carbon fibres, not possible with polyester resin.

Incorporating carbon is seen as a must for blades this size — for holding down weight and feasibility of operation.

The blade’s shape is optimised for carbon use, interlinked with matching the allowed tip clearance, power production and load demands.

The LM-type airfoils are designed for aerodynamic and structural efficiency. A manufacturing novelty is the two-stage infusion process, the first for making the shells, followed by the second infusion step after putting in the carbon fibres.

Longer-term leading-edge erosion risk is minimised by applying LM’s in-house ProBlade leading-edge protection coating system, despite a rated tip speed in the 80m/s range.
The modest 4.18-metre bolt circle diameter has positive additional impact at pitch bearing and hub sizes and masses.

Two blades have been through the critical static and extreme tests and are currently going through fatigue testing to simulate a 25-year lifetime.