Blade design

Pre-bending - the distinguishing feature of LM blades
LM blades are pre-bent, which means they flex towards the wind when mounted and are not subject to loading. LM Glasfiber developed this pre-bending solution for several reasons.

Clearance to the tower: One of the design parameters when we develop new blades for a particular wind turbine is the tip to tower distance. We have to design the blades so that they do not strike the turbine when turning, even in strong winds. There are different ways to do this. One is to tilt the rotor so that the blades are not at right angles to the nacelle when viewed from the side. Using the same principle, it is possible to cone the rotor, thus ensuring clearance for the blades. However, both these methods require adjustments to the nacelle design to position the centre of gravity accurately.

Pre-bending the blades means that the nacelle design stays compact. Bending of the blades from their resting position to the tower is greater. LM blades are straightened in correlation with the approximate average wind strength at the erection site.

Lighter blades
Pre-bending the blades means less material is required. The blades do not need to be quite as rigid because the amount of allowable bending is greater. This makes it possible to use less material overall and fewer processed materials, which means we not only produce lighter blades, but they are cheaper as well. Lighter blades make it possible to increase the length and thus make them more capable of producing more electricity.

Larger swept area
When blades are exposed to the wind, they normally bend backwards, thus slightly reducing the rotor area. Pre-bending the blades means the opposite. In maximum wind conditions, the rotor area is also at a maximum. Rotor area is crucial for the annual production of the wind turbine.

Tip design
The very end of the blade is called its tip. This plays a very important part in the blade's overall performance and the noise it makes during operation.

LM Glasfiber has carried out extensive research in this field, and LM blades have had different tip designs over the years. From an aerodynamic viewpoint, the best possible shape would feature a relatively wide blade tip. However, this would result in considerable noise and increased loading. A larger area at the tip would also affect the distance from the tower to the blade. A wide tip design would also entail using more materials to strengthen the blade and make it more rigid.

One way to reduce noise emissions from the tip is to slow the blade's speed of rotation. However, this has a negative effect on production. An alternative solution is to optimise the blade tip as regards both noise and performance.




Welcome to LM Glasfiber - Leading skills every step of the way
LM Glasfiber is the world's leading supplier of blades for wind turbines, and the only supplier that operates on a global basis. To maintain our leading position in the development of blade technology and production methods, we rely on the exceptional know-how and responsibility of our employees all over the world.

We currently have more than 100 employees engaged exclusively in R&D work. As a result, we are the blade producer with the most extensive specialist knowledge in the world in fields that include material and process technology, aero-elastic calculations, aerodynamic design, structural design, power calculations, cross-section calculations, geometric design, testing of materials and components, testing of blades and use of 3D CAD.

We hire some of the best-qualified engineers and bring major resources to bear in building up a wide-reaching body of specialist know-how and to constantly maintain our technical expertise.

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Blade design
Pre-bending - the distinguishing feature of LM blades LM blades are pre-bent, which means they flex towards......