A wind turbine blade comprising an aerodynamic blade shell with recess and pre-manufactured spar cap

Abstract

A wind turbine blade has a load carrying structure including at least a first spar cap and an aerodynamic shell having an outer surface forming at least part of an exterior surface of the wind turbine blade and an inner surface. The aerodynamic shell includes a first recess at the inner surface of the blade shell with a first thickened part at a first side of the first recess and a second thickened part at a second side of the first recess. The first recess is tapered towards the first side of the recess and tapered towards the second side of the recess, and the first spar cap is arranged in the first recess of the aerodynamic shell. The first spar cap is tapered towards a first side of the spar cap and further is tapered towards a second side of the spar cap.

Description

TECHNICAL FIELD[0001]The present invention relates to a method of manufacturing a wind turbine blade and intermediate products of a wind turbine blade. The invention further relates to a wind turbine blade and intermediate products of the wind turbine blade.BACKGROUND[0002]Wind turbine blades are often manufactured according to one of two constructional designs, namely a design where a thin aerodynamic shell is glued onto a spar beam, or a design where spar caps, also called main laminates, are integrated into the aerodynamic shell.[0003]In the first design, the spar beam constitutes the load bearing structure of the blade. The spar beam as well as the aerodynamic shell or shell parts are manufactured separately. The aerodynamic shell is often manufactured as two shell parts, typically as a pressure side shell part and a suction side shell part. The two shell parts are glued or otherwise connected to the spar beam and are further glued to each other along a leading edge and trailing...

AI Technical Summary

Benefits of technology

The patent describes a wind turbine blade design that reduces stress concentrations and improves fatigue resistance. This is achieved by using a tapered spar cap that matches the tapered sides of the recess in the blade shell structure. The design also includes vacuum bags that form separate mold cavities, which are easy to remove without applying a releasing material or coating to the inserts.

Problems solved by technology

Ensuring a complete distribution of the polymer in the entire mould cavity is, however, often difficult, and accordingly this often results in so-called dry spots, i.e. areas with fibre material not being sufficiently impregnated with resin.

Thus dry spots are areas where the fibre material is not impregnated, and where there can be air pockets, which are difficult or impossible to remove by controlling the vacuum pressure and a possible overpressure at the inlet side.

This is a time-consuming and tiresome process.

This is not desirable, especially not when the polymer has not hardened, as it can result in deformations in the inserted fibre material and thus in a local weakening of the structure, which can cause for instance buckling effects.

Furthermore the infusion process has become more complicated, as the impregnation of large shell members, such as blades, requires control of the flow fronts to avoid dry spots, said control may e.g. include a time-related control of inlet channels and vacuum channels.

This increases the time required for drawing in or injecting polymer.

As a result the polymer has to stay liquid for a longer time, normally also resulting in an increase in the curing time.

The disadvantage with prepregs is that the material cost is higher than for non-impregnated fibres.

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