Blade Dynamics’ Spar Assemblies Go to Great Lengths

Blade Dynamics is a UK-based company that develops advanced rotors for utility-scale wind turbines. The company focuses on modular assembly technology to enable longer blades and has developed and GL certified the world’s lightest 49-meter blade.

According to this TechnologyReview.com article, the Blade Dynamics makes blades entirely out of carbon fiber using smaller sections (12-20 meters) seamlessly spliced together. The company recently received funding from the Energy Technologies Institute (ETI), a public-private partnership between the UK government and companies such as BP, Shell and Caterpillar, to build 80 to 100-meter blades.

Blade Dynamics owns at least one U.S. patent and at least eight pending U.S. applications relating to its wind turbine technology.

U.S. Application Publication Nos. 2010/0260611 (’611 Application) and 2011/0103962 (’962 Application) are each entitled “Wind turbine blade” and are directed to, respectively, a load-bearing spar and a blade comprising an elongate spar.

The ’611 Application is directed to a load-bearing spar (30) for a wind turbine blade (10). The spar (30) is connected to a root subassembly (20) and supports frame members (40, 50).

Skin panels (60, 70) are mounted on the frame members to form a continuous outer surface of the blade (10).

The ’962 Application is directed to a wind turbine blade having a sub-assembly including a spar (6) and a root (7). Successive skin panels (1) are bonded to the spar (6) with flange (4) adjacent to an opening (5) and being bonded to the spar (6).

U.S. Application Publication No. 2012/0294724, entitled “Aerodynamic fairing for a wind turbine and a method of connecting adjacent parts of such a fairing” (’724 Application), is directed to methods for connecting the skin panels mentioned above. The ’724 describes use of recesses (10, 11) and adhesive channels (14) defined in the skin panels (1A, 1B).

A bead of adhesive (17) is applied between the recess (11) and flange (16), which projects inwardly at an acute angle to form a hook-like structure. The distal end of the first skin panel (1A) is located within the groove formed between the recess (11) and flange (16) to ensure lateral alignment between the two skin panels. Spacers (12, 13) abut against the face of the recess (11), thereby precisely determining the dimensions of the adhesive channel (14).

Another bead of adhesive (18) is then applied to the outer surface of the assembled skin panels (1A, 1B) to seal the channel at the left-hand side. The adhesive runs along the adhesive channel (14), assisted by the flow channels (15), ensuring even distribution of the adhesive along the channel.

According to the ’962 Application, this modular assembly structure eliminates the need for separate ribs used by prior designs, significantly reduces the number of components required to create a finished blade, and eliminates at least one alignment step in the construction process.

The TechnologyReview.com article quotes the company’s senior technical manager on other advantages such as enabling greater precision in aerodynamic structures and improving performance. In addition, because the company’s blades weigh less than fiberglass ones, they can provide longer blades for existing wind turbine designs.

Eric Lane is a patent attorney at McKenna Long & Aldridge LLP in San Diego and the author of Green Patent Blog. Mr. Lane can be reached at elane@mckennalong.com