Riblet4Wind

Development of an industrial procedure for the application of aerodynamically advanced coatings for wind turbine rotor blades

Presentation of the innovation
The innovation features a technology for the design and automatic application of a riblet-like micro-structure (in the micrometer range) to rotor blade surfaces in order to improve the aerodynamics of the rotor blades and to increase the power outcome of the wind turbine. (The riblet structure is illustrated in the upper left image in the figure below.)

The innovation consists of two parts:

• Numerical simulation and design of a riblet scheme for a given rotor blade geometry (profile). The results deliver the particular structure of the riblets and the sections on the rotor blade where the riblets deploy the maximum efficiency;
• Robot-based application of the riblet structure onto the designated sections of the rotor blade under production conditions. (The robot is shown in the upper right image in the figure below.

Added value
The added value is particularly the gain in electric power outcome of a wind turbine due to the riblet application.

• Wind tunnel tests have revealed an increase in the glide ratio by 30%.
• Long-term (1.5 years) on-site tests at a near-shore wind power turbine (Bremerhaven) have proven an increase in electric power outcome compared with a turbine without riblets.
• Equal wind conditions provided, an average increase in electric power outcome of 5% was recorded.
• The application of the riblets can be performed under production conditions in rotor blade coating facilities by means of a special robotized, environmentally friendly rolling procedure (no overspray, no VOCs) with extremely high accuracy. (The roller is shown in the upper right image in the graph below.)
• Capital investment costs and application costs are low compared with the total manufacturing costs of large offshore rotor blades.

Innovative character

• The industrial application of the riblet structure to real rotor blades has not been done before. The application technology developed guarantees a highly accurate, well defined application of the micro-structure onto curved surfaces.

• The combination with numerical simulation and robot application guarantees the most effective performance of the riblets in operation. This link between big data processing and robot-controlled application is a novelty world-wide.
• The procedure is an optimization procedure by design and, thus, much more than a simple application procedure. It can be specifically adapted to given rotor blade geometries and meteorological conditions at the (offshore) site.