In-house research in applied aerodynamics

Until recently, the aerodynamics of wind turbine blades have been largely based on models and calculations from the aeronautical industry. At LM Glasfiber, however, we decided to create our own development environment in applied aerodynamics and invest in a customised wind tunnel. We have also designed a software-based tool – LM Blades – for the integrated calculation of aerodynamics and structure.

Selecting the blade profile

At the start of a blade project, our customer sends us the specifications for the wind turbine. We can use these specifications to perform initial calculations of the geometry and structure (using LM Blades), and the annual output and total load on the wind turbine.

The aerodynamic design of a wind turbine blade defines its width, thickness, direction and profile. It is a matter of finding the best compromise between air flow and strength (profile and structure). The purpose is to optimise performance while minimising loads.

All LM Glasfiber’s aerodynamic models and calculations are kept in our design database. This means we are able to provide our customers with preliminary designs in a very short time and to a high level of precision.
More about our working relationship with customers

Customised wind tunnel

At LM Glasfiber, we decided to build our own wind tunnel, focusing on 2D simulations to optimise our profiles and specially developed features. We mainly use the wind tunnel and CFD (Computational Fluid Dynamics) for long-term development work. Our research includes making the blades more intelligent so they can adapt to operating conditions, for example by changing their profile by using different flaps or spoilers.
More about our wind tunnel

 

CFD 3D calculations

CFD calculations are performed in the preliminary design phase in order to determine the wind flow patterns.
Computational Fluid Dynamics (CFD) simulations can be used to determine how the wind forces affect a wind turbine blade as it rotates (i.e. in three dimensions). The results are used to adjust the aerodynamic design of the blade. At LM Glasfiber, we use CFD as a supplement to wind tunnel testing, which is used to verify the calculations.

Flex5 indicates loads throughout the wind turbine

Once the relationship between the effects of the wind and the load on an aerodynamic profile have been established (for example using CFD), we can calculate the load on a section of a wind turbine blade. By subdividing the blades into sections, the operational load on the entire blade can be determined using Flex5, the most widely used calculation software in the industry. Flex5 has been specially developed for this purpose, and is able to calculate loads on the entire structure of the wind turbine.

VT8 computes annual output

Clearly, energy output is a very important parameter for a wind turbine blade. Energy output is calculated in a similar way to loads. The method uses software developed in-house: VT8. This program is extremely fast because it is based on less complex calculations than Flex5. The method is still precise enough to produce a reliable calculation of energy output. The short response time is a big advantage when we are developing a new blade type, because many different parameters have to be investigated and varied.