Wind tunnel test is the primary method to investigate the aerodynamic performance of airfoils. That is why we carried out a study with Vestas and the Technical University of Denmark (DTU) using DTU’s world-renowned wind tunnel testing facility. In the study, we examined how erosion and leading edge protection (LEP) solutions affect the blade’s aerodynamics.

We tested airfoils under conditions up to 6 million Reynolds number, giving extremely high-quality data. The tests consisted of scenarios including:

• airfoil with or without LEP
• airfoil with LEP using no chamfering (sealing) or chamfering with various lengths
• airfoil with various erosion categories

The LEP solution during testing was our ELLE™ softshell.

The study showed that:

1. Erosion impacts both lift and drag
2. LEP has no impact on the lift
3. LEP impacts the drag but much less than erosion does. The quality, length, and position of the LEP chamfering, however, can reduce this impact on the drag.
4. The value using LEP depends on how much the environment erodes the blade, which in turn depends on the site conditions.
   
   

This study proves that eroded blades should never be the choice for operation. It also proves that LEP with the right chamfering can in fact restore the airfoil’s aerodynamic performance.

The study also verifies that aerodynamic performance using LEP is highly dependent on site conditions. As such, one cannot put a single number on the annual energy production (AEP) loss, because this will be site dependent.

That is why we developed our erosion calculator based on the results from this study, where we include site-specific information on any wind turbine sites in the world to calculate the erosion rates and provide recommended LEP solutions.

Get your site-specific erosion calculation here. 

And download the full report on the wind tunnel study here.