DNV GL has launched a Joint Industry Project with ten commercial partners to develop a COmprehensive methodology for Blade Rain erosion Analysis (COBRA). The COBRA Joint Industry Project has been set up to investigate the damage caused to leading edge wind turbine blades from the high-speed impacts of foreign objects, such as raindrops, and identify how best to develop protection systems.
While the damage caused doesn’t often impact the structural integrity of a blade, it can influence energy generation over the life of a turbine due to degrading the aerodynamic performance of blades. DNV GL has partnered with Vestas, Siemens Gamesa Renewable Energy, LM Wind Power, Ørsted, Senvion, Mankewiecz, Akzo Nobel, Aerox-CEU, Polytech, Hempel and PPG, to take up the challenge of analysing the effect that rain erosion damage can have on the blades of operating wind turbines.
The outcome of the Joint Industry Project will be a Recommended Practice for designing a protection system against rain erosion which will be published by July 2020. The working group aims to address the following technical topics:
- Identify and define relevant material properties for a protection system
- Develop and methodology to handle and derive design loads from rain data
- Develop a model to conduct raindrop impact analysis
- Develop a design methodology for leading edge protection systems