Recent studies demonstrate that severe cases of erosion can lead to an annual energy production (AEP) loss of up to 20%. This can add up to thousands of dollars annually, underscoring the importance of proactively protecting turbine blades before issues arise.

Utility-scale turbine blades are often more than 40m long and are made of lightweight materials such as fiberglass, epoxy, or polyester. As blades rotate at up to 250mph, they come into contact with rain, hail, salt spray, and other debris, causing often-unseen damage. Ultimately, even small particles can have a significant effect at these speeds, especially if the impact occurs throughout time. As the blade wears, pitting, gouging, and delamination can occur, causing a significant loss in aerodynamic efficiency. This loss can be exacerbated by the downtime that is necessary to make turbine repairs, underlining the importance of protecting blades against erosion and making repairs quickly. Fortunately, several solutions are available for leading-edge protection.

Wind protection tape

Originally developed for helicopter blades and aircraft radomes, wind protection tape can resist erosion, puncture, tearing, and weathering. In addition, a high-quality tape shields wind turbine surfaces from pitting, wear, and water ingression.

When evaluating wind protection tapes, operators must determine if the product is UV stable and if the installation requires specialty tools. Due to recent product innovations, wind protection tapes can easily be applied in the factory or in the field via rope or platform access.

In the field, wind protection tape is often one of the best choices to repair damage as it provides a consistent solution with uniform thickness and finish. Many installations of wind protection tape have surpassed the seven-year mark with the material still performing well.

Protective coating

Factory-applied coatings are also available for wind blade protection. Designed to protect leading edges from damage caused by sand and rain erosion and minor impact, a two-component polyurethane solution provides a single layer of protection and can be applied using a brush.

When examining coatings, turbine manufacturers should look for a product that can be easily applied and quick-curing to maintain efficiency. It is also important to consider additional repair options, such as fillers, abrasives and accessories, as these solutions are often used in conjunction with coatings to mitigate damage.

Wind epoxy, polyurethane fillers

If a blade is past the point of protection and needs repair, minor damage can be treated with fillers made of epoxy or polyurethane. Fillers can also be used to finish and smooth surfaces during the manufacturing process.

When selecting a filler to repair the blade surface, one must determine product chemistry and performance time. Some solutions offer innovative cartridge and applicator systems to ensure accurate mixing, reducing waste and eliminating messy and time-consuming hand-mix operations. Ultimately, this allows for the flexibility to finish and repair blades at the manufacturing facility or during standard operation and maintenance repairs.

Conclusion

As technologies improve, research on leading edge erosion can provide the wind industry with ways to maximize wind blade performance and consequently, AEP. With easy, proactive solutions owners are able to extend the service life of their turbines and achieve optimal performance.

3M Renewable Energy Division

www.3m.com

About the Author: Santhosh Chandrabalan is the global business manager of 3M’s Renewable Energy Division and can be reached at schandrabalan@mmm.com.