Mapping of Meteorological Observations over the Island of Ireland to Enhance the Understanding and Prediction of Rain Erosion in Wind Turbine Blades

Abstract

Leading edge erosion is becoming increasingly important as wind turbine size and rainfall are predicted to increase. Understanding environmental conditions is key for laboratory testing, maintenance schedules and lifetime estimations to be improved, which in turn could reduce costs. This paper uses weather data in conjunction with a rain texture model and wind turbine RPM curve to predict and characterise rain erosion conditions across Ireland during rainfall events in terms of droplet size, temperature, humidity and chemical composition, as well as the relative erosivity, in terms of number of annual impacts and kinetic energy, as well as seasonal variations in these properties. Using a linear regression, the total annual kinetic energy, mean temperature and the mean humidity during impact are mapped geospatially. The results indicate that the west coast of Ireland and elevated regions are more erosive with higher kinetic energy. During rain events, northern regions tend to have lower temperatures and lower humidities and mountainous regions have lower temperatures and higher humidities. Irish rain has high levels of sea salt, and in recent years, only a slightly acidic pH. Most erosion likely occurs during winters with frequent rain infused with salt due to increased winds. After this analysis, it is concluded that Ireland’s largest wind park (Galway) is placed in a moderate-highly erosive environment and that RET protocols should be revisited.

A Comprehensive Analysis of Wind Turbine Blade Damage

“…In warm and arid climates, sand and dust may be a common type of airborne particulate and therefore may pose leading edge erosion problems, whereas in wetter, greener habitats, the problem may be non-existent. Likewise, at near-shore locations, the issue of sand erosion may be a considerable threat [56][57][58][59]. Leading edge erosion can be a result of rain, with the raindrops' kinetic energy, diameter, temperature and sea salt content being critical parameters [56].…”

“…Likewise, at near-shore locations, the issue of sand erosion may be a considerable threat [56][57][58][59]. Leading edge erosion can be a result of rain, with the raindrops' kinetic energy, diameter, temperature and sea salt content being critical parameters [56]. It has been also observed that careful handling of the blade during manufacturing, transport and installation is essential to avoid small tears or scratches that may act as initiation sites for further wear and erosion [60].…”

The Springer Model for Lifetime Prediction of Wind Turbine Blade Leading Edge Protection Systems: A Review and Sensitivity Study

“…The meteorological data are used to predict erosion behavior based on the Springer model. It has been shown that offshore locations have more severe rain conditions than inland locations in several areas, such as Denmark [ 20 , 21 ], the British Isles [ 22 , 23 , 24 ] and Netherlands [ 25 ]. In the USA, inland conditions vary heavily, as measured by a radar [ 26 ], yet they have a significant effect on leading edge lifetime.…”