Dr. Melissa Riley, BMedSci PhD CEng FIMMM, FWeldI
,
TWI Ltd, Cambridge, Cambridgeshire, United Kingdom
Mr. Andrzej Tabecki
,
TWI Ltd, Cambridge, United Kingdom
Mr. Frank A S Nolan
,
TWI Ltd, Cambridge, Cambridgeshire, United Kingdom
Mr. Charlie Borley
,
TWI Ltd, Cambridge, Cambridgeshire, United Kingdom
Dr. Andy Wilson
,
TWI Ltd, Cambridge, Cambridgeshire, United Kingdom
Dr. Kirsten Dyer
,
Offshore Renewable Energy Catapult, Glasgow, Scotland, United Kingdom
Dr. Cameron Gallagher
,
The University of Exeter, Exeter, Devon, United Kingdom
Prof. Alastair P Hibbins
,
The University of Exeter, Exeter, Devon, United Kingdom
Prof. J R Sambles
,
The University of Exeter, Exeter, Devon, United Kingdom
The moving blades on windfarms cause clutter and therefore a reduction in detection capability on primary surveillance radar, and, due to the Doppler shifted returns from rotating turbine blades, can be confused with fast moving aircraft. The requirement for UK Security contiguous radar coverage around the UK can lead to over 90% of wind farm development proposals being rejected. This is an important issue given the UK’s ambition to increase offshore wind electricity generation by >500% by 2030. This work demonstrated a potential solution by applying metasurfaces tuned to the appropriate RF frequency as part of the wind turbine blade manufacturing process, which can significantly reduce the blades RF scattering “footprint” thus lowering the disruption to radar rather than relying on modifications to signal generation hardware at the radar end and/or software filtering.
The two UK Dstl/DESNZ funded projects described here, embarked on the development of novel manufacturing methods for the creation of patterned conductive coatings applied to composite blade structures for radar cross section (RCS) reducing purposes. The techniques involve highly scalable, thermal spraying and laser micromachining processes with the potential to be implemented onto complex shaped composite structures, specifically in this case within the wind turbine blade manufacturing environment.
A section of wind turbine blade was spray coated with metal and laser etched to produce a predefined patterned metasurface, which demonstrated up to a 90% reduction in measured reflectivity, which could realise a RCS reduction of up to 10dB compared to an unpatterned coating across the frequency range of interest.
The project demonstrated production of metasurfaces on blade sections, metres in scale, through the use of advanced metrology, offline programming and simulation of metasurface manufacturing methods to create functional surfaces. Their mechanical performance, in representative service environments, such as salt spray corrosion and rain erosion, were also assessed.
