An experimental investigation of the frictional drag characteristics of nanostructured and fluorinated fouling-release coatings using an axisymmetric body

The hydrodynamic performance of two, recently developed, nanostructured and fluorinated polymer coatings was explored in a systematic experimental study using the Newcastle University Cavitation Tunnel. The experiments consisted of testing the two coatings on an axisymmetric body apparatus to measure their boundary layer flow and frictional drag simultaneously. The tests also included a smooth reference surface as well as a state-of-the-art commercial fouling-release coating (Intersleek® 900). The boundary layer measurements were performed using a two-dimensional Laser Doppler Velocimetry (LDV) system whilst the direct frictional force measurements were taken using a special load cell installed in the testing body. Careful surface roughness measurements of the test surfaces were also performed including the use of a non-contact high precision laser profilometer. The tests and subsequent analysis of the data highlighted the exceptionally good frictional properties of all the coatings tested as well as some of the drag benefits of the new polymer coatings in the investigated Reynolds number range.