Bureau Veritas (BV) has awarded an approval in principle (AiP) to Singapore-based GILLS for its GILLS air lubrication system
The gas-injected liquid lubrication system (GILLS) deploys NACA airfoils to create self-generating micro-bubbles for ‘turbulent modulation’ which has a ‘hull-tightening’ effect to reduce the drag of the hull, thereby improving ship efficiency and decreasing fuel consumption.
The AiP was awarded following an indepth assessment by Bureau Veritas in Singapore, covering safe installation and updated Class compliance, and covers the design of the system and installation on board vessels as reviewed against the BV’s Rules for Steel Ships NR 467.
BV’s southeast Asia zone vice-president David Barrow said “The collaboration with GILLS is timely as the industry seeks performance improvements in line with the EEXI energy efficiency targets. Pressure is building to find cost-effective solutions that work and can be financed.”
“The GILLS system has been installed on an existing vessel for a number of years and the vessel owners are confident the fuel savings are approximately 10%. The next step is a full-scale measurement and validation exercise led by Bureau Veritas Solutions (BVS) to identify confirmed performance. BVS, our consultancy arm, is also working with GILLS to assess the potential of access to Singapore ‘Green Funds’ to provide financial support to owners considering using such energy-saving systems.”
GILLS’s managing director Peter Kneipp said “The GILLS air lubrication system is a nature-based innovative technology that not only uses the microbubbles to reduce the drag, emissions, fuel and biofouling, but also utilises the ship speed to generate a negative pressure and minimises the required external compressor power.”
The hull tightening effect of the GILLS technology is a phenomenon of the various factors and forces acting on the microbubbles generated by a GILLS vortex generator installed at the bow of the ship.
These factors include a ship’s forward movement and shape of the hull, the creation of microbubbles by negative pressure and Kelvin Helmholtz instability (KHI) exiting the vortex generator, the random shape of microbubbles with turbulence, eddies and vortices from KHI and buoyancy acting on the microbubbles inducing an upward force.
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