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revolutionary new HUB design


MARIN combined


CFD with fast-time simulations and intensive testing on its bridge simulator to explore the


full potential of the new SSP HUB


T


uses CFD to assess SSP’s


MARIN


o save on costly helicopter crew transport, SSP Offshore took a good look at its SSP Plus design


and decided to add a large crew boat docking tunnel, running straight through the centre of the big round floater. The tunnel allows fast sailing crew boats to dock inside the HUB, thereby cutting out helicopter transfers. MARIN was put to work testing the HUB design to make sure a safe crew boat entry into the unit was possible under extreme operational conditions. A multi-stage campaign was required, ranging from CFD calculations to determine the complex interaction of the HUB’s exceptional design with the environment, to intensive simulation exercises on the bridge simulator with experts from SSP, Austal and MARIN.


To be located offshore Brazil, the SSP HUB features an omnidirectional shape and the ability to rotate, thereby redirecting its tunnel position depending on the environ- mental conditions. If beneficial, the tunnel can be closed by weather tight doors on the wave-ward side of the unit.


Joop Helder & Dimitri van Heel j.helder@marin.nl


18 report


Safe crew boat entry One of the key questions SSP needed answering was whether the HUB was able to accommodate safe crew boat entry in the harsh environ-


mental conditions of the Santos Basin. For this, the unique design of the shallow docking tunnel running through the floater could be a determining factor. Waves typically change their height, length and direction when travelling over a sudden transition from deep to shallow water, and could thereby hamper the crew boat pilot during entry into the tunnel. Current and wind travelling around the HUB, and possibly through the tunnel, could further restrict the approach and docking operation.


By using a combination of CFD tools, MARIN set out to study the complex wave, wind and current flow phenomena that occur around the entrance of the HUB tunnel. As these flows are driven by non-linear effects, conventional linear potential flow tools are simply not capable of capturing the flow details with enough accuracy.


Environmental conditions Wind and current velocities inside and outside the HUB were computed using ReFRESCO, for both a completely open tunnel and a tunnel that was closed on the side affected by the environment. For a range of environmental conditions flow fields could be visualised in detail and showed recirculation, shielding and intensification zones. The results will


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