Patent ID: 6148751
Filing Date: 2000-11-21
Classification: B63B,F15D,Y02T

Abstract:
A system for reducing hydrodynamic drag and vortex-induced-vibration (""VIV"") of a bluff hull beset by a current, comprising:a. a bluff hull, designed to be at least partially submerged in an exterior fluid, the bluff hull having a hull interior and a hull surface, the hull surface having an up-current side and a down-current side such that the up-current side may be beset by a current present in the exterior fluid, wherein the bluff hull has an axis and is substantially cylindrical with the axis running along the height of the cylinder, and wherein the current has a current velocity, andb. at least one opening of the hull surface for passing an interior fluid out of the hull interior into the exterior fluid so as to reduce flow separation of the current on the down-current side of the hull surface, wherein the opening passes the interior fluid out of the hull interior at an angle substantially tangential to the hull surface at the location of the opening and substantially parallel to the direction of the current, wherein the opening blows the interior fluid out of the hull interior at a blowing velocity greater than the current velocity, wherein the opening is a slot-nozzle substantially aligned with the axis of the bluff hull;c. the at least one opening comprising a plurality of slot-nozzles substantially aligned with the axis and disposed around the surface of the bluff cylindrical hull; andd. a control system for controllably opening and closing the plurality of slot-nozzles, wherein the control system includes a hydraulic system for opening and closing the plurality of slot-nozzles and includes a valves and wherein the hydraulic system includes a valve, coupled to a bladder, for controllably passing high-pressure fluid into the bladder to expand the bladder, the bladder being coupled to a slot-nozzle such that when the bladder is expanded the slot-nozzle is open.