Ship with reduced frictional resistance and its operation method
AssigneeK & I Inc.
InventorYoshiaki Takahashi
Life of this patent
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Abstract
Micro-bubble generators attached to a ship hull below the waterline decrease frictional resistance during navigation and improve fuel efficiency. Each micro-bubble generator is supplied with air and has a wing positioned outside the hull for generating negative pressure. The negative pressure created by the wing increases with an increase in ship's speed, which pushes the air-liquid interface outwardly toward the wing. As the air and the water move at different speeds due to difference in their densities, micro-bubbles are generated in the micro-bubble generator according to the Kelvin-Helmholtz Instability mechanism and discharged downstream to move closely along the outside surface of the hull.
Claims6
A ship having reduced frictional resistance, said ship comprising:
- micro-bubble generators formed in openings on a hull, each micro-bubble generator comprising a plate affixed to one of the openings and a wing attached to the plate, said wing disposed outside the hull and configured for generating negative pressure on a side facing the hull;
- a window formed in each plate at a point directly opposite the wing of the plate, said window being in fluid communication with an inside of the opening and the outside of the hull;
- an air charging pipe to supply each opening with air, said air charging pipe connected to a side of the opening;
- an air pressure source connected to each said air charging pipe, said air pressure source configured to depress air-liquid interface in said air charging pipe outwardly toward a micro-bubble generation region;
- an air supply system to supply air from the air pressure source to the micro-bubble generators, said air supply system comprising a pipe, a header and a valve, said air supply system being closed except at an end facing the opening;
- wherein a first shortest distance between a rear edge of the wing and the plate is substantially greater than a second shortest distance between a front edge of the wing and the plate;
- and
- wherein said micro-bubble generators are configured to discharge micro-bubbles that move downstream closely along an outside surface of said hull when water flows between the hull and the wing during ship motion.
Dependencies are inferred from the claim text.