# US 2014/0150704 A1 · Hydrodynamic duct of flow management at the bow of a vessel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150704 A1 - Document ID: US20140150704A1 - Status: Published application - Kind: A1 - Application number: 14/234,374 - Filed: 2012-07-16 - Published: 2014-06-05 - Earliest claimed: 2011-07-18 - Assignees: Milan Shipping and Investment Limited - Inventors: E. Emmanuel Petromanolakis; E. Kalomoira Petromanolakis; E. Evagelos Petromanolakis - Web page: https://patentgrep.com/patent/US20140150704A1 ## CPC - B63B 1/40: by diminishing wave resistance - B63B 1/06: Shape of fore part - Y02T 70/10: Measures concerning design or construction of watercraft hulls - B63B: SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING (arrangements of vessel ventilation, heating, cooling, or air-conditioning B63J2/00; floating substructures as supports of dredgers or soil-shifting machines E02F9/06) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Hydrodynamic duct mounted at the bow of a vessel, comprising a horizontal wall portion (1) and two lateral wall portions (2,3), whereby the flow through the duct acquires substantially different characteristics from the flow outside it and thereby wave making and frictional resistances are reduced and the fuel conventionally required for the propulsion of the vessel is reduced accordingly. The duct is arranged with the Center of Low Pressure (1c) corresponding to a zero angle of attack onto the horizontal wall portion (1) being located in the region of generation of the first bow wave and with the Centers of Low Pressure (2c,3c) of the lateral wall portions (2,3) in the region of connection thereof with the horizontal wall portion (1) being located in a selected position between the Center of Low Pressure (1c) and up to or slightly forwardly the leading edge (1a) of the horizontal wall portion (1). ## Claims ### Claim 1 Hydrodynamic duct mounted at the bow of a vessel in a position such that it may under any circumstances be immersed in water underneath the sea surface, said duct producing an effect of reduction of wave making and frictional resistances encountered during propulsion of the vessel, comprising a horizontal wall portion (1) having a section (al) of a specific geometrical shape with a length (¾) in the direction of flow and a thickness (at), said horizontal wall portion (1) extending on either side of the bow line with an internal surface (10) within the duct and an external surface (11) outside of the duct and a pair of lateral wall portions (2, 3) of section (b) of a specific geometrical shape with a length (bl) in the direction of flow and a thickness (bt), said lateral wall portions (2, 3) being connected to said horizontal wall portion (1) and extending upwardly on either side of the bow thereby forming together with said horizontal wall portion (1) and with the surfaces of the bow sides to which they are connected by means of supporting pillars (4) a region within the duct wherein the flow is substantially differentiated from the flow of water outside of the duct, such differentiation resulting in the improvement of cruising characteristics of the vessel, said lateral wall portions (2, 3) having internal surfaces (20, 30) within the duct and external surfaces (21, 31) outside of the duct, wherein the hydrodynamic duct is characterized in that the section (a) of said horizontal wall portion (1) and the section (b) of said lateral wall portions (2, 3) are being arranged with their leading edges (1a) and (2a, 3a) respectively at the frontal ends thereof wherein flow enters the duct and their trailing edges (1b) and (2b, 3b) respectively at the rear ends thereof wherein flow exits the duct, wherein the position of the Center of Low Pressure (1c) located along the internal surface (10) of section (a) of the horizontal wall portion (1) is appropriately selected in correspondence with the angle of attack onto said horizontal wall portion (1) to lie in the region of generation of the first bow wave, along or marginally forwardly the bow line and wherein the position of the Centers of Low Pressure (2c, 3c) located along the internal surfaces (20, 30) of section (b) of the lateral wall portions (2, 3) in the region of connection of the lateral wall portions (2, 3) with the horizontal wall portion (1) is appropriately selected in correspondence with the angle of attack onto said lateral wall portions (2,3) to lie at a selected position in between the Center of Low Pressure (1c) and the leading edge (1a) of the horizontal wall portion (1) or projecting forwardly beyond the leading edge (1a), wherein the lateral wall portions (2, 3) are made at a suitable length so as to obtain coincidence of the trailing edges (2b, 3b) thereof with the trailing edge (1b) of the horizontal wall portion (1). ### Claim 2 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the specific geometrical shape of section (a) of the horizontal wall portion (1) and/or the specific geometrical shape of section (b) of the lateral wall portions (2, 3) is an airfoil section being arranged with the leading edge (1a) and (2a, 3a) thereof at the frontal end of the flow entering the duct and the trailing edge (1b) and (2b, 3b) thereof at the rear end of the flow exiting the duct. ### Claim 3 (depends on 2) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 2, characterized in that the airfoil section (a) of the horizontal wall portion (1) and/or the airfoil section (b) of the lateral wall portions (2, 3) comprises a convex duct-internal surface (10) and (20, 30) respectively and an external surface (11) of the horizontal wall portion (1) and (21, 31) of the lateral wall portions (2, 3), which may be planar or hollow inwardly or it may be a combination of partially planar and partially hollow inwardly surface. ### Claim 4 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the specific geometrical shape of section (a) of the horizontal wall portion (1) and/or the specific geometrical shape of section (b) of the lateral wall portions (2, 3) is a curved plate (1′) and curved plates (2′, 3′) respectively, said curved plate (1′) and curved plates (2′, 3′) being arranged so that the duct-internal surface (10) of the horizontal wall portion (1) or the duct-internal surfaces (20, 30) of the lateral wall portions (2, 3) correspond to the convex side of the curved plate (1′) and curved plates (2′, 3′) respectively and the duct-external surface (11) of the horizontal wall portion (1) or the duct-external surfaces (21, 31) of the lateral wall portions (2, 3) correspond to the hollow side of curved plate (1′) and curved plates (2′, 3′) respectively, wherein the Center of Low Pressure (1c) appropriately selected in correspondence with the angle of attack onto the horizontal wall portion (1) located along the duct-internal surface (10) of section (a) of the horizontal wall portion (1) and/or the Centers of Low Pressure (2c, 3c) appropriately selected in correspondence with the angle of attack onto the lateral wall portions (2, 3) located along the duct-internal surfaces (20, 30) of section (b) of the lateral wall portions (2, 3) are being arranged in the vicinity of the region of maximal convexity of the curved plate (1′) and/or of the curved plates (2′, 3′). ### Claim 5 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the specific geometrical shape of section (a) of the horizontal wall portion (1) and/or the specific geometrical shape of section (b) of the lateral wall portions (2, 3) is an acutely angled plate (1″) and (2″, 3″) respectively with two legs (10a, 10b) and (20a, 20b), (30a, 30b) extending on either side of a top (10″) of the horizontal wall portion (1) and on either side of tops (20″), (30″) of the lateral wall portions (2, 3) respectively, said leg (10a) and corresponding legs (20a, 30a) being disposed at the end wherein flow enters the duct and said leg (10b) and corresponding legs (20b, 30b) being disposed at the end wherein flow exits the duct, said legs (10a, 10b), (20a, 20b), (30a, 30b) forming at the corresponding tops (10″, 20″, 30″) an angle larger than 180° within the duct and an angle less than 180° outside the duct, wherein the Center of Low Pressure (1c) appropriately selected in correspondence with the angle of attack onto the internal surface (10) of section (a) of the horizontal wall portion (1) and/or the Centers of Low Pressure (2c, 3c) appropriately selected in correspondence with the angle of attack onto the internal surfaces (20, 30) of section (b) of the lateral wall portions (2, 3) is being arranged in the vicinity of the top (10″) and of the tops (20″, 30″) of said acutely angled plates (1″) and (2″, 3″) respectively. ### Claim 6 (depends on 5) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 5, characterized in that both said leg (10a) of said acutely angled plate (1″) disposed at the side wherein flow enters the duct and said leg (10b) of said acutely angled plate (1″) disposed at the side wherein flow exits the duct are planar plates or plates of small convexity. ### Claim 7 (depends on 5) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 5, characterized in that said leg (10a) of said acutely angled plate (1″) disposed at the side wherein flow enters the duct is a planar plate or a plate of small convexity, whilst said leg (10b) of said acutely angled plate (1″) disposed at the side wherein flow exits the duct is a plate with an airfoil section or said leg (10a) of said acutely angled plate (1″) disposed at the side wherein flow enters the duct is a plate with an airfoil section, whilst said leg (10b) of said acutely angled plate (1″) disposed at the side wherein flow exits the duct is a planar plate or a plate of small convexity. ### Claim 8 (depends on 5) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 5, characterized in that the tops (10″) and (20″, 30″) of said acutely angled plate (1″) and (2″, 3″) respectively take the form of a linear portion of short length and/or of a rounded angle with a specified curved configuration. ### Claim 9 (depends on 4) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 4, characterized in that a plate (40) is employed to close the duct-external side of the curved plate (1′) or of the acutely angled plate (1″) of said section (a) of the horizontal wall portion (1) and/or the duct-external side of the curved plates (2′, 3′) or of the acutely angled plates (2″, 3″) of said section (b) of the lateral wall portions (2, 3), said plate (40) extending from the leading edge to the trailing edge of the duct-external side of the curved plate (1′) or of the acutely angled plate (1″) of said section (a) of the horizontal wall portion (1) and/or the duct-external side of the curved plates (2′, 3′) or of the acutely angled plates (2″, 3″) of said section (b) of the lateral wall portions (2, 3). ### Claim 10 (depends on 9) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 9, characterized in that said plate (40) adapted to close the duct-external side of the curved plate (1′) or of the acutely angled plate (1″) of said section (a) of the horizontal wall portion (1) and/or the duct-external side of the curved plates (2′, 3′) or of the acutely angled plates (2″, 3″) of said section (b) of the lateral wall portions (2, 3) can be selected to be either a planar plate (40a) or a curved plate (40b) or an acutely angled plate (40c) or a combination of the above. ### Claim 11 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that it is constituted of a selected combination of a horizontal wall portion (1) made from a plate with an airfoil section or a curved plate (1′) or an acutely angled plate (1″) and of lateral wall portions (2, 3) made from a plate with an airfoil section or a curved plate (2′, 3′) or an acutely angled plate (2″, 3″), wherein the selected combination satisfies the requirement of optimization of the ratio CL/CD of the lift coefficient CL to the drag coefficient CD, said ratio CL/CD having values as high as possible both with respect to the horizontal wall portion (1) and with respect to the lateral wall portions (2, 3) and the requirement of optimization of the ratio of the lift coefficient CL1 of the horizontal wall portion (1) to the lift coefficient CL2,3 of the lateral wall portions (2, 3) in each particular case, said ratio CL1/CL2,3 being under all circumstances >1.00 and depending on the geometry of the bow become increasingly higher for each particular bow selected as the nominal cruising speed of the vessel increases. ### Claim 12 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the length (al) of section (a) of the horizontal wall portion (1) in the direction of flow coincides with the length (bl) of section (b) of the lateral wall portions (2, 3) and in that the duct is being arranged so that at the region of connection of the lateral wall portions (2, 3) with the horizontal wall portion (1), the center of low pressure (1c) appropriately selected in correspondence with the angle of attack onto the horizontal wall portion (1) is located in the vicinity of the centers of low pressure (2c, 3c) appropriately selected in correspondence with the angle of attack onto the lateral wall portions (2, 3). ### Claim 13 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the length (¾) of section (a) of the horizontal wall portion (1) in the direction of flow is less than the length (bl) of section (b) of the lateral wall portions (2, 3) and the duct is being arranged so that, at the region of connection of the lateral wall portions (2, 3) with the horizontal wall portion (1), the leading edge (1a) of the horizontal wall portion (1) is located in the vicinity of the Centers of Low Pressure (2c, 3c) of the lateral wall portions (2, 3). ### Claim 14 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that, when the horizontal wall portion (1) has a length different to the length of the lateral wall portions (2, 3), the duct further comprises forwardly or rearwardly projecting guide plate extensions with a scope of equalising the length of the horizontal wall portion (1) to the length of the lateral wall portions (2, 3), whereby the section (a) of the horizontal wall portion (1) may include a guide plate extension (1d) projecting forwardly thereof and/or a guide plate extension (1e) projecting rearwardly thereof and/or the section (b) of the lateral wall portions (2, 3) may include guide plate extensions (2d, 3d) projecting forwardly thereof and/or guide plate extensions (2e, 3e) projecting rearwardly thereof, whilst always complying with the requirement of the centers of low pressure (2c, 3c) of the lateral wall portions (2, 3) being disposed forwardly of the position of the center of low pressure (1c) of the horizontal wall portion (1) and up to or slightly beyond the leading edge (1a) thereof, wherein the forwardly and/or rearwardly projecting guide plate extension (1d, 1e) of the horizontal wall portion (1) and/or the forwardly and/or rearwardly projecting guide plate extensions (2d-3d, 2e-3e) of the lateral wall portions (2, 3) are being arranged in the direction of the linear portion (50) that connects the leading edge with the trailing edge of the horizontal wall portion (1) and of the lateral wall portions (2, 3) respectively or at a certain inclination relatively to the direction of the linear portion (50). ### Claim 15 (depends on 14) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 14, characterized in that the forwardly and/or rearwardly projecting guide plate extension (1d, 1e) of section (a) of the horizontal wall portion (1) and/or the forwardly and/or rearwardly projecting guide plate extensions (2d-3d, 2e-3e) of section (b) of the lateral wall portions (2, 3) is a planar plate or a curved plate, which is being arranged in the direction of the linear portion (50) that connects the leading edge with the trailing edge of the horizontal wall portion (1) and accordingly the leading edge with the trailing edge of the lateral wall portions (2, 3) or at a certain inclination relatively to the direction of the linear portion (50), wherein the rearwardly projecting guide plate extension (1e) of section (a) of the horizontal wall portion (1) presents a downwardly directed convexity and the rearwardly projecting guide plate extensions (2e, 3e) of section (b) of the lateral wall portions (2, 3) presents an outwardly directed convexity. ### Claim 16 (depends on 15) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 15, characterized in that the forwardly and/or rearwardly projecting guide plate extension (1d, 1e) of section (a) of the horizontal wall portion (1) and/or the forwardly and/or rearwardly projecting guide plate extensions (2d-3d, 2e-3e) of section (b) of the lateral wall portions (2, 3) are adjusted so as to desirably enter within and be incorporated into said horizontal wall portion (1) and/or lateral wall portions (2, 3) and fully or partially project forwardly or rearwardly therefrom at a variable angle of inclination with respect to the horizontal wall portion (1) and/or the lateral wall portions (2, 3). ### Claim 17 (depends on 1) Hydrodynamic duct mounted at the bow of the vessel according to the above claim 1, characterized in that the lift coefficient CL1 of section (a) of the horizontal wall portion (1) is under all circumstances equal or higher than the lift coefficient CL2,3 of section (b) of the lateral wall portions (2, 3), the duct being designed so that the ratio CL1/CL2,3 for a specified hull designed for a specific nominal speed of the vessel is increasingly higher as the nominal speed of the vessel is increased, such increased nominal speed consequently resulting in the increase of wave making. ### Claim 18 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the horizontal wall portion (1) and/or the lateral wall portions (2, 3) comprise means of control and adjustment of the angle of attack thereof, thereby effecting regulation of the angle of attack in correspondence with the increase or decrease in the speed of the vessel. ### Claim 19 (depends on 18) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 18, characterized in that the angle of attack for the horizontal wall portion (1) is being adjusted through displacement of the trailing edge (1b) at a negative inclination upwardly or at a positive inclination downwardly, whilst maintaining the leading edge (1a) at a fixed position, said displacement of the trailing edge (1b) of the horizontal wall portion (1) lying within a range from −10° to +20° with the position of 0° corresponding to the position where the linear portion (50) that connects the leading edge (1a) with the trailing edge (1b) is being oriented in a direction parallel to the direction of the keel of the vessel and in that the angle of attack of the lateral wall portions (2, 3) is being adjusted through displacement of the leading edge (2a, 3a) at a negative inclination outwardly in a direction away from the bow sides or at a positive inclination inwardly in a direction of rapprochement of the bow sides, whilst maintaining the trailing edge (2b, 3b) at a fixed position, said displacement of the leading edge (2a, 3a) of the lateral wall portions (2, 3) lying within a range from −40° to +40° for the lateral wall portions (2, 3) with the position of 0° corresponding to the position where the linear portion (50) that connects the leading edge (2a, 3a) with the trailing edge (2b, 3b) is being oriented in a direction parallel to the bow line of the vessel. ### Claim 20 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the lateral wall portions (2, 3) follow the geometry of the bow in the keel-to-deck direction, maintaining a constant distance from the sides of the bow and in that the wall portions (2, 3) are being oriented in a position parallel or at a certain inclination with respect to the waterline of the fully loaded condition of the vessel, whilst the imaginary line passing through the successive positions of the leading edges (2a, 3a) of the lateral wall portions (2, 3) is oriented in a direction parallel to the bow line. ### Claim 21 (depends on 20) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 20, characterized in that the distance of the lateral wall portions (2, 3) from the sides of the bow of the vessel, wherein said distance is defined as the distance of the trailing edges of section (b) from the directly opposite bow sides, is fixedly constant throughout the height of the lateral wall portions (2, 3) due to the latter having a twist appropriately corresponding to the twist of the sides of the bow, said distance of the lateral wall portions (2, 3) from the sides of the bow of the vessel being a function of the geometry of the bow, of the characteristics and the length of section (b) and of the nominal cruising speed of the vessel and varies within a range from 0.30 to 10.00 m. ### Claim 22 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the duct is being arranged so that the Center of Low Pressure (1c) of section (a) of the horizontal wall portion (1) is located in the region of generation of the first bow wave, said first bow wave being generated at a distance from the bow that is dependent on the geometry of the bow and the nominal cruising speed of the vessel, said distance varying within a range from 10% of the length of the linear portion (50) that connects the leading edge with the trailing edge of section (a) of the horizontal wall portion (1) rearwardly the bow line up to 50% of the length of the linear portion (50) that connects the leading edge with the trailing edge of section (a) of the horizontal wall portion (1) forwardly of the bow line. ### Claim 23 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the duct-internal surface (10) of the horizontal wall portion (1) and/or the duct-internal surfaces (20, 30) of the lateral wall portions (2, 3) comprise an arrangement of protruding ribs (5) and/or the duct-external surface (11) of the horizontal wall portion (1) and/or the duct-external surfaces (21, 31) of the lateral wall portions (2, 3) comprise an arrangement of protruding ribs (6) respectively, said protruding ribs (5) and (6) serving to optimize laminar flow characteristics of the flow coming in contact with the duct-internal surface (10) or duct-external surface (11) of the horizontal wall portion (1) and of the flow coming in contact with the duct-internal surfaces (20, 30) and the duct-external surfaces (21, 31) of the lateral wall portions (2, 3) respectively. ### Claim 24 (depends on 1) Hydrodynamic duct mounted at the bow of a vessel according to the above claim 1, characterized in that the section (a) of the horizontal wall portion (1) and/or the section (b) of the lateral wall portions (2, 3) comprise thin tubes of distribution of air attached at suitable positions thereupon or suitably arranged holes (7) onto the horizontal wall portion (1) and suitably arranged holes (8) onto the lateral wall portions (2, 3) respectively, said suitably arranged holes (7) and (8) adapted to provide an air supply onto the duct-internal and/or duct-external surfaces (10, 11) of the horizontal wall portion (1) and/or the duct-internal and/or duct-external surfaces (20, 30), (21, 31) of the lateral wall portions (2, 3) thereby creating an air boundary layer onto the duct internal and/or duct external surfaces of the horizontal wall portion (1) and/or of the lateral wall portions (2, 3) accordingly.