WO2023135289A1 - A strut for a profiled element of a marine vessel - Google Patents

A strut for a profiled element of a marine vessel Download PDF

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Publication number
WO2023135289A1
WO2023135289A1 PCT/EP2023/050843 EP2023050843W WO2023135289A1 WO 2023135289 A1 WO2023135289 A1 WO 2023135289A1 EP 2023050843 W EP2023050843 W EP 2023050843W WO 2023135289 A1 WO2023135289 A1 WO 2023135289A1
Authority
WO
WIPO (PCT)
Prior art keywords
strut
vessel
profiled element
strut part
skirt
Prior art date
Application number
PCT/EP2023/050843
Other languages
French (fr)
Inventor
Ivan Anagrius WEST
Olivier Philippot
Gustav HASSELSKOG
Claes BONDE
Original Assignee
Candela Technology Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Candela Technology Ab filed Critical Candela Technology Ab
Publication of WO2023135289A1 publication Critical patent/WO2023135289A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
    • B63B1/28—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils
    • B63B1/285—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils changing the angle of attack or the lift of the foil
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
    • B63B1/248—Shape, hydrodynamic features, construction of the foil
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
    • B63B1/28—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils

Definitions

  • the invention relates to a strut for a marine vessel, for example a hydrofoil vessel, for connecting a structure of the vessel to an elongated a profiled element, so that the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure.
  • the invention also relates to a profiled element assembly for a marine vessel, and a marine vessel.
  • Hydrofoil vessels typically comprises one or more profiled elements in the forms of hydrofoils.
  • a vessel can assume a hydrofoil mode of progress.
  • a hull of the vessel is lifted out of the water. Thereby, the propulsion power requirement may be reduced. Further examples can be seen in JP-H07165155-A and US-2584347-A.
  • a hydrofoil may typically be of two different types: A surface piercing hydrofoil or a submerged hydrofoil.
  • a submerged, or immersed hydrofoil is a hydrofoil that is designed to be fully submerged during a hydrofoil mode of the vessel.
  • a submerged hydrofoil may be held by one, two, or more struts.
  • a submerged hydrofoil may, for roll stability, be arranged to be controlled so as to present different lift coefficients, and/or different angles of attack, along the length of the foil, e.g. as described in SE540588C2.
  • FR3089200 discloses a support assembly for a profile element, comprising a support element, a pivot shaft, and control means for the control of an incidence of the profiled element by pivoting of the profiled element relative to the support element.
  • the document also discloses a fairing that is integral with the profiled element.
  • An object of the invention is to decrease the water flow drag of a marine vessel, in particular a hydrofoil vessel.
  • a strut for a marine vessel for example a hydrofoil vessel
  • the strut comprising a first strut part and a second strut part
  • a primary of the first and second strut parts referred to as a primary strut part, is fastened to, or adapted to be fastened to, a structure of the vessel,
  • the primary strut part having an elongated shape
  • the primary strut part presenting, in a cross-section which is perpendicular to a longitudinal direction of the primary strut part, an elongated streamlined shape
  • a secondary of the first and second strut parts referred to as a secondary strut part
  • a secondary strut part is fixed to, or adapted to be fixed to, an elongated profiled element, so that, when the primary strut part is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure.
  • the second strut part is connected to the first strut part via an articulated joint.
  • the first strut part comprises a skirt presenting an edge forming an end of the skirt, wherein the second strut part extends into the skirt.
  • a shape of at least 50% of a contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part along the edge of the skirt is substantially constant within an angular interval of rotation of the second strut part in relation to the first strut part around the articulated joint.
  • the profiled element may be adapted generate, when the secondary strut part is fixed to the elongated profiled element, and when the primary strut part is fastened to the structure of the vessel, a force that is transferred to the structure via the strut.
  • the profiled element may be a hydrofoil.
  • the profiled element may present, in a transverse cross-section, a streamlined shape.
  • the profiled element may present an airfoil shaped transverse crosssection.
  • the airfoil may be symmetric or non-symmetric.
  • the profiled element may be arranged to create a lift force for the structure of the vessel.
  • the strut may be arranged to hold the profiled element, by itself, or together with one or more additional struts.
  • additional struts may present said inventive features.
  • the profiled element may generate a force that is transferred to the structure via the one or more struts.
  • Each of the one or more struts may be joined with the profiled element and extend from the profiled element in an angle of more than zero degrees and less than 180 degrees, for example 70-110 degrees, preferably substantially perpendicularly.
  • the structure of the vessel may be a hull of the vessel.
  • the hull may be the main body of the vessel.
  • the hull may comprise an outside covering or skin.
  • the skin may have a single layer, or be of a sandwich construction.
  • the hull may further comprise inside stiffeners, a framework, and/or one or more bulkheads, to which the skin is secured.
  • Parts of the hull may be made in any suitable material, such as fiber-reinforced plastics, wood, aluminum, or steel.
  • the hull may further include a fixture for fixing the primary strut part to the skin. Such a fixture may be located in the interior of the skin.
  • the primary strut part may present a chord line which is substantially parallel with a direction of straight forward travelling of the vessel.
  • the primary strut part cross-section may be symmetrical or non-symmetrical.
  • the angle of attack of the profiled element may be adjusted by adjustment of a pitch angle of the profiled element.
  • a control device e.g. in the form of a control rod extending through the strut(s) may be used to rotate the secondary strut part in relation to the primary strut part, to thereby adjust the pitch angle of the profiled element.
  • the articulated joint may be formed by a ball joint.
  • the edge of the skirt may form a lower edge of the skirt.
  • the skirt edge may have an elongated streamlined shape, which shape may be symmetrical or non-symmetrical.
  • the second strut part may have an elongated streamlined shape at the skirt edge, which shape may be symmetrical or non-symmetrical.
  • the second strut part may extend towards the first strut part and within the skirt.
  • the contour of the second strut part along the edge of the skirt may be formed in a cross-section along the skirt edge.
  • the cross-section may be perpendicular to the primary strut part longitudinal direction.
  • the rotation of the second part in relation to the first strut part may be around a rotational axis of the articulated joint.
  • the rotational axis may be substantially parallel with the longitudinal direction of the profiled element.
  • the angular interval may be non-zero, e.g. more than 5 degrees, or more than 10 degrees.
  • the angular interval may be less than 40 degrees, or less than 30 degrees.
  • the second strut part may be shaped so as to present, within the angular interval, a substantially constant cross- sectional shape along the edge of the skirt. Thereby, the cross-sectional shape of the second part along the edge of the skirt, may be, within the angular interval, independent of the angular position of the second strut part in relation to the first strut part.
  • a contour part forming said at least 50% of the contour of the second strut part may be a delimitation of the second strut part, in a crosssection which coincides with the skirt edge, which delimitation follows the skirt edge.
  • said contour part may have substantially the same shape as the part of the skirt edge which it follows.
  • the three-dimensional shape of the second strut part, at the articulated joint is such that the shape of said contour part is substantially the same regardless of the angle of rotation of the second strut part in relation to the first strut part around the articulated joint constant within the angular interval.
  • a gap between the second strut part and the skirt may be kept minimal, regardless of the pitch angle of the profiled element.
  • the water transportation in and out of the skirt may be minimized. This allows for a water flow past the strut with a minimal turbulence, and hence a minimal drag. This will reduce drag losses of the vessel.
  • the edge of the skirt is, as seen along a rotational axis of the articulated joint, substantially straight.
  • the edge is arranged to be parallel with the water free-flow, the water transportation in and out of the skirt may be further reduced, further reducing turbulence and drag.
  • the second strut part presents, at the articulated joint, a leading edge, wherein the leading edge is part-circular within the angular interval, with a circle center in a rotational axis of the articulated joint.
  • a center of a circle of which the leading edge forms a part is preferably in the rotational axis.
  • the second strut part presents, at the articulated joint, a trailing edge, wherein the trailing edge is part-circular within the angular interval, with a circle center in a rotational axis of the articulated joint.
  • a center of a circle of which the trailing edge forms a part is preferably in the rotational axis.
  • a part of the contour of the second struct part preferably at least 50% thereof, preferably follows the skirt edge, which contour is formed in a cross-section of the strut, which cross-section coincides with the edge of the skirt.
  • this contour part following the skirt edge, forms less that all of the second strut part contour in said cross-section, the contour part preferably intersects a leading edge of the second strut part.
  • the contour part includes the front part of the second strut part along the edge of the skirt.
  • the rotational axis of the articulated joint is located at the edge of the skirt.
  • the external shape of the strut lower part is kept substantially the same as the internal shape of the skirt, for a plurality of different pitch angles of the profiled element.
  • the rotational axis of the articulated joint may intersect the edge of the skirt.
  • a shape of at least 50% of the contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part is substantially the same as a shape of an internal contour of the skirt along the edge of the skirt.
  • a minimal gap between the second strut part and the skirt may be secured.
  • the shape of at least 50% of the contour, preferably at least 70% of the contour e.g.
  • the entire contour, of the second strut part is substantially the same as a shape of the internal contour of the skirt along the edge of the skirt, in any angle within the angular interval within which the shape of at least 50% of the contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part is substantially constant.
  • the gap between the second strut part and the skirt is less than 5.0 mm, preferably less than 3.0 mm, preferably less than 2.0 mm, preferably less than 1.5 mm, preferably less than 1.0 mm, along at least 50% of the contour, preferably along at least 70% of the contour, e.g. along the entire contour, of the second strut part.
  • the gap between the second strut part and the skirt is preferably less than 5.0 mm along the at least 50% of the contour of the second strut part.
  • the second strut part and the skirt may be rigid.
  • the strut may comprise one or more elements of a flexible material, e.g. a strip of a flexible material, for closing the gap between the second strut part and the skirt.
  • the one or more elements of a flexible material may be fastened to the second strut part or the skirt.
  • the one or more elements of a flexible material may bridge the gap between the second strut part and the skirt. Thereby, an interior space between the first and second strut parts may be sealed from the surrounding water.
  • the first strut part is the primary strut part
  • the second part is the secondary part
  • the first strut part is fastened to, or adapted to be fastened to, the structure of the vessel, wherein the second strut part is fixed to, or adapted to be fixed to, the profiled element.
  • the first strut part is fixed to, or adapted to be fixed to, the profiled element
  • the second strut part is fastened to, or adapted to be fastened to, the structure of the vessel.
  • the primary strut part is the second strut part
  • the secondary strut part may be the first strut part.
  • a profiled element assembly for a marine vessel for example a hydrofoil vessel, comprising an elongated a profiled element, one or more elongated struts, each strut presenting the features of any one of claims 1-9, wherein the respective secondary strut part is fixed to the profiled element, wherein each of the one or more struts extends from the profiled element in an angle to a longitudinal direction of the profiled element of more than zero degrees and less than 180 degrees.
  • a marine vessel comprising a profiled element assembly as mentioned above, wherein the respective primary strut part is fastened to a structure of the vessel.
  • the profiled element may be a first hydrofoil of the vessel.
  • the vessel may comprise a second hydrofoil mounted to the vessel structure by means of one or more further struts.
  • a propeller arrangement may be mounted to one or more of the one or more struts by means of which the second hydrofoil mounted to the vessel structure.
  • the vessel is arranged so that, on each strut for the profiled element, at straight forward travel of the vessel, the respective edge of the skirt of the first strut part extends substantially in parallel with a free-flow of the water.
  • the water transportation in and out of the skirt may be minimized or eliminated, allowing a minimal turbulence and drag formed by the profiled element pitch adjustment mechanism.
  • the vessel may be a hydrofoil vessel, wherein the profiled element is a hydrofoil.
  • the structure of the vessel may be a hull of the vessel.
  • An aspect of the invention provides a profiled element assembly for a marine vessel, for example a hydrofoil vessel, comprising a profiled element unit comprising an elongated profiled element, a fastening arrangement adapted to connect the profiled element unit to a structure of the vessel,
  • the profiled element when the fastening arrangement is fastened to the structure of the vessel, can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure via the fastening arrangement,
  • the profiled element unit is connected to the fastening arrangement via an articulated joint
  • the profiled element assembly further comprising a pitch adjustment assembly comprising an actuation assembly, - the actuation assembly comprising an actuator arranged to adjust the pitch angle of the profiled element,
  • the actuation assembly further comprises an elastic element arrangement , and a second elastic element
  • the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator in a first direction from a neutral pitch angle, a first moment to the profiled element which is opposite to the first direction,
  • the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator in a second direction from the neutral pitch angle, which second direction is opposite to the first direction, a second moment to the profiled element which is opposite to the second direction.
  • the aspect may also provide a marine vessel comprising a profiled element assembly according to claim 14, wherein the fastening arrangement is fastened to a structure of the vessel.
  • the vessel may be a hydrofoil vessel, wherein the profiled element is a hydrofoil, wherein the structure of the vessel is a hull of the vessel.
  • the fastening arrangement is fastened to, or adapted to be fastened to, the structure of the vessel.
  • the comprising the actuator of the actuation assembly is arranged to adjust the pitch angle of the profiled element around the articulated joint.
  • the neutral pitch angle may be an angle that the profiled element assumes when no external forces are applied to the profiled element, i.e. when no force is applied by the actuator to the profiled element.
  • the elastic element arrangement comprises a first elastic element, and a second elastic element.
  • the first elastic element may be adapted to exert, when the pitch angle of the profiled element is changed in the first direction from the neutral pitch angle, the first moment to the profiled element
  • the second elastic element may be adapted to exert, when the pitch angle of the profiled element is changed in the second direction from the neutral pitch angle, the second moment to the profiled element.
  • the elastic element arrangement comprises a single elastic element.
  • the elastic element may be spring, such as a helical spring, which can be compressed and stretched in opposite directions from a neutral position.
  • fig. l is a perspective view of a hydrofoil vessel according to an embodiment of the invention
  • fig. 2 is a sideview of the vessel of fig. 1
  • fig. 3 and fig. 4 are partly sectioned
  • fig. 5 is a partially sectioned side view of a portion of a strut for a profiled element of the vessel in fig.
  • fig. 6 is a cross-sectional view of the portion in fig. 5, with the section oriented as indicated by the arrows VI- VI in fig. 5, fig.
  • fig. 7 is a cross-sectional view similar to the one in fig. 6, of a strut according to an alternative embodiment of the invention
  • fig. 8 is a cross-sectional view of a part of the strut in fig. 7, with the cross-section oriented as indicated by the arrows VIII- VIII in fig. 7,
  • fig. 9 is a side view of a profiled element assembly for a marine vessel, according to an aspect of the invention.
  • Fig. 1 depicts a hydrofoil vessel 1 according to an embodiment of the invention.
  • the vessel could of any type, e.g. a pleasure boat, or a passenger boat.
  • the vessel may have fully submergible hydrofoils.
  • the hydrofoil vessel 1 is shown with reference to a cartesian coordinate system having three orthogonal axes X, Y and Z-axis with corresponding reference numerals.
  • the X-axis is parallel to a direction of straight forward travel of the watercraft. Titling or rotation of the hydrofoil watercraft 1 about the X-axis is commonly referred to as roll. Hence, the X-axis may be referred to as the roll axis X.
  • the Y-axis is horizontal.
  • Titling or rotation of the hydrofoil vessel 1 about the Y-axis is commonly referred to as pitch.
  • the Y-axis may be referred to as the pitch axis Y.
  • titling or rotation of the hydrofoil vessel 1 about the Z-axis is commonly referred to as yaw.
  • the Z-axis may be referred to as the yaw axis Z.
  • the vessel 1 comprises a structure in the form of a hull 2.
  • the hull is at least partly submerged into the water when the vessel 1 is at rest.
  • the hull 2 may be made of aluminium, fiber-reinforced plastics, or the like.
  • the vessel 1 comprises a profiled element in the form of a first hydrofoil 301.
  • the profiled element 301 is fastened to the hull 2 by means of two struts 302, herein also referred to as first struts.
  • the profiled element 301 is a submerged type hydrofoil.
  • the profiled element 301 has an adjustable pitch orientation so as to change the angle of attack of the profiled element, as exemplified below.
  • the profiled element 301 is connected to the hull by means of the struts 302.
  • Each of the struts 302 extends from the profiled element at an angle to a longitudinal direction of the profiled element of about 90 degrees.
  • the first hydrofoil 301 may be, as exemplified in fig. 2, in the direction of travel of the boat 1, located substantially at a center of gravity CG of the boat.
  • the profiled element 301 may be made of fiber-reinforced plastics, or the like.
  • the vessel also comprises a second hydrofoil 601.
  • the second hydrofoil 601 is a submerged type hydrofoil.
  • the second hydrofoil is fastened to the hull 2 by means of a second strut 503 arranged to extend downwards from the hull 2.
  • the second hydrofoil is fixed to the second strut 503.
  • the second strut 503 is fastened to the hull at a stem of the hull.
  • the second hydrofoil 601 is located behind the first hydrofoil 301 as seen in a direction of straight forward travel of the boat.
  • the second hydrofoil is arranged to support, in a hydrofoil driving mode, an aft part of the hull.
  • the vessel also comprises a motor pod 502.
  • the motor pod 502 is fixed to the second strut 503.
  • Two electric motors 5051, 5052 are housed coaxially in a casing of the motor pod.
  • Two propellers 5011, 5012 are each arranged to be driven by a respective of the motors.
  • the propellers 5011, 5012 are counter-rotating.
  • the motors are arranged to be powered by a power source such as a battery pack 504. Thereby, cables for electric power to the motors may extend through the second strut.
  • a single propeller driven by a single motor may be provided.
  • the propeller(s) may be arranged to be driven, by means of a shaft extending through the second strut, by a motor or an internal combustion engine located at an upper end of the second strut 503.
  • the second strut 503 with the motor pod 502 is tumable in relation to the hull 2 for steering the vessel. Thereby, the second strut 503 may assume the function of a rudder.
  • a pitch angle of the profiled element is herein defined as an angle between a chord of the profiled element 301 to the direction of straight forward travel of the vessel.
  • the pitch angle of the profiled element can be adjusted by an adjustment mechanism in each of the first struts 302. Thereby, by identical adjustments by the adjustment mechanisms the pitch angle may be the same along the profiled element. Such adjustments may be used for pitch control of the vessel.
  • the profiled element may be twisted. Thereby, the pitch angle at one end of the profiled element may be different from the pitch angle at the other end of the profiled element. Such adjustments may be used for roll control of the vessel.
  • the angle of attack of the profiled element may be adjusted.
  • the angle of attack is the angle between the chord of the profile element and the relative water free-stream.
  • each first strut 302 comprises a first strut part 3021 and a second strut part 3022.
  • a primary of the first and second strut parts is fastened to the hull 2 of the vessel.
  • a secondary of the first and second strut parts is fixed to the profiled element 301.
  • the first strut part 3021 is the primary strut part
  • the second strut part 3022 is the secondary strut part.
  • the first strut part 3021 with the features described below
  • the second strut part 3022 is the primary strut part.
  • the first strut part 3021 has an elongated shape.
  • the first strut part 3021 presents, in a crosssection which is perpendicular to a longitudinal direction of the first strut part, an airfoil shape.
  • the air foil shape is symmetrical.
  • the air foil shape of the first strut part is non-symmetrical.
  • the second strut part 3022 is connected to the first strut part 3021 via an articulated joint 13.
  • the articulated joint is in this example, a ball-joint.
  • the articulated joint has a truncated ball 320 to limit the width of the strut 302 at the joint 13.
  • the truncated ball 320 is fixed to the first strut part 3021.
  • the truncated ball 320 is fixed to the first strut part 3021 by means of a stem 321.
  • the articulated joint further comprises a socket 322 which is fixed to the second strut part 3022.
  • the socket 322 partly encloses the truncated ball 320.
  • a low friction between the socket 322 and the truncated ball 320 allows the socket 322, and hence the second strut part 3022 to rotate around the truncated ball 320.
  • the first strut part 3021 comprises a skirt 121 presenting an edge 122 forming an end of the skirt.
  • the first strut part airfoil cross section is widened in a plane perpendicular to the first strut longitudinal axis.
  • the first strut part is widened in a direction which is perpendicular to a chord line of the first strut part airfoil cross-sectional shape.
  • the first strut part is extended in a direction which is parallel to the chord line of the first strut part airfoil cross-sectional shape. This extension is provided by a forward offset of the first strut part leading edge.
  • a distal part 312 of the second strut part 3022 extends into the skirt 121.
  • the distal part 312 of the second strut part 3022 is not shown in fig. 3.
  • a proximal part 310, shown in fig. 3, of the second strut part 3022 is fixed to the profiled element 301.
  • the distal part 312 of the second strut part 3022 is fixed to the proximal part 310 of the second strut part 3022.
  • the edge 122 of the skirt 121 is, as seen along a rotational axis R1 (fig. 3) of the articulated joint, substantially straight.
  • the edge 122 is arranged in relation to the remainder of the vessel so that, at straight forward travel of the vessel, the edge 122 extends substantially in parallel with a free-flow of the water.
  • the rotational axis R1 of the articulated joint 13 is located at the edge 122 of the skirt 121.
  • the rotational axis R1 of the articulated joint is located where the distal part 312 of the second strut part 3022 joins the proximal part of the second strut part 3022.
  • each strut 302 comprises a respective adjustment rod 324.
  • the adjustment rod extends in the longitudinal direction of the respective strut 302.
  • the adjustment rod extends inside the respective strut 302.
  • the respective adjustment rod 324 is, in this example, connected to the second strut part 3022 at a distance from the articulated joint 13.
  • the adjustment rod 324 is movable in a longitudinal direction of the respective strut 302, 303 to cause a rotation of the second strut part, and hence the profiled element, around the articulated joint.
  • the adjustment rod 324 comprises a truncated sphere 326 at its distal end, and the second strut portion 3022 forms a rod socket which partly encloses the truncated sphere 326.
  • the shape of the contour of the second strut part 3022 is substantially the same as a shape of an internal contour of the skirt 121 along the edge 122 of the skirt. Thereby a small gap is provided between the second strut part 3022 and the skirt 121.
  • the profile of the second strut part in an imaginary plane is constant when the imaginary plane is rotated around the rotational axis R1 from a position in which it is parallel with the X-Y-plane.
  • the shape of the contour of the second strut part 3022 along the edge 122 of the skirt 121 is substantially constant within an angular interval Aa (fig. 5) of rotation of the second strut part 3022 in relation to the first strut part 3021 around the articulated joint 13.
  • a leading edge LE of the second strut part 3022 is, at the articulated joint, part-circular within the angular interval Aa, with a circle center in the rotational axis R1 of the articulated joint 13.
  • a trailing edge TE of the second strut part 3022 is, at the articulated joint, part-circular within the angular interval Aa, with a circle center in the rotational axis R1 of the articulated joint 13.
  • the gap between the second strut part 3022 and the skirt 121 may be kept minimal, regardless of the pitch angle of the profiled element 301. This will reduce drag losses of the vessel.
  • the second strut part 3022 is provided with a truncated trailing edge TE.
  • the shape of around 80% of the contour 3022c of the second strut part 3022 along the edge 122 of the skirt 121 is substantially constant within the angular interval Aa (fig. 5) of rotation of the second strut part 3022 in relation to the first strut part 3021 around the articulated joint 13.
  • fig. 7 shows the strut in a cross-section which coincides with the skirt edge 122.
  • a contour part 3022cp forming approximately 80% of the contour 3022c of the second strut part, forms a delimitation of the second strut part, in said cross-section, which delimitation follows the skirt edge 122.
  • said contour part 3022cp has substantially the same shape as the part of the skirt edge which it follows.
  • the three-dimensional shape of the second strut part, at the articulated joint is such that the shape of said contour part 3022cp is substantially the same regardless of the angle of rotation of the second strut part in relation to the first strut part around the articulated joint constant within the angular interval Aa (fig. 5).
  • the strut comprises, at the edge 122 of the skirt 121, an element 14 of a flexible material for closing the gap between the second strut part 3022 and the skirt 122.
  • the element of a flexible material is fastened to the skirt 121.
  • the element of a flexible material is a strip 14 of a flexible material. The element of a flexible material bridges the gap between the second strut part and the skirt. In this embodiment with the truncated trailing edge TE, the strip may be terminated at the trailing edge TE.
  • a further aspect of the invention provides a profiled element assembly for a marine vessel, for example a hydrofoil vessel.
  • the profiled element assembly comprises a profiled element unit 301, 3022.
  • the profiled element unit comprises an elongated profiled element 301, and a secondary strut part 3022 fixed to the profiled element.
  • the profiled element forms a hydrofoil 301.
  • a primary strut part 3021 forms a fastening arrangement adapted to connect the profiled element unit to a structure of the vessel.
  • the structure may be a hull of the vessel.
  • the primary strut part 3021 extends from the profiled element unit 301, 3022 in an angle to a longitudinal direction of the profiled element 301 of more than zero degrees and less than 180 degrees, in this example about 90 degrees.
  • the primary strut part 3021 is fastened to, or adapted to be fastened to, the structure of the vessel.
  • the primary strut part has an elongated shape.
  • the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure via the fastening arrangement.
  • the profiled element unit 301, 3022 is connected to the primary strut part 3021 via an articulated joint 13. More specifically, the secondary strut part 3022 is connected to the primary strut part 3021 via the joint 13. The secondary strut part extends into a skirt 121 of the primary strut part.
  • the articulated joint is formed by a ball joint 13.
  • the secondary strut part 3022 may be omitted, and the primary strut part may be connected directly to the profiled element 301.
  • the profiled element assembly further comprises a pitch adjustment assembly comprising an actuation assembly.
  • the pitch adjustment assembly further comprises a control device 324 connecting the profiled element unit 301, 3022 with the actuation assembly.
  • the control device 324 is provided in the form of a control rod which extends along and through the primary strut part 3021.
  • control rod 324 is used to rotate the secondary strut part 3022 and the hydrofoil 301 around the joint 13.
  • the control rod is driven by the actuator 401 via a bracket 402 which rotates around a hinge 403.
  • the actuation assembly comprises an actuator 401 arranged to adjust the pitch angle of the profiled element via the control device.
  • the actuation assembly further comprises a first elastic element 404, in the form of a helical spring, and a second elastic element 405, in the form of a helical spring.
  • first elastic element 404 in the form of a helical spring
  • second elastic element 405 in the form of a helical spring.
  • the hydrofoil’s articulation point formed by the joint 13 is, in the chord direction of the hydrofoil transverse cross-section, in the center of lift of the hydrofoil 301 at a relatively low angle of attack thereof.
  • the center of lift moves towards the foil leading edge at increasing angles of attack, and vice versa.
  • the actuator 401 there may be a desire to refrain from hydraulics in the vessel. However, electric motors are relatively slow and weak.
  • the first elastic element 404 is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator 401 in a first direction from a neutral pitch angle, a first moment to the profiled element 301 which is opposite to the first direction.
  • the second elastic element is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator 401 in a second direction from the neutral pitch angle, which second direction is opposite to the first direction, a second moment to the profiled element 301 which is opposite to the second direction.
  • the first and second elastic elements 404, 405 are arranged to provide forces on the adjusting mechanism, in opposite directions.
  • the hydrofoil 301 assumes the neutral pitch angle
  • the spring forces are balanced. Deflections away from the neutral pitch angle increases the spring force in the opposite direction. Therefore, stability is achieved.

Abstract

A strut (302) for a marine vessel, - the strut comprising a first strut part (3021) fastened to a structure (2) of the vessel, and a second strut part (3022) fixed to an elongated profiled element (301), - wherein the second strut part (3022) is connected to the first strut part (3021) via an articulated joint (13), - wherein the first strut part (3021) comprises a skirt (121) presenting an edge (122) forming an end of the skirt, wherein the second strut part extends into the skirt (121), - wherein a shape of at least 50% of a contour of the second strut part (3022) along the edge (122) of the skirt is substantially constant within an angular interval (Ac) of rotation of the second strut part in relation to the first strut part around the articulated joint (13).

Description

A STRUT FOR A PROFILED ELEMENT OF A MARINE VESSEL
TECHNICAL FIELD
The invention relates to a strut for a marine vessel, for example a hydrofoil vessel, for connecting a structure of the vessel to an elongated a profiled element, so that the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure. The invention also relates to a profiled element assembly for a marine vessel, and a marine vessel.
BACKGROUND
Hydrofoil vessels, e.g. as presented on the web site candela.com, typically comprises one or more profiled elements in the forms of hydrofoils. By means of hydrofoils, a vessel can assume a hydrofoil mode of progress. During the hydrofoil mode, a hull of the vessel is lifted out of the water. Thereby, the propulsion power requirement may be reduced. Further examples can be seen in JP-H07165155-A and US-2584347-A.
A hydrofoil may typically be of two different types: A surface piercing hydrofoil or a submerged hydrofoil. A submerged, or immersed hydrofoil, is a hydrofoil that is designed to be fully submerged during a hydrofoil mode of the vessel. A submerged hydrofoil may be held by one, two, or more struts.
Thereby, typically, for hull elevation control, the pitch angle of a submerged hydrofoil can be adjusted, in order to control the hydrofoil angle of attack. Also, a submerged hydrofoil may, for roll stability, be arranged to be controlled so as to present different lift coefficients, and/or different angles of attack, along the length of the foil, e.g. as described in SE540588C2.
There is a desire to present a mechanism for the hydrofoil pitch angle control which does not create any water flow drag as the vessel travels.
FR3089200 discloses a support assembly for a profile element, comprising a support element, a pivot shaft, and control means for the control of an incidence of the profiled element by pivoting of the profiled element relative to the support element. The document also discloses a fairing that is integral with the profiled element. A problem with the arrangement disclosed in this document is that the water flow drag caused by the incidence adjustment assembly itself will vary with the incidence. Thereby, for certain incidences, the water flow drag caused by the incidence adjustment assembly itself will be relatively high.
SUMMARY
An object of the invention is to decrease the water flow drag of a marine vessel, in particular a hydrofoil vessel.
The object is achieved with a strut for a marine vessel, for example a hydrofoil vessel,
- the strut comprising a first strut part and a second strut part,
- wherein a primary of the first and second strut parts, referred to as a primary strut part, is fastened to, or adapted to be fastened to, a structure of the vessel,
- the primary strut part having an elongated shape, the primary strut part presenting, in a cross-section which is perpendicular to a longitudinal direction of the primary strut part, an elongated streamlined shape,
- wherein a secondary of the first and second strut parts, referred to as a secondary strut part, is fixed to, or adapted to be fixed to, an elongated profiled element, so that, when the primary strut part is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure.
- For an adjustment of an angle of attack of the profiled element, the second strut part is connected to the first strut part via an articulated joint.
According to the invention, the first strut part comprises a skirt presenting an edge forming an end of the skirt, wherein the second strut part extends into the skirt. A shape of at least 50% of a contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part along the edge of the skirt is substantially constant within an angular interval of rotation of the second strut part in relation to the first strut part around the articulated joint.
As understood, the profiled element may be adapted generate, when the secondary strut part is fixed to the elongated profiled element, and when the primary strut part is fastened to the structure of the vessel, a force that is transferred to the structure via the strut. The profiled element may be a hydrofoil. The profiled element may present, in a transverse cross-section, a streamlined shape. The profiled element may present an airfoil shaped transverse crosssection. The airfoil may be symmetric or non-symmetric. The profiled element may be arranged to create a lift force for the structure of the vessel.
The strut may be arranged to hold the profiled element, by itself, or together with one or more additional struts. Such additional struts may present said inventive features. Thus, when the strut is fastened to the structure of the vessel, the profiled element may generate a force that is transferred to the structure via the one or more struts.
Each of the one or more struts may be joined with the profiled element and extend from the profiled element in an angle of more than zero degrees and less than 180 degrees, for example 70-110 degrees, preferably substantially perpendicularly.
The structure of the vessel may be a hull of the vessel. The hull may be the main body of the vessel. The hull may comprise an outside covering or skin. The skin may have a single layer, or be of a sandwich construction. The hull may further comprise inside stiffeners, a framework, and/or one or more bulkheads, to which the skin is secured. Parts of the hull may be made in any suitable material, such as fiber-reinforced plastics, wood, aluminum, or steel. The hull may further include a fixture for fixing the primary strut part to the skin. Such a fixture may be located in the interior of the skin.
By the elongated streamlined cross-sectional shape, the primary strut part may present a chord line which is substantially parallel with a direction of straight forward travelling of the vessel. The primary strut part cross-section may be symmetrical or non-symmetrical.
The angle of attack of the profiled element may be adjusted by adjustment of a pitch angle of the profiled element. A control device, e.g. in the form of a control rod extending through the strut(s) may be used to rotate the secondary strut part in relation to the primary strut part, to thereby adjust the pitch angle of the profiled element. The articulated joint may be formed by a ball joint.
The edge of the skirt may form a lower edge of the skirt. The skirt edge may have an elongated streamlined shape, which shape may be symmetrical or non-symmetrical. The second strut part may have an elongated streamlined shape at the skirt edge, which shape may be symmetrical or non-symmetrical.
The second strut part may extend towards the first strut part and within the skirt. The contour of the second strut part along the edge of the skirt may be formed in a cross-section along the skirt edge. The cross-section may be perpendicular to the primary strut part longitudinal direction. The rotation of the second part in relation to the first strut part may be around a rotational axis of the articulated joint. The rotational axis may be substantially parallel with the longitudinal direction of the profiled element.
The angular interval may be non-zero, e.g. more than 5 degrees, or more than 10 degrees. The angular interval may be less than 40 degrees, or less than 30 degrees. The second strut part may be shaped so as to present, within the angular interval, a substantially constant cross- sectional shape along the edge of the skirt. Thereby, the cross-sectional shape of the second part along the edge of the skirt, may be, within the angular interval, independent of the angular position of the second strut part in relation to the first strut part.
Thus, in embodiments of the invention, a contour part forming said at least 50% of the contour of the second strut part, may be a delimitation of the second strut part, in a crosssection which coincides with the skirt edge, which delimitation follows the skirt edge. Thereby, said contour part may have substantially the same shape as the part of the skirt edge which it follows. Further, preferably the three-dimensional shape of the second strut part, at the articulated joint, is such that the shape of said contour part is substantially the same regardless of the angle of rotation of the second strut part in relation to the first strut part around the articulated joint constant within the angular interval.
Thereby, within the angular interval, a gap between the second strut part and the skirt may be kept minimal, regardless of the pitch angle of the profiled element. Thereby, the water transportation in and out of the skirt may be minimized. This allows for a water flow past the strut with a minimal turbulence, and hence a minimal drag. This will reduce drag losses of the vessel.
Preferably, the edge of the skirt is, as seen along a rotational axis of the articulated joint, substantially straight. Thereby, if the edge is arranged to be parallel with the water free-flow, the water transportation in and out of the skirt may be further reduced, further reducing turbulence and drag.
Advantageously, the second strut part presents, at the articulated joint, a leading edge, wherein the leading edge is part-circular within the angular interval, with a circle center in a rotational axis of the articulated joint. Thus, a center of a circle of which the leading edge forms a part, is preferably in the rotational axis. Advantageously, the second strut part presents, at the articulated joint, a trailing edge, wherein the trailing edge is part-circular within the angular interval, with a circle center in a rotational axis of the articulated joint. Thus, a center of a circle of which the trailing edge forms a part, is preferably in the rotational axis.
As suggested, a part of the contour of the second struct part, preferably at least 50% thereof, preferably follows the skirt edge, which contour is formed in a cross-section of the strut, which cross-section coincides with the edge of the skirt. Where this contour part, following the skirt edge, forms less that all of the second strut part contour in said cross-section, the contour part preferably intersects a leading edge of the second strut part. Thereby, the contour part includes the front part of the second strut part along the edge of the skirt.
Preferably, the rotational axis of the articulated joint is located at the edge of the skirt. Thereby, it may be secured that the external shape of the strut lower part is kept substantially the same as the internal shape of the skirt, for a plurality of different pitch angles of the profiled element. The rotational axis of the articulated joint may intersect the edge of the skirt.
Preferably, at the edge of the skirt, a shape of at least 50% of the contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part is substantially the same as a shape of an internal contour of the skirt along the edge of the skirt. Thereby, a minimal gap between the second strut part and the skirt may be secured. Preferably, at the edge of the skirt, the shape of at least 50% of the contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part is substantially the same as a shape of the internal contour of the skirt along the edge of the skirt, in any angle within the angular interval within which the shape of at least 50% of the contour, preferably at least 70% of the contour, e.g. the entire contour, of the second strut part is substantially constant. Preferably, at the edge of the skirt, the gap between the second strut part and the skirt is less than 5.0 mm, preferably less than 3.0 mm, preferably less than 2.0 mm, preferably less than 1.5 mm, preferably less than 1.0 mm, along at least 50% of the contour, preferably along at least 70% of the contour, e.g. along the entire contour, of the second strut part. Thus, the gap between the second strut part and the skirt is preferably less than 5.0 mm along the at least 50% of the contour of the second strut part.
The second strut part and the skirt may be rigid. In some embodiments, the strut may comprise one or more elements of a flexible material, e.g. a strip of a flexible material, for closing the gap between the second strut part and the skirt. The one or more elements of a flexible material may be fastened to the second strut part or the skirt. The one or more elements of a flexible material may bridge the gap between the second strut part and the skirt. Thereby, an interior space between the first and second strut parts may be sealed from the surrounding water.
Preferably, the first strut part is the primary strut part, and the second part is the secondary part, Thereby, the first strut part is fastened to, or adapted to be fastened to, the structure of the vessel, wherein the second strut part is fixed to, or adapted to be fixed to, the profiled element. This allows for providing a straight skirt edge, the angle of which to the water freeflow is independent on the pitch angle of the profiled element.
However, in some embodiments, the first strut part is fixed to, or adapted to be fixed to, the profiled element, and the second strut part is fastened to, or adapted to be fastened to, the structure of the vessel. In such embodiments, the primary strut part is the second strut part, and the secondary strut part may be the first strut part.
The object is also reached with a profiled element assembly for a marine vessel, for example a hydrofoil vessel, comprising an elongated a profiled element, one or more elongated struts, each strut presenting the features of any one of claims 1-9, wherein the respective secondary strut part is fixed to the profiled element, wherein each of the one or more struts extends from the profiled element in an angle to a longitudinal direction of the profiled element of more than zero degrees and less than 180 degrees.
The object is also reached with a marine vessel comprising a profiled element assembly as mentioned above, wherein the respective primary strut part is fastened to a structure of the vessel. Thereby, the profiled element may be a first hydrofoil of the vessel. The vessel may comprise a second hydrofoil mounted to the vessel structure by means of one or more further struts. A propeller arrangement may be mounted to one or more of the one or more struts by means of which the second hydrofoil mounted to the vessel structure.
Preferably, the vessel is arranged so that, on each strut for the profiled element, at straight forward travel of the vessel, the respective edge of the skirt of the first strut part extends substantially in parallel with a free-flow of the water. Thereby, the water transportation in and out of the skirt may be minimized or eliminated, allowing a minimal turbulence and drag formed by the profiled element pitch adjustment mechanism.
The vessel may be a hydrofoil vessel, wherein the profiled element is a hydrofoil. The structure of the vessel may be a hull of the vessel.
An aspect of the invention provides a profiled element assembly for a marine vessel, for example a hydrofoil vessel, comprising a profiled element unit comprising an elongated profiled element, a fastening arrangement adapted to connect the profiled element unit to a structure of the vessel,
- wherein, when the fastening arrangement is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure via the fastening arrangement,
- wherein, for an adjustment of a pitch angle of the profiled element, the profiled element unit is connected to the fastening arrangement via an articulated joint,
- the profiled element assembly further comprising a pitch adjustment assembly comprising an actuation assembly, - the actuation assembly comprising an actuator arranged to adjust the pitch angle of the profiled element,
- wherein the actuation assembly further comprises an elastic element arrangement , and a second elastic element,
- wherein the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator in a first direction from a neutral pitch angle, a first moment to the profiled element which is opposite to the first direction,
- wherein the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator in a second direction from the neutral pitch angle, which second direction is opposite to the first direction, a second moment to the profiled element which is opposite to the second direction.
Advantages of such a profiled element assembly is understood from the examples in the detailed description below. The aspect may also provide a marine vessel comprising a profiled element assembly according to claim 14, wherein the fastening arrangement is fastened to a structure of the vessel. The vessel may be a hydrofoil vessel, wherein the profiled element is a hydrofoil, wherein the structure of the vessel is a hull of the vessel.
It is understood that the fastening arrangement is fastened to, or adapted to be fastened to, the structure of the vessel. The comprising the actuator of the actuation assembly is arranged to adjust the pitch angle of the profiled element around the articulated joint.
The neutral pitch angle may be an angle that the profiled element assumes when no external forces are applied to the profiled element, i.e. when no force is applied by the actuator to the profiled element.
In some embodiments, the elastic element arrangement comprises a first elastic element, and a second elastic element. Thereby, the first elastic element may be adapted to exert, when the pitch angle of the profiled element is changed in the first direction from the neutral pitch angle, the first moment to the profiled element, and the second elastic element may be adapted to exert, when the pitch angle of the profiled element is changed in the second direction from the neutral pitch angle, the second moment to the profiled element. However, in some embodiments, the elastic element arrangement comprises a single elastic element. For example, the elastic element may be spring, such as a helical spring, which can be compressed and stretched in opposite directions from a neutral position.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Below, embodiments of the invention will be described with reference to the drawings, in which: fig. l is a perspective view of a hydrofoil vessel according to an embodiment of the invention, fig. 2 is a sideview of the vessel of fig. 1, fig. 3 and fig. 4 are partly sectioned, perspective views of a portion of a strut for a profiled element of the vessel in fig. 1, fig. 5 is a partially sectioned side view of a portion of a strut for a profiled element of the vessel in fig. 1, fig. 6 is a cross-sectional view of the portion in fig. 5, with the section oriented as indicated by the arrows VI- VI in fig. 5, fig. 7 is a cross-sectional view similar to the one in fig. 6, of a strut according to an alternative embodiment of the invention, fig. 8 is a cross-sectional view of a part of the strut in fig. 7, with the cross-section oriented as indicated by the arrows VIII- VIII in fig. 7, and fig. 9 is a side view of a profiled element assembly for a marine vessel, according to an aspect of the invention.
DETAILED DESCRIPTION
Fig. 1 depicts a hydrofoil vessel 1 according to an embodiment of the invention. The vessel could of any type, e.g. a pleasure boat, or a passenger boat. The vessel may have fully submergible hydrofoils. The hydrofoil vessel 1 is shown with reference to a cartesian coordinate system having three orthogonal axes X, Y and Z-axis with corresponding reference numerals. The X-axis is parallel to a direction of straight forward travel of the watercraft. Titling or rotation of the hydrofoil watercraft 1 about the X-axis is commonly referred to as roll. Hence, the X-axis may be referred to as the roll axis X. The Y-axis is horizontal. Titling or rotation of the hydrofoil vessel 1 about the Y-axis is commonly referred to as pitch. Hence, the Y-axis may be referred to as the pitch axis Y. Likewise, titling or rotation of the hydrofoil vessel 1 about the Z-axis is commonly referred to as yaw. Hence, the Z-axis may be referred to as the yaw axis Z.
The vessel 1 comprises a structure in the form of a hull 2. The hull is at least partly submerged into the water when the vessel 1 is at rest. The hull 2 may be made of aluminium, fiber-reinforced plastics, or the like.
Reference is made also to fig. 2. The vessel 1 comprises a profiled element in the form of a first hydrofoil 301. The profiled element 301 is fastened to the hull 2 by means of two struts 302, herein also referred to as first struts. The profiled element 301 is a submerged type hydrofoil. The profiled element 301 has an adjustable pitch orientation so as to change the angle of attack of the profiled element, as exemplified below. The profiled element 301 is connected to the hull by means of the struts 302. Each of the struts 302 extends from the profiled element at an angle to a longitudinal direction of the profiled element of about 90 degrees. The first hydrofoil 301 may be, as exemplified in fig. 2, in the direction of travel of the boat 1, located substantially at a center of gravity CG of the boat.
The profiled element 301 may be made of fiber-reinforced plastics, or the like.
The vessel also comprises a second hydrofoil 601. The second hydrofoil 601 is a submerged type hydrofoil. The second hydrofoil is fastened to the hull 2 by means of a second strut 503 arranged to extend downwards from the hull 2. The second hydrofoil is fixed to the second strut 503. The second strut 503 is fastened to the hull at a stem of the hull. The second hydrofoil 601 is located behind the first hydrofoil 301 as seen in a direction of straight forward travel of the boat. The second hydrofoil is arranged to support, in a hydrofoil driving mode, an aft part of the hull. The vessel also comprises a motor pod 502. The motor pod 502 is fixed to the second strut 503. Two electric motors 5051, 5052 are housed coaxially in a casing of the motor pod. Two propellers 5011, 5012 are each arranged to be driven by a respective of the motors. The propellers 5011, 5012 are counter-rotating. The motors are arranged to be powered by a power source such as a battery pack 504. Thereby, cables for electric power to the motors may extend through the second strut. Alternatively, a single propeller driven by a single motor may be provided. In a further alternative, the propeller(s) may be arranged to be driven, by means of a shaft extending through the second strut, by a motor or an internal combustion engine located at an upper end of the second strut 503.
The second strut 503 with the motor pod 502 is tumable in relation to the hull 2 for steering the vessel. Thereby, the second strut 503 may assume the function of a rudder.
A pitch angle of the profiled element is herein defined as an angle between a chord of the profiled element 301 to the direction of straight forward travel of the vessel. The pitch angle of the profiled element can be adjusted by an adjustment mechanism in each of the first struts 302. Thereby, by identical adjustments by the adjustment mechanisms the pitch angle may be the same along the profiled element. Such adjustments may be used for pitch control of the vessel. By dissimilar adjustments by the adjustment mechanisms, the profiled element may be twisted. Thereby, the pitch angle at one end of the profiled element may be different from the pitch angle at the other end of the profiled element. Such adjustments may be used for roll control of the vessel.
By adjusting the pitch angle of the profiled element 301, the angle of attack of the profiled element may be adjusted. The angle of attack is the angle between the chord of the profile element and the relative water free-stream.
As shown, with reference to Fig. 3, each first strut 302 comprises a first strut part 3021 and a second strut part 3022. A primary of the first and second strut parts is fastened to the hull 2 of the vessel. A secondary of the first and second strut parts is fixed to the profiled element 301. In this embodiment, the first strut part 3021 is the primary strut part, and the second strut part 3022 is the secondary strut part. However, in some embodiments, the first strut part 3021, with the features described below, is the secondary strut part, and the second strut part 3022, with the features described below, is the primary strut part. The first strut part 3021 has an elongated shape. The first strut part 3021 presents, in a crosssection which is perpendicular to a longitudinal direction of the first strut part, an airfoil shape. In this embodiment, the air foil shape is symmetrical. However, in some embodiment, the air foil shape of the first strut part is non-symmetrical.
For an adjustment of the pitch angle of the profiled element, the second strut part 3022 is connected to the first strut part 3021 via an articulated joint 13. The articulated joint is in this example, a ball-joint. The articulated joint has a truncated ball 320 to limit the width of the strut 302 at the joint 13. The truncated ball 320 is fixed to the first strut part 3021. The truncated ball 320 is fixed to the first strut part 3021 by means of a stem 321. The articulated joint further comprises a socket 322 which is fixed to the second strut part 3022. The socket 322 partly encloses the truncated ball 320. A low friction between the socket 322 and the truncated ball 320 allows the socket 322, and hence the second strut part 3022 to rotate around the truncated ball 320.
As illustrated in fig. 4, at an end which is opposite to an at which the first strut part 3021 is fastened to the hull, the first strut part 3021 comprises a skirt 121 presenting an edge 122 forming an end of the skirt. At the skirt, the first strut part airfoil cross section is widened in a plane perpendicular to the first strut longitudinal axis. Thus, at the skirt, the first strut part is widened in a direction which is perpendicular to a chord line of the first strut part airfoil cross-sectional shape. Also, at the skirt, the first strut part is extended in a direction which is parallel to the chord line of the first strut part airfoil cross-sectional shape. This extension is provided by a forward offset of the first strut part leading edge.
A distal part 312 of the second strut part 3022 extends into the skirt 121. For illustrative reasons the distal part 312 of the second strut part 3022 is not shown in fig. 3. A proximal part 310, shown in fig. 3, of the second strut part 3022 is fixed to the profiled element 301. The distal part 312 of the second strut part 3022 is fixed to the proximal part 310 of the second strut part 3022.
The edge 122 of the skirt 121 is, as seen along a rotational axis R1 (fig. 3) of the articulated joint, substantially straight. The edge 122 is arranged in relation to the remainder of the vessel so that, at straight forward travel of the vessel, the edge 122 extends substantially in parallel with a free-flow of the water.
As understood from fig. 3 and fig. 5, the rotational axis R1 of the articulated joint 13 is located at the edge 122 of the skirt 121. The rotational axis R1 of the articulated joint is located where the distal part 312 of the second strut part 3022 joins the proximal part of the second strut part 3022.
For the purpose of adjusting the pitch angle of the profiled element 301, the adjustment mechanism of each strut 302 comprises a respective adjustment rod 324. The adjustment rod extends in the longitudinal direction of the respective strut 302. The adjustment rod extends inside the respective strut 302. The respective adjustment rod 324 is, in this example, connected to the second strut part 3022 at a distance from the articulated joint 13. The adjustment rod 324 is movable in a longitudinal direction of the respective strut 302, 303 to cause a rotation of the second strut part, and hence the profiled element, around the articulated joint. For the connection to the second strut part 3022, the adjustment rod 324 comprises a truncated sphere 326 at its distal end, and the second strut portion 3022 forms a rod socket which partly encloses the truncated sphere 326.
Reference is made also to fig. 5 and fig. 6. As can be seen in fig. 6, at the edge 122 of the skirt, the shape of the contour of the second strut part 3022 is substantially the same as a shape of an internal contour of the skirt 121 along the edge 122 of the skirt. Thereby a small gap is provided between the second strut part 3022 and the skirt 121.
In addition, the profile of the second strut part in an imaginary plane, that includes the rotational axis Rl, is constant when the imaginary plane is rotated around the rotational axis R1 from a position in which it is parallel with the X-Y-plane. Thereby, the shape of the contour of the second strut part 3022 along the edge 122 of the skirt 121 is substantially constant within an angular interval Aa (fig. 5) of rotation of the second strut part 3022 in relation to the first strut part 3021 around the articulated joint 13. This means that within the angular interval Aa, an intersection between the surface of the second strut part 3022 and an imaginary plane which is perpendicular to the rotational axis Rl, will be at a constant distance from the rotational axis Rl. For example, a leading edge LE of the second strut part 3022 is, at the articulated joint, part-circular within the angular interval Aa, with a circle center in the rotational axis R1 of the articulated joint 13. Further, a trailing edge TE of the second strut part 3022 is, at the articulated joint, part-circular within the angular interval Aa, with a circle center in the rotational axis R1 of the articulated joint 13.
Thereby, within the angular interval Aa, the gap between the second strut part 3022 and the skirt 121 may be kept minimal, regardless of the pitch angle of the profiled element 301. This will reduce drag losses of the vessel.
Reference is made to fig. 7, showing a view similar to the one in fig. 6, of a strut according to an embodiment of the invention which is similar to the one described with reference to fig. 1 - fig. 6, with the following exception:
The second strut part 3022 is provided with a truncated trailing edge TE. As a result, the shape of around 80% of the contour 3022c of the second strut part 3022 along the edge 122 of the skirt 121 is substantially constant within the angular interval Aa (fig. 5) of rotation of the second strut part 3022 in relation to the first strut part 3021 around the articulated joint 13.
More specifically, fig. 7 shows the strut in a cross-section which coincides with the skirt edge 122. In the embodiment in fig. 7, a contour part 3022cp forming approximately 80% of the contour 3022c of the second strut part, forms a delimitation of the second strut part, in said cross-section, which delimitation follows the skirt edge 122. Thereby, said contour part 3022cp has substantially the same shape as the part of the skirt edge which it follows. Further, preferably the three-dimensional shape of the second strut part, at the articulated joint, is such that the shape of said contour part 3022cp is substantially the same regardless of the angle of rotation of the second strut part in relation to the first strut part around the articulated joint constant within the angular interval Aa (fig. 5).
It should be noted that in the embodiment in fig. 7, the approximately 80% of the contour 3022c of the second strut part along the edge 122 of the skirt intersects the leading edge LE of the second strut part.
Reference is made to fig. 8. In this embodiment, the strut comprises, at the edge 122 of the skirt 121, an element 14 of a flexible material for closing the gap between the second strut part 3022 and the skirt 122. In this example, the element of a flexible material is fastened to the skirt 121. In this example, the element of a flexible material is a strip 14 of a flexible material. The element of a flexible material bridges the gap between the second strut part and the skirt. In this embodiment with the truncated trailing edge TE, the strip may be terminated at the trailing edge TE.
Reference is made for fig. 9. A further aspect of the invention provides a profiled element assembly for a marine vessel, for example a hydrofoil vessel.
The profiled element assembly comprises a profiled element unit 301, 3022. The profiled element unit comprises an elongated profiled element 301, and a secondary strut part 3022 fixed to the profiled element. The profiled element forms a hydrofoil 301. A primary strut part 3021 forms a fastening arrangement adapted to connect the profiled element unit to a structure of the vessel. The structure may be a hull of the vessel. The primary strut part 3021 extends from the profiled element unit 301, 3022 in an angle to a longitudinal direction of the profiled element 301 of more than zero degrees and less than 180 degrees, in this example about 90 degrees.
The primary strut part 3021 is fastened to, or adapted to be fastened to, the structure of the vessel. The primary strut part has an elongated shape. When the fastening arrangement 3021 is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure via the fastening arrangement.
For an adjustment of a pitch angle of the profiled element, for adjusting the angle of attack of the profiled element, the profiled element unit 301, 3022 is connected to the primary strut part 3021 via an articulated joint 13. More specifically, the secondary strut part 3022 is connected to the primary strut part 3021 via the joint 13. The secondary strut part extends into a skirt 121 of the primary strut part. The articulated joint is formed by a ball joint 13.
Alternatively, the secondary strut part 3022 may be omitted, and the primary strut part may be connected directly to the profiled element 301.
The profiled element assembly further comprises a pitch adjustment assembly comprising an actuation assembly. The pitch adjustment assembly further comprises a control device 324 connecting the profiled element unit 301, 3022 with the actuation assembly. The control device 324 is provided in the form of a control rod which extends along and through the primary strut part 3021.
Thus, the control rod 324 is used to rotate the secondary strut part 3022 and the hydrofoil 301 around the joint 13. The control rod is driven by the actuator 401 via a bracket 402 which rotates around a hinge 403.
The actuation assembly comprises an actuator 401 arranged to adjust the pitch angle of the profiled element via the control device.
The actuation assembly further comprises a first elastic element 404, in the form of a helical spring, and a second elastic element 405, in the form of a helical spring. The advantage of these elastic elements are as follows:
The hydrofoil’s articulation point formed by the joint 13 is, in the chord direction of the hydrofoil transverse cross-section, in the center of lift of the hydrofoil 301 at a relatively low angle of attack thereof. The center of lift moves towards the foil leading edge at increasing angles of attack, and vice versa. This means that without the elastic elements 404, 405, the hydrofoil attachment is unstable. This in turn means that without the elastic elements 404, 405, there is a risk of high loads on the actuator 401. Regarding the actuator 401, there may be a desire to refrain from hydraulics in the vessel. However, electric motors are relatively slow and weak.
The first elastic element 404 is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator 401 in a first direction from a neutral pitch angle, a first moment to the profiled element 301 which is opposite to the first direction. The second elastic element is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator 401 in a second direction from the neutral pitch angle, which second direction is opposite to the first direction, a second moment to the profiled element 301 which is opposite to the second direction.
Thus, the first and second elastic elements 404, 405 are arranged to provide forces on the adjusting mechanism, in opposite directions. When the hydrofoil 301 assumes the neutral pitch angle, the spring forces are balanced. Deflections away from the neutral pitch angle increases the spring force in the opposite direction. Therefore, stability is achieved.
It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A strut (302) for a marine vessel, for example a hydrofoil vessel,
- the strut comprising a first strut part (3021) and a second strut part (3022),
- wherein a primary of the first and second strut parts, referred to as a primary strut part, is fastened to, or adapted to be fastened to, a structure (2) of the vessel,
- the primary strut part having an elongated shape, the primary strut part presenting, in a cross-section which is perpendicular to a longitudinal direction of the primary strut part, an elongated streamlined shape,
- wherein a secondary of the first and second strut parts, referred to as a secondary strut part, is fixed to, or adapted to be fixed to, an elongated profiled element (301), so that, when the primary strut part is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure,
- wherein, for an adjustment of an angle of attack of the profiled element, the second strut part (3022) is connected to the first strut part (3021) via an articulated joint (13), characterised in that
- the first strut part (3021) comprises a skirt (121) presenting an edge (122) forming an end of the skirt, wherein the second strut part extends into the skirt (121), and in that a shape of at least 50% of a contour (3022c) of the second strut part (3022) along the edge (122) of the skirt is substantially constant within an angular interval (Aa) of rotation of the second strut part in relation to the first strut part around the articulated joint (13).
2. A strut according to claim 1, wherein the edge (122) of the skirt (121) is, as seen along a rotational axis of the articulated joint, substantially straight.
3. A strut according to any one of the preceding claims, wherein the second strut part (3022) presents, at the articulated joint, a leading edge (LE), wherein the leading edge (LE) is part-circular within the angular interval (Aa), with a circle center in a rotational axis (Rl) of the articulated joint (13).
4. A strut according to any one of the preceding claims, wherein the second strut part (3022) presents, at the articulated joint, a trailing edge (TE), wherein the trailing edge (TE) is part-circular within the angular interval (Aa), with a circle center in a rotational axis (Rl) of the articulated joint (13).
5. A strut according to any one of the preceding claims, wherein the at least 50% of the contour (3022c) of the second strut part along the edge (122) of the skirt intersects a leading edge (LE) of the second strut part.
6. A strut according to any one of the preceding claims, wherein a rotational axis (Rl) of the articulated joint is located at the edge (122) of the skirt (121).
7. A strut according to any one of the preceding claims, wherein, at the edge (122) of the skirt, a shape of at least 50% of the contour, preferably at least 70%, e.g. the entire contour, of the second strut part (3022) is substantially the same as a shape of an internal contour of the skirt (121) along the edge (122) of the skirt.
8. A strut according to any one of the preceding claims, wherein, at the edge of the skirt, the gap between the second strut part and the skirt is less than 5.0 mm, preferably less than 3.0 mm, preferably less than 2.0 mm, preferably less than 1.5 mm, preferably less than 1.0 mm, along the at least 50% of the contour (3022c), preferably along at least 70% of the contour, e.g. along the entire contour, of the second strut part.
9. A strut according to any one of the preceding claims, wherein the first strut part is the primary strut part, and the second part is the secondary part.
10. A profiled element assembly for a marine vessel, for example a hydrofoil vessel, comprising an elongated a profiled element (301), one or more elongated struts (302), each strut presenting the features of any one of the preceding claims, wherein the respective secondary strut part is fixed to the profiled element, wherein each of the one or more struts extends from the profiled element in an angle to a longitudinal direction of the profiled element of more than zero degrees and less than 180 degrees.
11. A marine vessel comprising a profiled element assembly according to claim 10, wherein the respective primary strut part is fastened to a structure (2) of the vessel.
12. A vessel according to claim 11, wherein, at straight forward travel of the vessel, the respective edge (122) of the skirt of the first strut part (3021) extends substantially in parallel with a free-flow of the water.
13. A vessel according to any one of claims 11-12, wherein the vessel is a hydrofoil vessel, wherein the profiled element is a hydrofoil (301), wherein the structure of the vessel is a hull (2) of the vessel.
14. A profiled element assembly for a marine vessel, for example a hydrofoil vessel, comprising a profiled element unit (301, 3022) comprising an elongated profiled element (301), a fastening arrangement (3021) adapted to connect the profiled element unit to a structure (2) of the vessel,
- wherein, when the fastening arrangement (3021) is fastened to the structure of the vessel, the profiled element can generate, by interaction with water passing the vessel as the vessel travels, a force that is transferred to the structure via the fastening arrangement,
- wherein, for an adjustment of a pitch angle of the profiled element, the profiled element unit (301, 3022) is connected to the fastening arrangement (3021) via an articulated joint (13),
- the profiled element assembly further comprising a pitch adjustment assembly comprising an actuation assembly,
- the actuation assembly comprising an actuator (401) arranged to adjust the pitch angle of the profiled element,
- wherein the actuation assembly further comprises an elastic element arrangement (404, 405), - wherein the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element (301) is changed by means of the actuator in a first direction from a neutral pitch angle, a first moment to the profiled element which is opposite to the first direction, - wherein the elastic element arrangement is adapted to exert, when the pitch angle of the profiled element is changed by means of the actuator in a second direction from the neutral pitch angle, which second direction is opposite to the first direction, a second moment to the profiled element which is opposite to the second direction.
PCT/EP2023/050843 2022-01-17 2023-01-16 A strut for a profiled element of a marine vessel WO2023135289A1 (en)

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SE2250037-5 2022-01-17
SE2250037A SE2250037A1 (en) 2022-01-17 2022-01-17 A strut for a profiled element of a marine vessel

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2584347A (en) 1950-04-11 1952-02-05 Allyn B Hazard Hydrofoil boat
US3141437A (en) * 1958-05-23 1964-07-21 Scherer Constant lift system for craft
US3465704A (en) * 1964-11-05 1969-09-09 John Gordon Baker Hydrofoil system for boats
WO1984001137A1 (en) * 1982-09-15 1984-03-29 Daniel Elie Chaumette Hydrofoil device stabilized by a tail unit and nautical vehicle provided therewith
WO1994027862A1 (en) * 1991-12-20 1994-12-08 Payne Peter R Hydrofoil craft
JPH07165155A (en) 1993-12-16 1995-06-27 Yanmar Diesel Engine Co Ltd Vessel equipped with hydrofoil
SE540588C2 (en) 2017-09-22 2018-10-02 Candela Speed Boat Ab Hydrofoil
FR3089200A1 (en) 2018-12-04 2020-06-05 Universite De Montpellier Support assembly for profiled element

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1419584A (en) * 1964-01-23 1965-12-03 Improvements to submerged load-bearing surfaces
GB1201021A (en) * 1966-04-27 1970-08-05 Peter Thomas Mence Nott Improvements in or relating to hydrofoil watercraft
US3417722A (en) * 1967-06-28 1968-12-24 Navy Usa Hydraulic suspension and control system for hydrofoil craft

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2584347A (en) 1950-04-11 1952-02-05 Allyn B Hazard Hydrofoil boat
US3141437A (en) * 1958-05-23 1964-07-21 Scherer Constant lift system for craft
US3465704A (en) * 1964-11-05 1969-09-09 John Gordon Baker Hydrofoil system for boats
WO1984001137A1 (en) * 1982-09-15 1984-03-29 Daniel Elie Chaumette Hydrofoil device stabilized by a tail unit and nautical vehicle provided therewith
WO1994027862A1 (en) * 1991-12-20 1994-12-08 Payne Peter R Hydrofoil craft
JPH07165155A (en) 1993-12-16 1995-06-27 Yanmar Diesel Engine Co Ltd Vessel equipped with hydrofoil
SE540588C2 (en) 2017-09-22 2018-10-02 Candela Speed Boat Ab Hydrofoil
FR3089200A1 (en) 2018-12-04 2020-06-05 Universite De Montpellier Support assembly for profiled element

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