System and Methods to Provide Lift to a Vessel

This application claims priority to U.S. Provisional Patent Application No. 63/637,787, filed Apr. 23, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

The present disclosure relates to structures, uses and methods of increasing the lift of hydrofoils and aerofoils by accelerating fluid by constriction within a chamber.

Foils in the form of hydrofoils and aerofoils provide lift to vessels traveling in the air and on water. For aerofoils, this lift provides the means for airplanes to fly. For hydrofoils, this lift raises marine vessels upwards from the water, reducing sinkage, and thereby drag forces. Pairs of hydrofoils are further useful in dampening vessel motion caused by wave action. However, conventional hydrofoils on large marine vessels such as cruise ships and naval vessels can be massive, and are typically attached at a single pivot point, placing considerable constraints on materials and methods of use.

According to some embodiments, a lift unit is disclosed for providing lift to a vessel moving through a fluid, wherein the lift unit includes a passageway configured to allow the fluid to flow within as the vessel moves through the fluid, the passageway including a tapered chamber having a mouth with an inflow area at a fore end, configured for inflow of the fluid into the fore end through the mouth as the vessel moves through the fluid and an aft end opposite the fore end, the tapered chamber narrowing from the fore end toward the aft end, and a constricted chamber having a fore end and an aft end, the fore end of the constricted chamber connected to the aft end of the tapered chamber, the aft end of the constricted chamber having an exit for outflow of the fluid, the exit having an outflow area which is less than the inflow area.

The lift unit further includes a foil situated within the constricted chamber, the foil having an axle about which the foil is configured to rotate, the axle having a outboard-side end and a inboard-side end, the axle being attached to the lift unit at the outboard-side end and at the inboard-side end. The lift unit further includes a drive mechanism disposed in a drive mechanism compartment, the drive mechanism compartment fluidically isolated from the constricted chamber, the drive mechanism connected to the foil and configured to rotate the foil about the axle so as to control the lift as the fluid flows through the constricted chamber.

According to some embodiments, the constricted chamber and the tapering chamber may overlap. The lift unit may be retractable into the hull of the vessel. The foil may be a hydrofoil or a flat plate, and the fluid may be water. The drive mechanism may be housed in a compartment separate from the hydrofoil. The compartment may be watertight. The watertight compartment may be configured to hold oil. The drive mechanism may be rotatably connected to the axle. The drive mechanism may be coupled to a rod which connects at an end of the foil forward or aft of the axle, the drive mechanism configured to move the rod in a linear direction so that the foil rotates about the axle.

According to some embodiments, a system is disclosed for providing lift to a vessel having a hull moving through a fluid. The system includes one or more lift units, as described above, configured to be disposed on the hull of the vessel, and one or more motion sensors, disposed on the vessel, configured to monitor pitch, roll, and heave motions of the vessel. The system further includes a motion control command unit (MCCU) configured to receive signals from the one or more motion sensors, the MCCU configured with a processor and instructions for control of the one or more lift units, based, at least in part, on the signals received from the one or more motion sensors.

According to some embodiments, at least one of the lift units may be retractable into the hull of the vessel. The one or more lift units may include a port lift unit and a starboard lift unit symmetrically disposed with respect to each other on the hull of the vessel. The one or more lift units may include two fore lift units positioned on opposing sides at a forward location on the hull, two midship lift units positioned on opposing sides close to the midship location on the hull, and two aft lift units positioned on opposing sides at an aft location on the hull.

According to another embodiment, the total number of lift units on the vessel can be three, and can include a single lift unit at either an extreme forward location or an extreme aft location on the hull, close to the center line of the ship and two lift units positioned on opposing sides at close to midship on the hull.

According to some embodiments, a method is disclosed of providing lift to a vessel having a hull moving through a fluid. The method includes configuring the vessel with a system for providing lift, as described above, monitoring pitch, roll, and heave motions of the vessel with the one or more motion sensors, transmitting signals related to pitch, roll, and heave motions of the vessel to the motion control command unit from the motion sensors, receiving the transmitted signals from the motion sensors by the motion control command unit, and based, at least in part, on the signals received from the one or more motion sensors, controlling the lift units.

According to some embodiments, controlling the one or more lift units may include controlling the attack angles of the foils disposed in the lift units. Controlling the attack angles provides control of the drag and lift of the vessel. Controlling the attack angles may result in a reduction in vessel motions selected from the group consisting of pitch, roll, heave, and combinations thereof.

Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:

The “port” side of a vessel is the left side of the vessel when the vessel is facing forward.

The “starboard” side of a vessel is the right side of the vessel when the vessel is facing forward.

“Fore” refers to the front of a forward-facing vessel.

“Aft” refers to the rear of a forward-facing vessel.

“Midship” refers to the middle region of a vessel.

A first chamber is “fluidically isolated” from a second chamber when fluid entering the second chamber is blocked from entering the first chamber.

A “foil” is a flat or shaped plate configured to provide a lift force on a vessel moving through a fluid.

A “lift force” is a force perpendicular to the motion of the vessel.

A “hydrofoil” is a foil configured to provide a lift force when the fluid flowing is a liquid.

An “aerofoil” is a foil configured to provide a lift force when the fluid flowing is a gas.

“Roll” is side to side tilting motion of a vessel about the roll axis of the vessel, where the roll axis runs horizontally through the length of the ship, from fore to aft, through the vessel's center of mass.

“Pitch” is an up/down rotation of a vessel about the pitch axis of the vessel, where the pitch axis runs horizontally across the ship, from port to starboard, through the vessel's center of mass.

“Heave” is a linear up/down motion of a vessel.

It is known that foils can provide lift forces for vessels moving through a fluid. For aerofoils, such lift forces allow planes to lift off and fly. As indicated in, lift from hydrofoilsmoving through water can reduce sinkage and thereby reduce drag on a marine vessel. In, the initial levelof water on the hull of the vessel decreases to a new levelas the vessel is raised out of the in the water by lift force L. Foils can also help to stabilize vessels in the presence of wave motion. Such stabilization is illustrated in, which shows how the action of waves can be counteracted by applying positive lift force (L) on a hydrofoilon one side of a marine vessel and negative lift force (−L) on another hydrofoilsymmetrically disposed on an opposing side of the vessel, in order to minimize roll.

A conventional hydrofoil configurationis illustrated in. Here, the hydrofoilextends outwards from a hullwhen operational, and pivots back into the hullabout a pivot pointwhen not in use. The pivot pointis conventionally a cantilevered, universal joint support. It is noteworthy that in such a configuration, the entire force of the hydrofoil moving through water is placed on the single pivot point, placing considerable structural constraints on this universal joint support.

The lift force L and the drag force D on a foilmoving through a fluid, the fluid moving with velocity v (distance per unit time) relative to the foilat an attack angle α are illustrated in. Here a is defined as the angle between a chord lineof the foil and the direction of the incoming flow of fluid.

A foil can take on a variety of shapes, and a person skilled in the art of foil design would understand that the current disclosure applies equally well to any number of such shapes. As illustrated in, a foil can be a simple flat plate, and the core features of this disclosure can be understood with reference to such a plate. With respect to the forces on such a plate, the force Fdue to fluid flow against the plate at an attack angle α provides a normal force Fwhich is the vector sum of the lift force L and the drag force D. The normal force Fis given by F=Fcos(90−α)=Fsin(α) from which it is readily seen that L=Fcos(α)=Fsin(α)cos(α) and that D=Fsin(α)=Fsin(α).

shows a foilhaving a wing-type shape. General hydrodynamic models of a foil having a modest attack angle α moving through a fluid with density ρ with a velocity v provide a lift force L described by:

where S is the surface area of the foil, and Cis the lift coefficient, a parameter which depends on the attack angle of the foil with the fluid, and on various hydrodynamic parameters including the viscosity of the fluid. The drag force D can be described by an equation with similar form:

where Cis the drag coefficient. Notably, as discussed in more detail below, because both the lift force and the drag force depend as the square of the velocity v, increasing the velocity of fluid by channel constriction allows a dramatic reduction of size of the foil without sacrificing lift, while maintaining a constant ratio of lift to drag.

This principle is embodied in, which shows a passagewayhaving a fore end and an aft end, forming part of a lift unit for a vessel, the passageway having a mouththrough which fluid can flow as the vessel moves forward. The mouthprovides an inlet area Athrough which the fluid enters at the fore end. The passagewaytapers from the mouth, forming a tapered chamber, the tapered chamberconnecting to a constricted chamber, the constricted chamberterminating at the aft end in an exit, the exit providing an outlet area A. A foilfor providing lift for the vessel as the vessel moves through the fluid is disposed inside the constricted chamber. The foilis attached at both ends of an axleto interior attachment points on the constricted chamber. The attack angle α of the foil with fluid flowing into the constricted chamberis controlled by means discussed below. Notably, in contrast to the conventional retractable foil of, which are attached at a single pivot point, attachment at both ends of the axleeliminates the requirement that the entire force of the hydrofoil moving through water be placed on the single pivot point.

According to the embodiment of, as the vessel moves through the fluid, the fluid in turn moves into the passagewayat a free stream velocity v. The fluid enters through the mouth, into the tapered chamber, and into the constricted chamber. As the fluid passes through the tapered chamberand into the constricted chamber, its velocity increases, with the velocity in the constricted chamberbeing given by v. According to this embodiment, because of the conservation of mass, the volume per unit time entering the mouthmust equal the volume per unit time leaving the exit, meaning that the following equation of continuity must hold:

The velocity of the fluid in the constricted chamber can be written as v=Cv, where

is the constriction ratio.

Comparing the lift force Lfor a foil subject to free flow velocity and the lift force Lin the constricted chamber, we obtain:

Based on this equation, it is evident that for a constant area of foil, the increase in lift for a foil subject to constricted flow compared to free flow is by a factor of

For example, a two-fold reduction in the outflow area compared to the inflow area gives a four-fold increase in lift.

Looked at another way, to obtain a given value of lift (L=L) the surface area of a foilin the constricted chambercan be reduced by a factor of

compared to the surface area of a foil subject to free flow. For example, a two-fold reduction in the outflow area compared to the inflow area allows the surface area of the foil to be reduced 4-fold.

Compare for example a constricted chamber foilin, with a free-flow foilin. The foils inandhave the same width w, but different lengths, land l, respectively. If the area ratio