Methods and systems for pressurized fluid-driven propulsion

Abstract

Methods and systems are provided for propelling an object deployed in an aquatic environment. In one example, a system may include a turbine circumferentially surrounded by a propeller. The propeller may be driven to rotate in unison, or nearly in unison, with the turbine by a helical flow of a pressurized fluid. In this way, the object may be propelled, e.g., by the system, without relying on an electric motor.

Description

METHODS AND SYSTEMS FOR PRESSURIZED FLUID-DRIVEN PROPULSIONFIELD

[0001] Embodiments of the subject matter disclosed herein relate to propulsion utilizing a pressurized fluid source, and more particularly to propulsion of a body deployed in an aquatic environment.BACKGROUND

[0002] At least due to largescale effects on climate, the terrestrial biosphere, and public health, it is desirable to reduce dependence on less sustainable forms of energy generation. To do so, in general, it is desirable to maximize net energy output while limiting implementation, operational, and maintenance costs. One possible source of energy is pressurized fluid, such as water, that is expelled from a body during its deployment in an aquatic environment.

[0003] For example, a free-floating body may receive fluid in a manner that causes the fluid to be pressurized, e.g., the free-floating body may passively store pressurized fluid or have a mechanism for actively pressurizing fluid received therein. The pressurized fluid that may subsequently be expelled from the body may contain useful energy, e.g., energy which is desirably captured for useful work.SUMMARY OF THE INVENTION

[0004] Methods and systems are provided for propelling an object deployed in an aquatic environment. Techniques described and suggested herein include a propulsion system having a turbine concentric with a propeller, the propeller driven to rotate in unison with the turbine by a helical flow of a pressurized fluid. In at least one embodiment, a device for propelling an object in an aquatic environment may include a channel through which a pressurized fluid is to flow, a stationary unit positioned to generate a vortex in the pressurized fluid flow, and a rotatable unit including a plurality of propeller blades, the rotatable unit positioned between portions of the stationary unit and driven by the vortex to rotate.

[0005] In at least one embodiment, a method for propelling an object using a propulsion system may include generating a helical flow of a pressurized fluid and receiving the helical flow at a turbine to rotate a plurality of propeller blades circumferentially surrounding the turbine at a same rotational speed as the turbine.

[0006] In at least one embodiment, a two-stage marine propulsion system may include a first stage to generate a vortex in a flow of pressurized fluid, and a second stage to receive the vortex at a turbine concentric with and fixedly coupled to a propeller.

[0007] For example, the following description relates to various embodiments of systems and methods for a propulsion system, such as a PF-driven propulsion system, for an object in an aquatic environment, where the object may be a floatable watercraft, device, or other apparatus. In one embodiment, and as described further below with reference to FIG. 1, the object may be a free-floating body included in a wave energy harvesting system. The object may be a passive device, e.g., without any mechanism for propulsion excepting the PF-driven propulsion system, such that the PF-driven propulsion system may be a singular system for providing steering and translation of the object in a body of water. In some embodiments, the PF-driven propulsion system may be retrofit to an object to enable movement and steering of the object. In other embodiments, the object may have a primary propulsion system and the PF-driven propulsion system may be a secondary or auxiliary system for propelling the object.

[0008] In at least one embodiment, the PF-driven propulsion system, as described herein, may be a compact device packaged as an assembly that can be readily adapted to various types of objects deployed in an aquatic environment, including free-floating bodies, motorized vehicles, etc.. The device may convert energy stored via pressurization into torque that may propel an object. This may enable the object to be translated through the aquatic environment with minimal additional energy consumption.

[0009] More particularly, given a pressurized or fast-flowing stream of fluid, the PF-driven propulsion system may achieve maximal thrust at low or zero object speed by transferring the fluid’s energy to a slow-turning propeller that moves a large quantity of fluid slowly rearward, rather than directly (e.g., with no intervening propeller or other energy transfer element) ejecting the fluid rearward with a nozzle. Further, the turbine may be configured to maximize thrust generated by the PF-driven propulsion system, e.g., when the object is stationary or translating at low speed, without relying on a gearing system or a motor. For example, for maximum efficiency of power transfer, thrust may be increased by increasing a diameter of a propeller, which allows the propeller to move a larger amount of water when placed in a body of water. Maximal thrust, at low or zero object speed, may be achieved by obtaining power provided by the pressurized, fast- flowing stream of fluid and transferring thepower to slower movement of a larger quantity of fluid. Furthermore, in order to achieve high efficiency, a driving torque of the turbine of the PF-driven propulsion system may be equal to a torque required to spin the propeller at a given revolutions per minute (rpm) and forward velocity.

[0010] In at least one embodiment, the PF-driven propulsion system delivers thrust for propelling the object by directing the pressurized fluid in a helical manner through a stator of the PF-driven propulsion system to generate a vortex. The stator may be included in a first stage of the PF-driven propulsion system, where the first stage is a stationary unit of the PF- driven propulsion system. The vortex generated by the stator may be received at a second stage of the PF-driven propulsion system, the second stage including a rotatable unit. In one embodiment, as shown herein, the rotatable unit may be positioned (e.g., sandwiched or otherwise interposed) between portions of the stationary unit. In yet another embodiment, also shown herein, the rotatable unit may be at least partially concentric with the stationary unit, where the rotatable unit may be at least partially surrounded by the stationary unit or the stationary unit may be at least partially surrounded by the rotatable unit, such as radially surrounded, circumferentially surrounded, or enclosed thereby.

[0011] The second stage, or rotatable unit, of the PF-driven propulsion system includes a turbine positioned immediately (e.g., without intervening components) downstream of the stator, e.g., after the stator relative to an axial direction of flow through the PF-driven propulsion system. The turbine may be configured to receive the pressurized fluid via any of an axial flow, a radial flow, or a circumferential flow. The turbine may be fixedly coupled to a propeller such that the propeller is either attached to an outer region of the turbine and extends away from the turbine, external to a casing of the PF-driven propulsion system or attached to an inner region of the turbine to extend inwards, towards a central axis of rotation of the turbine. In at least one embodiment, the turbine and the propeller may be at least partially concentric with one another around a circumference of the PF-driven propulsion system. For instance, the turbine may be outside of and concentric with the propeller or the propeller may be outside of and concentric with the turbine around the circumference of the PF-driven propulsion system. A diameter of the turbine may be of a minimum size, relative to an outer diameter of the propeller, that allows the propeller and the turbine to rotate at the same rotation speed (e.g., rpm).

[0012] In at least one embodiment, the diameter of the turbine may be in a range that is dependent on the desired operational conditions. As an example, a propulsion speed of an object propelled by the PF-driven propulsion system may be targeted to be less than 2 m / s, e.g., to maximize efficiency or to travel through a fluid medium with a desired amount of friction and / or turbulence. For the given target propulsion speed, the diameter of the turbine may increase as the pressure of the fluid increases. For fluid pressures that are low, e.g., low relative to an available range of fluid pressures, the diameter of the turbine may be 10% to 50% of the diameter of the propeller. At higher pressures, an embodiment of the PF-driven propulsion system where the turbine is instead positioned around the propeller with the propeller oriented inwards, may be used. Further, the turbine and the propeller may rotate in unison, or nearly in unison as a single unit, thereby minimizing losses and delivering a power transfer efficiency of at least 80%. As described herein, the term “nearly” refers to deviation from rotating at the same rpm by less than 5%.

[0013] In at least one embodiment, the PF-driven propulsion system has a single rotatable unit supported by stationary components having hydrodynamic bearings that do not directly contact the rotatable unit. This circumvents wear and tear and eventual degradation of the PF- driven propulsion system components that may otherwise occur if using bearings that directly contact with other components. A fluid film layer may be formed between surfaces of the turbine and the hydrodynamic bearings based on a viscosity of the pressurized fluid to allow the turbine to rotate substantially unimpeded. In one embodiment, the fluid may be seawater, as described further below. In other embodiments, the fluid may be another type of fluid including, but not limited to, fresh water, oil, gas, or vapor. The dimensions and geometry of the PF-driven propulsion system components may be modified depending on the type of fluid used to drive rotation of the turbine. For example, a distance between the surfaces of the turbine and surfaces of the hydrodynamic bearings may be greater when the fluid is oil compared to when the fluid is seawater. Tolerances of the components with respect to their geometry in relation to adjacent components may therefore be lower and more demanding for fluids of lower viscosity than for fluids of higher viscosity.

[0014] The PF-driven propulsion system therefore provides propulsion for an object deployed in a body of water by dispersing a high-speed, concentrated fluid flow with a small volume, over a larger area associated with moving a large volume of fluid slowly, whileminimizing losses. Thrust is provided at high efficiency for movement and steering of the object without increasing drag or relying on a motor and gearing.

[0015] These, as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various embodiments and techniques will be described with reference to the drawings, in which:

[0017] FIG. 1 shows a schematic diagram of an energy harvesting system, including a free- floating body which may be propelled by a pressurized fluid-driven (PF-driven) propulsion system;

[0018] FIG. 2 shows a simplified perspective view of a free-floating body, including a PF- driven propulsion system;

[0019] FIG. 3 shows a first perspective view of a first example of a PF-driven propulsion system;

[0020] FIG. 4 shows a second perspective view of the PF-driven propulsion system of FIG. 3;

[0021] FIG. 5 shows a cross-sectional view of the PF-driven propulsion system of FIG. 3;

[0022] FIG. 6 shows an exploded view of the PF-driven propulsion system of FIG. 3 ;

[0023] FIG. 7 shows a perspective view of a nose cone of the PF-driven propulsion system of FIG. 3;

[0024] FIG. 8 shows a perspective view of a stator of the PF-driven propulsion system of FIG. 3;

[0025] FIG. 9 shows a cross-sectional view of the stator of FIG. 8;

[0026] FIG. 10 shows a first perspective view of a forward thrust bearing of the PF-driven propulsion system of FIG. 3 ;

[0027] FIG. 11 shows a second perspective view of the forward thrust bearing of FIG. 10;

[0028] FIG. 12 shows a perspective view of a turbine wheel of the PF-driven propulsion system of FIG. 3;

[0029] FIG. 13 shows a cross-sectional view of the turbine wheel of FIG. 12;

[0030] FIG. 14 shows a perspective view of a rotor of the PF-driven propulsion system of FIG. 3;

[0031] FIG. 15 shows a perspective view of a prop-standoff of the PF-driven propulsion system of FIG. 3;

[0032] FIG. 16 shows a perspective view of a rear thrust bearing of the PF-driven propulsion system of FIG. 3 ;

[0033] FIG. 17 shows a perspective view of a tail cone of the PF-driven propulsion system of FIG. 3;

[0034] FIG. 18 shows a schematic diagram illustrating an effect of fins of a stator on fluid flow;

[0035] FIG. 19 shows a first perspective view of a second example of a PF-driven propulsion system;

[0036] FIG. 20 shows a second perspective view of the PF-driven propulsion system of FIG. 19;

[0037] FIG. 21 shows a cross-sectional view of the PF-driven propulsion system of FIG. 19;

[0038] FIG. 22 shows a perspective view of a nose ring of the PF-driven propulsion system of FIG. 19;

[0039] FIG. 23 shows a perspective view of a stator of the PF-driven propulsion system of FIG. 19;

[0040] FIG. 24 shows a perspective view of a forward thrust bearing of the PF-driven propulsion system of FIG. 19;

[0041] FIG. 25 shows a perspective view of a rotatable unit of the PF-driven propulsion system of FIG. 19;

[0042] FIG. 26 shows a flowchart of a method for utilizing a free-floating body to capture energy from wave movements in a body of water;

[0043] FIG. 27 shows a flowchart of a method for stationkeeping and / or adjusting a translational position of a free-floating body on a surface of a body of water; and

[0044] FIG. 28 shows a flowchart of a method of propelling an object using a PF-driven propulsion system.DETAILED DESCRIPTION OF THE INVENTORS’ PREFERRED EMBODIMENTS

[0045] Referring now to FIG. 1, a schematic diagram of a wave energy harvesting system 100 is shown. A set of Cartesian coordinate axes 150 is shown in FIG. 1, for contextualizing positions of the various components of the wave energy harvesting system 100. Specifically, x-, y-, and z-axes are provided which are mutually perpendicular and / or orthogonal to one another. In some embodiments, a direction of gravity may be parallel to and coincident with a negative direction of the z-axis. In some embodiments, a surface 105 of a body of water 104 may include (e.g., be coincident with), at rest, the x- and y-axes and / or may be parallel to the x- and y-axes.

[0046] The wave energy harvesting system 100 may include a free-floating body 101 , which may be, as described above, an object deployed in a body of water. In an example embodiment, the free-floating body 101 may be configured as a wave engine 101. FIG. 2, for example, details one embodiment of such a wave engine which may be included in the wave energy harvesting system 100 and propelled by device utilizing energy from pressurized water, such as a PF-driven propulsion system. In some embodiments, the wave engine 101 may include one or more assemblies 120a, 120b operable to perform stationkeeping (e.g., within a geographic area 124) and / or adjust translational position on the surface 105 of the body of water 104 on which the free-floating body 101 floats and moves (e.g., translates and / or rotates).

[0047] In an example embodiment, the one or more assemblies 120a, 120b may be configured to induce motion of the wave engine 101 so as to adjust horizontal (e.g., along thesurface 105) translational motion thereof via conversion of energy from a pressurized fluid into torque. At least some of the one or more assemblies 120a, 120b, such as one or more first assemblies 120a, may be configured as devices for propelling the free-floating body 101 without demanding use of motors or gears. The devices may be PF-driven propulsion systems 120a, each having a propeller 121 coupled to a turbine (not shown in FIG. 1) to assist with adjusting a translational position of the free-floating body 101. In another example embodiment, the one or more first assemblies 120a may be configured to induce rotation of the wave engine 101 to produce a lift force resulting from a Magnus effect generated by the induced rotation. Further propulsion of the free-floating body 101 along a desired direction (e.g., along the x-y plane) may be provided by others of the one or more first assemblies 120a configured as the PF-driven propulsion systems 120a, as shown in FIGS. 2-17. Details of controlling a position of an object, such as the free-floating body 101 , in an aquatic environment is depicted in a flow chart in FIG. 18 and corresponding adjustments to parameters of the PF-driven propulsion systems is shown in a flow chart in FIG. 19. Operation of the PF-driven propulsion systems 120a is described in detail with reference to the flow chart of FIG. 20.

[0048] As described above, the one or more first assemblies 120a may be configured as PF- driven propulsion systems 120a, although the one or more first assemblies 120a may take any one or a combination of various other configurations. In some embodiments, for instance, the first assemblies 120a may be limited to one or more extensions outwardly protruding from an external or exterior housing 102 of the free-floating body 101, e.g., the propeller 121 and the turbine are not included. In such embodiments, the one or more first assemblies 120a may expel the pressurized fluid in a manner that similarly generates the Magnus effect to enable stationkeeping and / or adjustment of the translational position of the free-floating body 101. In additional or alternative embodiments, the one or more assemblies 120a, 120b may be configured as one or more recesses inwardly extending into the external housing 102.

[0049] Though exemplified herein in the context of wave engines, the free-floating body 101 may be configured as any free-floating body capable of self-propulsion, e.g., by extracting energy from stored fuel, inducing a flow of pressurized water, and / or harnessing one or more ambient environmental forces, and / or propulsion driven by energy extracted from stored fuel so as to translate along the surface 105 of the body of water 104. For example, the free-floating body 101 may he a ship 101 (such as a deployment ship, a tankership or other storage vessel, or another transport vessel), a buoy 101, a wind turbine 101, an offshore platform 101, such as a data center, etc.

[0050] In some embodiments, the external housing 102 of the free-floating body 101 may be formed from a sufficiently durable material so as to withstand extremes of one or more ambient environmental conditions, such as winds, water waves, ambient temperature, etc. For example, the external housing 102 may be formed from steel, aluminum, and / or other metals or alloys thereof, and / or cement, fiberglass, carbon fiber, and / or plastic.

[0051] In some embodiments, the external housing 102 may be configured as a rotationally symmetric body. Specifically, the external housing 102 may exhibit a rotational and / or axial symmetry defined with respect to a central rotational axis 151 (e.g., a vertical, or nominally vertical, axis parallel with the z-axis and / or nominally orthogonal to the surface 105 of the body of water 104 at rest). The rotationally symmetric body may be configured so as to include any one of a variety of three-dimensional shapes, such as spherical, ellipsoidal, and / or polygonal shapes. For example, the rotationally symmetric body may be cylindrical or quasi- cylindrical in shape [such shapes may generate larger lift coefficients from the Magnus effect relative to certain other shapes, such as spherical configurations (e.g., lift coefficients of about 15 as compared to lift coefficients of about 0.5, respectively)]. As used herein, “quasi- cylindrical” may refer to an otherwise cylindrical shape which is modified in one or more dimensions. For example, the rotationally symmetric body may be configured in a substantially cylindrical shape at a first end and a substantially spherical shape at an opposing second end (e.g., the opposing second end opposing the first end with respect to the z-axis). As such, the external housing 102 may be configured for substantially unencumbered translational and / or rotational motion in the body of water 104.

[0052] In embodiments where the free-floating body 101 is configured as the wave engine 101, water may pass into and through the wave engine 101 with upward and downward (e.g., heave) motion 106 (e.g., in a positive direction of the z-axis and the negative direction of the z-axis, respectively) of water waves. As described in greater detail below with reference to FIG. 2, the upward and downward motion 106 may induce the water passing into and through the wave engine 101, energy from which may be captured and converted to an energy product 108 (as indicated by a dashed arrow 126a). The energy product 108, for example, may include one or more of an electrolysis product or other fuel, such as H2 gas, HC1, etc.,removed carbon, minerals, or an executed computational algorithm, such as a proof-of-work mechanism for a cryptocurrency.

[0053] In some embodiments, the free-floating body 101 may include an onboard controller or other computing device 110, which may include non-transitory memory on which executable instructions may be stored. The executable instructions may be executed by one or more processors of the onboard controller 110 to perform various functionalities of the free- floating body 101. Accordingly, the executable instructions may include various routines for operation, propulsion, maintenance, tracking, and testing of the free-floating body 101. The onboard controller 110 may be communicably coupled to various components (e.g., valves, power supplies, etc.) of the free-floating body 101 to command actuation and use thereof (wired and / or wireless communication paths between the controller 1 10 and the various components are omitted from FIG. 1 for clarity).

[0054] In certain embodiments, the onboard controller 110 may be communicably coupled to a remote controller or computing device 114 via a wireless network 112. The remote controller 114 may be configured in a substantially similar manner to controller 110, excepting, in some examples, one or more modifications or differences for a given use case (when the term “substantially” is used herein, it is meant that the recited relationship, characteristic, parameter, or value need not be realized with exact precision, but that deviations or variations known to those of skill in the art may occur to an extent that does not preclude the effect the relationship, characteristic, parameter, or value was intended to provide). For example, the remote controller 114 may be positioned so as to be accessible to an operator of the wave energy harvesting system 100, e.g., on a ship or in a physical structure 1 16 on land 1 18 (as illustrated in FIG. 1 ). As such, even when the free-floating body 101 is not geographically located within a national or subnational jurisdiction, the free- floating body 101 may nevertheless be in continuous (e.g., substantially uninterrupted) or periodic communication with the remote controller 114 which may be geographically located within a national or subnational jurisdiction (e.g., on the land 118).

[0055] In some embodiments, because the remote controller 114 may be configured for use by the operator, the remote controller 114 may include a user interface at which the operator may enter commands or otherwise modify operation of the wave energy harvesting system 100. The user interface may include various components for facilitating operator use of the wave energy harvesting system 100 and for receiving operator inputs (e.g., requests to adjusttranslational motion of the free-floating body 101), such as one or more displays, input devices (e.g., keyboards, touchscreens, computer mice, depressible buttons, mechanical switches, other mechanical actuators, etc.), lights, etc. In additional or alternative embodiments, the controller 110 may be configured with the user interface as described hereinabove.

[0056] In some embodiments, the remote controller 114 may be configured to operate autonomously or semi-autonomously to modify, control, adjust, and / or alter operation of the wave energy harvesting system 100 and / or components thereof, including, but not limited to, adjusting, configuring, specifying, programming, and / or controlling translational motion of the free-floating body 101.

[0057] In an example embodiment, the one or more assemblies 120a, 120b may include the one or more first assemblies 120a and / or one or more second assemblies 120b. In some embodiments, the one or more first assemblies 120a may outwardly protrude from one or more side surfaces of the external housing 102 (e.g., extending substantially perpendicular to the z-axis). In additional or alternative embodiments, and as shown in FIG. 1, the one or more first assemblies 120a may be submersed within the body of water 104 when the free-floating body 101 is floating on, and / or at, the surface 105 of the body of water 104. As such, the one or more first assemblies 120a may assist with propulsion of the free-floating body 101 by generating one or more localized currents within the body of water 104, e.g., resulting in creation of a torque or moment inducing rotation of the free-floating body 101. In other embodiments, the one or more first assemblies 120a may be exposed to air and winds above the surface 105 of the body of water 104 when the free-floating body 101 is floating on, and / or at, the surface 105.

[0058] In one example, at least one of the one or more first assemblies 120a may include one or more ports (not shown at FIG. 1) configured to expel pressurized water from within the free-floating body 101 into or above the body of water 104 (depending on whether or not the one or more first assemblies 120a is submersed within the body of water 104). The pressurized water may be pressurized by a combination of wave motion, a specific arrangement of internal components of the free-floating body 101, and / or a gas pressure exerted by a stored gas. In an additional or alternative example, at least one of the one or more first assemblies 120a may include one or more inboard turbines or propellers [e.g., one or more turbines or propellers enclosed or otherwise housed within the external housing 102(as used herein, a first component may be “enclosed” within a second component when the first component is contained and housed within physical bounds of a second component without any portion of the first component protruding outwardly from the second component, with the first component optionally in fluidic communication with an environment external to the second component)] configured to propel a flow of water from within the free-floating body 101 and through at least one of the one or more ports.

[0059] In an additional or alternative example, the one or more first assemblies 120a may include one or more outboard propellers (e.g., the propellers 121 positioned external to the external housing 102) configured to propel a flow of water within the body of water 104. In an additional or alternative example, the one or more first assemblies 120a may be configured as one or more adjustable rudders or flaps. In some embodiments, as described herein, the free-floating body 101 the one or more first assemblies 120a may be the PF-driven propulsion systems 120a arranged external to the external housing 102 and coupled to the ports expelling the pressurized water. Expulsion of the pressurized water may drive rotation of the turbines located within the PF-driven propulsion systems 120a. The turbines may be coupled to the propellers 121 such that energy captured from the pressurized water may be converted to torque to drive rotation of the propellers 121 via a two-stage system described further below.

[0060] In some embodiments, the one or more second assemblies 120b may outwardly protrude from a top surface of the external housing 102 (e.g., extending substantially parallel to the z-axis). In additional or alternative embodiments, and as shown in FIG. 1, the one or more second assemblies 120b may be exposed to air and winds above the surface 105 of the body of water 104 when the free-floating body 101 is floating on, and / or at, the surface 105. As such, the one or more second assemblies 120b may assist with propulsion of the free- floating body 101 by harnessing an external force, e.g., from the wind (as indicated by arrows 107). In one example, the one or more second assemblies 120b may be configured as a static (e.g., rigidly affixed) wind turbine configured to harness external force from the wind, the static wind turbine including one or more vanes rigidly affixed to a portion of the external housing 102 extending above the surface 105 of the body of water 104 (e.g., the top surface of the external housing 102).

[0061] In some embodiments, the one or more assemblies 120a, 120b may include one or more continuously adjustable parameters such that the direction and / or the magnitude of the translational motion may be dynamically adjusted and / or maintained. In some embodiments,dynamically adjusting the one or more continuously adjustable parameters may concomitantly adjust a speed at which the free-floating body 101 is rotated 122, a direction (e.g., clockwise or counterclockwise) in which the free-floating body 101 is rotated 122, e.g., so as to adjust a lift coefficient and / or a direction of the lift force generated via the Magnus effect, and / or a speed and direction that the free-floating body is translated. In one example, a change in one or more ambient environmental parameters affecting the translational motion of the free-floating body 101 may be detected and accounted for by dynamically adjusting the one or more continuously adjustable parameters of the one or more assemblies 120a, 120b. In an additional or alternative example, the one or more continuously adjustable parameters may be adjusted responsive to receiving, e.g., from the remote controller 114, an indication to adjust the translational motion (e.g., the direction and / or the magnitude of the translational motion) of the free-floating body 101. In some embodiments, the one or more continuously adjustable parameters may include port angles, valve openings, and / or propellor speeds. In some embodiments, dynamic adjustments to the one or more continuously adjustable parameters may be executed on a periodic basis, such as every 12 hours.

[0062] In some embodiments, the translational motion of the free-floating body 101 may be adjusted by changes to a rate and / or a direction of the rotation of the free-floating body 101 (and thus a direction and a magnitude of lift due to the Magnus effect) so as to maintain the free-floating body 101 within a defined geographic area 124 of the body of water 104. In one example, the defined geographic area 124 may be selected so as to prevent collisions of the free-floating body 101 with the land 118 (e.g., a rock, an island, or a continent), other free- floating bodies 101, ships, buoys, offshore platforms, etc. Accordingly, the defined geographic area 124 may be selected to be an open and sufficiently deep expanse of water in a low trafficked area (e.g., away from shipping lanes). In some embodiments, the defined geographic area 124 may be a bounded geographic area, such as a polygonal or elliptical region. The bounded geographic area may be defined by a largest dimension, such as 500 miles, and / or a total area. In other embodiments, the defined geographic area 124 may be an annular geographic area encircling the Earth, e.g., within a defined distance of a given latitude.

[0063] In some embodiments, the adjustments to the translational motion may be executed based on a manual operator input, e.g., at the user interface of the remote controller 114. In additional or alternative embodiments, the adjustments to the translational motion may beautomatically adjusted, e.g., to maintain the free-floating body 101 within the defined geographic area 124, based on feedback from one or more sensors and / or data received via the wireless network 112. As an example, the free-floating body 101 may include an accelerometer (e.g., an inertial measurement unit; not shown) configured to gather changes in local positional data, e.g., resulting from water wave motions. As an additional or alternative example, the free-floating body 101 may include a global positioning system (not shown) configured to gather geographic positional data. As an additional or alternative example, the free-floating body 101 may include a wind speed sensor (not shown) configured to measure wind speed. As an additional or alternative example, such data (e.g., the positional data and / or the wind speed) may be received via the wireless network 112, in addition to other data such as meteorological data (e.g., water wave height, direction of water wave propagation, water wave period, weather, etc.). In some embodiments, directions and magnitudes of applied forces may be inferred based on the feedback from the one or more sensors and / or the data received via the wireless network 112, such that specific operational parameters (e.g., the one or more continuously adjustable parameters) may be adjusted responsive such that changes in individual applied forces may be accounted for with specificity.

[0064] An overall energy flow 126 of the wave energy harvesting system 100 is schematically depicted in FIG. 1, in which energy captured at the free-floating body 101 from water induced therethrough by the upward and downward motion 106 of the water waves (as indicated by the dashed arrow 126a) may be converted to the energy product 108 and transferred to a ship 128 (as indicated by a dashed arrow 126b) and then transferred from the ship 128 to a land-based vehicle 130 (as indicated by a dashed arrow 126c) to be transported to a storage facility and / or an end user for consumption. For example, in some embodiments, the wave energy harvesting system 100 may include a plurality of nodes including a plurality of free-floating bodies 101, one or more ships 128 to transport a plurality of energy products 108 from the plurality of free-floating bodies 101 to the land 118, and one or more land-based vehicles 130 to transport the plurality of energy products 108 from the one or more ships 128 to the storage facility and / or the end user.

[0065] In an example embodiment, the energy product 108 may be a fluid (e.g., a liquid or a gas) which is transferred from the free-floating body 101 to the ship 128 via one or more conduits being configured to transiently fluidly couple an internal reservoir of the ship 128 toan internal reservoir of the free-floating body 101. In certain embodiments, the one or more conduits may include a plurality of internal passages (not shown at FIG. 1), each of which may convey a different fluid between the free-floating body 101 and the ship 128. As an example, the one or more conduits may include a first internal passage configured to supply an energy product precursor (e.g., an electrolysis reactant, such as deionized water) from the ship 128 to the free-floating body 101 so as to replace the energy product 108 being transferred to the ship 128. Accordingly, in such an example, the one or more conduits may further include a second internal passage configured to siphon the energy product 108 (e.g., an electrolysis product, such as hydrogen gas) from the free-floating body 101 to the ship 128. As such, the overall energy flow 126 may be maintained by periodically replenishing a capacity of the free-floating body 101 to capture energy.

[0066] Referring now to FIG. 2, a simplified perspective view of a wave engine 201 is shown. A set of Cartesian coordinate axes 250 is shown in FIG. 2 for contextualizing positions of the various components of the wave engine 201 and for comparison between views shown. Specifically, x-, y-, and z-axes are provided which are mutually perpendicular and / or orthogonal to one another. In some embodiments, a direction of gravity may be parallel to and coincident with a negative direction of the z-axis.

[0067] The wave engine 201 may be an embodiment of the free-floating body 101 of FIG. 1 and may include an external or exterior housing 202 and assemblies 220, similar to the external housing 102 and the one or more assemblies 120a of FIG. 1, respectively. The assemblies 220 may optionally include a pair of extensions 230 protruding outwardly from the external housing 202, the pair of extensions 230 operable to rotate the wave engine 201 in a body of water, as described above with respect to the assemblies 120a of FIG. 1 . The assemblies also include one or more PF-driven propulsion systems 240, similarly protruding outwardly form the external housing 202 of the wave engine 201.

[0068] In some embodiments, the wave engine 201 may freely float (e.g., float untethered to land, a seafloor, a lakebed, another floating body, etc.) on a surface of a body of water (not shown at FIG. 2). Specifically, buoyancy of the wave engine 201 may be assisted, at least in part, by gas captured and enclosed or otherwise housed within an upper hull enclosure or buoy 202a of the external housing 202. In an example embodiment, the upper hull enclosure 202a may be at least partially hollow [e.g., the upper hull enclosure 202a may include an internal reservoir enclosed or otherwise housed therein (not shown at FIG. 2)] so as to befilled with the captured gas. The captured gas may include, for example, air and / or another gas, such as hydrogen and / or nitrogen, supplied at a manufacturing location or a deployment location. Additionally or alternatively, the air and / or another gas may enter the upper hull enclosure 202a from a surrounding, ambient environment. Additionally or alternatively, the captured gas may be generated via a conversion process occurring within the wave engine 201, wherein the conversion process may convert energy captured by the wave engine 201 to an energy product (e.g., the conversion process may be an electrolysis reaction and the energy product may include an electrolysis product such as hydrogen gas).

[0069] In an example embodiment, the captured gas within the upper hull enclosure 202a may be compressed therein so as to exhibit a gas pressure greater than a pressure of the surrounding ambient environment (e.g., atmospheric pressure at the surface of the body of water on which the wave engine 201 floats). In some embodiments, the captured gas may be compressed, at least in part, by water that has entered the external housing 202 via a lower aperture 203. More specifically, the external housing 202 may include a lower inertial water tube or pipe 202c connected to the upper hull enclosure by a collar 202b and fluidly coupled to each of the lower aperture 203 and the upper hull enclosure 202a through which the water that has entered the external housing 202 may pass and enter into the upper hull enclosure 202a. In certain embodiments, the water that has entered the external housing 202 may be injected, propelled, or otherwise induced through the lower aperture 203 as a result of water wave motion, whereby entering water may rise and fall, e.g., proportionate with or otherwise responsive to the water wave motion.

[0070] In some embodiments, the water that has entered the external housing 202 may be released into the surrounding ambient environment via one or more upper apertures 232 fluidly coupled to the internal reservoir enclosed within the upper hull enclosure 202a such that a pressure and / or a flow of the water through the external housing 202 may be maintained and / or adjusted and / or the wave engine 201 may be propelled by inducing a localized current within the body of water, e.g., along a negative direction of the y-axis. Specifically, the one or more upper apertures 232 may be respectively fluidly coupled to the internal reservoir via one or more passages (not shown at FIG. 2), each of the one or more passages housing a turbine configured to capture energy via water exiting the internal reservoir (e.g., the turbine may be configured to adjust a torque thereof dynamically responsive to a pressure of the exiting water). The one or more upper apertures 232 may bepositioned on the upper hull enclosure 202a as shown in FIG. 2, or, in additional or alternative embodiments, the one or more upper apertures 232 may be positioned elsewhere on the external housing 202, such as on the collar 202b. Though one upper aperture 232 is visible in FIG. 2, in additional or alternative embodiments, a plurality of upper apertures 232 may be included, each of the plurality of upper apertures 232 fluidly coupled to the internal reservoir. In such embodiments, the plurality of upper apertures 232 may be positioned on the external housing 202 substantially adjacent to one another (e.g., on a same side of a plane including a central rotational axis 251 ) or substantially distant from one another (e.g., on opposite sides of a plane including the central rotational axis 251 and parallel to a plane defined by the y- and z-axes). In an example embodiment, a pair of upper apertures 232 may be positioned on opposite sides of the external housing 202 from one another (e.g., along the y-axis and on opposite sides of a plane parallel to a plane formed by the x- and z-axes).

[0071] As shown in FIG. 2, a PF-driven propulsion system 240 may be coupled to the upper hull enclosure 202a, external to the upper hull enclosure 202a. In one embodiment, the PF- driven propulsion system 240 may be attached to the upper hull enclosure 202a via a feed plate 242 (depicted as transparent for clarity). The PF-driven propulsion system 240 may be positioned such that a feed pipe 244 of the PF-driven propulsion system 240 is aligned with the upper aperture 232 of the upper hull enclosure 202a to deliver the pressurized water through the feed pipe 244 to an interior of the PF-driven propulsion system 240.

[0072] In at least one embodiment, the PF-driven propulsion system 240 may include a propeller 246, which may either form a portion of an outer casing of the PF-driven propulsion system 240 with blades extending outwards (as shown in FIG. 2), or may be at least partially circumferentially surrounded by the outer casing with the blades extending inwards. The propeller 246, as well as a turbine coupled to the propeller 246, may be driven by the pressurized water to rotate about a central axis of rotation 241 of the PF-driven propulsion system 240, which is depicted as parallel with the x-axis. At least one additional PF-driven propulsion system may be coupled to the wave engine 201, opposite of the PF-driven propulsion system 240 shown in FIG. 2, and oriented to provide synchronized thrust in a common direction. For example, as the propellers 246 rotate, the wave engine 201 may be propelled along the x-axis, as indicated by arrow 243.

[0073] While the PF-driven propulsion system 240 is depicted with the propeller 246 having blades that extend outwards and away from the central axis of rotation 241 of the PF-driven propulsion system 240, at higher fluid pressures (e.g., of an available range of fluid pressures), an embodiment having inward-pointing blades may provide more efficient energy transfer for propulsion, as described further below. Further, variations to the propeller configurations depicted herein are possible without departing from the scope of the present disclosure. For example, the blades may vary in shape and size, and orientation. As one example, the blades may be inward pointing blades that are coupled to a ring base or sleeve that circumferentially surrounds the turbine. The ring base may be connected to the turbine to spin with the turbine in unison. Additionally or alternatively, the blades, whether inward or outward pointing, may be angled along a forward or backward direction relative to a direction that the wave engine 201 may travel, as indicated by arrow 243.

[0074] A first embodiment of a PF-driven propulsion system 300, which may be similar to the embodiment of the PF-driven propulsion system 240 of FIG. 2, is depicted from a first perspective view in FIG., 3, a second perspective view in FIG. 4, a cross-sectional view in FIG. 5, and an exploded view in FIG. 6. A set of Cartesian axes 350 are provided for contextualization and comparison between views. Outer surfaces of the PF-driven propulsion system 300 may be smooth and curved and shaped to minimize drag. A main body 302 of the PF-driven propulsion system 300 has a cross-sectional shape along its central axis of rotation 301, resembling a tear drop. For example, an upstream end 304 of the main body 302 may be more rounded and blunt than a downstream end 306 of the main body 302, the downstream end 306 having a tapered profile.

[0075] Components forming an exterior or outer portion of the PF-driven propulsion system 300 include, along a downstream direction 303, a feed pipe 308, a nose cone 310, a turbine wheel 12, a propeller 314, a prop-standoff 316, and a tail cone 318. As indicated in FIGS. 3 and 5, the feed pipe 308, the nose cone 310 may be included in a first portion 305a of a stationary unit 305 of the PF-driven propulsion system 300 and the tail cone 318 may be included in a second portion 305b of the stationary unit, where the stationary unit 305 may be a first stage 305 of the PF-driven propulsion system 300. The turbine wheel 312 may be included in a rotatable unit 307 of the PF-driven propulsion system 300, which may also be a second stage 307 of the PF-driven propulsion system 300.

[0076] As shown in FIGS. 3 and 4, the feed pipe 308, the nose cone 310, and the tail cone 318 may have continuous surfaces without any openings through which water can pass between an interior and an exterior of the components. The main body 302 (e.g., includingthe nose cone 310, the turbine wheel 312, the prop-standoff 316, and the tail cone 318) of the PF-driven propulsion system 300, however, is not a sealed body. Instead, the prop-standoff 316 may have a plurality of openings through which water may exit the PF-driven propulsion system 300. Detailed views of the components of the PF-driven propulsion system 300 are shown in FIGS. 7-17 and described further below.

[0077] As shown in FIG. 5, the PF-driven propulsion system 300 also comprises inner components that are at least partially surrounded by one or more outer components. The configuration and relative positioning of the components may increase an efficiency of turbine operation without relying on draft tubes or expanders to generate a pressure differential, e.g., by creating suction downstream of a turbine. For example, water exiting the turbine may have non-zero velocity, and therefore, non-zero kinetic energy (e.g., axial velocity). In some examples, turbine efficiency may be increased via a draft tube coupled to the turbine to use kinetic energy available at an exit of the turbine runner by causing water exiting the turbine to expand and convert the remaining kinetic energy into potential energy (e.g., suction pressure). In the embodiments described herein, however, incorporation of the draft tubes may be obviated because water flowing between components of the PF-driven propulsion system (e.g., between the propeller 314 and the rotor 412) undergoes expansion due to geometries of the components as shown herein. As such, an effect of a draft tube is provided by the PF-driven propulsion system 300, as well as an alternate embodiment described further below, without physically including the hardware for the draft tube.

[0078] The inner components include a stator 402, a forward thrust bearing 404, a shaft 406, a turbine 408, and a rear thrust bearing 410. The stator 402, the forward thrust bearing 404, the shaft 406, and the rear thrust bearing 410 may be included in the stationary unit 305 of the PF-driven propulsion system 300 and the turbine 408 may be included in the rotatable unit 307 of the PF-driven propulsion system 300. In one embodiment, the stator 402 and the forward thrust bearing 404 may be included in the first portion 305a of the stationary unit 305, the rear thrust bearing 410 may be included in the second portion 305b of the stationary unit 305 and the turbine 408 may be located in between the first and second portions 305a, 305b of the stationary unit 305, with the shaft 406 connecting the first and second portions 305a, 305b to one another.

[0079] The turbine 408 includes the turbine wheel 312, the prop-standoff 316, and a rotor412. Although depicted to receive an axial flow of incoming pressurized fluid and output anaxial flow of depressurized fluid, it will be appreciated that various other turbine configurations may be used in the embodiments of the PF-driven propulsion system described herein. For example, the turbine may instead receive and / or output radial or circumferential flows of fluid, or any combination of axial, radial, and circumferential input and output flows. The turbine 408 is coupled to the propeller 314 at the turbine wheel 312 and the prop-standoff 316 is coupled to each of the rotor 412 and the propeller 314. Further, the rotor 412 is circumferentially surrounded by the propeller 314 and spaced away from the propeller 314. In other words, the propeller 314 encircles an entire diameter of the rotor 412 but does not contact the rotor 412. Water may therefore flow between inner surface of the propeller 314 and an outer surface of the rotor 412.

[0080] The turbine 408 and the propeller 314 may spin together, in unison, as a single unit. When rotation of the turbine 408 is compelled by a flow of pressurized water through the PF- driven propulsion system 300, the propeller 314 spins with the turbine 408 at a same rpm as the turbine 408. Rotation of the turbine 408 is transferred to the propeller 314 through the turbine wheel 312.

[0081] The rotor 412 is positioned between the forward thrust bearing 404 and the rear thrust bearing 410 along the central axis of rotation 301. In at least some embodiments, the rear thrust bearing 410 may be omitted from the PF-driven propulsion system 300. For example, the rear thrust bearing 410 may be omitted in instances where zero load is anticipated to be imposed thereat. In other examples, the rear thrust bearing 410 may be present to inhibit axial sliding of the propeller 314 when the propeller is stationary. Further, a hydrodynamic fluid film may not be formed between the rear thrust bearing 410 and the rotor 412. Instead, a gap 416b between the rear thrust bearing 410 and the rotor 412 may be larger than a gap 416a between the forward thrust bearing 404 and the rotor 412, and may allow water to leak therethrough. Each of these components may circumferentially surround the shaft 406, which may be a cylindrical tube. However, the rotor 412 may rotate around the shaft 406 while the forward thrust bearing 404 and the rear thrust bearing 410 are fixedly coupled to the shaft 460. For example, an inner surface 418 of the forward thrust bearing 404 may have a press-fit or shrink-fit interaction with an outer surface 420 of the shaft 460 such that the surfaces are in face-sharing contact. The forward thrust bearing 404, rear thrust bearing 410, and the shaft 406 do not rotate and may be fixed in place.

[0082] The rotor 412 may have planar surfaces 414 that are perpendicular to the central axis of rotation 301 that are proximate to but spaced away from planar surfaces of the forward thrust bearing 404 and the rear thrust bearing 410. For example, the gaps 416a, 416b may be present between the planar surfaces 414 of the rotor 412 and the planar surfaces of the forward and rear thrust bearings 404, 410, respectively. Further, a gap 417 may be present between an inner surface 415 of the rotor 412 and the outer surface 420 of the shaft 406. Within the gaps 416a and 417, fluid films may form which may stabilize rotation of the turbine 408. Widths (e.g., measured along the central axis of rotation 301 ) of the gaps 416a, 417 may be varied, e.g., during manufacture and assembly of the system 300, according to a viscosity of the fluid forming the film therein. For example, the widths of the gaps 416a, 417 may be smaller when the fluid is seawater and wider when the fluid is oil. As another example, the width of the gaps 416a, 417 may be decreased when the PF-driven propulsion system is to be used in warmer seawater than in colder seawater.

[0083] The forward thrust bearing 404 may be fixed in place and maintained stationary relative to the turbine 408 by the stator 402. The stator 402 may be a ring with an inner diameter and geometry that matches an outer diameter and geometry of the forward thrust bearing 404. The forward thrust bearing 404 may be coupled to the stator 402 by fasteners, for example, and an outer rim of the stator 402 may be mated to an edge of the nose cone 310. The stator 402 may be fixedly coupled to the edge of the nose cone 310, such as by welding, fasteners, etc., which may anchor the stator 402 in place.

[0084] The anchoring of the stator 402 in place may further allow the shaft 406 to be locked in place such that shaft 406 does not rotate or translate axially along the central axis of rotation 301 . For example, face-sharing contact between the inner surface 418 of the forward thrust bearing 404 and the outer surface 420 of the shaft 406 may maintain a stationary position of the shaft 406. The shaft 406 may have a length that extends between an outermost end of the forward thrust bearing 404 and an outermost end of the rear thrust bearing 410.

[0085] The rear thrust bearing 410 may be maintained in place by face-sharing contact between an inner surface 422 of the rear thrust bearing 410 and the outer surface 420 of the shaft 406. The rear thrust bearing 410 may, in turn, hold the tail cone 318 in place via coupling of an outer rim of the rear thrust bearing 410 to an edge of the tail cone 318. In this way, only a central portion of the PF-driven propulsion system 300 rotates (e.g., the rotatable unit 307), where the central portion comprises the propeller 314 and the turbine 408, whichmay be arranged concentrically. The relative positioning of the components allows the length of the shaft 406 to be minimized and an overall footprint of the PF-driven propulsion system 300 to be compact. Components of the PF-driven propulsion system 300 may be formed of materials that are rigid, durable, and tolerant to harsh environmental conditions. For example, the components may be formed of one or more of plastic, a composite, aluminum, stainless steel, other metals and metal alloys, carbon fiber, and fiberglass.

[0086] Turning now to FIG. 6, the PF-driven propulsion system 300 is shown in an exploded view. It will be noted that an order of the components does not reflect an actual order of the components, when assembled, along the downstream direction 303, but is, instead, arranged to reduce obscured views of the components. At the upstream end 304 of the PF-driven propulsion system 300, the feed pipe 308 may be a detachable tube that may be coupled to the nose cone 310 via, for example, fasteners at one end of the feed pipe 308 and coupled to a feed plate, such as the feed plate 242 of FIG. 2. The feed pipe 308 may have a cross-sectional geometry resembling a tear drop with a blunt end oriented upstream and a tapered end oriented downstream. The cross-sectional profile of the feed pipe 308 may minimize drag.

[0087] An interior of the feed pipe 308 may have smooth, curved surfaces to minimize friction between the surfaces and fluid flowing therethrough. In one embodiment, pressurized water, such as seawater, may flow from an object to which the PF-driven propulsion system 300 is coupled, such as the wave engine 201 of FIG. 2, into the nose cone 310 through the feed pipe 308.

[0088] The shaft 406 may be located in a mid-portion of the PF-driven propulsion system 300 and fixedly coupled to the forward thrust bearing 404 and the rear thrust bearing 410, as described above. As such, a length of the shaft 406, as measured along the central axis of rotation 301, may be less than a length of the main body 302 of the PF-driven propulsion system. The shaft 406 may be a smooth cylinder with a wall thickness that is sufficient to support the thrust bearings. The propeller 314 is also located at the mid-portion of the PF- driven propulsion system 300, and may include a plurality of propeller blades 602.

[0089] The plurality of propeller blades 602 may each form an individual, separate segment of the propeller 314. For example, each of the plurality of propeller blades 602 may include a base that forms a section of an annular collar of the propeller 314 when the propeller 314 isassembled. The collar of the propeller 314 may be coupled, along one edge, to the turbine wheel 312, as shown in FIG. 5. Dimensions of the plurality of propeller blades 602 may provide an outer diameter of the propeller 314 that is sized to be proportional to a diameter of the turbine 408 (as indicated in FIG. 4). For example, the outer diameter of the propeller 314 may be maximum diameter that allows the propeller 314 to rotate at the same rpm as the turbine 408. Although the propeller 314 is shown having four propeller blades, the propeller 314 may have a different quantity of propeller blades in other examples, such as 3, 6, or 10.

[0090] The remaining components of the PF-driven propulsion system 300 are shown individually and in greater detail in FIGS. 7-17. It will be appreciated that the components shown and described herein are non-limiting examples, and variations in relative dimensions and geometry may vary in other embodiments without departing from the scope of the present disclosure.

[0091] The nose cone 310 is shown in FIG. 7, which may form a section of an outer casing of the PF-driven propulsion system 300 having a semi-spherical portion 702 with a flanged conduit 704 extending tangentially from the shell. The flanged conduit 704 may have a cross- sectional geometry that matches the cross-sectional geometry of the feed pipe 308. A flanged end of the flanged conduit 704 may therefore be coupled to an end of the feed pipe 308 to form a continuous unit with the feed pipe 308. By positioned the flanged conduit 704 tangential to the semi-spherical portion of the nose cone 310, pressurized water flowing into the semi-spherical portion 702 may be swirled as the pressurized water enters the semi- spherical portion 702.

[0092] For example, the pressurized water may enter the nose cone 310 through the flanged conduit 704 as indicated by arrows 706. As the pressurized water flows into the semi- spherical portion 702, the flow may be compelled by an inner surface of the nose cone 310 to swirl, as shown by arrows 706. As the pressurized water flows along the downstream direction within the nose cone 310, a flow of the pressurized water may follow a helical path that compels the pressurized water to strike airfoils or fins (e.g., fins 804 of FIG. 8) of the stator 402 at, or at least close to, an angle of incidence of zero.

[0093] The pressurized water may flow from the nose cone 310 into nozzles 802 of the stator 402, as shown in FIG. 8, the nozzles 802 located along an outer perimeter of the stator 402. The stator 402 may be a ring with an outer portion formed of the nozzles 802 distributedaround a circumference of the stator 402. The nozzles 802 may be channels separated by the fins 804, which may form walls between the nozzle 802 and guide flow of water therethrough. The fins 804 may be angled and shaped to deflect the flow of water to cause the flow to form a vortex when the water exits the nozzles 802.

[0094] In one embodiment, the fins 804 may have a geometry as shown in a cross-sectional view of the stator 402 depicted in FIG. 9. The cross-sectional view may be obtained by slicing the stator 402 along line A-A’ shown in FIG. 8. Each of the fins 804 may have a tapered cross-sectional geometry, including a rounded blunt end along an upstream edge of the stator 402 and a narrow tail along a downstream edge of the stator 402. In at least one embodiment, the fins 804 may have a high amount of camber. As indicated by arrows 902, pressurized water may flow through the nozzles 802, impinge on surfaces of the fins 804 and be deflected at an increased angle a relative to the central axis of rotation 301. As one nonlimiting example, the fins 804 may be angled relative to the central axis of rotation 301 at an angle a of 70 degrees. As another example, the angle a of the fins 804, relative to the central axis of rotation 301, may be in a range of 10 degrees to 80 degrees. In another example, the fins 804 may not be parallel with or orthogonal to the central axis of rotation 301.

[0095] As an example, an effect of the fins 804 of the stator 402 on flow is depicted in FIG. 18. Incoming flow of pressurized water, as indicated by arrows 1802, may flow strike a forward end 1804 of the fins 804 at an incidence angle [>„>• Upon flowing between the fins 804 through the nozzles 802, the water may be forced to curve according to a profile of the fins 804 and emerge from the nozzles 802, as indicated by arrows 1806 at an exit angle pout. As shown in FIG. 18, Pout may be greater than Pm, which causes the water to swirl. As described above, in at least one embodiment, Pin may be zero. In at least one embodiment, P™ may be in a range of 0 degrees to 85 degrees and pout may be in a range of 60 degrees to 85 degrees.

[0096] Returning to FIG. 8, the stator 402 may include an inner portion 806 with a plurality of apertures 808 for receiving fasteners for coupling the forward thrust bearing 404 to the stator 402. As shown in FIG. 10 in a first view, the forward thrust bearing 404 may have an annular body 1002 with a sleeve 1004 protruding from an upstream face of the annular body 1002. The sleeve 1004 of the stator 402 may include a plurality of through-holes 1006 around a circumference of the sleeve 1004. The plurality of through-holes 1006 may extend entirelythrough a depth (e.g., as measured along the central axis of rotation 301) of the sleeve 1004, as illustrated in FIG. 11 in a second view of the forward thrust bearing 404.

[0097] The plurality of through-holes 1006 may enable water (e.g., seawater) to be drawn through the plurality of through-holes 1006, as indicated by arrow 1008, into the gap 416a between the forward thrust bearing 404 and the rotor 412 (as shown in FIG. 4). For example, as the rotor 412 spins, fluid in the gap 416a may form a fluid film. The rotation of the rotor 412 causes the water forming the fluid film to move radially outwards, resulting in the water being removed from the gap 416. The removal of the water may create a pressure differential that drives suction flow of the water from the interior of the nose cone 310 into the gap 416a through the plurality of through-holes 1006, thereby maintaining a constant fluid film between the rotor 412 and the forward thrust bearing 404 when the PF-driven propulsion system 300 is operating.

[0098] Formation of the fluid film to operate as a hydrodynamic bearing may further be dependent on flat landings 1106 located between grooves 1104 disposed in a downstream face of the annular body 1002. The flat landings 1106 may be segments of a planar surface of the downstream face of the annular body 1002 along which the hydrodynamic bearing may be maintained. In at least one embodiment, the flat landings 1106 may be perpendicular to the central axis of rotation 301. In other embodiments, the flat landings 1106 may be inclined pads or ramps, or articulated tilting pads. By modifying a geometry of the flat landings 1106, properties of the hydrodynamic bearing may be adjusted.

[0099] As depicted in FIG. 1 1 by arrows 1 102, water drawn into the plurality of through- holes 1006 may exit the plurality of through-holes 1006 at a downstream face of the annular body 1002 of the forward thrust bearing 404. The downstream face of annular body 1002 may include the grooves 1104 that guide inflow of the water into the gap 416a between the forward thrust bearing 404 and the rotor 412.

[0100] As shown in FIG. 12, the turbine wheel 312 may be a ring with a plurality of channels 1202 extending entirely through a depth (e.g., as measured along the central axis of rotation 301) of the turbine wheel 312. Water flowing out of the nozzles 802 of the stator 402 may flow into and through the plurality of channels 1202 of the turbine wheel 312. The plurality of channels 1202 may be separated from one another by curved walls, or buckets 1204. The buckets 1204 may extend between an outer rim 1206 and an inner rim 1208 of theturbine wheel 312. A shape of the buckets 1204 is shown in a cross-sectional view of the turbine wheel 312 illustrated in FIG. 13, where the cross-sectional view is obtained by slicing through line B-B’ indicated in FIG. 12.

[0101] As shown in FIG. 13, the buckets 1204 may have a crescent-shaped cross-sectional geometry. The shape of the buckets 1204 may allow the turbine wheel 312 to extract energy from moving water with high efficiency. For example, as shown in FIG. 4, the turbine wheel 312 may be positioned in close proximity to the stator 402 without contacting the stator. By minimizing a distance between the stator 402 and the turbine wheel 312, pressurized water that is swirled upon flowing through the nozzles 802 of the stator 402 to form a vortex upon leaving the stator 402 may flow into of the plurality of channels 1202 of the turbine wheel 12 with minimal loss of angular momentum.

[0102] The water exiting the stator 402 as a vortex may flow through the plurality of channels 1202 of the turbine wheel 312 as indicated by arrows 1302. As the water impinges on curved surfaces (e.g., concave surfaces) of the buckets 1204, energy is transferred from the water to the surfaces of the buckets 1204, which shifts the angular momentum of the water to the turbine wheel 312. As a result, the turbine wheel 312 may rotate about the central axis of rotation 301, as indicated by arrow 1210 shown in FIG. 12.

[0103] The turbine wheel 312 may have a geometry and positioning relative to adjacent components (e.g., the stator 402, the rotor 412, and the propeller 314) that allows transfer of angular momentum with maximum efficiency. For example, the turbine wheel 312 may be separated from the stator 402 by a distance that is less than 10 mm, although in embodiments where a size of the PF-driven propulsion system 300 is large, the distance between the turbine wheel 312 and the stator 402 may be greater than 10 mm. In yet other embodiments, the turbine wheel 312 may be separated from the stator 402 by less than three of the buckets 1204 (e.g., nozzle blade chords) to maximize efficiency. This may reduce loss of angular momentum of the water to less than 10%. In at least one embodiment, loss of angular momentum may be reduced to less than 1%. As a result, water leaving the turbine wheel 312 and flowing out of the PF-driven propulsion system 300 through a space between the rotor 412 and the collar of the propeller 314 (as shown in FIG. 5) may have a small amount of remaining kinetic energy that may be converted to potential energy via a draft tube effect, as described above.

[0104] The turbine wheel 312 may be fixedly coupled to the rotor 412 such that the turbine wheel 312 and the rotor 412 rotate in unison when pressurized water impinges on the buckets 1204 of the turbine wheel 312. As shown in FIG. 14, the rotor 412 may be a toroid having a groove 1402 along a portion of a depth (e.g., as measured along the central axis of rotation 301) of the rotor 412. The turbine wheel 312 may be received and coupled to the rotor 412 at the groove 1402.

[0105] An inner surface 1404 of the rotor 412 may circumferentially surround and be in face-sharing contact with the shaft 406. The inner surface 1404 may include curved grooves, or tracks 1406 extending helically along the inner surface 1404. The tracks 1406 allow matter such as debris, particulate matter, and the like, trapped between the rotor 412 and the shaft 406 to be collected into the tracks 1406 and expelled from the tracks 1406, thereby reducing wear and tear imposed on the components due to the trapped matter.

[0106] The prop-standoff 316, as depicted in FIG. 15, may be fixedly coupled to a downstream end of the rotor 412. A geometry of the prop-standoff 316 may be that of the stator 402, the prop-standoff 316 also having channels 1502 arranged around a circumference of the prop-standoff 316 along an outer portion of the prop-standoff 316 separated by fins 1504. The fins 1504 may be larger and spaced apart further from one another than the fins 804 of the stator 402. For example, the channels 1502 of the prop- standoff 316 may be larger than the nozzles 802 of the stator 402. The fins 1504 may have a similar cross-section profile as the fins 804 of the stator 402, with a blunt head of the fins 1504 arranged proximate to an upstream edge of the prop- standoff 316 and a tapered tail arranged proximate to a downstream edge of the prop-standoff 316. As the prop- standoff 316 rotates with the rotor 412, the fins 1504 may be angled, relative to the central axis of rotation 301 to move through water passing through the PF-driven propulsion system 300 at an incidence angle of zero, or near zero. In other embodiments, posts may be used instead of the fins 1504, but may create more turbulence than the fins 1504.

[0107] The rear thrust bearing 410 may be positioned downstream of the rotor 412 and spaced away from the rotor by the gap 416, as shown in FIG. 5. As illustrated in FIG. 16, the rear thrust bearing 410 may have an overall shape that is similar to the forward thrust bearing 404. For example, the rear thrust bearing 410 may have an annular body 1602 with a sleeve 1604 protruding from a downstream face of the annular body 1602, around an inner rim of the annular body 1602. The sleeve 1604 may include a plurality of slots 1606 extending alongthe central axis of rotation 301 and through an entire depth of the sleeve 1604 (e.g., along the central axis of rotation 301). The plurality of slots 1606 may increase a tolerance for misalignment between the rear thrust bearing 410 and adjacent components, and may be omitted in other embodiments. An upstream face of the rear thrust bearing 410 (not shown in FIG. 16) may be planar, smooth, and without any grooves, in contrast to the downstream face of the forward thrust bearing 404.

[0108] The rear thrust bearing 410 may be fixedly coupled to the tail cone 318, as shown in FIG. 17, at an inner groove 1702 of the tail cone 318. The tail cone 318 may form a downstream section of the outer casing of the PF-driven propulsion system 300. An inner surface 1704 of the tail cone 318 may be smooth and continuous while an outer surface 1706 of the tail cone 318 may also be smooth but may include features, such as apertures 1708 for maintaining an alignment of bolts used to secure a position of the tail cone 318. The outer surface 1706 may be curved and the tail cone 318 may taper along the downstream direction 303 to terminate at a point. An outer profile of the tail cone 318 may reduce drag and shield the inner components of the PF-driven propulsion system 300 from external objects. In at least one embodiment, the tail cone 318 may optionally include ventilation holes to allow foreign objects and debris to exit therefrom without passing through the forward and rear thrust bearings 404, 410.

[0109] A second embodiment of a PF-driven propulsion system 1900 is depicted in FIGS. 19-21 in a front perspective view, a rear perspective view, and a cross-sectional view, respectively. A set of Cartesian axes 1950 are provided for contextualization and comparison of the views shown. The PF-driven propulsion system 1900 may be used when fluid pressures delivered thereto are higher than those provided to the PF-driven propulsion system 300 of FIGS. 3-6. For example, the PF-driven propulsion system 1900 may demonstrate higher efficiency of energy conversion when fluid pressures entering the system are high, relative to a range of available fluid pressures.

[0110] The PF-driven propulsion system 1900 may have a central axis of rotation 1901 and may have an annular outer geometry with a more compact axial profile than the PF-driven propulsion system 300 of FIGS. 3-6, despite incorporating similar components to the system 300. Moreover, a shaft may be precluded from the PF-driven propulsion system 1900. As shown in FIG. 19, an upstream end 1902 of an outer surface of the system 1900 may be at least partially formed of a nose ring 1904 and a downstream end 1906 of the outer surfacemay include an outer shell 1908. A stator 1910 may be arranged between the nose ring 1904 and the outer shell 1908 and form a portion of the outer surface of the system 1900 therebetween.

[0111] An inner surface of the PF-driven propulsion system 1900 may be at least partially formed of the nose ring 1904, a forward thrust bearing 1911, a rotor 1912, and a tail ring 1914, where the forward thrust bearing 1911 may be at least partially concentric with the stator 1910 with the forward thrust bearing 1911 positioned inside (e.g., closer to the central axis of rotation 1901) of the stator 1910. The rotor 1912 and the tail ring 1914 may be formed as a single, continuous unit of a turbine 1916 that further includes a turbine wheel 1918, as shown in FIGS. 20-21. The turbine 1916 may be positioned inside of the outer shell 1908 such that the turbine 1916 may be at least partially concentrically and circumferentially surrounded by the outer shell 1908. In at least one embodiment, the turbine wheel 1918 may be concentric with and positioned inside of the outer shell 1908. Further, a shape of the outer shell 1908 may maintain an axial position of the turbine 1916 and inhibit axial sliding of the turbine 1916. The turbine 1916 may be located downstream, e.g., closer to the downstream end 1906, of the forward thrust bearing 1911.

[0112] The turbine 1916 may at be least partially concentric with a propeller 1920 that forms a central portion of the PF-driven propulsion system 1900. In at least one embodiment, at least a portion of the propeller 1920 may be circumferentially surrounded by the turbine 1916 such that the propeller 1920 is closer to the central axis of rotation 1901 than the turbine 1916. Blades 1922 of the propeller 1920 may extend from an inner surface of the turbine 1916, e.g., from inner surfaces of the rotor 1912 and the tail ring 1914, towards the central axis of rotation 1901 , without coming into contact with one another. As noted above for the propeller 314 of FIGS. 3-6, a configuration of the propeller 1920 may deviate from that shown in FIGS. 19-21 without departing from the scope of the present disclosure.

[0113] The PF-driven propulsion system 1900 may include a stationary unit 2102 and a rotatable unit 2104, as indicated in FIG. 21. In at least one embodiment, the stationary unit 2102 includes the nose ring 1904, the stator 1910, the forward thrust bearing 1911, and the outer shell 1908, and the rotatable unit 2104 includes the turbine 1916 and the propeller 1920. The rotatable unit 2104 may be supported by hydrodynamic bearings formed between components of the system, as described above for the PF-driven propulsion system 300. For example, a first gap 2106 may be present between a downstream-facing surface of theforward thrust bearing 1911 and an upstream- facing surface of the rotor 1912. In at least some embodiments, the system 1900 may include a second gap 2108 between an outer surface of the turbine wheel 1918 and an inner surface of the outer shell 1908. As described previously, a size (e.g., width) of the first and second gaps 2106, 2108, may accommodate an anticipated viscosity and temperature of a fluid medium to be flowed through the PF-driven propulsion system 1900 and leveraged to generate torque. The hydrodynamic bearings, which may be formed of the fluid medium, may promote low friction rotation of the rotatable unit 2104 while supporting a position of the rotatable unit 2104 within the PF-driven propulsion system 1900. Additionally, the hydrodynamic bearings may maintain surfaces of the rotatable unit 2104 spaced away from (e.g., not directly contacting) surface of the stationary unit 2102 which may reduce wear and tear on the components.

[0114] A relative positioning of the components of the system 1900 may compel a driving torque of the turbine 1916 (e.g., a force provided by a pressurized fluid) to equal an amount of torque demanded to spin the propeller 1920 at a target rpm and forward velocity of an object propelled by the system 1900. The components are depicted individually, in greater detail, in FIGS. 22-25.

[0115] The nose ring 1904 is shown in FIG. 22 from a rear perspective view and may include a first portion 2202, which may be shaped as an annular, hollow structure, and a second portion 2204, which may be a feed pipe 2204. Similar to the feed pipe 308 of FIGS. 3-6, the feed pipe 2204 may channel incoming pressurized fluid into the nose ring 1904 and a tangential orientation of the feed pipe 308, relative to the first portion 2202 of the nose ring 1904, may cause the incoming pressurized fluid to swirl, as indicated by arrow 2206.

[0116] As described above, by swirling the pressurized fluid as the pressurized fluid travels into an inner volume of the nose ring 1904, the inner volume at least partially enclosed by the nose ring 1904 and the forward thrust bearing 1911 (as shown in FIGS. 19-21), the pressurized fluid may strike airfoils or fins of the stator 1910 at a target incidence angle, such as a low incidence angle. In at least one embodiment the target incidence angle may be near zero degrees.

[0117] At least a portion of the pressurized fluid may pass through nozzles 2302 of the stator 1910, as shown in FIG. 23. The stator 1910 may be similar to the stator 402 of FIGS. 5- 6 and 8-9, with fins 2304 of the stator 1910 separating the nozzles 2302. The fins 2304 maybe arranged to have an effect on flow as illustrated in FIG. 18, e.g., having a high degree of camber to cause the pressurized fluid to enter the nozzles 2302 at the incidence angleand emerge from the nozzles 2302 with the exit angle [3Out.

[0118] The stator 1910 may be coupled to an outer region of the forward thrust bearing 1911, which is depicted in FIG. 24. The forward thrust bearing 1911 may have a downstream face 2402 that includes grooves 2404 separating flat landings 2406. As described above with reference to the flat landings 1 106 of FIG. 1 1, in at least one embodiment, the flat landings 2406 may be planar and oriented perpendicular to the central axis of rotation 1901. In other embodiments, however, the flat landings 2406 may be angled, inclined, and / or articulated to adjust properties of the hydrodynamic bearing formed between the forward thrust bearing 1911 and the rotor 1912.

[0119] The rotatable unit 2104 is depicted in FIG. 24 with the turbine 1916 and the propeller 1920 forming a single, continuous structure. In at least one embodiment, the rotatable unit 2104 may be a monolithic structure. In other embodiments, however, the turbine 1916 and the propeller 1920 may be separate structures. The turbine wheel 1918 may be similar to the turbine wheel 312 of FIGS. 3-6 and 12-13, having buckets 2502 that receive the pressurized fluid leaving the stator 1910 and drive rotation of the rotatable unit 2104. The buckets 2502 may extend outwards from an outer surface of the rotor 1912. As described above, the rotor 1912 and the tail ring 1914 may be continuous with one another, with the tail ring extending downstream of the rotor 1912 along the central axis of rotation 1901.

[0120] The blades 1922 of the propeller 1920 may extend inwards towards the central axis of rotation 1901 from the inner surfaces of the rotor 1912 and the tail ring 1914. The blades 1922 may be angled and / or curved to maximize propulsion provided by the blades 1922 when the rotatable unit 2104 is spinning. In at least one embodiment, the propeller 1920 and the turbine 1916 may be manufactured as a single unit such the blades 1922 are continuous with the rotor 1912 and the tail ring 1914.

[0121] Referring now to FIG. 26, a flowchart of a method 2600 for utilizing a free-floating body, such as the free-floating bodies or wave engines variously described above with reference to FIGS. 1-2, to capture energy from wave movements in a body of water is shown. In an example embodiment, water may pass through the free-floating body, induced and pressurized, at least in part, by the wave movements, exiting via one or more apertures in thefree-floating body. In some embodiments, at least a first portion of the water exiting the free- floating body may drive conversion of the captured energy into an energy product. In additional or alternative embodiments, and as described in greater detail below with reference to FIG. 27, at least a second portion of the water exiting the free-floating body may be leveraged to power propulsion of the free-floating body via one or more PF-driven propulsion systems, as described above with reference to FIGS. 2-25.

[0122] In some embodiments, the method 2600, or a portion thereof, may be implemented as executable instructions stored in non-transitory memory of a computing device, such as a controller communicably coupled to one or more actuators of the free-floating body. However, embodiments of methods for utilizing free-floating bodies to capture energy from water wave movements are not limited to the below description of the method 2600. For instance, in certain embodiments, additional or alternative sequences of steps may be implemented, e.g., as executable instructions on such a computing device, where individual steps discussed with reference to the method 2600 may be added, removed, substituted, modified, or interchanged. As one example, block 2606 is represented in dashing to indicate that implementation of the block 2606 is optional in some embodiments (such as when no rotation of the free-floating body is requested).

[0123] At block 2602, the method 2600 may include inducing water into a reservoir of the free-floating body via water wave movements. Specifically, a first aperture may permit oscillatory water wave movements into a fluid passage housed within the free-floating body.

[0124] At block 2604, the method 2600 may include transferring energy of the water wave movements to an energy product via at least the first portion of the water exiting the free- floating body. Specifically, the fluid passage may direct the first portion of the water to a second aperture, wherefrom the first portion of the water may exit the free-floating body. As the water passes through the fluid passage, the water may be pressurized, e.g., via a shape of the fluid passage and / or by gas pressure of a captured gas enclosed within the free-floating body, so as to force at least the first portion of the water through the second aperture. As at least the first portion of the water flows through the fluid passage and toward the second aperture, the flowing water may drive an energy conversion process, e.g., by powering a generator included in the free-floating body via rotation of an inboard turbine, to convert the energy of the water wave movements to the energy product.

[0125] At the block 2606, the method 2600 may include rotating the free-floating body via at least a second portion of the water exiting the free-floating body. Specifically, and as described in greater detail below with reference to FIG. 27, the fluid passage may be fluidly coupled to one or more PF-driven propulsion systems. As an example, at least the second portion of the water exiting the free-floating body may be released through the one or more PF-driven propulsion systems in one or more respective pressurized and / or propelled streams to induce the rotation and / or translation of the free-floating body. As an additional or alternative example, at least the second portion of the water may pass through one or more turbines before being released from the free-floating body into the one or more PF-driven propulsion systems, such that energy may be captured from at least the second portion of the water, e.g., to power movement of the free-floating body.

[0126] In an example embodiment, translational motion of the free-floating body may be adjusted by rotating the free-floating body, as the rotation of the free-floating body may induce a Magnus effect resulting in a lift force which adjusts the translational motion of the free-floating body. As such, in certain embodiments, the translational motion of the free- floating body may be adjusted by rotating the free-floating body via actuation of the one or more PF-driven propulsion systems without any additional auxiliary support from other components of the free-floating body (e.g., without directed translational propulsion induced by one or more additional outboard propellers generating a localized current in the body of water in an opposing direction of the translational motion, etc.). Alternatively, translational motion of the free-floating body may be adjusted by expelling at least the second portion of the water from the second aperture into at least one of the one or more PF-driven propulsion systems. Energy captured from at least the second portion of the water may drive rotation of a rotatable unit of the PF-driven propulsion system.

[0127] At block 2608, the method 2600 may include transporting the energy product, e.g., to land, for storage or end use. Specifically, a supply chain may be established in which a transport or chain of transports (e.g., one or more tanker ships, land-based vehicles, etc.) may transport the energy product for storage in a watercraft or land-based storage facility or to an end user for consumption.

[0128] Referring now to FIG. 27, a flowchart of a method 2700 for stationkeeping and / or adjusting a translational position of a free-floating body, such as any of the free-floating bodies or wave engines variously described above with reference to FIGS. 1-2, on a surfaceof a body of water is shown. The free-floating body may include one or more PF-driven propulsion systems, as described above with reference to FIGS. 2-25. In an example embodiment, water exiting the free-floating body may be utilized to induce rotation of the free-floating body. As an example, the water may be released in one or more pressurized and / or propelled streams to induce the rotation of the free-floating body. As an additional or alternative example, at least a portion of energy by the free-floating body may be utilized to power a propulsion system, such as a PF-driven propulsion system, to induce rotation of the free-floating body. In one embodiment, the method 2700 is performed as part of the method 2600 of FIG. 26, such as at the block 2606.

[0129] In some embodiments, the method 2700, or a portion thereof, may be implemented as executable instructions stored in non-transitory memory of a computing device, such as a controller communicably coupled to one or more actuators of the free-floating body. However, embodiments of methods for stationkeeping and / or adjusting translational positions of free-floating bodies are not limited to the below description of the method 2700. For instance, in certain embodiments, additional or alternative sequences of steps may be implemented, e.g., as executable instructions on such a computing device, where individual steps discussed with reference to the method 2700 may be added, removed, substituted, modified, or interchanged.

[0130] At block 2702, the method 2700 may include determining whether a first indication that the free-floating body is deviating from an intended trajectory has been received. As an example, the free-floating body may deviate from the intended trajectory when the free- floating body is approaching (e.g., is within a threshold distance of) a boundary of a geographic area. As an additional or alternative example, the free-floating body may deviate from the intended trajectory as a result of a change in one or more ambient environmental parameters, such as wind, water wave movement, water currents, etc. As an additional or alternative example, the free-floating body may deviate from the intended trajectory when the free-floating body is commanded by an operator to move towards a designated location or area, e.g., to take advantage of favorable environmental conditions, to transiently couple to a ship or other free-floating body, to undergo maintenance, etc. As an additional or alternative example, the free-floating body may deviate from the intended trajectory when a permanent obstruction (e.g., a rock, an island, etc.) or a transient obstruction (e.g., a watercraft, debris,etc.) is identified along the intended trajectory. In certain embodiments, the indication may be received from a remote land-based controller.

[0131] If the indication that the free-floating body is deviating from the intended trajectory has not been received, the method 2700 may proceed to block 2704, where the method 2700 may include maintaining a current trajectory of the free-floating body. In such an example, rotation of the free-floating body may not be induced.

[0132] If the indication that the free-floating body is deviating from the intended trajectory has been received, the method 2700 may proceed to block 2706, where the method 2700 may include determining a flow rate of pressurized water, e.g., at least the second portion of the water described with respect to FIG. 26, to be expelled into the one or more PF-driven propulsion systems. As an example, the flow rate of the water into the one or more PF-driven propulsion systems may be selected so as to adjust the translational motion of the free- floating body to maintain the free-floating body within the geographic area (e.g., to perform stationkeeping within the geographic area). As another example, the free-floating body may include more than one valve to expel water at different flows rates to multiple PF-driven propulsion systems, where compelling the multiple PF-driven propulsion systems to rotate at different speeds may provide more precise control of the translation of the free-floating body.

[0133] As an additional or alternative example, the flow rate of water expelled from the free-floating body into the one or more PF-driven propulsion systems may be selected so as to adjust the translational motion of the free-floating body to move toward the designated location or area. As an additional or alternative example, the flow rate of water may be selected so as to adjust the translational motion of the free-floating body to avoid the permanent or transient obstruction. Further, the flow rate of water may be selected to account for ambient environmental parameters, such as wind speed and direction, water current speed and direction, to maintain the free-floating body moving along a desired trajectory while compensating for the ambient environmental parameters.

[0134] At block 2708, the method 2700 may include adjusting the flow of at least the second portion of water to the one or more PF-driven propulsion systems to the determined flow rate to propel the free-floating body at a desired speed and direction. For example, the fluid passage housed within the free-floating body may include a valve controlling flow of at least the second portion of water therethrough. Adjustment to an opening of the valve mayvary the flow rate of water flowing out of an aperture of the free-floating body into a feed pipe of the one or more PF-driven propulsion systems. The opening of the valve may be varied based, at least in part, on the first indication to determine a desired direction of translation. As an example, the flow rate of the water into the one or more PF-driven propulsion systems may be selected so as to adjust the translational motion of the free- floating body to maintain the free-floating body within the geographic area (e.g., to perform stationkeeping within the geographic area). As another example, the free-floating body may include more than one valve to expel water at different flow rates to multiple PF-driven propulsion systems, or the valve may control flow variably through more than one fluid passage, each fluid passage fluidically coupled to a PF-driven propulsion system. By compelling the multiple PF-driven propulsion systems to rotate at different speeds, more precise control of the translation of the free-floating body may be achieved.

[0135] A method 2800 is shown in FIG. 28 for providing propulsion of an object deployed in an aquatic environment, such as a free-floating body as described above with reference to FIGS. 1-2, via a PF-driven propulsion system, as described above with reference to FIGS. 2- 25. In some embodiments, the method 2800, or a portion thereof, may be implemented as executable instructions stored in non-transitory memory of a computing device, such as a controller communicably coupled to one or more actuators of the free-floating body.However, embodiments of methods for stationkeeping and / or adjusting translational positions of free-floating bodies are not limited to the below description of the method 2800. For instance, in certain embodiments, additional or alternative sequences of steps may be implemented, e.g., as executable instructions on such a computing device, where individual steps discussed with reference to the method 2000 may be added, removed, substituted, modified, or interchanged.

[0136] At block 2802, the method 2800 may include flowing pressurized fluid, e.g., pressurized seawater, into a first stage or stationary unit of the propulsion system through a feed pipe. For example, a fluid passage enclosed within the object may be coupled to the PF- driven propulsion system by a feed pipe. A flow of pressurized seawater from the fluid passage into the feed pipe may be controlled by at least one valve. The feed pipe may be coupled tangentially to a semi-spherical portion of a nose cone or an annular nose ring of the PF-driven propulsion system and a positioning of the feed pipe relative to the semi-spherical portion causes the pressurized seawater to swirl as it enters the nose cone or nose ring.

[0137] At block 2804, the method 2800 may include forming a vortex of pressurized seawater as the pressurized seawater flows through a stator of the PF-driven propulsion system, the stator included in the first stage or stationary unit of the PF-driven propulsion system. For example, the swirling pressurized water may flow through nozzles of the stator. Fins separating the nozzles may be angled, relative to a central axis of rotation or longitudinal axis of the PF-driven propulsion system to deflect the pressurized seawater as the pressurized water impinges on the fins. The deflection of the pressurized seawater may accelerate the seawater flow and generate the vortex as the pressurized seawater exits the stator.

[0138] At block 2806, the method 2800 may include receiving the vortex at a turbine wheel included in a second stage or rotatable unit of the PF-driven propulsion system. The turbine wheel may be positioned immediately downstream (e.g., without any intervening components) of the stator. A moment of the pressurized seawater forming the vortex may compel the seawater to flow through channels of the turbine wheel along a helical path. The pressurized seawater may impinge upon fins separating the channels, forcing rotation of the turbine wheel and causing at least a rotor and a propeller of the second stage / rotatable unit of the PF-driven propulsion system to spin with the turbine wheel as a single unit.Hydrodynamic bearings of the propulsion system stabilize the rotor and allow the turbine to rotate with minimal friction.

[0139] In this way, a compact, two-stage propulsion system may propel an object through a liquid medium without relying on a motor. The propulsion system may be driven by a pressurized fluid and may comprise a rotatable unit that rotates based on torque generated using the pressurized fluid. By utilizing hydrodynamic bearings, the rotatable unit does not directly contact non-rotating components of the propulsion system, which prolongs a useful life of the propulsion system components. The components of the propulsion system may be oriented and shaped to minimize drag and energy transfer losses, providing an efficient and readily adaptable system for powering motion.

[0140] The specification and drawings are to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims. Moreover, for brevity sake each feature of each embodiment has not been incorporated into each other embodiment, but it is understood and intended that, wherepossible, each feature may be applied to and incorporated in each other embodiment whether expressly stated or not.

[0141] Other variations are within the spirit of the present disclosure. Thus, while the disclosed techniques are susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed but, on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims.

[0142] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosed embodiments (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Similarly, use of the term “or” is to be construed to mean “and / or” unless contradicted explicitly or by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected,” when unmodified and referring to physical connections, is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of the term “set” (e.g., “a set of items”) or “subset” unless otherwise noted or contradicted by context, is to be construed as a nonempty collection comprising one or more members. Further, unless otherwise noted or contradicted by context, the term “subset” of a corresponding set does not necessarily denote a proper subset of the corresponding set, but the subset and the corresponding set may be equal. The use of the phrase “based on,” unless otherwise explicitly stated or clear from context, means “based at least in part on” and is not limited to “based solely on.”

[0143] Conjunctive language, such as phrases of the form “at least one of A, B, and C,” or “at least one of A, B and C,” (i.e., the same phrase with or without the Oxford comma) unless specifically stated otherwise or otherwise clearly contradicted by context, is otherwise understood within the context as used in general to present that an item, term, etc., may beeither A or B or C, any nonempty subset of the set of A and B and C, or any set not contradicted by context or otherwise excluded that contains at least one A, at least one B, or at least one C. For instance, in the illustrative example of a set having three members, the conjunctive phrases “at least one of A, B, and C” and “at least one of A, B and C” refer to any of the following sets: {A}, {B}, {C}, {A, B }, {A, C], {B, C], {A, B, C], and, if not contradicted explicitly or by context, any set having {A}, { B } , and / or { C } as a subset (e.g., sets with multiple “A”). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of A, at least one of B and at least one of C each to be present. Similarly, phrases such as “at least one of A, B, or C” and “at least one of A, B or C” refer to the same as “at least one of A, B, and C” and “at least one of A, B and C” refer to any of the following sets: {A}, {B } , { C } , {A, B }, {A, C}, {B, C}, {A, B, C}, unless differing meaning is explicitly stated or clear from context. In addition, unless otherwise noted or contradicted by context, the term “plurality” indicates a state of being plural (e.g., “a plurality of items” indicates multiple items). The number of items in a plurality is at least two but can be more when so indicated either explicitly or by context.

[0144] Operations of processes described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. In an embodiment, a process such as those processes described herein (or variations and / or combinations thereof) is performed under the control of one or more computer systems configured with executable instructions and is implemented as code (e.g., executable instructions, one or more computer programs or one or more applications) executing collectively on one or more processors, by hardware or combinations thereof. In an embodiment, the code is stored on a computer-readable storage medium, for example, in the form of a computer program comprising a plurality of instructions executable by one or more processors. In an embodiment, a computer-readable storage medium is a non-transitory computer-readable storage medium that excludes transitory signals (e.g., a propagating transient electric or electromagnetic transmission) but includes non-transitory data storage circuitry (e.g., buffers, cache, and queues) within transceivers of transitory signals. In an embodiment, code (e.g., executable code or source code) is stored on a set of one or more non-transitory computer-readable storage media having stored thereon executable instructions that, when executed (i.e., as a result of being executed) by one or more processors of a computer system, cause the computer system to perform operations described herein. The set of non-transitory computer-readable storage media, in an embodiment, comprises multiplenon-transitory computer-readable storage media, and one or more of individual non-transitory storage media of the multiple non-transitory computer-readable storage media lack all of the code while the multiple non-transitory computer-readable storage media collectively store all of the code. In an embodiment, the executable instructions are executed such that different instructions are executed by different processors — for example, in an embodiment, a non- transitory computer-readable storage medium stores instructions and a main CPU executes some of the instructions while a graphics processor unit executes other instructions. In another embodiment, different components of a computer system have separate processors and different processors execute different subsets of the instructions.

[0145] Accordingly, in an embodiment, computer systems are configured to implement one or more services that singly or collectively perform operations of processes described herein, and such computer systems are configured with applicable hardware and / or software that enable the performance of the operations. Further, a computer system, in an embodiment of the present disclosure, is a single device and, in another embodiment, is a distributed computer system comprising multiple devices that operate differently such that the distributed computer system performs the operations described herein and such that a single device does not perform all operations.

[0146] The use of any and all examples or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0147] Embodiments of this disclosure are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for embodiments of the present disclosure to be practiced otherwise than as specifically described herein. Accordingly, the scope of the present disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the scope of the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

We Claim:

1. A wave engine, comprising: a body having a buoyant bulbous portion and a tubular lowermost portion; an assembly having a rotational unit, said assembly coupled to the body and configured to controllably receive water from within the body, the water pressurized within the body; a processor storing executable instructions in non-transitory memory that causes the wave engine to receive, from a remote land-based controller, an indication to adjust a direction of translational motion of the wave engine along a surface of water on which the wave engine floats so as to maintain the wave engine within a geographic area, and adjust a flow of the water into the assembly to propel the body along the surface of water, wherein the assembly propels the body by generating a vortex within the assembly to drive rotation of the rotatable unit, the rotatable unit including a turbine circumferentially surrounded by a propeller to rotate in unison with the propeller.

2. The wave engine of Claim 1 , wherein the body is quasi-cylindrical.

3. The wave engine of Claim 1 , additionally comprises a plurality of processors. A propulsion system, comprising: a turbine concentric with a propeller, the propeller driven to rotate in unison with the turbine by a helical flow of a pressurized fluid.

5. The propulsion system of claim 4, wherein the propeller rotates at a same speed as the turbine.

6. The propulsion system of Claim 5, wherein the turbine comprises a turbine wheel and a rotor, the turbine wheel coupled to an upstream end of the rotor.

7. The propulsion system of Claim 6, wherein the propeller is coupled to an inner surface of the turbine, and wherein blades of the propeller extend inwards, towards a central axis of rotation of the propulsion system.

8. The propulsion system of any one of claims 4, wherein the propeller is coupled to an outer surface of the turbine, and wherein blades of the propeller extend outwards, away from the turbine.

9. The propulsion system of Claim 4, wherein the turbine is positioned between two hydrodynamic bearings, the hydrodynamic bearings including fluid-filled gaps between surfaces of the propulsion system.

10. The propulsion system of Claim 9, wherein the fluid-filled gaps include a first gap between a rear-facing surface of a forward thrust bearing and a forward-facing surface of the rotor and a second gap between an inner surface of the rotor and an outer surface of a shaft.

11. The propulsion system of Claim 10, wherein the rear- facing surface of the forward thrust bearing includes a plurality of flat landings separated by grooves.

12. A device for propelling an object in an aquatic environment, the system comprising: a channel through which a pressurized fluid is to flow; a stationary unit positioned to generate a vortex in the pressurized fluid flow; and a rotatable unit including a plurality of propeller blades, the rotatable unit positioned between portions of the stationary unit and driven by the vortex to rotate.

13. The device of Claim 12, wherein the stationary unit includes nozzles separated by fins, the nozzles and the fins located around an outer perimeter of the stationary unit, and wherein the fins do not extend parallel or orthogonal to a central axis of rotation of the rotatable unit.

14. The device of Claim 12, wherein an incidence angle of water flowing into the nozzles is in a range of 0 degrees to 85 degrees and an exit angle of water flowing out of the nozzles is in a range of 60 degrees to 85 degrees.

15. The device of Claim 12, wherein the stationary unit is spaced away from the rotatable unit by a distance of less than 10 mm.

16. The device of Claim 12, wherein the vortex is generated when the pressurized fluid flow passes through nozzles of the stationary unit, and wherein the vortex causes the pressurized fluid flow to swirl in a helical path to impinge on buckets of the rotatable unit.

17. The device of Claim 16, wherein buckets of the rotatable unit are positioned to receive the vortex and transfer angular momentum of the vortex to rotation of the rotatable unit.

18. The device of Claim 12, wherein the rotatable unit includes a turbine, and wherein the turbine receives a pressurized fluid via one of an axial flow, a radial flow, and a circumferential flow of the pressurized fluid and expels depressurized fluid via one of an axial flow, a radial flow, and a circumferential flow of the depressurized fluid.

19. The device of Claim 12, wherein the rotatable unit is supported by hydrodynamic bearings formed between the rotatable unit and the stationary unit.

20. A method for propelling an object using a propulsion system, the method comprising: generating a helical flow of a pressurized fluid; and receiving the helical flow at a turbine to rotate a plurality of propeller blades circumferentially surrounding the turbine at a same rotational speed as the turbine.

21. The method of Claim 20, wherein generating the helical flow of the pressurized fluid includes introducing the pressurized fluid into an upstream portion of the propulsion system through a feed pipe arranged tangential to a semi-spherical portion of the upstream portion.

22. The method of Claim 20, wherein generating the helical flow of the pressurized fluid includes flowing the pressurized fluid from the upstream portion of the propulsion system into nozzles of a stator coupled to the upstream portion.

23. The method of Claim 20, wherein receiving the helical flow at the turbine includes receiving the helical flow of the pressurized fluid at buckets of a turbine wheel with loss of angular momentum of the helical flow of less than 10%.

24. A two-stage marine propulsion system, comprising:a first stage to generate a vortex in a flow of pressurized fluid; and a second stage to receive the vortex at a turbine concentric with and fixedly coupled to a propeller.

25. The two-stage marine propulsion system of Claim 24, wherein the first stage is a stationary portion of the two-stage marine propulsion system.

26. The two-stage marine propulsion system of Claim 24, wherein the second stage is a rotatable portion of the two-stage marine propulsion system that rotates as a single unit.

27. The two-stage marine propulsion system of Claim 24, wherein a forward thrust bearing arranged upstream of the turbine maintains a fluid film between the forward thrust bearing and the turbine as the turbine spins.

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