Wingsail end plate

Abstract

A system comprising: a wingsail having a first end and a second end, the first end being at a base of the wingsail when the wingsail is raised and the second end being at top of the wingsail when the wingsail is raised; a first end plate for the first end or the second end, wherein the first end plate is configured to be deployed from a first position in which the surface area of the first end plate is maximised to a second position in which the surface area of the first end plate is minimized.

Description

[0001] WINGSAIL END PLATE

[0002] Field of the Invention

[0003] The present disclosure relates to wind propulsion systems for marine transport, e.g., for shipping. Some examples relate to one or more articulating endplates for a wingsail used in such a wind propulsion system.

[0004] Background

[0005] Wingsails can be used for marine vessels to reduce energy requirements during operation, for example during transport of goods. This reduction in energy requirements can reduce carbon emissions.

[0006] Example wingsails are described in WO2023126346 A1.

[0007] Summary of invention

[0008] In a first aspect, there is provided a system comprising: a wingsail having a first end and a second end, the first end being at a base of the wingsail when the wingsail is raised and the second end being at top of the wingsail when the wingsail is raised; a first end plate for the first end or the second end, wherein the first end plate is configured to be deployed from a first position in which the surface area of the first end plate is increased to a second position in which the surface area of the first end plate is reduced.

[0009] According to some examples, in the second position the width of the end plate is less than the width of the end plate in the first position.

[0010] According to some examples, in the first position the first end plate is configured to improve the aerodynamic efficiency of the wingsail.

[0011] According to some examples, in the second position the first end plate is configured to minimize interference with folding down of the wingsail from the base of the wingsail.

[0012] According to some examples, the system comprises a second end plate is configured to be deployed from a third position in which the surface area of the second end plate is maximised to a fourth position in which the surface area of the second end plate is minimized, wherein: the first end plate is for the first end of the wingsail and the second end plate is for the second end of the wingsail; or the second end plate is for the first end of the wingsail and the first end plate is for the second end of the wingsail.

[0013] According to some examples, the first end plate comprises at least one hinge, wherein at least one portion of the first end plate can be rotated around the at least one hinge to reduce or increase the surface area of the first end plate.According to some examples, the first end plate comprises a plurality of foldable panels, wherein the foldable panels can be folded on top of each other to reduce the surface area of the first end plate.

[0014] According to some examples, the first end plate comprises one or more telescopic segments that can be retracted or extended to modify the surface area of the first end plate.

[0015] According to some examples, the first end plate comprises an inflation mechanism for increasing the surface area of the first end plate and a deflation mechanism for decreasing the surface area of the first end plate.

[0016] According to some examples, the first end plate comprises segments that are configured to overlap in the second position and configured to be moveable to create a single surface in the first position.

[0017] According to some examples, the system comprises: at least one sensor to control an automated mechanism to move the first end plate between the first position and the second position.

[0018] According to some examples, the first end plate comprises a composite material or a flexible polymer material.

[0019] According to some examples, the wingsail comprises a double element wingsail. According to some examples, the wingsail comprises a boundary layer flow control system.

[0020] According to some examples, the wingsail comprises at least one of: a sucking mechanism or a blowing mechanism for controlling air flow.

[0021] According to some examples, the first end plate comprises at least one of: a liftable plate; slotted end plate edges; porous end plate edges; serrated endplate edges; wavy endplate edges; at least one vortex generator.

[0022] According to some examples, the first position comprises an operational position and the second position comprises a stowed position.

[0023] According to some examples, in the first position the surface area of the first end plate is maximised and in the second position the surface area of the first end plate is minimized According to a second aspect, there is provided a method comprising: deploying an end plate for a wingsail from a first position in which the surface area of the end plate is maximised to a second position in which the surface area of the end plate is minimized.

[0024] According to some examples, the method comprises: folding down the wingsail while the end plate is in the second position.

[0025] According to some examples, the method comprises: raising the wingsail; and deploying the end plate to the first position.Brief description of Figures

[0026] Figures 1A to 1D shows a perspective view of a first wingsail having a hinged end plate;

[0027] Figures 2A to 2E shows a perspective view of a second wingsail having a hinged end plate;

[0028] Figures 3A to 3C shows a third wingsail having a segmented end plate;

[0029] Figures 4A and 4B shows a telescopic end plate;

[0030] Figures 5A and 5B shows a multi-panel end plate;

[0031] Figures 6A and 6B shows a shutter end plate;

[0032] Figures 7A and 7B shows an inflatable end plate;

[0033] Figure 8 shows vortex structure generated over a wingsail and their intensity;

[0034] Figure 9 shows five examples of vortex control features;

[0035] Figure 10A shows a wingsail with a porous edge for vortex control;

[0036] Figure 10B shows a serrated edge that can be used for a wingsail;

[0037] Figure 11 shows an example of a double element wingsail.

[0038] Detailed description

[0039] An end plate can be provided for a wingsail to enhance aerodynamic efficiency, i.e. to increase the lift and / or decrease drag achieved by the wingsail and in addition to increase the lift to drag ratio of the wingsail. This increase in aerodynamic efficiency results in the wingsail producing greater forward thrust for the vessel and in turn lower fuel consumption and carbon emissions as a result. An end plate can be provided at the top and / or bottom of a wingsail to reduce vortex formation at the tips of the wingsail, thereby increasing the lift-to-drag ratio of the wingsail. This can be used in e.g., commercial shipping in an aim to reduce fuel consumption and emissions by harnessing wind energy. Vortex formation occurs at the ends of a lifting device, such as a wing or wingsail, due to the pressure difference between the suction side and the pressure side. This pressure differential causes higher-pressure air to flow toward the suction side, generating vortices at the wingtip. As these vortices travel downstream, they are periodically shed from the wing in a process known as vortex shedding. This vortex shedding results in a loss of aerodynamic efficiency and so a loss in lift and / or drag of the device, this negatively impacting the effectiveness of the wing to reduce fuel consumption and carbon emissions of the wing.

[0040] End plates can be used for wingsails that provide boundary layer flow manipulation using suction and / or blowing.

[0041] Fixed end plates can cause issues when a wind propulsion system comprising the wingsail is not in use. An operator may wish to fold down a wingsail during port operations (e.g., cargo operations, mooring activity, docking activity, passing under bridges, etc.).However when folded down, a fixed end plate increases the distance between the deck of the ship and the total height of the folded wingsail. This can cause obstruction of port operations.

[0042] Some examples described herein provide articulating end plates that can be deployed from a first state (deployed / operational position) where the end plate can provide aerodynamic benefit to a second state where the end plate is retracted (stowed position), minimizing interference with port operations of the marine vessel either when the wingsail is in an upright or folded configuration.

[0043] EXAMPLE WINGSAIL

[0044] To provide context, an example of a wingsail is shown in FIG. 11. It will be understood that this is an example only, and that the end plates described herein are suitable for application to various other wingsails.

[0045] FIG. 11 shows an example dual element wingsail 1001. It will be understood that example end plates described herein could also be applied to single element wingsails or other multi element wingsails. It will also be understood that features of wingsail 1001 are exemplary only and all of the features in FIG. 11 shown are not necessarily required to be considered to be a wingsail.

[0046] Wingsail 1001 may be used for a watercraft. A watercraft may comprise, for example, at least one of: a marine vessel, a boat, a ship. In some examples, the watercraft may comprise a powered watercraft. In some examples, the watercraft may comprise a commercial vessel such a bulk carrier or a product tanker.

[0047] According to some examples, wingsail 1001 may be positioned on a surface of a watercraft, for example on the deck of a watercraft.

[0048] An exemplary wingsail may be rigid. Wingsail 1001 may be fitted to a marine vessel (e.g., a powered watercraft, a ship, etc.). A wingsail may be considered to be a variablecamber aerodynamic structure that is fitted to a vessel, e.g., a marine vessel.

[0049] A typical marine vessel length to be fitted with wingsail 1001 may be between 150m and 360m but may also be fitted to a smaller or larger vessel. In some examples, wingsail 1001 is used to produce thrust which is transferred to the vessel to propel it forwards and reduce the thrust required from the ship’s engine. In some examples, this can reduce the power required from the main engine and reduces fuel consumption and carbon emissions by around 20-30%, dependent on vessel type, route, number of wingsail units and other considerations.

[0050] Example wingsail 1001 comprises two wingsail elements 1003 and 1005. Each wingsail element may comprise a leading edge and a trailing edge. Each wingsail element may have an aerodynamic shape (for example, a shape similar to the shape of aerofoil element 1003 or aerofoil element 1005 in Figure 11). The aerodynamic shape of each wingsailelement may generate a lift force when air flow passes over the surface of the respective wingsail element. Each wingsail element may comprise an aerofoil.

[0051] According to some examples, the leading edge of each aerofoil is closer to the broadest part of the aerofoil, while the trailing edge of each aerofoil is further from the broadest part of the aerofoil. Other example shapes may be used for the aerofoils, however.

[0052] Wingsail 1001 may incorporate boundary layer flow control. A boundary layer of a wingsail may be considered to comprise a thin layer of air flowing over the surface. According to some examples, the flow of air in the boundary layer is controlled to prevent separation of air flow over the wingsail and thus reduce the wingsails propensity to stall. This enables a greater achievable lift of the wingsail.

[0053] Figure 11 shows a perspective view of an example wingsail 1001. Wingsail 1001 is a double element wingsail having a first aerofoil 1003 and a second aerofoil 1005. One of the double elements of wingsail 1001 is first aerofoil 1003 and one of the double elements of wingsail 1001 is second aerofoil 1005. First aerofoil 1003 comprises a leading edge 1003a, a trailing edge 1003b and a section 1003c of maximum cross-sectional width. As can be seen in the example of Figure 11 , leading edge 1003a is closer to section 1003c of maximum cross-sectional width than trailing edge 1003b. A portion of aerofoil 1003 comprising leading edge 1003a is rounded, and a portion of aerofoil 1003 comprising trailing edge 1003b is pointed (or may be a rounded shape which has a radius smaller than that of the leading-edge curvature). In some examples, the portion of aerofoil 1003 comprising leading edge 1003a has a wider cross-sectional width than the portion of aerofoil 1003 comprising trailing edge 1003b. It is envisaged that other shapes may be used for first aerofoil 1003, however.

[0054] Second aerofoil 1005 comprises a leading edge 1005a, a trailing edge 1005b and a section 1005c of maximum cross-sectional width. Leading edge 1005a is closer to section 1005c of maximum cross-sectional width than trailing edge 1005b. A portion of aerofoil 1005 comprising leading edge 1005a is rounded, and a portion of aerofoil 1005 comprising trailing edge 1005b is pointed. It is envisaged that other shapes may be used for first aerofoil 1003, however.

[0055] Second aerofoil 1005 may be symmetrical along a chord line of second aerofoil 1005, as shown in Figure 11.

[0056] First aerofoil 1003 may be symmetrical along a chord line of second aerofoil 1005, as shown in Figure 11.

[0057] A chord line of an aerofoil may be considered to be a longitudinal axis from the leading edge to the trailing edge of the aerofoil.

[0058] Leading edge 1003a may be considered to be at a nominal “front” of wingsail 1001. Trailing edge 1003b is behind leading edge 1003a. In the feathered configuration of Figure11 , the second aerofoil 1005 is behind the first aerofoil 1003, and the leading edge 1005a of the second aerofoil 1005 is in front of the trailing edge 1005b of the second aerofoil 1005.

[0059] Aerofoils 1003 and 1005 have “teardrop” shapes but other aerodynamic shapes may be used. In general, an aerofoil such as aerofoils 1003 or 1005 can have any shape that produces an aerodynamic reaction (lift) perpendicular to the direction of air flow over it, for a small resistance (drag) force in the direction of air flow.

[0060] The wingsail device 1001 may rotate around its base to vary an angle of attack to the apparent wind direction. In this way, wingsail device 1001 can optimise lift produced. The lift is generated by the creation of a pressure differential between either side of wingsail 101, leading to a high pressure and a low-pressure side due to a difference in air velocity over each side of the wingsail device 1001. Apparent wind is the wind that a moving watercraft experiences. Apparent wind is a combination of the wind experienced because of forward motion of the ship combined with the prevailing wind. The two vectors combine to produce ‘apparent wind’ which may have a different angle and wind speed than the wind experienced because of the forward motion of the ship and the prevailing wind.

[0061] The second aerofoil 1005 is rotatable relative to the first aerofoil 1003, allowing the camber of the device 101 to be adjusted and inverted.

[0062] When the wingsail device 1001 is on a port tack (when the apparent wind is hitting the port side of the device 1001) the second aerofoil 1005 can be rotated to the port side relative to the first aerofoil 1003.

[0063] When the wingsail device 1001 is on a starboard tack (when the apparent wind is hitting the starboard side of the device) the second aerofoil 1005 is rotated to the starboard side relative to the first aerofoil 1003.

[0064] When second aerofoil 105 is rotated relative to first aerofoil 1003, the chord lines of the first aerofoil 1003 and second aerofoil 1005 are not parallel. This provides a cambered configuration for the wingsail device 1003. This can be achieved by rotating the second aerofoil 1005 relative to first aerofoil 1003.

[0065] In a cambered configuration of device 1001 , a slot is formed between the first aerofoil 103 and the second aerofoil 1005. This slot allows a high-pressure stream of air to flow from the high-pressure side to the surface of the low-pressure side. This re-energises the flow travelling over the second aerofoil and allows the flow to stay attached at more extreme angles of attack and avoid stall of the wingsail, allowing greater lift coefficients to be achieved.

[0066] In some examples, wingsail 1001 can be fitted with a pressure differential generator 1011 (as shown in Figure 11). Pressure differential generator 1011 can be used to provide control of the flow of air around the device 1001. This controlled flow allows the device to be used at a greater angle of attack and greater camber angle without stalling, thus greatly increasing the achievable lift coefficients for wingsail 1001. In some examples pressuredifferential generator may comprise one or more rotary blades (e.g., fan blades) which may be connected by a shaft.

[0067] To provide control of airflow around wingsail 1001 , air inlet 1007 draws air into an interior of wingsail 1001. Wingsail 1001 may also comprise an outlet 1009. In some examples, for example as shown in Figure 11 , outlet 1009 may be positioned at a trailing edge 1003b of first aerofoil 1003. However, it will be appreciated that in other examples outlet 1009 may be positioned at other positions in first aerofoil 1003.

[0068] Air drawn in at inlet 1007 can be directed through an interior channel 1019 inside of aerofoil 1003. The interior channel 1019 connects air inlet 1007 and air outlet 1009. Air outlet 1009 emits air flow, which may comprise a focused jet of air, out of aerofoil 1003. This air flow may be directed towards the surface of the second aerofoil element 1003. In the example of Figure 11 , the air flow can be emitted out of outlet 1009 at trailing edge 1003b of first aerofoil 1003 towards and onto a leading edge 1005a of aerofoil 1005.

[0069] Pressure differential generator 1011 may be powered by one or more motors. These motors may comprise hydraulic or electric motors, for example. When operated, pressure differential generator 1011 may create an area of low pressure at inlet 1007 of channel 1019 such that air is sucked in, and an area of high pressure at outlet 1009 of channel 1019 such that air is pushed out of outlet 1009.

[0070] Pressure differential generator 1011 may be configured to create negative internal pressure in the first aerofoil, wherein the negative internal pressure draws air into the main body of the first aerofoil through air inlet 1007.

[0071] Pressure differential generator 1011 may comprise, for example, a fan driven by a motor; or a series of fans connected by one fan shaft and driven by a motor.

[0072] According to some examples, flow hits the leading edge of the first aerofoil element 103 and flows around the surface (on both sides). As air flow travels over the low pressure surface the laminar boundary layer starts to transition into turbulent flow, if the angle of attack of the device 1001 is increased at this point the flow will separate and the device 1001 will stall. So that the device 1001 can operate at higher angles of attack (and therefore generate more lift), in some examples the air traveling over the surface of the front aerofoil 1003 is sucked internally at a location near the back end of the front aerofoil 1003. This removes part of the turbulent boundary layer and keeps the flow attached at higher angles of attack, thus achieving greater producible thrust of device 1001.

[0073] A second aerofoil 1005 is located behind the first aerofoil 1003 and when aerofoil 1005 is cambered it produces a slot between the first aerofoil 1003 and second aerofoil 1005. This slot allows a high-pressure jet of air from the high-pressure side allowing the flow again to stay attached at higher angles of attack and camber angles - which in a similar way means that the device can produce greater thrust to the vessel.An air outlet 1009 may be positioned at the trailing edge of the first aerofoil element 1003 to further enhance the high-pressure jet of air traveling through the slot and thus allow the wingsail 1001 to maximise the achievable angle of attack before stall and maximise the thrust produced whilst also reducing drag.

[0074] As such, by using at least one inlet 1003 and at least one outlet 1009 on the first aerofoil 1003 higher angles of attack of device 1001 can be achieved without stalling. Additionally, or alternatively, higher angles of attack of device 1001 can be achieved without stalling by cambering second aerofoil 1005 relative to first aerofoil 1003.

[0075] ARTICULATING END PLATES

[0076] Examples are shown in FIG. 1 A to 7B of articulating end plates. These end plates are retractable from a first position in which their surface area is maximized to a second position where their surface area is minimized. In the first position, the end plates can be used to provide an aerodynamic benefit of reducing vortices at the tips of wingsail. In the second position, the retracted end plates minimize interference with port operations of a marine vessel. While the end plates are in the second, retracted, position (stowed position), the wingsail may be folded down onto the deck of a marine vessel.

[0077] Examples described herein relate to an articulating end plate system designed to enhance the aerodynamic performance of wind propulsion systems for commercial shipping while offering flexibility in its configuration to reduce operational impact when not in use. The system includes various types of articulating end plates such as:

[0078] • A folding end plate (FIG. 1 A to 1 D and 2A to 2E) - A single-surface plate that folds along one or more hinges when the wind propulsion system is deactivated. This minimizes the plate’s footprint, allowing for unimpeded cargo handling and docking activities.

[0079] • A segmented end plate (FIG. 3A to 3C) - Overlapping portions may be expanded out to increase the surface area of the end plate and retracted to decrease the surface area of the end plate.

[0080] • A telescopic end plate (FIG. 4A and 4B) - This may use telescopic portions to expand the end plate and retract the end plate.

[0081] • A multi-surface folding end plate (FIG. 5A and 5B) - A multi-panel configuration that collapses or folds in stages (e.g., by using hinges), providing enhanced flexibility and compactness. This design allows for varying degrees of retraction, enabling the system to adjust based on the specific requirements of the vessel’s operation or the docking environment. This multi-surface folding end plate (or any variation thereof) mayincorporate a pliable webbed material or a durable skin (e.g. some are shown at Y in Fig. 5B) positioned between rigid folding plates (e.g., some are shown at X in Fig. 5B). This material enables the rigid plates to fold along a hinge line while remaining aerodynamically connected.

[0082] • A shutter type end plate (FIG. 6A and 6B) - This may act similar to a camera shutter to provide an expanded configuration and varying degrees of a retracted configuration.

[0083] • An inflatable end plate (FIG. 7A and 7B) - A lightweight inflatable structure that can be deployed during wind propulsion and deflated when the system is inactive. The endplate may be rigid and inflatable. A deflation mechanism allows the end plate to retract into a compact form, offering minimal interference with vessel operations. • Other end plates - Other end plates may be used, for example flexible material based designs.

[0084] The end plates described herein may be expanded and retracted manually or may be expanded and retracted using computational control. In some examples the end plates may be expanded and retracted using automation.

[0085] The end plates described herein provide enhanced aerodynamic efficiency of a wingsail when the are in an expanded configuration. The end plates improve the lift-to-drag ratio by reducing vortex formation at the tips of the wings or sails, resulting in greater thrust efficiency and reduced fuel consumption.

[0086] The end plates also provide enhanced operational flexibility, as the folding or retractable nature of the end plates ensures they do not interfere with cargo loading / unloading, mooring operations, or docking when the wind propulsion system is inactive, thus maintaining the vessel's operational efficiency.

[0087] Further, the end plates are scalable and adaptable. The different types of articulating end plates allow for application across various vessel sizes and types of wind propulsion systems, making the technology adaptable to different commercial shipping needs.

[0088] In some examples, sensors may be integrated in the end plates to automate the deployment (expansion) and retraction processes based on environmental factors or vessel status.

[0089] In some examples, the end plates may include locking mechanisms to secure the end plates in a retracted or deployed configuration.

[0090] The folding / retraction of the end plates can ensure the vessel’s operational profile, ensuring that end plates can be compacted to align with a wingsail or stored within a wingsail structure when not needed.

[0091] The end plates described herein can be applied to any wind propulsion system but most importantly to wind propulsion systems incorporating suction and / or blowingtechnologies for boundary layer manipulation. Such systems aim to increase the lift coefficient significantly, leading to improved propulsion efficiency. However, as the lift coefficient increases, the induced drag due to vortex generation also increases. To counteract this, larger end plates are required to reduce induced drag and maximize the lift coefficient. The ability of the end plates to articulate or fold is crucial in this context, as these larger surfaces need to be minimized during port operations, loading, or docking to avoid interference. By retracting or folding, these large end plates can be effectively managed, providing a solution that balances the need for maximum aerodynamic performance with operational practicality.

[0092] In some examples, the end plate may be constructed from lightweight composite materials or flexible polymers to ensure durability and maintain low weight. In other examples the end plate may be constructed from steel and or fabricated sheets and / or bars.

[0093] FIG. 1 A shows a front view of a wingsail 101 with a hinged end plate, viewed towards a leading edge 103a of a first aerofoil 103 of wingsail 101.

[0094] In FIG. 1A, the surface area of end plate 119u along line A-A is reduced by folding down port and starboard panels 111p and 111s using port and starboard hinges 121p and 121s respectively. Similarly, the surface area of end plate 119d along line B-B is minimized by folding down port and starboard panels 112p and 112s using port and starboard hinges 122p and 122s respectively. With the end plate in this configuration, interference of the end plates with the compact folding down of wingsail 101 around base 104 is minimized. This folding down may be performed for e.g., port operations.

[0095] FIG. 1B shows wingsail 101 from the same perspective as FIG. 1A, with port and starboard panels 111 p and 111s extended about port and starboard hinges 121 p and 121s. This increases the surface area of end plate 119u along line A-A. Similarly, the surface area of end plate 119d is extended along line B-B of end plate 119d is extended by folding up port and starboard panels 112p and 112s using port and starboard hinges 122p and 122s respectively. In this configuration, the end plates can be used to reduce vortices generated by wingsail 101, increasing the aerodynamic efficiency of the wingsail.

[0096] FIG. 1 C shows an isolated view of endplate 119u in a retracted configuration so that a wingsail including endplate 119u can be easily folded down. Plates 112s and 112p are both perpendicular to the middle section of end plate 119u by hinging the plates around hinges 121 s and 121 p. Endplate 119d may be retracted similarly.

[0097] FIG. 1 D shows an isolated view of endplate 119u in an extended configuration so that a wingsail including endplate 119u provides more aerodynamic benefit that in FIG. 1 C. Plates 112s and 112p are both parallel to the middle section of end plate 119u by hinging the plates around hinges 121 s and 121 p. End plate 119d may be extended similarly.

[0098] FIG. 2A to 2E show a side perspective view of a second example of a hinged endplate for a wingsail 201 . In this example, wingsail 201 is a double element wingsail.In FIG. 2A, two end plates 219u and 219d are in an extended configuration for increasing the aerodynamic benefit of the end plates to wingsail 201. Plates 211s and 211p are rotated around hinges 221 p and 221s to maximize the surface area of end plate 219u. Plates 212s and 212p are rotated around hinges 222p and 222s to maximize the surface area of end plate 219d.

[0099] Wingsail 201 comprises a starboard air inlet 207s as well as a port air inlet (not shown) in a front element 203, which has a leading edge at 203a and a trailing edge at 203b. Front element 203 may also comprise an outlet expelling air sucked in through the inlet(s) of front element 203 towards second element 205, which has a leading edge 205a and trailing edge 205b.

[0100] In FIG. 2B, two end plates 219u and 219d are in a retracted configuration for allowing the wingsail 201 to be folded around base 204. Plates 211s and 211p are rotated around hinges 221 p and 221s to minimize the effective surface area of end plate 219u. Plates 212s and 212p are rotated around hinges 222p and 222s to minimize the effective surface area of end plate 219d.

[0101] FIG. 2C shows a starboard side view of wingsail 201 where end plates 219u and 219d are in a retracted configuration and FIG. 2D shows a rear view.

[0102] FIG. 2E shows an isolated view of endplate 219d in a retracted configuration so that a wingsail including endplate 219d is not prevented from being folded down flat on the surface of a marine vessel by end plate 219d. Plates 211s and 211p are both perpendicular to the middle section of end plate 219d by hinging the plates around hinges 221s and 221 p. End plate 219u may be retracted similarly.

[0103] As well as using hinges as in Fig. 1 A to 2E, in other examples the surface area of an end plate can be increased and decreased using other methods, as detailed further below with respect to FIG. 3A to 7B.

[0104] FIG. 3A to 3C show segmented end plates 319u and 319d. FIG. 3A shows a front perspective view of the two end plates 319u and 319d connected to a wingsail 301 , where the end plates are in an expanded configuration. FIG. 3B and 3C show a rear perspective view of endplate 319u. In FIG. 3B endplate 319u is in a retracted configuration, and in FIG. 3C endplate 319u is in an expanded configuration.

[0105] As seen in FIG. 3A, endplates 319u and 319d can be connected at opposite ends (the top and bottom) of example wingsail 301 . The endplates may be applied to other wingsails in other examples. Further, although this example shows two end plates, it should be noted that in some examples (and this applies for any of the examples described herein), only one of a top or bottom end plate may be connected to a wingsail.

[0106] Wingsail 301 comprises front aerofoil 303 having a leading edge 303a and a trailing edge 303b. Front aerofoil 303 comprises a starboard air inlet 307s and port air inlet 307pand an outlet 309 that pushes air from the inlets towards the leading edge 305a of rear aerofoil 305. Inlets 307s and 307p may be connected to outlet 309 by an internal channel. Rear aerofoil 305 comprises a trailing edge 305b.

[0107] Endplate 319u comprises fixed top portions 323s and 323p (in some examples these may be connected to form a single top portion, similar to the example fixed portion shown at portion 324). Underneath top portions 323s and 323p, there is provided moveable portions 311s and 311p that can be opened out to increase the surface area of endplate 319u for aerodynamic benefit. During port operations, these portions can be retracted under top portions 323s and 323p to minimize difficulty in folding down wingsail 301 . Although in this example, portions 323s and 323p are above 311s and 311 p, in other examples portions 311s and 311 p may instead be provided on top of portions 323s and 323p.

[0108] Endplate 319d may operate similarly to endplate 319u, with fixed portion 324 (which in some examples may be split into two portions similar to portions 323s and 323p) and moveable portions 312s and 312p, which may be provided above or below fixed portion 324.

[0109] FIG. 4A to 7B show further examples of expandable and retractable end plates for wingsails. These figures are shown for a top end of a wingsail, but in other examples they may also be provided at a bottom end of a wingsail, or at both a bottom end and top end of a wingsail in other examples. It should be noted that in some examples, one type of end plate may be provided at a bottom end of a wingsail and a different types of end plate may be provided at a top end of the wingsail.

[0110] Fig. 4A shows a telescopic end plate 450 for an example wingsail 401 . In FIG. 4A, end plate 450 is in a retracted configuration to prevent end plate 450 from interfering with deck operations when wingsail 401 is folded down. Wingsail 450 may be folded down so that it rests on a side from which wingsail 450 can expand.

[0111] FIG. 4B shows end plate 450 in an expanded configuration, where the surface area of end plate 450 has increased by expanding the width of end plate 450. Telescopic portions 450a and 450b expand outwards from a starboard side of end plate 450 and telescopic portions 450c and 450d expand outwards from a port side of end plate 450. In other examples, there may only be a single telescopic portion on each side, or there may be more than two telescopic portions on each side.

[0112] FIG. 5A shows a multi-panel end plate 550a for wingsail 501. In FIG. 5A, the panels are stacked on top of one another to minimize the surface area of end plate 450a to provide a retracted configuration. In FIG. 5B, the panels are expanded to increase the surface area of end plate 550b to provide an expanded configuration.

[0113] FIG. 6A shows a “shutter” type end panel, that may be considered to operate similarly to a camera shutter. In a retracted configuration shown in FIG. 6A, end plate 650a of wingsail 601 is in a configuration that minimizes the surface area of end plate 650a. Portions of endplate 650a may be rotated as shown at in FIG. 6B at 650b to provide an expanded configuration of end plate. This design comprises multiple overlapping segments arranged in a circular (or in other examples, semi-circular) configuration. The segments of the end plate are connected to a central actuation mechanism that allows them to open and close in a synchronized manner. When deployed, the segments extend outward to form a cohesive end plate surface, enhancing the aerodynamic performance of the wind propulsion system. When the system is not in use, the segments retract and overlap, minimizing the end plate’s footprint and reducing interference with vessel operations such as cargo handling and docking. The lens shutter-like design provides precise control over the deployment and retraction process, making it possible to adjust the end plate’s surface area dynamically based on wind conditions or operational requirements. The segments can be constructed from lightweight composite materials or flexible polymers to ensure durability and maintain low weight.

[0114] FIG. 7A and 7B show an inflatable end plate for wingsail 701 , the end plate shown in a retracted configuration 750a and an expanded configuration 750b. End plate configuration 750a can be inflated to expand to configuration 750b.

[0115] FIG. 8 shows an example of air flow over a wingsail, where vorticity is shown. Tip vortices are formed due to the pressure differences between the suction side and the pressure side of the wing. Similar to an airplane wing, the aerofoil generates low pressure on the suction side, creating lift and thrust. However, at the wing tips, the high-pressure flow moves towards the low-pressure side, causing the flow to roll. This rolling motion is intensified at the endplate edge, generating vortices that dissipate energy, increase drag, and create large swirling structures that block or misdirect the flow along the wing, reducing lift.

[0116] When deployed, the endplates discussed above are effective in reducing the impact of tip vortices on the wing. Ideally, large endplates would move the tip vortices outward, reducing their direct impact on the wing and allowing a larger area for the flow to circulate along the wing.

[0117] As well as using endplates, passive control structures can also be used to weaken the intensity of tip vortices and improve wing performance. These can be used in combination with the endplates discussed herein or can be used without being combined with an endplate. These passive control structures are discussed further below.

[0118] VORTEX CONTROL STRUCTURES

[0119] As discussed above, control structures can be used at least one endplate or at least one end of a wingsail.

[0120] Example control structures are shown at examples A) to E) of FIG. 9.Example A) shows an example that comprises a liftable plate 960 that can be used to give the endplate a delta shape, (when looking at the end plate from a planform view, i.e., from top down, the shape of the end plate forms a delta shape. This delta shape could be created so the D section flat edge is on the port or starboard side of the wingsail dependent on the angle of wind onto the wingsail. This can be used to move the vortices outward away from the wingsail.

[0121] Example B) shows an example having porous and or slotted endplate edges 962a and 962b. A porous edge to the end plate could be comprised of holes or slots to allow airflow to pass through the end plate before it reaches the end of the end plate. In this way the vortex intensity (or strength) is reduced thus increasing the aerodynamic efficiency of the end plate. The porous edge could be comprised of holes or slots of varying sizes that vary with distance from the edge of the end plate, to further increase the efficiency of the end plate and the effectiveness of the porosity. Porous edges 962 and 962b may be fenced, so comprise rings or fences in which the flow is directed. Edges 962a and 962b can be used to disrupt vortex formation, reducing vortex intensity and increasing the aerodynamic efficiency of the wingsail, i.e. increasing the lift or lift coefficient, and decreasing the drag.

[0122] Example C) shows porous endplate edges 964a and 964b that are fenced. These can also be used to disrupt vortex formation, reducing vortex intensity. Porous end plates that are fenced refer to structures designed with a perforated or porous surface, allowing controlled airflow through them. These fences influence the aerodynamic behavior of the flow, reducing vortex formation and modifying turbulence patterns. Depending on their porosity, they can create varying degrees of flow separation and reattachment, affecting downstream wake characteristics. Such designs are particularly useful for optimizing aerodynamic performance in applications where managing boundary layer behavior and turbulence is critical.

[0123] Example D) shows serrated / wavy endplate edges that can be used to disrupt vortex formation that can break down vortices and reduce their intensity. FIG. 10B shows an example of a serrated edge that might be suitable. The addition of serrated or wavy edges break down vortices so as a result reduce the drag and increase the lift generated by the wingsail.

[0124] Example E) shows vortex generators 968a that can be used to reduce vortex intensity. Vortex generators (VGs) are small aerodynamic devices, typically in the form of fins or vanes, designed to generate controlled vortices in a flow field. These vortices enhance mixing within the boundary layer, delaying flow separation and reducing drag or increasing lift. When applied at the edge of an end plate, vortex generators can increase efficiency by reducing vortex shedding and vortex induced drag, increasing the lift generated by the wingsail, enhancing boundary layer control of the wingsail, and improving the wingsail’s lift to drag ratio.

[0125] FIG. 10A shows an example aerofoil (NACA0012) lying on its side with porous edges at a tip of the aerofoil.It will of course be understood that the examples described are by way of example only and are not intended to limit the scope of the invention. The term “wingsail” does not place any limitations on the size or application of the wingsail. The term “marine vessel” does not place any limitations on the size or application of the marine vessel. The marine vessel and / or wingsail may be provided at different scales.

[0126] It will of course be understood that the examples described are by way of example only and are not intended to limit the scope of the invention. It will be also understood that any of the aforementioned examples may be combined.

[0127] The Figures are schematic in nature and not necessarily drawn to scale. It will be further understood that aspects of the described examples can be combined in any way.

Claims

Claims1. A system comprising:a wingsail having a first end and a second end, the first end being at a base of the wingsail when the wingsail is raised and the second end being at top of the wingsail when the wingsail is raised;a first end plate for the first end or the second end, wherein the first end plate is configured to be deployed from a first position in which the surface area of the first end plate is increased to a second position in which the surface area of the first end plate is reduced.

2. The system of claim 1 , wherein in the second position the width of the end plate is less than the width of the end plate in the first position.

3. The system of claim 1 or claim 2, wherein in the first position the first end plate is configured to improve the aerodynamic efficiency of the wingsail.

4. The system of any preceding claim, wherein in the second position the first end plate is configured to minimize interference with folding down of the wingsail from the base of the wingsail.

5. The system of any preceding claim, wherein the system comprises a second end plate is configured to be deployed from a third position in which the surface area of the second end plate is maximised to a fourth position in which the surface area of the second end plate is minimized, wherein:the first end plate is for the first end of the wingsail and the second end plate is for the second end of the wingsail; orthe second end plate is for the first end of the wingsail and the first end plate is for the second end of the wingsail.

6. The system of any preceding claim, wherein the first end plate comprises at least one hinge, wherein at least one portion of the first end plate can be rotated around the at least one hinge to reduce or increase the surface area of the first end plate.

7. The system according to any of claims 1 to 5, wherein the first end plate comprises a plurality of foldable panels, wherein the foldable panels can be folded on top of each other to reduce the surface area of the first end plate.

8. The system according to any of claims 1 to 5, wherein the first end plate comprises one or more telescopic segments that can be retracted or extended to modify the surface area of the first end plate.

9. The system according to any of claims 1 to 5, wherein the first end plate comprises an inflation mechanism for increasing the surface area of the first end plate and a deflation mechanism for decreasing the surface area of the first end plate.

10. The system according to any of claims 1 to 5, wherein the first end plate comprises segments that are configured to overlap in the second position and configured to be moveable to create a single surface in the first position.

11. The system according to any preceding claim, the system comprising:at least one sensor to control an automated mechanism to move the first end plate between the first position and the second position.

12. The system according to any preceding claim, wherein the first end plate comprises a composite material or a flexible polymer material.

13. The system according to any preceding claim, wherein the wingsail comprises a double element wingsail.

14. The system according to any preceding claim, wherein the wingsail comprises a boundary layer flow control system.

15. The system according to any preceding claim, wherein the wingsail comprises at least one of: a sucking mechanism or a blowing mechanism for controlling air flow.

16. The system according to any preceding claim, wherein the first end plate comprises at least one of:a liftable plate;slotted end plate edges;porous end plate edges;serrated endplate edges;wavy endplate edges;at least one vortex generator.

17. The system according to any preceding claim, wherein the first position comprises an operational position and the second position comprises a stowed position.

18. The system according to any preceding claim, wherein in the first position the surface area of the first end plate is maximised and in the second position the surface area of the first end plate is minimized.

19. A method comprising:deploying an end plate for a wingsail from a first position in which the surface area of the end plate is maximised to a second position in which the surface area of the end plate is minimized.

20. The method according to claim 19, wherein the method comprises:folding down the wingsail while the end plate is in the second position.

21. The method according to claim 19 or claim 20, wherein the method comprises:raising the wingsail; anddeploying the end plate to the first position.18

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