Fluid coupling device with vortex mitigation component

Abstract

A fluidic junction device comprising a vortex mitigation component configured to be integrated in or assembled to a vortex inducing region of the fluidic junction device, the vortex mitigation component (2) comprising a vortex reducing structure (3) comprising at least one network (5, 5a, 5b) of interconnected meandering channels delimited by an outer boundary (4) having at least a first surface portion (4a) and a second surface portion (4b), the network of interconnected channel segments (6) extending between an inlet-outlet opening (7) located at the first surface portion and an inlet-outlet opening located at the second surface portion, such that fluid from outside the outer boundary can flow through the inlet-outlet openings and the channel segments between the first and second surface portions.

Description

[0001] The present invention relates to a component or structure that mitigates the formation of coherent eddies in the fluid flow around a device for engaging fluid flow and their effects on mechanical structures.

[0002] The generation of eddies is a problem in many fluid dynamics and aerodynamic applications, including those in aircraft, ships, submarines, turbines, and automobiles. When a solid is placed in a fluid flow, it generates a separated flow that extends to its wake. Above the critical Reynolds number, the separated shear layer formed behind the trailing edge becomes unstable, leading to the formation of a periodic array of discrete and alternating vortices, commonly known as a von Kármán vortex street. The resulting undulating lift on the object is the source of so-called vortex-induced vibrations (VIVs) and noise radiation. When the vortex leakage frequency approaches the resonant frequency of the combined fluid-structure system, the amplitude of structural vibrations can be significantly amplified. Under resonant conditions, fatigue cracks may occur, potentially leading to premature failure of the mechanical system. VIVs and noise remain serious problems in various applications, such as hydraulic turbines and pumps, marine propulsion, aircraft wings, hydrocarbon risers, and tall buildings.

[0003] Trailing-edge vortices are an inherent characteristic of flows on finite-span lift surfaces. They cause increased drag through what is known as lift-induced drag. They can become unstable (fail) with increased vibration and noise. In the case of liquid flow, the static pressure at the center of these vortices can drop far below the free-flow pressure, leading to an increased risk of cavitation. In fact, tip vortex cavitation (TVC) is a common problem in axial pumps and turbines, as well as marine propulsion, accompanied by a high risk of erosive damage to the runner blades and casing.

[0004] Hub vortices that may form at the hub of a rotating propeller or turbine during non-designed operation can become unstable, leading to pressure fluctuations and large structural vibrations.

[0005] Flow control techniques to mitigate eddy current effects can be active or passive. Active control typically relies on suction or blowing (e.g., venting) aided by microjet streams, which can be stable or unstable, straight or swept. Active control techniques may be too complex, expensive, or unreliable to implement and maintain in many applications.

[0006] Passive control is typically achieved by altering the surface geometry or characteristics of the vortex-inducing component, such as changing surface roughness or shape, or providing winglets or various micro-vortex generators. Conventional passive vortex mitigation devices are either limited to a single construction with a narrow range of operating parameters, inefficient, or expensive to implement.

[0007] In many hydraulic and aerodynamic applications, the goal is to reduce drag, delay cavitation, reduce flow-induced vibrations, delay flow separation, improve stability, or optimize energy utilization. However, measures to address these goals may require consideration of safety, reliability, cost, and / or overall performance.

[0008] In view of the foregoing, the object of the present invention is to provide a fluid coupling device with eddy current mitigation components that is efficient and economical to manufacture and implement.

[0009] Preferably, a vortex mitigation component for a fluid coupling device is provided, the vortex mitigation component being compact.

[0010] Preferably, a vortex mitigation component for a fluid coupling device is provided, which is reliable.

[0011] Preferably, a vortex mitigation component is provided, which can be easily implemented in a wide range of fluid flow connection devices.

[0012] Preferably, a vortex mitigation component for a fluid coupling device is provided, which has high performance in reducing vortex-induced noise.

[0013] Preferably, a vortex mitigation component for a fluid coupling device is provided, which has high performance in reducing vortex-induced noise.

[0014] Preferably, a vortex mitigation component for a fluid coupling device is provided, which has high performance in eliminating or delaying the occurrence of cavitation.

[0015] The object of the present invention is achieved by providing a fluid engagement device with eddy current mitigation components according to the independent claim. The dependent claims set forth various advantageous features of embodiments of the invention.

[0016] This document discloses a fluid coupling device including a vortex mitigation component configured to be integrated into or assembled to a vortex induction zone of the fluid coupling device. The vortex mitigation component is disposed at any one or more of the leading edge, trailing edge, tip, and hub of the fluid coupling device. The vortex mitigation component includes a vortex reduction structure comprising at least one network of interconnected tortuous channels defined by an outer boundary having at least a first surface portion and a second surface portion. The interconnected channel segment network extends between an inlet-outlet opening located at the first surface portion and an inlet-outlet opening located at the second surface portion, such that fluid from outside the outer boundary can flow through the inlet-outlet opening and the channel segment between the first surface portion and the second surface portion.

[0017] According to the first aspect, at least one network of the interconnected channels consists of or includes a helical structure.

[0018] According to the second aspect, at least one network of the interconnected channels is formed within a continuous solid material.

[0019] In a preferred embodiment, the average curvature of the channel segment l / L Greater than 1.1, preferably greater than 1.2, for example in the range of 1.3 to 2.

[0020] The helical structure can have a cell size larger than the thickness of the attachment eddy current mitigation component of the fluid coupling device. L For example, half-cell size L / 2 This can correspond to the thickness of the portion of the fluid bonding device. However, in the embodiments, the cell size... L The thickness can be less than the thickness of the portion of the fluid coupling device to which the eddy current mitigation component is attached. The thickness of the portion of the fluid coupling device to which the eddy current mitigation component is attached can correspond to the size of the coupling interface.

[0021] In a preferred embodiment, the helical structure has... L / 50 to L / 2 Within the range, preferably in L / 30 to L / 4 The wall thickness of the partitioned channel segment within the range, of which L It is the cell size of the helical structure.

[0022] In a preferred embodiment, the eddy current mitigation component includes a coupling interface comprising a bottom wall configured for bonding or welding to a complementary interface of a fluid coupling device.

[0023] In one embodiment, the fluid engagement device includes, or is composed of, a hydrofoil, wing, propeller, or blade, and eddy current mitigation components are arranged at the tips of the hydrofoil, wing, propeller, or blade.

[0024] In one embodiment, the fluid engagement device includes, or is composed of, a hydrofoil, a wing, a propeller, or a blade, and eddy current mitigation components are arranged at the trailing edge of the hydrofoil, wing, propeller, or blade.

[0025] In one embodiment, the fluid engagement device includes, or is composed of, a hydrofoil, a wing, a propeller, or a blade, and eddy current mitigation components are arranged at the leading edge of the hydrofoil, wing, propeller, or blade.

[0026] In one embodiment, the fluid engagement device includes or is composed of the front end of the hub of a rotary propeller or turbine, and eddy current mitigation components are arranged on the front end of the hub.

[0027] In one embodiment, the eddy current mitigation component is configured for hydraulic applications.

[0028] In a preferred embodiment, the eddy current mitigation component is configured to reduce cavitation.

[0029] In a preferred embodiment, the eddy current reduction structure is manufactured using an additive manufacturing process such as 3D printing.

[0030] This document also discloses an apparatus including a fluid coupling device according to any of the above embodiments.

[0031] The device can be any one of a marine propulsion system, a wind turbine, a hydro turbine, a marine hydrofoil, or an aircraft wing.

[0032] Other objects and preferred features of the invention will be apparent from the claims, detailed description and drawings, wherein: Figure 1 This is a simplified schematic diagram of the trailing edge of a blade in fluid flow, which exhibits a von Kármán vortex. Figure 2a It is similar to an embodiment of the present invention. Figure 1 However, it has a schematic simplified view of the vortex mitigation component located on the trailing edge; Figures 2b to 2e These are simplified schematic examples of various fluid engagement devices having eddy current mitigation components according to embodiments of the present invention; Figures 3a to 3d This is an illustrative example of a device equipped with an eddy current regulating component according to an embodiment of the present invention. Figure 3a A turbine with a hub-front end and vortex mitigation components is shown. Figure 3b A marine propulsion device with a hub front end according to an embodiment of the present invention is shown, the hub front end including an eddy current regulating component. Figure 3c A marine propulsion system with vortex mitigation components positioned on the trailing edge and tip of the blades is shown, as well as... Figure 3d A portion of a wind turbine is shown, featuring vortex mitigation components on the trailing edge and tip of the turbine blades. Figure 4a This is a perspective view of a cross-sectional portion of an eddy current mitigation component according to an embodiment of the present invention, which shows a network of interconnecting channels with a helical structure; Figure 4b This is a view of part of a spiral structure, showing the fluid flow path through certain channels; Figure 4c This is a schematic, simplified view illustrating a tortuous passage segment used to explain and define the degree of tortuosity; Figures 5a to 5fThis is a view of a portion of a vortex mitigation component consisting of a spiral network of interconnected channels. Figure 5a The diagram shows a structure with a bottom for connection with a fluid coupling device. Figure 5b It shows Figure 5a The structure, in which one side of the structure is closed. Figure 5c It shows Figure 5a The structure, wherein the channels of a network in the structure have closed surfaces, Figure 5d Showing something similar Figure 5b The view shows that only one face of one of the network channels is closed. Figure 5e Similar to Figure 5d It has a low height, and Figure 5f Similar to Figure 5c It has a relatively low height; Figures 6a to 6c A portion of the eddy current mitigation component is shown, illustrating a network of interconnecting channels according to another embodiment. Figure 6a The top view and front view are shown. Figure 6c A view showing the top cut off to better reveal the channels within the component; Figure 7a This is a schematic diagram of a hydrofoil-type fluid coupling device, in which vortex mitigation components are positioned along the trailing edge of the device; Figure 7b yes Figure 7a An enlarged view of a portion of the eddy current mitigation component of the device; Figure 8a yes Figure 7a A view of the device, showing the dimensions of the hydrofoil used for experimental testing; Figure 8b Is with Figure 8a A similar view of a conventional fluid coupling device with a Donaldson trailing edge but without vortex mitigation components, used for experimental testing and... Figure 8a Hydrofoils comparison; Figure 9 It shows Figure 8a and Figure 8b The graphs showing the amplitude and spectrum of the hydrofoil's vibration signal are shown, more specifically, those without vortex mitigation components (blunt trailing edge). Figure 8a The curve of the hydrofoil, Figure 8b The curve of the hydrofoil (Donaldson trailing edge) and the vortex mitigation component (spiral trailing edge). Figure 8a The curve of the blade; Figure 10 It shows the results based on the information about Figure 8a , 8b The curves of lift coefficient versus incident angle and drag coefficient versus incident angle for the three hydrofoils mentioned in 9. Figure 11a and Figure 11b These are perspective and top views of the tip of a hydrofoil-shaped fluid coupling device, which includes a vortex mitigation component located at the tip of the hydrofoil. Figure 11c and 11d yes Figure 11a , 11b Top and end views of the eddy current mitigation component of the device; Figure 12 Presented according to Figure 11a and Figure 11b A photograph of an embodiment of an elliptical hydrofoil with and without vortex mitigation components at its tip, wherein... Photo 12a shows an elliptical hydrofoil without vortex mitigation components at the tip when σ = 2.0, demonstrating tip vortex cavitation. Photo 12b shows an elliptical hydrofoil without vortex mitigation components at the tip when σ = 1.55, illustrating tip vortex cavitation and leading-edge cavitation. Photo 12c shows an elliptical hydrofoil without vortex mitigation components at the tip when σ = 1.15, illustrating tip vortex cavitation and leading-edge cavitation. Photo 12D shows an elliptical hydrofoil with vortex mitigation components at the tip at σ = 1.55, demonstrating leading-edge cavitation without tip vortex cavitation. Photo 12E shows an elliptical hydrofoil with vortex mitigation components at the tip at σ = 1.15, demonstrating leading-edge cavitation without tip vortex cavitation. Photo 12F shows an elliptical hydrofoil with vortex mitigation components at the tip when σ = 1.00, demonstrating leading-edge cavitation without tip vortex cavitation. First refer to Figure 1 and 2a In fluid flow of gas or liquid, the blunt trailing edge 10 of the fluid coupling device generates von Kármán vortices under flow conditions exceeding a certain Reynolds number. These vortices increase drag and produce vibrations that cause noise. For example, in... Figure 9 The figure shows the amplitude of the noise, and also shows a graph of the blunt trailing edge 10 of the hydrofoil, which has according to Figure 8a The blunt trailing edge 10 of the hydrofoil lacks vortex mitigation components. According to an embodiment of the invention, through the blunt trailing edge 10 of the hydrofoil, as shown... Figure 2a The eddy current moderating component 2 shown can break down or eliminate von Kármán eddies. The blunt trailing edge 10 with a helical structure and eddy current mitigation component is also shown in the embodiment of FIG8A in this example. Figure 9The graph showing the helical trailing edge 10 in the middle is compared with the conventional device having a blunt trailing edge 10 or a Donaldson trailing edge ( Figure 8b Compared to (as shown in the example), the vibration amplitude has been significantly reduced in this experimental example. The conventional Donaldson trailing edge shows improved performance compared to the blunt trailing edge 10, but still exhibits a significant vibration signal amplitude compared to the hydrofoil with the vortex mitigation component according to an embodiment of the invention.

[0033] Figures 3a to 3d Examples of devices 100 provided with eddy current regulating components according to embodiments of the present invention are shown, which may include gas and liquid turbines, marine propulsion, aircraft propulsion, ships with marine hydrofoils, aircraft wings and control surfaces, wind turbines and automotive aerodynamic control surfaces.

[0034] The fluid engagement device 1 may include, for example, a wing, propeller, blade, impeller, or front end 16 or hub, or be composed of them, to list some common examples of devices configured to engage with a flow of fluid, which may be gas or liquid. The fluid engagement device according to the invention includes a vortex mitigation component 2 located on a portion of the fluid engagement device responsible for vortex generation, in order to mitigate vortex generation. The position of the vortex mitigation component is variable and depends on the application and characteristics of the fluid flow on the fluid engagement device 1.

[0035] The eddy current mitigation component can be specifically located in -Along the leading edge 12 of the fluid coupling device - Along the tip 14 or end of the fluid coupling device - Along the rear edge 10 of the fluid coupling device, and / or - On the hub of a rotating system such as a turbine or propeller, the hub may be rotating or stationary.

[0036] An example of the construction of trailing edge 10 is in Figure 2b , 2c Examples of the leading edge 12 arrangement are shown in 3d, 7a and 8a. Figure 2d The example shown is an arrangement of the tip 14. Figure 2e and 11a As shown in 11e, and an example of the arrangement of the front end 16 of the hub is shown in Figure 3a and 3b As shown in the image.

[0037] The fluid flow engaged with the fluid coupling device 1 is separated to flow around the fluid coupling device. The separated flow flows over different surface portions, which for illustrative purposes are referred to as the first surface portion 4a and the second surface portion 4b constituting different sides or parts of the fluid coupling device. In the case of blades, wings, or hydrofoils, there is typically a first surface (e.g., a top surface) extending from the leading edge 12 and an opposing second surface (e.g., a bottom surface), which divides the fluid flow into at least two flows, one on the first surface and one on the second surface, which recombine at the trailing edge 10 to form a wake of the flow. The first and second portions can also be different portions joined by fluid flows 110a, 110b, for example, fluid flow 110 around the approximately axisymmetric front end 16 or hub of the fluid coupling device 1.

[0038] The eddy current mitigation component 2 includes a network 5 of interconnecting channels. The network 5 includes channel segments 6 extending between inlet-outlet openings 7 at the surface of the outer boundary 4 of the eddy current mitigation component. At least some of the channel segments 6 extend between the inlet-outlet openings 7 at a first surface portion 4a and the inlet-outlet openings 7 at a second surface portion 4b. The end-opening channel segments 6 provide porosity and permeability to the eddy current reduction structure 3, allowing fluid to flow from the inlet-outlet openings 7 at the first surface portion 4a through the channel segments 6 to the inlet-outlet openings at the second surface portion. The first and second surface portions can be, for example, the upper and lower surfaces of a blade, wing, or hydrofoil. In the case where the eddy current mitigation component 2 is on the front end of a hub, the first and second surface portions can be different portions surrounding the axis of the hub.

[0039] Channel segment 6 is provided with a certain curvature greater than 1. l / L (See further definitions provided), such that the fluid flowing into and out of channel segment 6 enters and exits the inlet-outlet opening at different angles (different from geometric angles), which has the effect of reducing vortices. In the absence of vortex-reducing components, or if the vortex-reducing components are replaced by conventional structures (e.g., flat edges or tips), the vortices typically originate at the location of the vortex-reducing components from the fluid connection device 1. As further described, the curvature can be considered as the length of channel segment 6. l The shortest orthogonal distance between the inlet and outlet 7 at the first and second surface portions 4a and 4b L The length of the channel segment is measured by the ratio of [the ratio of the length of the channel segment to the length of the channel segment]. l It is along the centerline of channel segment 6 C Measured.

[0040] Permeability and porosity together ensure that fluid can flow easily between the first and second surface portions 4a, 4b, which are interconnected by channel segments 6, forming an overall network 5 of interconnected channels. This differs from conventional systems, which have a rough or porous structure that does not have channel segments 6 interconnecting different surface portions; in other words, the porosity may be high, but the permeability is very low (if not zero).

[0041] In one aspect of the invention, the network 5 of interconnecting channels of the eddy current mitigation component 2 is formed within a continuous solid material. In contrast to wire mesh or wound fiber structures, this provides the ability to control the inlet-outlet openings on the first and surface portions, and thus also provides the ability to control the flow direction of fluid entering and leaving the channels, as well as the flow through the interconnecting channels. In conventional porous structures with wire mesh or wound fibers, although fluid can flow from the first surface portion (e.g., the lower surface of an wing or a pressure surface) to the second surface portion (e.g., the upper surface of an wing or a suction surface), the flow direction of the fluid through the channels, especially the flow direction entering and leaving the openings, is not well defined or well controlled, making the eddy current mitigation effect according to the invention less than optimal for such porous mesh structures. Using a continuous solid material, for example, produced by an additive manufacturing process, allows for a defined and well-controlled geometry of the interconnecting channels.

[0042] In one aspect of the invention, the network 5 of interconnecting channels has a helical or approximately helical structure, as described in more detail below. It can be noted that a mathematically defined helical structure can be deviated from by changing, for example, the thickness of the channel wall 9 and the channel shape, without substantially modifying the centerline of the channel segment 6 representing the intermediate flow direction. C One of the advantages of helical structures is that, since their geometry is described by mathematical functions, they can be easily modeled and then manufactured using additive processes such as 3D printing.

[0043] In the spiral structure, the network 5 of interconnecting channels forms two separate domains, with channels in each domain interconnected, but the two domains are separate and not interconnected. Therefore, the spiral structure can be considered as a network 5a, 5b with two interconnecting channels, thus closing the aperture of one network while achieving the effect of mitigating eddies, while the remaining network provides high permeability and tortuosity. For example, in... Figure 5c and 5f In the illustrated embodiment, one of the domains of a network 5b including interconnecting channels is closed. This configuration can be used to enhance the structural strength of the eddy current mitigation component while still benefiting from the eddy current mitigation effect of the open network 5a of the interconnecting channels in the first domain.

[0044] Channel network 5 can also be closed along an edge, for example, as shown below. Figure 5bAs shown, the orifices are located on a pair of opposite side surfaces. In... Figure 5d and 5e In another variant shown, one of the two domains of the network forming the interconnecting channel is closed on the side opposite to interface 18, at which part 2 is attached to fluid coupling device 1.

[0045] In other embodiments, the interconnecting channel network 5 may have a non-spiral structure, for example, as shown in... Figures 6a to 6c As shown, it illustrates a network of interconnecting channels, including a plurality of first and second zigzag channel segments 6a, 6b extending between an inlet-outlet opening 7 on a first surface portion 4a and an inlet-outlet opening 7 on a second surface portion 4b. In this embodiment, adjacent channel segments 6a, 6b are interconnected near their respective first and second surface portions, and the adjacent channels have alternating shapes, inverted relative to each other to form a generally zigzag interconnecting path, such as... Figure 6a It is best shown in the middle.

[0046] It is understood that various networks 5, 5a, 5b can be provided to interconnect the first and second surface portions 4a, 4b with tortuous path fluids and provide high porosity and permeability, including variations based on helical structures as described above, wherein irregular modifications can be provided, such as changing the thickness of the channel wall 9 to locally change the channel shape.

[0047] The eddy current mitigation component 2 can be integrally formed with the fluid bonding device 1 and extend as an integral part thereof. The fluid bonding device can be formed by additive manufacturing such as 3D printing, or by subtractive manufacturing or a combination of additive and subtractive manufacturing.

[0048] The eddy current mitigation component 2 can also be formed as a separate component assembled to the fluid coupling device 1. For example, the eddy current mitigation component includes a coupling interface 8 that can be welded, brazed, bonded with adhesive, or mechanically fixed to a complementary coupling interface 8 disposed on the fluid coupling device 1. For mechanical solutions, mechanical devices may include bolts, screws, or rivets extending from or through the coupling interface 8 of the eddy current mitigation component 2, or clamping or other mechanical devices that clamp the coupling interface 8 of the eddy current mitigation component 2 may be disposed on the fluid coupling device.

[0049] Porosity, permeability and tortuosity Porosity, σ, is the porosity of a material in its total volume. upper gap space Geometric measure.

[0050]

[0051] Permeability is a hydraulic property of porous media, defined as permeability per unit length. Pressure drop across the porous medium :

[0052] That The middle is the flow velocity, and It is a linear or quadratic function, which depends on the Reynolds number (e.g., velocity state).

[0053] Torque of porous media It is a measure of its winding length, and can be defined in different ways. Here, we use the simplest geometric definition, which is the length of the hole's centerline. and straight path The ratio. For example, a cylindrical hole has a curvature of 1, while a winding path has a greater curvature.

[0054]

[0055] The use of porous materials has attracted some attention, with some studies aiming to understand the fundamental mechanisms behind flow control. Researchers have primarily addressed this challenge from theoretical and numerical perspectives. Porous materials have been shown to be effective in mitigating aerodynamic noise and vibration in a variety of engineering contexts, including non-streamlined bodies, blunt edges, and airfoils; however, these studies have been limited to airflow structures with low permeability.

[0056] In terms of invention The eddy current mitigation component of this invention is provided with porosity and permeability, which, combined with a tortuous downstream gradient, locally redirects the flow in different directions at the outer boundary. This is achieved through an interconnected channel network 5 of tortuous channel segments connecting different surface portions, such as the upper and lower sides of a given body. These non-straight channels can be distributed along the spanwise direction and can have any arbitrary cross-section. Their principal axes are inclined relative to the transverse direction in the downstream direction, and their angles are opposite. The channels are entangled, causing the flow to be redirected non-uniformly from the near-end inlet to the far-end inlet. The resulting tortuous gradient is observed to enhance mixing and prevent the formation of coherent and intense eddies.

[0057] The advantages of this invention are the effectiveness and low cost of the passive flow control device, which can be integrally formed with or attached to any non-streamlined body to mitigate eddy formation. It can help reduce the adverse effects of eddy formation, including noise, flow-induced vibration, and cavitation.

[0058] Advantageous embodiments of interconnected channel networks are based on a spiral surface defined by the following isosurface equation:

[0059] in It is spatial coordinates, and ,in It is the space period (cell size). Spirals are part of the so-called family of triple-period minimal surfaces (TPMS), discovered by Alan Schoen in 1970. TPMS exhibit zero-mean curvature at every point and are characterized by the minimum area of ​​any surface within arbitrary boundaries. It should be noted that, referring to… Figure 4a Three-dimensional spatial periodicity ( L This leads to the side length L A cubic unit cell. As any other surface, the helical body separates the space on both sides. Due to the triple-cycle characteristics, these two separated regions are intricately intertwined.

[0060] To generate the channel network, the aforementioned isosurface equations can be used as the framework, and wall thicknesses can be provided for it. t Therefore, the spiral volume based on the sheet can be obtained using the following equation (2). The result is shown in... Figure 4a The diagram shows that the 2×2×2 unit cell exhibits two non-intersecting domains with red and blue colors.

[0061]

[0062] Each of these discontinuous domains can also be viewed as having a diameter and sweep amplitude The network of spiral pores 5. Although the pores within one domain are interconnected, none of them are connected to another domain. The two networks 5a and 5b are entangled in a remarkable manner to form a highly permeable medium, but with high tortuosity.

[0063] When placed in the vortex-forming region, the helical-based device guides the flow into a set of highly tortuous channels / holes, which act as a diverter during the early stages of vortex formation. As a result, instead of coherent and strong vortices, numerous incoherent and weaker vortices in different directions are generated. The inventors have observed that this flow diversion is a key mechanism for reducing vortex-induced vibrations and cavitation. The interconnection of the hole network enhances mixing and generates high-shear regions. The inventors have also observed that this shear further reduces vortex formation.

[0064] A coupling interface can be provided by embedding material along one side of the helical structure, thereby allowing the remaining outer boundary of the helical structure to remain open or partially sealed with a closed wall, such as... Figures 5b to 5f As shown in various examples. The coupling interface 8 can be planar, curved, or have various other shapes with complementary surfaces configured for coupling to the fluid coupling device 1.

[0065] Reduction of vortex-induced vibration It is well known that when non-streamlined or streamlined bodies are placed in a flow, they can exhibit separate boundary layers on opposite sides extending into the wake region. When the Reynolds number exceeds a critical threshold, these shear layers produce the shedding of periodic and alternating vortices, known as the von Kármán street. The resulting wave lift causes so-called vortex-induced vibrations. Notably, when the frequency of the vortex shedding closely matches the resonant frequency of the fluid-structure system, the amplitude of the structural vibration increases significantly. In this case, fatigue cracks may develop, potentially leading to premature mechanical system failure.

[0066] The eddy current mitigation device according to embodiments of the present invention can be attached to any non-streamlined or streamlined body to mitigate eddy-induced vibrations. When the eddy current mitigation device is precisely placed in the region where alternating eddies are forming, it can effectively interfere with their swirling process and prevent them from being continuous and periodic, resulting in a significant reduction in the risk of eddy current-induced vibrations and cavitation.

[0067] Mitigating tip vortex formation The vortex mitigation device according to embodiments of the invention can be used to mitigate vortex formation at the tip of a limited-span lifter. It can be attached to the tip region to interfere with the formation of tip vortices. It can also extend to the leading edge to prevent the formation of so-called leading-edge vortices. In both cases, if the vortex mitigation device is precisely positioned, its porosity and tortuosity allow it to effectively disrupt vortices immediately at the initiation of vortex formation. Instead of single, coherent, and intense vortices, numerous small vortices in all directions are obtained. In the case of water flow, this alteration of vortices can prevent or reduce the occurrence of cavitation.

[0068] Implementation: Reduction of hub vortices in rotating machinery The eddy current mitigation device according to embodiments of the present invention can be used to mitigate so-called rope or hub eddies in various rotating machinery, such as Francis turbines, Kaplan turbines, propeller turbines, bulb turbines, tidal turbines, or marine propulsion systems. Hub eddies typically form during non-designed operation, originating at the runner hub and extending downstream. This coherent and intense eddy current can become unstable, leading to a significant increase in pressure fluctuations and posing a risk of mechanical failure. In the case of hydraulic turbines and marine propulsion systems, the eddy current mitigation device can be attached to the front end of the runner hub to disrupt the initiation of the hub eddy current and transform it from a coherent eddy current into numerous smaller eddies in all directions.

[0069] Practical examples of implementation: This invention can be applied to various engineering fields where eddy flow problems exist. These include hydraulic turbines and pumps, marine propulsion systems, wind and tidal turbines, aircraft wings and propulsion systems, hydrofoils, fans, turbocompressors, gas turbines, risers, high-rise buildings, etc. In all these cases, the eddy flow mitigation device can be integrated during the design process without altering the geometry. It can also be used on existing equipment with limited changes to the geometry by extending the blades with the eddy flow mitigation device.

[0070] The eddy current mitigation device according to embodiments of the present invention can be streamlined or non-streamlined, removable or permanently fixed, and its enclosure can be of any shape. It can also be telescopic, allowing it to be deployed as needed.

[0071] List of reference numerals used in the figures Equipment 100 Fluid connection device 1 Wings, propellers, blades, impellers First surface portion 4a Second surface portion 4b Interface 8 Trailing edge 10 Frontier 12 Tip 14 16-inch front wheel hub Eddy current reduction component 2 Eddy current reduction structure 3 Outer boundary 4 First surface portion 4a Second surface portion 4b Interconnection channel networks 5, 5a, 5b Channel segment 6 Entrance-exit opening 7 Channel wall 9 Closed wall 18 unit cell Three-period minimum surface (TPMS) spiral Interface 8 coupling Coupled surface 8b Fluid Flow 110 First Stream Section 110a Second Stream Section 110b curvature l / L Permeability

Claims

1. A fluid coupling device comprising a vortex mitigation component configured to be integrated into or assembled to a vortex induction zone of the fluid coupling device, the vortex mitigation component being disposed at any one or more of a leading edge, trailing edge, tip, and hub of the fluid coupling device, the vortex mitigation component comprising a vortex reduction structure (3) comprising at least one network (5, 5a, 5b) of interconnected tortuous channels defined by an outer boundary (4) having at least a first surface portion (4a) and a second surface portion (4b), the network of interconnected channel segments (6) extending between an inlet-outlet opening (7) located at the first surface portion and an inlet-outlet opening located at the second surface portion, such that fluid from outside the outer boundary can flow through the inlet-outlet opening and the channel segment between the first surface portion and the second surface portion, wherein, At least one network of the interconnected channels consists of or includes a helical structure.

2. The fluid coupling device according to claim 1, wherein the average tortuosity of the channel segment is... l / L Greater than 1.1, preferably greater than 1.2, for example in the range of 1.3 to 2.

3. The fluid coupling device according to any one of the preceding claims, wherein the helical structure has a unit cell size L This makes the half-cell size L / 2 It is equal to or less than the thickness of the fluid coupling device at the coupling interface to which the eddy current mitigation component is attached.

4. The fluid bonding device according to the preceding claims, wherein the cell size of the helical structure is... L The thickness is less than the thickness of the portion of the fluid coupling device attached to the eddy current mitigation component.

5. The fluid coupling device according to any one of the preceding claims, wherein the helical structure has a... L / 50 to L / 2 Within the range, preferably in L / 30 to L / 4 The wall thickness of the partitioned channel segment within the range, where L It is the cell size of the helical structure.

6. The fluid coupling device according to any one of the preceding claims, wherein, The eddy current mitigation component includes a coupling interface (8) which includes a bottom wall configured to be bonded or welded to a complementary interface of the fluid coupling device.

7. The fluid coupling device according to any one of the preceding claims, wherein, The fluid coupling device includes a hydrofoil, wing, propeller or blade, or is composed of a hydrofoil, wing, propeller or blade.

8. The fluid coupling device according to the preceding claims, characterized in that, The vortex mitigation components are arranged on the tip (14) of the hydrofoil, wing, propeller or blade.

9. The fluid coupling device according to any one of the preceding two claims, wherein the vortex mitigation component is disposed on the trailing edge of the hydrofoil, wing, propeller or blade.

10. The fluid coupling device according to any one of the preceding three claims, wherein the vortex mitigation component is disposed on the leading edge of the hydrofoil, wing, propeller or blade.

11. The fluid coupling device according to any one of claims 1 to 6, wherein the fluid coupling device comprises or is composed of a hub front end (16), and the eddy current mitigation component is disposed on the hub front end.

12. The fluid engagement device according to any one of the preceding claims, wherein the eddy current mitigation component is configured for hydraulic applications.

13. The fluid coupling device according to the preceding claim, wherein, The eddy current mitigation component is configured to reduce cavitation.

14. The fluid coupling device according to any one of the preceding claims, wherein, The eddy current reduction structure (3) is manufactured by additive manufacturing processes such as 3D printing.

15. An apparatus (100) comprising a fluid coupling device according to any one of the preceding claims, said apparatus being any one of a marine propulsion system, a wind turbine, a hydraulic turbine, a marine hydrofoil, or an aircraft wing.

16. A fluid coupling device comprising a vortex mitigation component configured to be integrated into or assembled to a vortex induction zone of the fluid coupling device, the vortex mitigation component being disposed at any one or more of a leading edge, trailing edge, tip, and hub of the fluid coupling device, the vortex mitigation component comprising a vortex reduction structure (3) comprising at least one network (5, 5a, 5b) of interconnected tortuous channels defined by an outer boundary (4) having at least a first surface portion (4a) and a second surface portion (4b), the network of interconnected channel segments (6) extending between an inlet-outlet opening (7) located at the first surface portion and an inlet-outlet opening located at the second surface portion, such that fluid from outside the outer boundary can flow through the inlet-outlet opening and the channel segment between the first surface portion and the second surface portion, wherein the at least one network of interconnected channels is formed within a continuous solid material.

17. The fluid coupling device according to the preceding claim, wherein the average tortuosity of the channel segment is... l / L Greater than 1.1, preferably greater than 1.2, for example in the range of 1.3 to 2.

18. The fluid coupling device according to claim 16 or 17, wherein at least one network of the interconnected channels consists of or includes a helical structure.

19. The fluid bonding device according to the preceding claim, wherein the helical structure has a unit cell size. L This makes the half-cell size L / 2 It is equal to or less than the thickness of the fluid coupling device at the coupling interface to which the eddy current mitigation component is attached.

20. The fluid bonding device according to the preceding claim, wherein the cell size of the helical structure is... L The thickness is less than the thickness of the portion of the fluid coupling device attached to the eddy current mitigation component.

21. The fluid coupling device according to any one of claims 18-20, wherein the helical structure has a... L / 50 to L / 2 Within the range, preferably in L / 30 to L / 4 The wall thickness of the partitioned channel segment within the range, where L It is the cell size of the helical structure.

22. The fluid coupling device according to any one of the preceding claims, wherein, The eddy current mitigation component includes a coupling interface (8) which includes a bottom wall configured to be bonded or welded to a complementary interface of the fluid coupling device.

23. The fluid coupling device according to any one of the preceding claims, wherein, The fluid coupling device includes a hydrofoil, wing, propeller or blade, or is composed of a hydrofoil, wing, propeller or blade.

24. The fluid coupling device according to the preceding claim, characterized in that, The vortex mitigation components are arranged on the tip (14) of the hydrofoil, wing, propeller or blade.

25. The fluid coupling device according to any one of the preceding two claims, wherein the vortex mitigation component is disposed on the trailing edge of the hydrofoil, wing, propeller or blade.

26. The fluid coupling device according to any one of the preceding three claims, wherein the vortex mitigation component is disposed on the leading edge of the hydrofoil, wing, propeller or blade.

27. The fluid coupling device according to any one of claims 16 to 22, wherein the fluid coupling device includes or is composed of a hub front end (16), and the eddy current mitigation component is disposed on the hub front end.

28. The fluid engagement device according to any one of claims 16-27, wherein the eddy current mitigation component is configured for hydraulic applications.

29. The fluid coupling device according to the preceding claim, wherein, The eddy current mitigation component is configured to reduce cavitation.

30. The fluid bonding device according to any one of claims 16-29, wherein the eddy current reduction structure (3) is manufactured by an additive manufacturing process such as 3D printing.

31. An apparatus (100) comprising a fluid coupling device according to any one of claims 16 to 30, wherein the apparatus is any one of a marine propulsion system, a wind turbine, a hydraulic turbine, a marine hydrofoil, or an aircraft wing.

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