Hydrofoil performance optimization device based on self-adaptive vortex generator and control method

Abstract

The invention discloses a hydrofoil performance optimization device based on a self-adaptive vortex generator and a control method, and aims to solve the problems of large attack angle boundary layer separation and small attack angle additional resistance of a hydrofoil. The device comprises a hydrofoil, a suction surface / pressure surface power transmission assembly, a rack sliding block, a vortex generator and a built-in cavity, the power transmission assembly is directly driven by fluid to rotate, and the sliding block is driven to move through gear-rack transmission. According to the control method, based on the flow velocity difference between the suction surface and the pressure surface of the hydrofoil, a threshold value of critical separation and the maximum working speed difference is set, and three-state adjustment of complete retraction, partial extension or complete extension of the vortex generator is automatically achieved. External energy sources are not needed, the structure is simple and reliable, additional resistance can be eliminated at a small attack angle, flow separation is restrained at a large attack angle, the requirements of multiple working conditions are met, the lift-drag characteristic and operation stability of the hydrofoil are remarkably improved, and the hydrofoil is suitable for the fields of high-performance ships, underwater vehicles and the like.

Description

Technical Field

[0001] This invention belongs to the field of fluid mechanics and marine engineering equipment technology, and in particular relates to a hydrofoil performance optimization device and supporting control method based on an adaptive vortex generator suitable for high-performance ships and underwater vehicles. Background Technology

[0002] Hydrofoils, as core hydrodynamic lifting components, generate lift in fluids through their special airfoil structures, lifting the hull or main body of underwater equipment above the water surface. This significantly reduces drag, increases speed, and improves seakeeping, making them widely used in high-performance ships and underwater vehicles. However, under high angle-of-attack or unsteady flow conditions, hydrofoils are prone to boundary layer separation, stall, and cavitation, leading to a sharp drop in lift, a surge in drag, and even structural vibration and fatigue damage. These issues severely restrict the overall performance and operational safety of hydrofoil equipment.

[0003] Vortex generators (VGs) are key passive control components for solving the aforementioned problems. They induce longitudinal vortices by incorporating small protrusions on the airfoil, transferring the momentum of the high-speed fluid in the main flow region to the near-wall boundary layer, thereby delaying boundary layer separation and postponing stall. However, traditional vortex generators have inherent drawbacks: First, their fixed structure, size, shape, and installation position cannot be adjusted, limiting their effectiveness to the designed angle of attack range. Their effectiveness diminishes or even becomes counterproductive when operating conditions deviate. Second, even at low angles of attack without separation, they still protrude from the airfoil, generating additional parasitic drag and vortex drag, reducing operating efficiency. Third, they have poor parameter adaptability; the vortex intensity and drag of different VG shapes exhibit a trade-off (e.g., rectangular VGs have high vortex intensity but high drag, while triangular VGs have low drag but weak vortex intensity), and the fixed structure cannot dynamically adapt to complex incoming flows.

[0004] To overcome the aforementioned shortcomings, researchers have proposed solutions such as retractable VGs, smart material-based adaptive VGs, and flap-linked VGs. However, these solutions suffer from structural complexity, response lag, insufficient control precision, or reliance on external energy sources. In existing technologies, passive solutions offer strong engineering practicality but lack adaptability, while active / semi-active solutions, although adaptable to various operating conditions, suffer from insufficient reliability. Therefore, developing a device and its corresponding control method that balances engineering practicality and operating condition adaptability without requiring additional energy input has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrofoil performance optimization device and control method based on an adaptive vortex generator. It does not rely on external power sources, internal combustion engines or other additional energy sources. It drives the mechanical transmission system through the kinetic energy of the fluid itself. With the help of precise working condition judgment and adjustment logic, it realizes the automatic activation, deactivation and linear adjustment of the extension height of the vortex generator under different angle of attack conditions. It can effectively suppress boundary layer separation under high angle of attack conditions and avoid generating additional drag under low angle of attack conditions without separation, thus ensuring the excellent flow performance of the hydrofoil in the entire working condition range.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A hydrofoil performance optimization device based on an adaptive vortex generator includes a hydrofoil, a suction surface power transmission component, a pressure surface power transmission component, a rack and pinion slider, and a vortex generator.

[0007] The hydrofoil has a gear cavity and a slider cavity, which are connected; the slider cavity is opened perpendicular to the span of the hydrofoil.

[0008] The suction surface power transmission assembly includes a suction surface main gear, a suction surface conveyor belt, a suction surface secondary gear, and a suction surface drive gear, all linked in sequence. The suction surface main gear is mounted on the hydrofoil's suction surface via a rotating shaft, with its teeth protruding from the suction surface and directly driven to rotate by the fluid flowing through it. Both the suction surface secondary gear and the suction surface drive gear are rotatably mounted within gear cavities. The suction surface main gear is connected to the suction surface secondary gear via the suction surface conveyor belt; the suction surface secondary gear meshes with the suction surface drive gear. The suction surface main gear is exposed on the hydrofoil's suction surface, directly contacting the fluid and driven to rotate using fluid kinetic energy, serving as the suction surface side power input. Power is transmitted to the suction surface secondary gear via the suction surface conveyor belt, and then, through the meshing of the suction surface secondary gear and the suction surface drive gear, the direction of power and rotational speed are converted.

[0009] The pressure surface power transmission assembly includes a pressure surface main gear, a pressure surface conveyor belt, a pressure surface secondary gear, and a pressure surface drive gear, all linked in sequence. The pressure surface main gear is mounted on the hydrofoil pressure surface via a rotating shaft, with its teeth protruding from the pressure surface and directly driven to rotate by the fluid flowing through the suction surface. Both the pressure surface secondary gear and the pressure surface drive gear are rotatably mounted within gear cavities. The pressure surface main gear is connected to the pressure surface secondary gear via the pressure surface conveyor belt; the pressure surface secondary gear meshes with the pressure surface drive gear. The pressure surface main gear is exposed on the hydrofoil pressure surface and is directly driven to rotate by the fluid flowing through the pressure surface, serving as the pressure surface-side power input. The transmission and conversion of pressure surface-side power are completed through the sequential transmission of the pressure surface conveyor belt, the pressure surface secondary gear, and the pressure surface drive gear.

[0010] The rack and pinion slider is slidably engaged in the slider cavity via the slider on its back side. The front side is machined with a rack structure, which meshes with the suction surface transmission gear and the pressure surface transmission gear respectively.

[0011] The suction surface power transmission component and the pressure surface power transmission component are symmetrically arranged about the vertical rack and slider, and the corresponding components have the same dimensions. That is, the suction surface power transmission component and the pressure surface power transmission component are symmetrically arranged about the vertical rack and slider. The suction surface main gear and the pressure surface main gear have the same dimensions; the suction surface conveyor belt and the pressure surface conveyor belt have the same dimensions; the suction surface auxiliary gear and the pressure surface auxiliary gear have the same dimensions; and the suction surface transmission gear and the pressure surface transmission gear have the same dimensions.

[0012] The vortex generator is fixedly installed at one end of the rack slider facing the hydrofoil suction surface. A suitable gap is opened at the corresponding position of the hydrofoil suction surface, so that the vortex generator can extend out of the hydrofoil or retract into the hydrofoil slider cavity through the gap as the rack slider moves.

[0013] Further optimization involves arranging multiple rectangular blades of the same specification in the vortex generator at equal intervals along the thickness direction of the rack and pinion slider. The height h of a single blade is 10% to 50% of the maximum thickness H of the hydrofoil. This height range takes into account both the longitudinal vortex separation intensity and flow resistance, and is preferably 20% to 40% of H.

[0014] Further optimization is achieved by satisfying the following condition: H2 = H1 + (30%~50%)h; Where H1 is the height of the rack slide. A space of 30%~50%h is reserved to accommodate the eddy current generator in its extended state and to provide a buffer for the movement of the rack slide, avoiding mechanical collisions.

[0015] Further optimization involves using soft iron or silicon steel as the material for the rack and pinion slider, and a polyurethane synchronous belt as the conveyor belt, which features wear resistance, water resistance, and high transmission accuracy. The gears and slider cavities of the hydrofoil, as well as the connections to the outside environment, all employ dynamic sealing structures to prevent underwater leakage.

[0016] Further optimization is achieved by using the following formula to calculate the center distance A between the suction surface main gear and the suction surface secondary gear connected by the suction surface in the suction surface power transmission assembly: A=[L-π(d1+d2) / 2] / 2; where L is the length of the suction surface transmission, d1 is the pitch circle diameter of the suction surface main gear, and d2 is the pitch circle diameter of the suction surface secondary gear.

[0017] The center distance A of the pressure surface power transmission component is the same as that of the suction surface power transmission component, ensuring the smoothness and tension of the conveyor belt transmission.

[0018] Further optimization is achieved by assuming the spanwise thickness of the rack and slide block is δ. The formula for calculating the number of teeth Z of the suction-side drive gear and the pressure-side drive gear is: Z = 2T / (ρH1δbm); where T is the input torque of the suction-side drive gear or the pressure-side drive gear, ρ is the density of the rack and slide block material, b is the width of the rack and slide block, H1 is the height of the rack and slide block, and m is the module of the suction-side drive gear and the pressure-side drive gear. This formula is designed based on the structural strength of the rack and slide block to avoid deformation of the rack and slide block due to excessive torque during transmission, thus ensuring the reliability of the meshing transmission.

[0019] Further optimization involves the use of the NACA0009 airfoil, with its maximum thickness H located at 29.7% of the chord. This airfoil is a symmetrical airfoil specifically designed for high-speed ships and underwater vehicles, and is adapted to the hydrodynamic requirements of high-speed flow.

[0020] A hydrofoil performance optimization control method based on the above-mentioned device utilizes the fluid velocity difference between the suction and pressure surfaces of the hydrofoil at different angles of attack to drive the mechanical transmission system to achieve adaptive adjustment of the vortex generator. Specifically, it includes the following steps: Step 1: Set the operating condition judgment threshold: Define the velocity difference between the suction surface main gear and the pressure surface main gear at the critical separation state under the design incoming flow velocity as ΔV1; when the hydrofoil is at its maximum working angle of attack, the difference in pitch circle linear velocity between the two is ΔV2, and ΔV1 < ΔV2.

[0021] Step 2: Real-time acquisition of velocity difference: When fluid flows through the hydrofoil, the velocity difference between the suction surface and the pressure surface drives the corresponding main gear to rotate. The speed difference between the main gears of the suction surface and the main gears of the pressure surface is directly converted into the actual surface velocity difference ΔV. No additional sensors are required, realizing real-time and power-free acquisition of velocity difference.

[0022] Step 3: Adaptive adjustment of eddy current generator state: The driving forces of the suction surface power transmission component and the pressure surface power transmission component on the rack slider are opposite. The lower limit position and upper limit position of the rack slider are limited by the mechanical limiting structure. Under the condition of zero angle of attack and no separation, the rack slider is initially in the lower limit position.

[0023] 1) When ΔV≤ΔV1: small angle of attack without separation, the velocity difference between the suction surface and the pressure surface is small, the rotation speed of the main gear of the suction surface and the main gear of the pressure surface are similar, and the driving force transmitted to the rack and slider through the transmission component is balanced with each other. The rack and slider is kept at the lower limit position, the eddy current generator is completely retracted into the slider cavity to avoid generating additional resistance, and is in a non-working state.

[0024] 2) When ΔV1<ΔV<ΔV2: Transitional condition, the flow velocity on the suction surface is higher than that on the pressure surface, the rotation speed of the main gear on the suction surface is higher than that on the pressure surface, the driving force imbalance pushes the rack and slider to move upward, and part of the vortex generator extends out of the hydrofoil suction surface and is in a partial working state, accurately matching flow control and resistance balance.

[0025] 3) When ΔV≥ΔV2: In the high angle of attack separation condition, the velocity difference reaches its maximum value, the rack and slider moves to the upper limit position, the vortex generator is fully extended from the hydrofoil suction surface and is in full working state, suppressing boundary layer separation to the greatest extent, inducing strong longitudinal vortices, suppressing boundary layer separation to the greatest extent, and ensuring hydrofoil lift and stability.

[0026] Further optimization is achieved by setting ΔV1 to the critical separation angle of attack αc of the hydrofoil (8°~10°) and ΔV2 to the maximum operating angle of attack αm of the hydrofoil (20°~25°).

[0027] Further optimization involves the following step 3: the extension height of the eddy current generator increases linearly with the increase of the actual velocity difference ΔV.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Strong self-adaptability, no external energy required: The device relies on the fluid's own kinetic energy for drive, and the control method is based on the velocity difference between the suction and pressure surfaces to autonomously determine the working conditions. It does not require an external power supply, sensor or control system, and achieves passive adaptive adjustment, which fundamentally reduces energy consumption and the risk of electronic component failure, and is suitable for harsh underwater working environments.

[0029] 2. Optimized performance under all operating conditions: Through three-state linear adjustment, the vortex generator is fully retracted at small angles of attack to eliminate additional drag and vortex drag and improve navigation efficiency; it is fully extended at large angles of attack to effectively suppress boundary layer separation, delay stall, and avoid sudden drop in lift and structural vibration; the extension height is linearly adjusted in transition conditions to achieve precise matching of flow control and drag balance, taking into account both lift enhancement and drag control. This effect cannot be achieved by existing passive adjustable vortex generators.

[0030] 3. Simple and reliable structure: It adopts a mechanical transmission structure of "gear-conveyor belt-rack", without complex electronic components or smart materials, which makes it easy to process and maintain, and is suitable for harsh working environments such as underwater.

[0031] 4. Scientific and controllable parameter design: By clearly defining key parameters such as vortex generator height, slider cavity size, and velocity difference threshold, and combining them with precise calculation formulas, and calibrating the angle of attack and velocity difference threshold under the design incoming flow velocity, the device can be flexibly adapted to the hydrofoil size and operating conditions of different application scenarios such as high-performance ships and underwater vehicles, thus solving the problem of poor adaptability of existing technical parameters. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention in its full working state at large angle of attack; Figure 2 This is a schematic diagram of the overall structure of the device of the present invention in a non-working state at a small angle of attack; Figure 3 This is a top view of the suction surface of the eddy current generator and rack and pinion slider described in this invention; Figure 4 This is a partial enlarged view of the eddy current generator in full working state according to the present invention; Figure 5 This is a partially enlarged view of the eddy current generator of the present invention in its non-operating state;

[0033] In the diagram: 1-hydrofoil; 2-suction surface main gear; 3-suction surface conveyor belt; 4-suction surface secondary gear; 5-suction surface transmission gear; 6-pressure surface main gear; 7-pressure surface conveyor belt; 8-pressure surface secondary gear; 9-pressure surface transmission gear; 10-rack and slide block; 11-eddy current generator; 12-gear cavity; 13-slide block cavity. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0035] Example 1: Refer to Appendix Figure 1 A hydrofoil performance optimization device based on an adaptive vortex generator includes a hydrofoil 1, a suction surface main gear 2, a suction surface conveyor belt 3, a suction surface secondary gear 4, a suction surface transmission gear 5, a pressure surface main gear 6, a pressure surface conveyor belt 7, a pressure surface secondary gear 8, a pressure surface transmission gear 9, a rack and pinion slider 10, and an vortex generator 11.

[0036] The hydrofoil 1 has a gear cavity 12 and a slider cavity 13, which are connected. The connection between the gear cavity 12 and the slider cavity 13 adopts a dynamic sealing structure.

[0037] The suction surface power transmission component and the pressure surface power transmission component are symmetrically arranged about the vertical rack and pinion slider 10, and the corresponding gears and conveyor belts have the same size and transmission ratio; the suction surface main gear 2 and the pressure surface main gear 6 are both fixed to the corresponding wing surface through a rotating shaft, with the teeth protruding from the wing surface, and the connection between the rotating shaft and the hydrofoil 1 adopts a dynamic sealing structure.

[0038] The suction surface conveyor belt 3 and the pressure surface conveyor belt 7 are polyurethane synchronous belts. The rack and pinion slider 10 is made of silicon steel and has a guide rail sliding structure on the back, which slides and engages with the slider cavity 13. Upper and lower mechanical limit blocks are set in the slider cavity 13 to limit the movement range of the rack and pinion slider 10.

[0039] The vortex generator 11 includes multiple rectangular small blades, which are arranged at equal intervals along the thickness span of the rack slider 10. The height of a single blade (i.e., the height of the vortex generator) h is 10% to 50% of the maximum thickness H of the hydrofoil 1. The suction surface of the hydrofoil 1 is provided with corresponding fitting gaps to ensure that the extension and retraction of the vortex generator 11 is smooth.

[0040] The center distance A between the suction surface main gear 2 and the suction surface secondary gear 4 is calculated according to the formula A=[L-π(d1+d2) / 2] / 2. The center distance A of the pressure surface power transmission component is the same as that of the suction surface side. The number of teeth Z of the transmission gear is calculated according to the formula Z=2T / (ρH1δbm) to ensure the structural strength and meshing transmission reliability of the rack and pinion slider 10.

[0041] The hydrofoil 1 adopts the NACA0009 airfoil, with the maximum thickness H located at 29.7% of the chord.

[0042] The working process of the device in this embodiment is as follows: When the hydrofoil 1 is in a small angle of attack without separation, the velocity difference between the suction surface and the pressure surface is small. The main gear 2 of the suction surface and the main gear 6 of the pressure surface rotate at similar speeds. The driving forces transmitted to the rack and slide block 10 by the power transmission components of the suction surface and the pressure surface are balanced. The rack and slide block 10 is in the lower limit position. The eddy current generator 11 is completely retracted into the slide block cavity 13 and does not participate in the flow, thus avoiding the generation of additional resistance.

[0043] When hydrofoil 1 is in a high angle of attack and easy separation condition, the suction surface flow channel contracts and the flow velocity increases, while the flow velocity on the pressure surface decreases relatively. The speed of the suction surface main gear 2 is higher than that of the pressure surface main gear 6. The driving force of the dual power transmission components is unbalanced, which pushes the rack slider 10 to move upward along the slider cavity 13, causing the vortex generator 11 to gradually extend out of the suction surface and induce longitudinal vortices to suppress boundary layer separation.

[0044] When the hydrofoil 1 is in the transition angle of attack condition, the velocity difference between the suction surface and the pressure surface is between the critical separation and the maximum working angle of attack. The moving distance of the rack and pinion slider 10 changes linearly with the velocity difference, and the extension height of the vortex generator 11 also increases linearly, so as to achieve a precise match between flow control and resistance balance.

[0045] Example 2: An adaptive vortex generator device suitable for high-speed ship hydrofoils, specifically improving cruise efficiency and maneuverability. Its basic structure is the same as that of Example 1. The parameters are quantitatively designed according to the operating conditions of high-speed ship hydrofoils. The specific parameters and control methods are executed as follows: 1) The parameters of the hydrofoil performance optimization device are as follows: Hydrofoil 1: NACA0009 airfoil, maximum thickness H=200mm, located at 29.7% chord, design incoming flow velocity 12m / s, critical separation angle of attack αc=10°, maximum operating angle of attack αm=25°.

[0046] Vortex generator 11: Rectangular small airfoils, height h=20%H=40mm, spanwise spacing 80mm, evenly spaced along the spanwise direction of the rack and slider.

[0047] Rack and pinion slider 10: Silicon steel material, ρ=7.85g / cm 3 The height H1=60mm, the width b=20mm, the span thickness δ=60mm, and the back is equipped with a guide rail sliding structure.

[0048] Slider cavity 13: Height H2 = 60mm + 35% × 40mm = 74mm, with a buffer space of 35% h reserved, and upper and lower mechanical limit blocks are installed inside the cavity.

[0049] Gears and conveyor belt: main gear pitch circle diameter 20mm, secondary gear pitch circle diameter 30mm, polyurethane synchronous belt length L=200mm, center distance A≈60.75mm; transmission gear module m=1mm, input torque T=280.8N・mm, number of teeth Z=20.

[0050] Sealing and limiting: All rotating shafts and chamber connections are sealed with rubber dynamic seals. The upper and lower limit blocks inside the slider cavity are made of wear-resistant engineering plastics to prevent mechanical collisions between the rack and slider.

[0051] 2) The control method execution process is as follows: Step 1: Set the operating condition judgment threshold: Under the design flow velocity of 12m / s, calibrate ΔV1=1.5m / s, corresponding to αc=10°; ΔV2=4.0m / s, corresponding to αm=25°.

[0052] Step 2: Real-time sensing of speed difference: When the ship is sailing, the water flows through the hydrofoil 1, and the main gear of the suction / pressure surface is driven to rotate by the corresponding water flow. The flow velocity difference is converted into the pitch circle linear velocity difference ΔV of the main gear in real time, which is sensed through mechanical transmission.

[0053] Step 3: Adaptively adjust the eddy current generator state: 1) Cruise condition (α=8°): The actual speed difference ΔV=1.2m / s≤ΔV1, the main gear speeds of the suction surface and the pressure surface are similar, the driving forces are balanced, the rack and slider 10 is kept at the lower limit position, the eddy current generator 11 is fully retracted, eliminating additional resistance and reducing ship fuel consumption; compared with the Chinese patent application, titled: A blade or wing with built-in adaptive eddy current generator, application publication number: CN117329165A, there is no spring preload loss in this condition, and the additional resistance is smaller.

[0054] 2) Sharp turn condition (α=18°): The actual speed difference ΔV=2.8m / s. At this time, ΔV1<ΔV<ΔV2, the driving force imbalance pushes the rack and pinion slider 10 to move upward, and the eddy current generator 11 extends out to a height of 22mm, linearly adapting to the change of angle of attack and balancing the lift and drag when the ship is maneuvering; while Chinese patent application CN117329165A can only achieve full extension or retraction. Under this condition, it is easy to have problems such as insufficient separation or excessive drag.

[0055] 3) Over-wave condition (α=25°): When the actual speed difference ΔV=4.0m / s≥ΔV2, the rack and pinion slider 10 moves to the upper limit position, the vortex generator 11 is fully extended, and strong longitudinal vortex is induced, which effectively suppresses hydrofoil boundary layer separation and avoids hull stall and vibration. Compared with Chinese patent application CN117329165A, this invention has no effect of spring elastic coefficient decay, the adjustment accuracy is more stable, and the separation suppression effect is more reliable.

[0056] This invention achieves passive adaptive flow control without external energy by deeply integrating the device structure and control method. Compared with the prior art, especially the comparative scheme in Chinese patent application CN117329165A, it has made significant breakthroughs in driving principle, structural reliability, adjustment accuracy, and working condition adaptability. It has a simple structure, reliable performance, and strong versatility, and can be widely used in various hydrofoil equipment such as high-performance ships and underwater vehicles. It has important engineering application value and promotion prospects.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydrofoil performance optimization device based on an adaptive vortex generator, characterized in that, It includes a hydrofoil (1), a suction surface power transmission assembly, a pressure surface power transmission assembly, a rack and pinion slider (10), and an eddy current generator (11). The hydrofoil (1) has a gear cavity (12) and a slider cavity (13) which are connected; the slider cavity (13) is opened perpendicular to the span of the hydrofoil (1); The suction surface power transmission component and the pressure surface power transmission component are symmetrically arranged about the vertical rack and pinion slider (10), and the corresponding components have the same size; The suction surface power transmission assembly includes a suction surface main gear (2), a suction surface conveyor belt (3), a suction surface secondary gear (4), and a suction surface transmission gear (5) that are linked in sequence. The suction surface main gear (2) is mounted on the suction surface of the hydrofoil (1) via a rotating shaft, with its teeth protruding from the suction surface and directly driven to rotate by the fluid flowing through the suction surface. The suction surface secondary gear (4) and the suction surface transmission gear (5) are both rotatably mounted in the gear cavity (12). The suction surface main gear (2) is connected to the suction surface secondary gear (4) via the suction surface conveyor belt (3). The suction surface secondary gear (4) meshes with the suction surface transmission gear (5). The pressure surface power transmission assembly includes a pressure surface main gear (6), a pressure surface conveyor belt (7), a pressure surface secondary gear (8), and a pressure surface transmission gear (9) that are linked in sequence. The pressure surface main gear (6) is mounted on the pressure surface of the hydrofoil (1) via a rotating shaft, with its teeth protruding from the pressure surface and directly driven to rotate by the fluid flowing through the pressure surface. The pressure surface secondary gear (8) and the pressure surface transmission gear (9) are both rotatably mounted in the gear cavity (12). The pressure surface main gear (6) is connected to the pressure surface secondary gear (8) via the pressure surface conveyor belt (7). The pressure surface secondary gear (8) meshes with the pressure surface transmission gear (9). The rack and pinion slider (10) is slidably mounted in the slider cavity (13) through the slider on its back side. The front side is machined with a rack structure, and the rack structure meshes with the suction surface transmission gear (5) and the pressure surface transmission gear (9) respectively. The vortex generator (11) is fixedly installed at one end of the rack slider (10) facing the suction surface of the hydrofoil (1). The suction surface of the hydrofoil (1) has a matching gap at the corresponding position, so that the vortex generator (11) can extend out of the hydrofoil (1) or retract into the slider cavity (13) of the hydrofoil (1) through the gap as the rack slider (10) moves.

2. The hydrofoil performance optimization device based on an adaptive eddy current generator according to claim 1, characterized in that, The vortex generator (11) includes multiple rectangular blades of the same size, which are arranged at equal intervals along the thickness direction of the rack and slider. The height h of a single blade is 10% to 50% of the maximum thickness H of the hydrofoil (1).

3. The hydrofoil performance optimization device based on an adaptive eddy current generator according to claim 2, characterized in that, The height H2 of the slider cavity (13) satisfies: H2=H1+(30%~50%)h; Where H1 is the height of the rack slider (10).

4. The hydrofoil performance optimization device based on an adaptive eddy current generator according to claim 3, characterized in that, The center distance A between the suction surface main gear (2) and the suction surface secondary gear (4) of the suction surface power transmission assembly is calculated as follows: A = [L - π(d1 + d2) / 2] / 2; where L is the length of the suction surface conveyor belt (3), d1 is the pitch circle diameter of the suction surface main gear (2), and d2 is the pitch circle diameter of the suction surface secondary gear (4); The center distance of the pressure surface power transmission component is the same as that of the suction surface power transmission component.

5. The hydrofoil performance optimization device based on an adaptive eddy current generator according to claim 4, characterized in that, Let the thickness of the rack slider (10) be δ, and the formula for calculating the number of teeth Z of the suction surface transmission gear (5) and the pressure surface transmission gear (9) is: Z=2T / (ρH1δbm); Where T is the input torque of the suction surface transmission gear (5) or the pressure surface transmission gear (9), ρ is the density of the material of the rack slider (10), b is the width of the rack slider (10), H1 is the height of the rack slider (10), and m is the module of the suction surface transmission gear (5) and the pressure surface transmission gear (9).

6. The hydrofoil performance optimization device based on an adaptive eddy current generator according to claim 5, characterized in that, The hydrofoil (1) adopts the NACA0009 airfoil, and its maximum thickness H is located at 29.7% chord.

7. A method for optimizing and controlling the performance of a hydrofoil based on the device according to any one of claims 1-6, characterized in that, By utilizing the difference in fluid velocity between the suction and pressure surfaces of the hydrofoil at different angles of attack, the mechanical transmission system is driven to achieve adaptive adjustment of the vortex generator. This specifically includes the following steps: Step 1: Set the working condition judgment threshold: Define the difference in pitch circle linear velocity between the suction surface main gear (2) and the pressure surface main gear (6) of the hydrofoil (1) at the critical separation state under the design incoming flow velocity as ΔV1; when the hydrofoil (1) is at its maximum working angle of attack, the difference in velocity between the two is ΔV2, and ΔV1 < ΔV2; the transmission ratio of the suction surface power transmission component and the pressure surface power transmission component is the same; Step 2: Real-time acquisition of velocity difference: When the fluid flows through the hydrofoil (1), the suction surface main gear (2) and the pressure surface main gear (6) are driven to rotate by the fluid on their respective surfaces, thus forming the actual surface velocity difference ΔV between the two in real time; Step 3: Adaptive adjustment of eddy current generator state: The driving forces of the suction surface power transmission component and the pressure surface power transmission component on the rack slider (10) are opposite. The lower limit position and upper limit position of the rack slider (10) are limited by the mechanical limiting structure. Under the condition of zero angle of attack and no separation of the hydrofoil (1), the rack slider (10) is initially in the lower limit position; then: 1) When ΔV≤ΔV1, the main gear (2) of the suction surface and the main gear (6) of the pressure surface rotate at similar speeds. The driving force transmitted to the rack slider (10) through the transmission assembly is balanced. The rack slider (10) is kept at the lower limit position. The eddy current generator (11) is completely retracted into the slider cavity (13) and is in a non-working state. 2) When ΔV1<ΔV<ΔV2, under the condition of the hydrofoil having an angle of attack, the speed of the suction surface main gear (2) is higher than that of the pressure surface main gear (6), the driving force imbalance pushes the rack slider (10) to move upward, and part of the vortex generator (11) extends out of the suction surface of the hydrofoil (1) and is in a partially working state. 3) When ΔV≥ΔV2, the rack slider (10) moves to the upper limit position, the vortex generator (11) extends fully out of the suction surface of the hydrofoil (1) and is in full working state, suppressing boundary layer separation to the greatest extent.

8. The hydrofoil performance optimization control method according to claim 7, characterized in that, In step 1, the critical separation angle of attack αc of the hydrofoil (1) corresponding to ΔV1 is 8°~10°, and the maximum working angle of attack αm of the hydrofoil (1) corresponding to ΔV2 is 20°~25°.

9. The hydrofoil performance optimization control method according to claim 8, characterized in that, In step 3, the extension height of the eddy current generator (11) increases linearly with the increase of the actual velocity difference ΔV.

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