An active control device for realizing flexible variable camber of a trailing edge of a leading edge slat

Abstract

The application provides an active control device for realizing flexible bending of a leading edge slat tail edge, and belongs to the technical field of aerospace vehicle aerodynamic shape control and structure design. The device comprises a slat main frame, a flexible bending skin connected to the outside of the slat main frame, and an actuating mechanism arranged in the inside of the slat main frame. The device can be applied to large transport aircraft wing components as a flexible lift-increasing device, and is used for realizing active deformation control of the leading edge slat in flight, so as to improve low-speed aerodynamic performance and noise characteristics. Meanwhile, the device can also be applied to wind tunnel experimental research, and the geometric shape after bending of the device is obtained through three-dimensional scanning, so as to provide accurate shape reference for wind tunnel experimental research on the aerodynamic characteristics and noise mechanism of the leading edge slat.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic shape control and structural design technology for aerospace vehicles, specifically to an active control device for achieving flexible bending of the trailing edge of a leading-edge slat. Background Technology

[0002] The continuous development of smart materials, flow control, and multi-objective disciplines has provided more possibilities for the design of flexible airfoils. Research on flexible airfoils began as early as the last century. Compared with traditional rigid airfoils, flexible airfoils have advantages such as adaptability, drag reduction and fuel saving, and potential noise reduction effects.

[0003] Numerous studies both domestically and internationally have demonstrated that flexible deformable wings offer superior lift enhancement compared to rigid wings. Flexible wings can effectively improve an aircraft's lift and lift-to-drag ratio during low-speed flight or takeoff and landing by varying camber and increasing wing area. The smooth, continuously cambered shape of flexible wings avoids unnecessary hydrodynamic phenomena and is more conducive to reducing aerodynamic noise. Depending on different airflow environments and flight speeds, flexible wings can actively change their aerodynamic shape, more precisely controlling flight attitude to achieve real-time optimization for various flight conditions. Furthermore, the shape of a flexible wing is adjustable throughout its entire span, and the entire wing can be considered a control surface, thus improving control efficiency. In terms of adaptability and safety, flexible wings can automatically deform according to aerodynamic loads, better distributing and bearing complex loads during flight, achieving a more uniform load distribution, thereby enhancing the aircraft's adaptability to complex loads and gust loads. When faced with airflow fluctuations or unstable wind speeds, flexible wings can better adapt to and absorb external forces, reducing the impact of air disturbances on the wings. Especially under conditions of strong winds or severe weather, they can alleviate excessive local stress on the wings, reduce structural fatigue, and effectively improve the overall safety of the aircraft. With the development of aerospace technology, flexible lift-enhancing devices, due to their adaptive aerodynamic shape adjustment capabilities, have become an important research direction for improving aircraft flight performance.

[0004] Leading-edge slats, as a core component of the lift-enhancing control surfaces of large transport aircraft wings, directly influence the aircraft's lift characteristics, stall performance, and noise levels. Especially during low-speed flight phases (such as takeoff and landing), aerodynamic optimization of leading-edge slats is crucial for flight safety and economy. Particularly in large passenger aircraft, existing leading-edge slats often employ rigid structural designs, capable only of fixed-angle deflection and unable to adjust their aerodynamic shape in real-time according to flight conditions. This makes it difficult for the aircraft to maintain optimal aerodynamic performance in complex flight environments. For example, while traditional three-position leading-edge slats have a mature mechanism, they cannot maintain the optimal lift-to-drag ratio across the entire flight envelope, resulting in insufficient lift at low speeds and excessive drag at high speeds. The technical reason lies in the lack of dynamic adjustment capability in rigid structures, making them ill-suited to complex and changing flight environments.

[0005] Unlike the rigid structure design of traditional aircraft leading-edge slats, experimental models of variable-camber slats must simultaneously meet two mutually restrictive core requirements: first, the internal structure must accommodate a power unit capable of providing sufficient driving force to overcome skin deformation resistance; second, the skin material must possess both sufficient strength to withstand aerodynamic loads and sufficient flexibility to achieve smooth, continuous camber. Due to the limited internal space of the leading-edge slat, conventional actuators (such as hydraulic cylinders and linear motors) are difficult to arrange. High-modulus skin materials (such as polyamide nylon) have high bending stiffness, leading to a surge in driving force requirements, while low-modulus skin materials (such as low-hardness silicone) struggle to maintain aerodynamic stability. This inherent contradiction represents a long-standing technical challenge in this field. Summary of the Invention

[0006] In view of the above problems, this invention proposes an active control device for achieving flexible bending of the trailing edge of a leading-edge slat. This device, within a limited space, achieves continuous and controllable flexible bending of the slat trailing edge through an embedded drive system. It can be applied as a flexible lift enhancement device to the wings of large aircraft to achieve active deformation control of the leading-edge slat trailing edge during flight. This device keeps the skin surface smooth and continuous before and after deformation, thereby improving the low-speed aerodynamic performance and aerodynamic noise characteristics of the aircraft. Simultaneously, this device can also be applied to wind tunnel experimental research, obtaining the geometric shape of the model after bending through three-dimensional scanning, providing a precise shape reference for wind tunnel experimental research on the aerodynamic characteristics and noise mechanisms of leading-edge slats.

[0007] This invention provides an active control device for achieving flexible bending of the trailing edge of a leading-edge slat, comprising: The slat main frame, the flexible bendable skin 4 connected to the outside of the slat main frame, and the actuation mechanism set inside the slat main frame; The actuation mechanism includes servo motor 1, servo motor 2, servo disc 1, servo disc 2, elastic traction cable 7, elastic traction cable 2, winding shaft 6, winding shaft 2, and steel shaft 3. Servo motor 1 and servo motor 2 are respectively installed on one side at both ends of the spanwise direction of the slat main frame via connecting plate 5 and connecting plate 2; Servo motor 1 and servo motor 2 are also connected to servo disc 1 and servo disc 2 on the other side, respectively; Rudder disk 1 and rudder disk 2 are also connected to winding shaft 1 and winding shaft 2, respectively. Among them, the second winding shaft 6 is a fixed guide shaft, which is installed inside the main frame of the slatted wing near the steel shaft 3, and is used to change the direction of the traction cable or fix one end of the elastic traction cable. One end of the elastic traction cable 7 and the elastic traction cable 2 are connected to the winding shaft 1 and the winding shaft 2 respectively. The elastic traction cable is used to change the direction of the tension so that the tension can be output in the direction pointing to the steel shaft 3. The other ends of elastic traction cable 7 and elastic traction cable 2 are respectively wrapped and fixed to both ends of steel shaft 3; The steel shaft 3 is set along the chord direction on the lower wing surface of the flexible bending skin and penetrates the flexible bending skin along the span direction. When the traction cable pulls the steel shaft 3, the steel shaft 3 causes the surrounding skin to move together, causing elastic deformation of part of the flexible bending skin. The flexible curved skin in the front 40% chord length area of ​​the upper wing of the slat main frame is fixed to the frame, while the flexible curved skin in the rear 60% chord length area is flexible. The flexible curved skin in the front 50% chord length area of ​​the lower wing is fixed to the frame, while the flexible curved skin in the rear 50% chord length area is flexible. Through the movement of the actuation mechanism, the trailing 60% chord region of the upper wing surface and the trailing 50% chord region of the lower wing surface of the slat trailing edge are driven to achieve a certain angle of downward deflection of the upper trailing edge and upward deflection of the lower trailing edge, respectively.

[0008] Alternatively, the slat main frame is a C-shaped skeletal structure extending along the wingspan. The upper wing surface of the slat main frame extends along the span of the slat, and its length corresponds to the span of the leading edge slat. The chord of the slat main frame has a rounded leading edge shape with a smooth surface, retaining only a portion near the leading edge, and an opening at the rear to allow for the flexible bending skin 4 to deform.

[0009] Optionally, the flexible bending skin is made of TPU polyurethane material with a Shore hardness of 95.

[0010] Optionally, the flexible bendable skin is connected to the leading edge slat main frame in a hybrid connection manner, wherein the front section of the flexible bendable skin is fixed to the slat main frame, and the rear section is free to deform.

[0011] Optionally, the servo motor is a magnetically encoded bus serial servo motor; the servo motor is controlled by serial port commands from a microcontroller, and two sets of servo motors can be controlled in parallel from 0 to 360° through command encoding, and operating parameters such as servo motor rotation angle can be output in real time.

[0012] Optionally, the diameter of the steel shaft 3 is not less than 2 mm.

[0013] Optionally, the winding shafts are located at 1 / 3 and 2 / 3 of the span of the slat main frame, respectively.

[0014] Optionally, the traction cable is a braided cable made of low-elasticity polymer material or a miniature steel wire rope.

[0015] An active control device enables the trailing edge of a leading-edge slat to flexibly bend, comprising: The microcontroller sends serial port commands to servo motor 1 and servo motor 2 according to the preset deflection angle target. After receiving the command, servo motors one and two rotate clockwise and output torque; The rudder discs 1 and 2, which are connected to the rudder output shaft, rotate accordingly, winding and tightening the elastic traction cable 1 and the elastic traction cable 2. After the elastic traction cable 7 and the elastic traction cable 2 are tightened, they pass around the winding shaft 6 and the winding shaft 2, and the direction of the tension is adjusted to point towards the trailing edge of the slat. The tension is ultimately transmitted to the steel shaft, and the steel shaft 3 is displaced under the action of the tension, which causes the skin in the trailing edge area of ​​the slat to undergo elastic bending deformation; At this time, servo motor one and servo motor two continuously output torque to overcome the elastic restoring force of the skin and maintain the deformed shape; Once servo motor 1 and servo motor 2 reach the target angle and stop rotating, the traction cable remains taut, and the skin maintains its current curvature, thus preserving the aerodynamic shape during wind tunnel testing or flight.

[0016] Optionally, the elastic bending deformation of the skin in the trailing edge region of the slat includes: The rear 60% area of ​​the upper wing surface is partially subjected to flexible bending skin under tension, achieving downward deflection of the upper trailing edge; The rear 50% area of ​​the lower wing surface is partially subjected to flexible bending skin under tension, achieving upward deflection of the lower trailing edge.

[0017] The third objective of this invention is to provide an application of an active control device in the wing components of large transport aircraft and in wind tunnel experimental research. In the wing components of large transport aircraft, this device enables active deformation control of the leading-edge slats during flight, thereby improving low-speed aerodynamic performance and noise characteristics. Simultaneously, this device can also be applied to wind tunnel experimental research, acquiring the device's geometric shape after bending through three-dimensional scanning, providing a precise shape reference for wind tunnel experimental research on the aerodynamic characteristics and noise mechanisms of leading-edge slats.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention utilizes a servo motor to control the tension and relaxation of the traction cable in forward / reverse rotation, combined with the high elastic recovery rate of the TPU skin, to achieve the function of the skin completing its own reset. When the servo motor reverses, the traction cable is completely relaxed and does not generate any tension. The skin recovers its original configuration by its own elasticity, without the need for additional reset components, which simplifies the drive system and reduces the complexity and weight of the mechanism; (2) Based on the aerodynamic characteristics analysis of the slat airfoil, this invention proposes a differentiated flexible region allocation scheme with a 40 / 60 division on the upper surface and a 50 / 50 division on the lower surface. Through finite element simulation verification, the allocation scheme proposed in this invention can obtain the maximum trailing edge deflection angle with the minimum driving displacement (the slot is completely closed when the maximum downward deflection angle is 9°), while maintaining uniform stress distribution on the skin surface (maximum equivalent stress 3.16MPa) and good consistency in spanwise deformation; (3) This invention forms a complete material screening-simulation analysis-experimental verification closed loop by conducting uniaxial tensile tests on five groups of TPU materials with different Shore hardness (55, 65, 75, 85, 95), combined with ABAQUS finite element simulation and 3D scanning geometric verification. This system not only provides a scientific basis for the selection of TPU-95HS material, but also provides a reproducible technical path for the material selection of the leading edge slat flexible bending device, which is different from the existing technology of selecting materials based solely on experience or a single experiment; (4) The present invention achieves active and continuous leading-edge slat trailing edge bending within a limited space; (5) The surface of the skin remains smooth after deformation according to the present invention; (6) This invention can provide accurate leading edge slat deformation shape data for wind tunnel experiments, which facilitates the systematic study of aerodynamic / aeroacoustic characteristics. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] Figure 1 This is a schematic diagram of a flat plate in an embodiment of the present invention; Figure 2 This is a schematic diagram of the three-dimensional structure in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the active control device in an embodiment of the present invention; Figure 4 This is a schematic diagram of the slat main frame in an embodiment of the present invention; Figure 5 This is a schematic diagram of the slat skin structure in an embodiment of the present invention; Figure 6 This is a wiring diagram of the servo motor and its microcontroller control board in an embodiment of the present invention; Figure 7 This is a top view of the model placed on a desktop in an embodiment of the present invention; Figure 8 This is a schematic diagram of the model space in an embodiment of the present invention; Figure 9 This is a schematic diagram of the geometric dimensions of the HX-35HM servo motor in an embodiment of the present invention; Figure 10 This is a schematic diagram illustrating the definition of the upper and lower trailing edge angles in an embodiment of the present invention; Figure 11 (a)-(b) are stress and strain distribution cloud diagrams under the maximum bending condition of the flexible slat in the embodiments of the present invention; Figure 12 These are schematic diagrams of four flexible slats with different curvatures in embodiments of the present invention; Figure 13This is a schematic diagram of the 3D scanning process of the flexible variable bending slat solid model in an embodiment of the present invention; Figure 14 (a)-(d) are schematic diagrams of the deformation results of the flexible variable bending slat in the embodiments of the present invention; Figure 15 (a)-(d) are schematic diagrams comparing the flexible slat entity and the finite element calculation results in the embodiments of the present invention; Figure 16 This is a schematic diagram of a tensile test specimen in an embodiment of the present invention.

[0021] Figure label: 1. Servo motor; 2. Servo disc; 3. Steel shaft; 4. Flexible bendable skin; 5. Connecting plate; 6. Winding shaft. Elastic traction cable 7. Detailed Implementation

[0022] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0023] A specific embodiment of the present invention, such as Figure 1-16 An active control device for achieving flexible bending of the trailing edge of a leading-edge slat is disclosed. The active control device includes a slat main frame, a flexible bending skin 4, and an actuation mechanism. The slat main frame is a C-shaped skeletal structure that extends along the wingspan. From the spanwise perspective, the upper wing surface of the slat main frame extends along the spanwise direction of the slat, and its length corresponds to the span of the slat. Viewed from the chord, the leading edge of the slat main frame is rounded and blunt, with a smooth surface that retains only a portion near the leading edge, and an opening at the rear to allow for skin deformation.

[0024] Optionally, the slat main frame is the external skeleton of the leading edge slat, internally connecting two servos, servo discs, and winding shaft components to support the shape of the skin and fix part of the skin; The slat main frame of the present invention is a C-shaped open frame, which adopts an asymmetrical chord length partitioning and fixing form.

[0025] Optionally, the actuation mechanism includes servo motor 1, servo motor 2, servo disc 2, servo disc 3, elastic traction cable 7, elastic traction cable 2, winding shaft 6, winding shaft 2, and steel shaft 3.

[0026] Servo motor 1 and servo motor 2 are respectively installed on one side at both ends of the slat main frame spanwise via connecting plate 5 and connecting plate 2; The servo motor 1 and servo motor 2 are fixed to the connecting plate 5 and the connecting plate 2 through holes and screws; The other side of servo motor 1 and servo motor 2 is the output shaft, which is also connected to servo disk 1 and servo disk 2 by splines or screws respectively. Servo disk 1 and servo disk 2 rotate synchronously with the output shaft of servo motor 1 and servo motor 2. The first rudder disk 2 and the second rudder disk 2 are also connected to the first winding shaft 6 and the second winding shaft respectively. The second winding shaft 6 is a fixed guide shaft, which is installed inside the slat main frame near the steel shaft 3, and is used to change the direction of the traction cable or fix one end of the elastic traction cable. One end of the elastic traction cable 7 and the elastic traction cable 2 are wound and fixed on the grooves of the winding shaft 1 and the winding shaft 2. The winding direction ensures that the elastic traction cable is tightened when the servo motor 1 and the servo motor 2 rotate forward and loosened when they rotate in reverse. The elastic traction cable is used to change the direction of the pulling force so that the pulling force can be output in the direction pointing to the steel shaft 3.

[0027] The other ends of elastic traction cable 7 and elastic traction cable 2 are respectively wrapped and fixed to both ends of steel shaft 3.

[0028] The steel shaft 3 is set along the chord direction at 50% of the rear of the lower flange of the flexible curved skin, and penetrates the flexible curved skin along the span direction. It is pre-embedded or subsequently inserted into the collar on the skin during the skin forming process. When the traction cable pulls the steel shaft 3, the steel shaft 3 drives the surrounding skin to move together, thereby causing the elastic deformation of the skin. The fixing points of elastic traction cable 7 and elastic traction cable 2 are located at both ends of steel shaft 3.

[0029] Optionally, the steel shaft 3 is provided with a cavity inside the trailing edge region of the flexible bending skin.

[0030] Optionally, servo motor one and servo motor two are the core components of two independent drive mechanisms, located at 1 / 3 and 2 / 3 of the span of the slat main frame, respectively, and the two mechanisms have the same structure.

[0031] The airfoil processing of this invention adopts a skin-skeleton structure, and the flexible bending skin 4 has a thickness of 2 mm.

[0032] Optionally, the flexible bending skin 4 includes a front skin and a rear skin; the front skin covers the fixed area at the front edge of the frame, and the rear skin covers the variable bending area.

[0033] The slat main frame is bolted to a flat plate, which provides a flat surface for the device, facilitating its placement and subsequent verification of the bending effect. The plate can be 150 mm × 150 mm in size.

[0034] For example, the upper wing surface of the slat main frame is fixed to a portion of the flexible curved skin from the leading edge to 40% of the chord length, and the portion of the flexible curved skin in the rear 60% chord length area can be curved. The lower wing surface of the slat main frame extends from the leading edge to 50% of the chord length and is fixed to a portion of the flexible curved skin. The portion of the flexible curved skin in the rear 50% chord length area can be curved.

[0035] Optionally, the flexible bending skin is made of TPU polyurethane material with a Shore hardness of 95, and the tail edge has no internal support, relying on its own rigidity to maintain its shape. Optionally, the flexible bending skin is connected to the leading edge slat main frame in a hybrid connection manner, wherein the front section of the flexible bending skin is fixed to the slat main frame, and the rear section is free to deform.

[0036] This invention eliminates rigid support components within the deformable trailing edge portion of the slat, relying solely on the stiffness of the flexible skin to maintain its basic shape and achieve airfoil shape changes after deflection. This allows for active control of the trailing edge deformation of the upper and lower slat surfaces. The flexible, bendable skin of this invention has a low Young's modulus, significantly reducing the maximum equivalent stress and driving force after the wing's trailing edge bends. Furthermore, the TPU material has a high elastic recovery rate, allowing the servo to fully recover to its original configuration during servo reversal without requiring an additional reset mechanism, thus simplifying the drive system design.

[0037] Optionally, the servo is a magnetically encoded bus serial servo, model HX-35HM; the HX-35HM serial servo has geometric dimensions of 45.2mm × 24.7mm × 35mm, a rated output torque of 25 kg·cm, and, ignoring torque loss caused by the servo disc, the servo can provide a maximum pulling force F. max The value is 60 N, which meets the deformation requirements of the flexible skin.

[0038] The servos are controlled by serial port commands from a microcontroller. Through command encoding, two sets of servos can be controlled in parallel from 0 to 360 degrees, and operating parameters such as servo angles can be output in real time. The controller controls the servos to rotate at a certain angle. This rotation causes the winding shaft to rotate counterclockwise, tightening the elastic traction cable 7 and generating tension. This tension causes displacement of the steel shaft 3 and the flexible bending skin, resulting in deformation of the upper and lower surfaces of the slat trailing edge. When the servos rotate in the opposite direction, the elastic traction cable is released, no tension is generated, and the flexible bending skin fully recovers its original configuration through its own elasticity.

[0039] To improve the accuracy and repeatability of flexible bending, this invention also introduces a position closed-loop control strategy into the microcontroller control program. Since the HX-35HM servo used is a magnetic encoder bus serial servo, it integrates a magnetic encoder and can transmit the current actual rotation angle value in real time via the serial bus. The microcontroller compares the preset target rotation angle with the read actual rotation angle. If the deviation exceeds the allowable threshold (e.g., ±0.5°), it automatically issues a correction command, forming a closed-loop servo control. Experimental verification shows that after adopting closed-loop control, the repeatability of each downward deflection angle can be improved from ±0.8° in open-loop control to within ±0.2°, significantly improving the reliability of the experimental data.

[0040] Optionally, the elastic traction cable is a low-elasticity polymer braided cable or a micro steel wire rope, and its elongation rate is controlled within 0.5% within the normal working tensile range to ensure displacement transmission accuracy. At the same time, under overload conditions, it can absorb impact loads through its own elastic elongation to avoid skin tearing or servo motor overload damage.

[0041] Optionally, the winding shafts are located at 1 / 3 and 2 / 3 of the span of the slat main frame, respectively.

[0042] Optionally, the steel shaft 3 has a diameter of 2 mm and is connected to two winding shafts via an elastic traction cable.

[0043] Optionally, the actuation mechanism meets the maximum size limit requirements of the slat for the actuator and can provide sufficient driving torque. By controlling the movement of the actuation mechanism in the active control device, the trailing 60% chord length region of the upper surface and the trailing 50% chord length region of the lower surface of the leading edge slat are driven to achieve a certain angle of downward deflection of the upper trailing edge and upward deflection of the lower trailing edge, respectively. Optionally, the geometric shape of the leading edge slat after flexible bending can be obtained by 3D scanning, providing accurate and reliable geometric parameters for the physical model of the wind tunnel experiment.

[0044] This invention employs a servo-driven mechanism, with the lower slat surface acting as the driven component. Under the action of the transmission mechanism, it moves and undergoes elastic deformation, achieving flexible deformation of the slat's trailing edge. Specifically, the upper trailing edge deflects downwards, and the lower trailing edge deflects upwards. The lower slat skin is driven by a stepping servo, and the inner side of the skin is connected to the servo actuator by a low-elasticity traction cable. The tangent point between the traction cable and the servo disc is located on the slat chord line. Under servo actuation, the upper trailing edge deflects downwards, and the lower trailing edge deflects upwards. When the servo reverses, the skin, under elastic action, returns to its original airfoil shape. To maintain spanwise consistency during testing, independently controllable drive mechanisms are installed at 1 / 3 and 2 / 3 of the spanwise direction of the leading-edge slat airfoil, respectively, with the drive mechanisms at these two positions being identical.

[0045] Under the drive of servo motor 1 and servo motor 2, the steel shaft 3 of the present invention causes a step displacement of part of the flexible bending skin in the slat cavity, and a part of the flexible bending skin undergoes elastic deformation to obtain a flexible slat with different curvatures. The tension provided by servo motor 1 and servo motor 2 makes the slat maintain its shape. When servo motor one and servo motor two reverse, the flexible bending skin restores its original shape due to elasticity.

[0046] In one embodiment of the present invention, the bending process of the leading edge slat includes: active deformation and maintenance and recovery, specifically: The microcontroller sends serial port commands to the servo motor according to the preset deflection angle target; After receiving the command, servo motors one and two rotate clockwise and output torque; The servo disks 1 and 2, which are connected to the servo motor output shaft, rotate accordingly, winding and tightening the elastic traction cable 1 and the elastic traction cable 2. After the elastic traction cable one and elastic traction cable two are tightened, they pass around the winding shaft one and winding shaft two, and the direction of the tension is adjusted to point towards the trailing edge of the slat; The tension is ultimately transmitted to the steel shaft, which displaces under the tension, causing the skin in the trailing edge area of ​​the slat to undergo elastic bending deformation. The skin in the rear 60% area of ​​the upper wing surface is under tension, resulting in downward deflection of the upper trailing edge; The skin in the rear 50% area of ​​the lower wing surface is under tension, resulting in the upward deflection of the lower trailing edge; At this time, servo motor one and servo motor two continuously output torque to overcome the elastic restoring force of the skin and maintain the deformed shape; Once servo motor 1 and servo motor 2 reach the target angle and stop rotating, the traction cable remains taut, and the skin maintains its current curvature, thus preserving the aerodynamic shape during wind tunnel testing or flight.

[0047] In one embodiment of this invention, to select a suitable skin material, five groups of TPU polyurethane and polyamide nylon materials with different Shore hardness (HS) of 55, 65, 75, 85, and 95 were selected for uniaxial tensile tests, and their stress-strain curves were measured. According to the uniaxial tensile test results, the Young's modulus of polyamide nylon material is much greater than that of TPU material. Under the same strain conditions, the stress of this material is tens of times higher than that of TPU-like materials, and the power requirements of the servo motor are also greater. TPU-95HS achieves the best balance between being able to withstand aerodynamic loads and being able to generate elastic deformation driven by a small servo motor. Therefore, this invention selects TPU material with a Shore hardness of 95 as the flexible slat skin material.

[0048] The geometry of the tensile test specimen is as follows: Figure 16 As shown; For anisotropic hyperelastic materials, ABAQUS software provides numerous constitutive models, such as NeoHooke, Ogden, and Yeoh, based on different strain potential energy models for each material. These models are widely applicable to various polymeric elastic materials, including rubber and silicone. Using the aforementioned fitting methods for elastic materials and different strain potential energy models, constitutive models were fitted to the materials used in this invention. The fitting result using the constitutive model of the elastic material yielded a Young's modulus of 12.86 MPa and a Poisson's ratio of 0.4, measured by tensile testing. Compared to the linear model of elastic materials, the fitting method for the constitutive model of hyperelastic materials has smaller errors and can more accurately characterize the elastic mechanical properties of the materials.

[0049] To calculate the slats with different curvatures under the action of the drive mechanism and to verify whether the material strength meets the bending requirements, the ABAQUS finite element software was used to solve and calculate the shape of the flexible slats under different displacements and the mechanical parameters such as skin stress and skin reaction force on the mechanism under this working condition.

[0050] A finite element model of the flexible slat was established based on appropriate boundary condition settings. By changing the magnitude of the displacement load, the slat shapes with different curvatures can be calculated. Calculations showed that when the displacement load is 4.96 mm, the skin reaches its maximum flexible curvature position, at which point the upper trailing edge of the slat is exactly tangent to the main airfoil surface, and the slat channel is completely closed. The maximum curvature result of the flexible slat is shown below. Figure 11 As shown, the maximum stress on the skin and the circular shaft at this time is σ. max = 3.16 MPa, with good skin cross-sectional consistency, and its maximum engineering strain is ε max = 9.26 × 10 -3 .

[0051] When the maximum stress is 3.16 MPa, the TPU material is still in the elastic deformation stage. Therefore, under this load, the skin will not undergo plastic deformation, the material strength meets the experimental requirements, and the material fitting method is reasonable.

[0052] The calculation results under different displacement loads were exported to CATIA using HyperMesh software to obtain slat airfoil data for different camber angles, as shown in Figure 12. Since there is a one-to-one correspondence between the upper trailing edge deflection angle δs and the lower trailing edge deflection angle δx during the flexible camber process of the slat, for ease of description, the upper trailing edge deflection angle is used to distinguish different camber airfoils, and δ is used to represent its deflection angle value. The initial position of the original airfoil is defined as a lower deflection angle δ = 0°. As the lower deflection angle δ increases, the gap decreases, and the slat overlap (OL) increases. When the lower deflection angle δ = 9°, the slat reaches its maximum lower deflection, and the gap is completely closed. Based on the finite element calculation results, the gap parameters and the maximum skin stress under this condition for the four different camber slat airfoils are shown in Table 1.

[0053] Table 1. Slot parameters, displacement load, and maximum skin stress at different downward deflection positions of the flexible slat.

[0054] To verify the bending effect of the solid mechanism, four different downward deflection angles δ were tested. The fabricated and assembled flexible bending slat solid mechanism is shown below. Figure 13 As shown in the figure, the circular markers are the positioning points of the 3D scanner, used to assist in model positioning and 3D geometric data acquisition. The scanner emits laser signals of a specific frequency band and receives the reflected signals from the model to form point cloud data in space. Then, using accompanying software, the real-time point cloud coordinate information acquired by the scanner is analyzed to reversibly model and obtain the 3D geometric data of the airfoil model. During the experiment, the servo's driving displacement remained consistent with the displacement load in the finite element calculation. The test results of the flexible variable bending slat are shown below. Figure 14 As shown.

[0055] Simultaneously, four slat airfoils with different downward deflection angles were scanned, and geometric data results under different cambers were obtained through post-processing. These results were then compared with the finite element calculation results, and the comparison error results are as follows: Figure 15 As shown in the figure, the 3D model is a reverse modeling model of the flexible slat entity, and the curves on the model are the results of finite element calculations.

[0056] Figure 15 (a) shows the comparison between the original airfoil and the airfoil CAD design. Due to model manufacturing errors, there is a maximum error of 2.73 mm compared to the original airfoil design, with a relative error of 0.91%. To reduce the interference of model manufacturing errors on subsequent analysis, the error results for the variable-bending airfoil are presented as corrected results, i.e., the results obtained by subtracting the manufacturing errors from the corresponding positions on the model. The corrected results are shown in... Figure 15 As shown in (b) to (d), as the slat deflection angle δ increases, the maximum relative error gradually decreases from 0.64% for a 3° deflection angle to 0.20%, and the areas with larger errors are all located at the leading edge of the lower surface of the slat, i.e., the area of ​​action of the flexure drive mechanism. The main reasons for this phenomenon are as follows: 1) In the finite element calculation, the traction cable is regarded as an inelastic ideal material. However, in the flexible slat physical test, due to the elasticity of the traction cable itself, the position of its tangent point with the winding axis is slightly offset, that is, the direction of displacement load changes slightly. 2) Due to manufacturing errors, the slat model used for physical testing exhibited slight spanwise inconsistency at the protrusion position on the inner wall of its lower wing surface. This resulted in changes in the load on the leading edge of the lower wing during the camber variation process, causing experimental errors. Although there are still errors between the slat test results and the finite element calculation results, the error results have always remained at a small level. Therefore, it can be considered that the mechanism designed in this invention can effectively realize the flexible camber function of the slat trailing edge.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An active control device for achieving flexible bending of the trailing edge of a leading-edge slat, characterized in that, include: The slat main frame, the flexible bendable skin (4) connected to the outside of the slat main frame, and the actuation mechanism set inside the slat main frame; The actuation mechanism includes servo motor one (1), servo motor two, servo disc one (2), servo disc two, elastic traction cable one (7), elastic traction cable two, winding shaft one (6), winding shaft two and steel shaft (3). One side of servo motor 1 (1) and servo motor 2 are respectively set at both ends of the spanwise direction of the slat main frame via connecting plate 1 (5) and connecting plate 2; The other side of servo motor 1 (1) and servo motor 2 are respectively connected to servo disc 1 (2) and servo disc 2; Rudder disk one (2) and rudder disk two are also connected to winding shaft one (6) and winding shaft two, respectively. Among them, the second winding shaft (6) is a fixed guide shaft, which is installed inside the main frame of the slatted wing near the steel shaft (3) to change the direction of the traction cable or fix one end of the elastic traction cable; One end of the elastic traction cable 1 (7) and the elastic traction cable 2 are respectively connected to the winding shaft 1 and the winding shaft 2. The elastic traction cable is used to change the direction of the tension so that the tension can be output in the direction pointing to the steel shaft (3). The other ends of elastic traction cable one (7) and elastic traction cable two are respectively wrapped and fixed to both ends of the steel shaft (3); The steel shaft (3) is set along the chord direction on the lower wing surface of the flexible bending skin and penetrates the flexible bending skin along the span direction. When the traction cable pulls the steel shaft (3), the steel shaft (3) causes the surrounding skin to move together, causing elastic deformation of part of the flexible bending skin. The flexible, curved skin in the front 40% chord length area of ​​the upper wing of the slat main frame is fixed to the frame, while the flexible, curved skin in the rear 60% chord length area can be bent. The flexible curved skin in the front 50% chord length area of ​​the lower wing is fixed to the frame, while the flexible curved skin in the rear 50% chord length area can be bent. Through the movement of the actuation mechanism, the trailing 60% chord region of the upper wing surface and the trailing 50% chord region of the lower wing surface of the slat trailing edge are driven to achieve a certain angle of downward deflection of the upper trailing edge and upward deflection of the lower trailing edge, respectively.

2. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The slat main frame is a C-shaped skeletal structure that extends along the wingspan. The upper wing surface of the slat main frame extends along the span of the slat, and its length corresponds to the span of the leading edge slat. The chord of the slat main frame is rounded and blunt at the front edge, with a smooth surface that retains only a part near the front edge. The rear is open to allow for flexible bending of the skin (4) deformation.

3. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The flexible bending skin is made of TPU polyurethane material with a Shore hardness of 95.

4. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The flexible bending skin is connected to the leading edge slat main frame in a hybrid connection manner, wherein the front section of the flexible bending skin is fixed to the slat main frame, and the rear section is free to deform.

5. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The servo motor is a magnetically encoded bus serial servo motor; the servo motor is controlled by serial port commands from a microcontroller. Through command encoding, two sets of servo motors can be controlled in parallel from 0 to 360 degrees, and operating parameters such as servo motor rotation angle can be output in real time.

6. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The diameter of the steel shaft (3) shall not be less than 2 mm.

7. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The winding shafts are located at 1 / 3 and 2 / 3 of the span of the slat main frame, respectively.

8. The active control device for achieving flexible bending of the trailing edge of a leading-edge slat according to claim 1, characterized in that, The traction cable is a braided cable or a miniature steel wire rope made of low-elasticity polymer material.

9. A process for achieving flexible bending of the trailing edge of a leading-edge slat using an active control device according to any one of claims 1-2, characterized in that, include: The microcontroller sends serial port commands to servo motor 1 (1) and servo motor 2 according to the preset deflection target; After receiving the command, servo motors one and two rotate clockwise and output torque; The rudder disk 1 (2) and rudder disk 2, which are connected to the rudder motor output shaft, rotate accordingly, winding and tightening the elastic traction cable 1 and the elastic traction cable 2. After the elastic traction cable 1 (7) and elastic traction cable 2 are tightened, they pass around the winding shaft 1 (6) and winding shaft 2, and the direction of the tension is adjusted to point towards the tail edge of the slat; The tension is eventually transmitted to the steel shaft, and the steel shaft (3) is displaced under the action of the tension, which causes the skin in the trailing edge area of ​​the slat to undergo elastic bending deformation; At this time, servo motor one and servo motor two continuously output torque to overcome the elastic restoring force of the skin and maintain the deformed shape; Once servo motor 1 and servo motor 2 reach the target angle and stop rotating, the traction cable remains taut, and the skin maintains its current curvature, thus preserving the aerodynamic shape during wind tunnel testing or flight.

10. The process of achieving flexible bending of the trailing edge of the leading-edge slat using the active control device according to claim 9, characterized in that, The elastic bending deformation of the skin in the trailing edge region of the slats includes: The rear 60% area of ​​the upper wing surface is partially subjected to flexible bending skin under tension, achieving downward deflection of the upper trailing edge; The rear 50% area of ​​the lower wing surface is partially subjected to flexible bending skin under tension, achieving upward deflection of the lower trailing edge.

Images