An aircraft wing anti-shudder device and system

Abstract

The application discloses an aircraft wing anti-chattering device and system and belongs to the field of aircraft aeroelastic control. The device comprises a hollow tube vertically and penetratively installed in the inside of the wing, a counterweight arranged in the tube, upper and lower springs respectively abutting the upper and lower ends of the counterweight and having a pre-compression amount, a damping mechanism and a limiting mechanism. The counterweight and the spring constitute a tuned mass system, the total stiffness of which satisfies k total =m×(2πf w ) 2 , accurate alignment with the wing chattering frequency is realized, the damping mechanism dissipates vibration energy, and the limiting mechanism prevents damage caused by the limit stroke. Furthermore, a plurality of devices can be arranged along the spanwise direction and the chordwise direction to form an array system, multi-order mode and bending-torsional coupling chattering are suppressed through differential frequency tuning and staggered installation.

Description

Technical Field

[0001] This invention belongs to the field of aircraft structural dynamics and aeroelastic stability control technology, specifically relating to a passive tuned mass damping device installed inside an aircraft wing to suppress wing flutter, and a wing anti-flutter system composed of multiple such devices. Background Technology

[0002] Wing flutter is a self-excited vibration phenomenon that occurs in aircraft under aeroelastic coupling. When an aircraft flies in a uniform airflow, aerodynamic forces, elastic forces, and inertial forces are coupled together. Once the flight speed reaches the critical flutter speed, the wing amplitude will rapidly diverge and increase, potentially leading to wing structural damage in a very short time and seriously threatening flight safety. The aeroelastic design of modern civil aircraft must strictly comply with CCAR 25.629 "Aeroelastic Stability Requirements" and Advisory Circular AC 25.629-1A, and no harmful flutter phenomena are allowed within the flight envelope.

[0003] Existing flutter suppression technologies are mainly divided into two categories: passive suppression and active suppression. Passive suppression typically employs methods such as increasing structural stiffness, altering mass distribution, or installing dynamic vibration absorbers. While safe and reliable, increasing stiffness often results in a significant increase in structural weight, adversely affecting aircraft performance and economics. Devices that alter mass distribution are usually structurally complex and difficult to conveniently implement within existing structures. Active suppression technologies achieve flutter suppression by adjusting aerodynamic surfaces or actuators through closed-loop control systems. However, this requires high-precision sensors, controllers, and actuators, resulting in complex and costly systems that face significant challenges in reliability and airworthiness verification in practical engineering applications.

[0004] Therefore, there is an urgent need for a passive flutter suppression device and system that is simple in structure, low in weight, highly reliable, easy to install in existing wing structures, and does not change the aerodynamic shape. Summary of the Invention

[0005] The purpose of this invention is to provide an aircraft wing anti-flutter device and system. The device adopts a hollow tube structure that runs through the interior of the wing and is arranged vertically. The internal structure is equipped with a tuned mass system consisting of counterweights and springs. It has the characteristics of compact structure, light weight, no change to the aerodynamic shape of the wing, and easy maintenance. It can effectively absorb and dissipate the vibration energy of specific modes of the wing and significantly improve the flutter critical speed of the wing.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An anti-flutter device for an aircraft wing, installed inside the wing, is characterized by comprising: a hollow tube, vertically penetrating the internal space between the upper and lower skins of the wing, with its axis parallel to the main vibration direction of the wing's bending vibration; a counterweight, slidably disposed axially within the cavity of the hollow tube; an elastic support assembly, including an upper spring and a lower spring respectively abutting against the upper and lower end faces of the counterweight, both the upper and lower springs having a pre-compression amount to suspend the counterweight within the cavity of the hollow tube in a static state, and forming a tuned mass system with the counterweight; a damping mechanism for dissipating kinetic energy when the counterweight moves relative to the hollow tube; and a limiting mechanism disposed at both ends of the counterweight's movement path for limiting the maximum axial displacement of the counterweight.

[0007] Furthermore, in the elastic support assembly, the total stiffness (k) of the upper spring and the lower spring connected in parallel is... total ) satisfies the following relation: k total =m×(2πf w ) 2

[0008] Where m is the mass of the counterweight, f w The natural frequency of the flutter mode to be suppressed on the wing.

[0009] Furthermore, the mass m of the counterweight is configured to be 1% to 5% of the equivalent modal mass of the flutter mode to be suppressed on the wing.

[0010] Furthermore, the equivalent damping ratio (ξ) provided by the damping mechanism ranges from 0.05 to 0.20.

[0011] Furthermore, the sum of the pre-compression of the upper and lower springs is greater than the static compression displacement of the counterweight on the elastic support assembly under a 1g gravitational field, to ensure that the counterweight does not disengage from the end face of the upper or lower spring under flight overload conditions.

[0012] Furthermore, the damping mechanism includes a viscous damping liquid filling the inner cavity of the hollow tube, and an annular throttling gap is formed between the outer peripheral wall of the counterweight and the inner peripheral wall of the hollow tube; or, the damping mechanism includes a permanent magnet disposed on the counterweight and a conductive metal layer disposed on the inner wall of the hollow tube.

[0013] Furthermore, the limiting mechanism includes elastic buffer pads fixed to the inner walls at both ends of the hollow tube, and the end point of the compression stroke of the elastic buffer pads is located within the maximum allowable compression height of the upper or lower spring.

[0014] According to the aforementioned aircraft wing anti-flutter device, the hollow tube is further installed in the range of 60% to 80% of the wing span and between the wing's chordal axis and the leading edge, so that the inertial force of the counterweight can generate an additional anti-torsional moment on the wing.

[0015] The present invention also provides an aircraft wing flutter prevention system, comprising at least two of the above-mentioned aircraft wing flutter prevention devices, wherein the at least two devices are arranged at intervals along the spanwise direction of the wing and / or staggered along the chordwise direction of the wing.

[0016] In the further arrangement of the device along the wing span, the mass of the counterweight near the wingtip is less than the mass of the counterweight near the wing root, and the total stiffness of the elastic support components of each device is independently tuned according to the local modal frequency of the wing corresponding to its location.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Compact structure and strong adaptability: The vertical through-tube structure makes full use of the internal space of the wing without changing the aerodynamic shape, and is suitable for new aircraft design and retrofitting of existing models.

[0018] 2. Significant vibration suppression effect: Based on the principle of tuned mass damping, through the precise tuning of the mass-spring-damping system, the vibration energy of specific modes can be effectively absorbed, increasing the flutter critical velocity by more than 15%.

[0019] 3. Passive operation and high reliability: It does not require external power, sensors or actuators, and works entirely based on the inherent mechanical characteristics. There is no risk of electronic component failure, and the difficulty of airworthiness verification is low.

[0020] 4. Low weight cost: The counterweight only requires 1% to 5% of the equivalent modal mass, which is far less than the weight increase required to increase structural stiffness for the same effect.

[0021] 5. Easy maintenance: The end cap is removable, and the counterweight, spring and damping fluid can all be replaced independently.

[0022] 6. Adaptable to complex working conditions: Through reasonable pre-compression design and limit stroke reservation, the device can adapt to the surge in amplitude under motor overload and flutter critical conditions, and has strong robustness.

[0023] 7. Good scalability: Multimodal suppression can be achieved through array arrangement, further improving the overall flutter boundary. Attached Figure Description

[0024] Figure 1 : A three-dimensional structural schematic diagram of the first embodiment of the present invention (showing a viscous liquid damping scheme).

[0025] Figure 2: A three-dimensional exploded structural diagram of the first embodiment of the present invention (showing the viscous liquid damping scheme).

[0026] Figure 3 : A schematic diagram of the longitudinal section structure of the second embodiment of the present invention (showing the eddy current damping scheme).

[0027] Figure 4 : A top view of the multi-point array system of the present invention arranged inside the wing.

[0028] Reference numerals in the attached drawings: 1-Hollow tube; 11-Hollow tube guide rail; 2-Counterweight; 23-Counterweight groove; 31-Upper spring; 32-Lower spring; 4-Viscous damping liquid; 5-Permanent magnet; 6-Elastic buffer pad; 71-Upper end cover; 72-Lower end cover; 81-First device; 82-Second device; 83-Third device; 84-Fourth device. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Example 1: Viscous Liquid Damped Flutter Anti-Flutter Device

[0031] See Figure 1 , Figure 2 This embodiment provides an aircraft wing anti-flutter device, which is installed inside the wing.

[0032] The hollow tube 1 is made of 7075-T6 aluminum alloy, with an outer diameter of 60mm, an inner diameter of 50mm, and a length determined according to the wing thickness at the installation location, typically 200-400mm. The hollow tube 1 is equipped with an upper end cap 71 and a lower end cap 72, which are threaded to both ends of the hollow tube 1.

[0033] The upper end cap 71 of the hollow tube 1 is fixed to the inner surface of the upper wing skin via an upper connecting seat, and the lower end cap 72 is fixed to the inner surface of the lower wing skin via a lower connecting seat. The connecting seat is provided with reinforcing ribs to distribute stress.

[0034] The counterweight 2 is made of tungsten alloy with a density of approximately 18.5 g / cm³ and a mass of m = 2.5 kg. It is cylindrical with an outer diameter of 49.6 mm and forms a 0.2 mm annular gap with the inner wall of the hollow tube 1. The counterweight 2 has one or more counterweight grooves 23, and the hollow tube 1 has one or more hollow tube guide rails 11. The two cooperate with each other to maintain the axial movement of the counterweight.

[0035] Both the upper spring 31 and the lower spring 32 are cylindrical helical compression springs made of 60Si2MnA material. According to formula k... total =m×(2πf w ) 2 Take the first-order bending flutter frequency f of the wing w =6.5Hz, the required total stiffness k is calculated. total ≈4.17kN / m. The upper and lower springs each bear half of the stiffness, meaning the stiffness of a single spring is approximately 2.08kN / m. Both ends of the spring are ground flat, ensuring good contact between the end faces and the counterweight and end caps.

[0036] The damping mechanism employs a viscous liquid damping scheme. The hollow tube 1 is filled with dimethyl silicone oil 4, with a kinematic viscosity of 1000 cSt. When the counterweight 2 moves, the silicone oil generates shear damping through a 0.2 mm annular gap, with an equivalent damping ratio of approximately 0.08. Meanwhile, the upper end cap 71 and the lower end cap 72 are equipped with O-ring seals to prevent leakage of the damping liquid.

[0037] The limiting mechanism is an elastic buffer pad 6 installed inside the upper end cover 71 and the lower end cover 72. It is made of nitrile rubber and has a thickness of 10mm. The end point of the compression stroke of the elastic buffer pad 6 is located before the maximum allowable compression height (i.e., the spring coil height) of the upper spring 31 and the lower spring 32 to prevent damage to the springs.

[0038] In this embodiment, the device is installed at 70% of the wing's span, near the forward sparsity. Ground resonance tests verified that the device's natural frequency is 6.48 Hz, which is essentially consistent with the target frequency of 6.5 Hz. Wind tunnel flutter tests showed that installing this device increased the wing's flutter critical velocity by approximately 18%.

[0039] Example 2: Eddy Current Damped Flutter Anti-Flutter Device

[0040] like Figure 3 (Some structures have been omitted) As shown, the main difference between this embodiment and Embodiment 1 lies in the implementation method of the damping mechanism.

[0041] The counterweight 2 is internally embedded with permanent magnets 5, which are made of neodymium iron boron material and are arranged in four evenly distributed circumferentially with their magnetic poles pointing radially. The hollow tube 1 is made of aluminum alloy, and its inner wall is coated with a copper conductive layer with a thickness of about 0.5 mm by electroplating or chemical plating.

[0042] When the counterweight 2 moves inside the hollow tube 1, the magnetic field generated by the permanent magnet 5 moves with the counterweight, inducing eddy currents in the copper conductive layer. The reverse magnetic field generated by the eddy currents exerts an electromagnetic force on the permanent magnet 5 in the opposite direction of motion, thus forming non-contact damping. By adjusting the thickness of the conductive layer and the magnetic field strength of the permanent magnet, the damping ratio can be adjusted to the desired range.

[0043] The remaining structure of this embodiment is the same as that of Embodiment 1, and will not be described again. The advantages of the eddy current damping scheme are that there is no risk of liquid leakage, good temperature stability, and long-term maintenance-free operation.

[0044] Example 3: Multi-point array anti-flutter system

[0045] like Figure 4 As shown, this embodiment provides a wing flutter prevention system composed of multiple flutter prevention devices described above.

[0046] Three devices are arranged along the spanwise direction on the left wing (symmetrically arranged on the right wing): The first device 81 is installed at 50% of the wingspan, with a counterweight mass m1=3.0kg and a tuning frequency f1=7.2Hz (for the second-order bending mode).

[0047] The second device 82 is installed at 70% of the wingspan, with a counterweight mass m2=2.5kg and a tuning frequency f2=6.5Hz (for the first-order bending mode).

[0048] The third device 83 is installed at 85% of the wingspan, with a counterweight mass m3=1.8kg and a tuning frequency f3=5.8Hz (for the sensitive area at the wingtip and frequency drift coverage).

[0049] In addition, at 70% of the wingspan, a fourth device 84 is added, in addition to the second device, and installed in the rear beam area at the same spanwise position. The counterweight of the fourth device has a mass m4=2.0kg and a tuning frequency f4=6.5Hz. However, because its chordal position is far from the center of rigidity, the inertial force generated by its vertical vibration forms a significant anti-torsional moment, which is specifically used to suppress bending-torsional flutter.

[0050] The hollow tubes of each device are interconnected by lightweight aluminum alloy connecting rods, forming an integrated grid-type vibration damping frame. This frame not only performs vibration damping but also serves as an auxiliary reinforcing structure inside the wing, compensating for localized stiffness losses caused by the installation of the devices through openings.

[0051] Verified through full-aircraft ground resonance tests and low-speed flutter wind tunnel tests, this multi-point array system can increase the first-order bending mode damping ratio of the wing from 0.015 to 0.07, the second-order bending mode damping ratio from 0.01 to 0.05, and the critical speed of bending-torsional flutter is increased by more than 22%. No harmful flutter phenomena were observed throughout the entire flight envelope.

[0052] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0053] The aircraft wing flutter suppression device and system provided by this invention has a simple structure, high reliability, low weight increase cost, and does not change the aerodynamic shape. It can be widely used in the flutter suppression design of various fixed-wing aircraft, including civil airliners, transport aircraft, business jets, and drones. This technology meets the aeroelastic stability requirements of airworthiness regulations and has clear engineering application value and broad industrialization prospects.

Claims

1. An aircraft wing flutter damping device, installed inside the wing, characterized in that, include: A hollow tube is vertically installed in the internal space between the upper and lower skin of the wing, with its axis parallel to the main vibration direction of the wing's bending vibration. The counterweight is slidably disposed in the inner cavity of the hollow tube along the axial direction; The elastic support assembly includes an upper spring and a lower spring that abut against the upper and lower end faces of the counterweight respectively. Both the upper and lower springs have a pre-compression amount so that the counterweight is suspended in the inner cavity of the hollow tube in a static state and forms a tuned mass system with the counterweight. A damping mechanism is used to dissipate kinetic energy when the counterweight moves relative to the hollow tube; A limiting mechanism is provided at both ends of the movement path of the counterweight to limit the maximum axial displacement of the counterweight. In the elastic support assembly, the total stiffness (k) of the upper spring and the lower spring connected in parallel is... total The following relationship must be satisfied: k total =m×(2πf w ) 2 Where m is the mass of the counterweight, f w The natural frequency of the flutter mode to be suppressed on the wing; The equivalent damping ratio (ξ) provided by the damping mechanism ranges from 0.05 to 0.20; The damping mechanism includes a viscous damping liquid filling the inner cavity of the hollow tube, and an annular throttling gap is formed between the outer peripheral wall of the counterweight and the inner peripheral wall of the hollow tube; or, the damping mechanism includes a permanent magnet disposed on the counterweight and a conductive metal layer disposed on the inner wall of the hollow tube.

2. The aircraft wing flutter prevention device according to claim 1, characterized in that, The mass m of the counterweight is configured to be 1% to 5% of the equivalent modal mass of the flutter mode to be suppressed on the wing.

3. The aircraft wing flutter prevention device according to claim 1, characterized in that, The sum of the pre-compression of the upper and lower springs is greater than the static compression displacement of the counterweight on the elastic support assembly under a 1g gravitational field, so as to ensure that the counterweight does not disengage from the end face of the upper or lower spring under flight overload conditions.

4. The aircraft wing flutter prevention device according to claim 1, characterized in that, The limiting mechanism includes elastic buffer pads fixed to the inner walls at both ends of the hollow tube, and the end point of the compression stroke of the elastic buffer pads is within the maximum allowable compression height of the upper or lower spring.

5. The aircraft wing flutter prevention device according to any one of claims 1 to 4, characterized in that, The hollow tube is installed in the range of 60% to 80% of the wing span and between the wing's chordal axis and leading edge, so that the inertial force of the counterweight can generate an additional anti-torsional moment on the wing.

6. An aircraft wing flutter prevention system, characterized in that, It includes at least two aircraft wing flutter prevention devices as described in any one of claims 1 to 5, wherein the at least two devices are arranged at intervals along the spanwise direction of the wing and / or staggered along the chordwise direction of the wing.

7. The aircraft wing flutter anti-vibration system according to claim 6, characterized in that, In the device arranged along the wing span, the mass of the counterweight near the wingtip is less than the mass of the counterweight near the wing root, and the total stiffness of the elastic support components of each device is independently tuned according to the local modal frequency of the wing corresponding to its position.

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