A flexible wing structure with passive flutter suppression based on multistable plates

Abstract

The present invention discloses a flexible wing structure for passively suppressing flutter based on a multistable plate, which relates to the field of high-altitude, long-endurance aircraft, and comprises a first wing shell, a second wing shell, a multistable thin plate and an I-beam; the first wing shell is divided into a front part and a rear part, and the I-beam penetrates and connects the front part of the first wing shell and the second wing shell; the tail of the multistable thin plate is connected to the rear part of the first wing shell by an adhesive fixation method, and the other end is fixed to one side of the I-beam by bolts, and a circular area with a bistable characteristic is provided on its surface, and a suction cup is connected to the surface of each circular area, and the suction cup is connected to the air source through an air source pipeline; the present invention describes a flexible wing structure for passively suppressing flutter based on a multistable plate, and through the passive switching of the multistable thin plate, the aerodynamic load fluctuation of the wing surface is reduced and the wing is changed to a large-scale vibration state, thereby solving the problem of large-scale vibration of high-altitude, long-endurance solar aircraft and ensuring the flight stability of the aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of high-altitude long-endurance aircraft equipment, in particular to a flexible wing structure for passively suppressing flutter based on a multi-stable plate. Background Art

[0002] The emerging applications of high-altitude, long-endurance drones in surveillance and reconnaissance have made them a significant force unmatched by traditional light aircraft and satellites. To achieve superior aerodynamic performance and thus increase range, these drones are typically designed with lightweight, high-aspect-ratio structures.

[0003] However, while this lightweight, high-aspect-ratio structure significantly enhances the blade's flexibility, it is more susceptible to significant bending and twisting deformation under the influence of aerodynamic loads. Furthermore, it is more susceptible to aeroelastic instability under extreme conditions such as strong winds and turbulence, causing large-scale vibrations and resulting in structural damage. Therefore, controlling the large-scale vibrations caused by aeroelastic instability in this high-aspect-ratio flexible wing structure is crucial.

[0004] Currently, methods that can effectively suppress large-scale vibrations are mainly divided into two categories. The first category is achieved by changing the wing structure. By designing and optimizing the wing structure to reduce deflection and increase stiffness, the possibility and impact of large-scale vibrations are reduced. The second category is achieved by controlling the flow field on the wing surface. Large-scale vibrations of the wing are often caused by periodic vortex shedding on the wing surface. These vortex shedding will cause large fluctuations in aerodynamics, causing large-scale vibrations of the wing. The flow field on the wing surface can be changed by adjusting the shape of the wing leading edge and the attitude of the trailing edge flaps in real time, or the flow separation on the wing surface can be controlled by using a wing surface blowing and suction device to prevent the wing from vibrating due to periodic vortex shedding, thereby ensuring the stability of the structure.

[0005] Existing methods for suppressing large-scale vibrations by modifying wing structures often introduce additional complexity, such as design, manufacturing, and maintenance, which can lead to system reliability and durability issues. Furthermore, wing structural modifications may require the addition of new structures, materials, or mechanisms, increasing the overall weight of the aircraft and potentially reducing its performance and efficiency. Consequently, this approach can result in a range of issues, including lower reliability, higher costs, and inconvenience.

[0006] A common approach to suppressing large-scale vibrations by controlling the flow field over the wing surface is to actively adjust the leading edge shape or the attitude of the trailing edge flaps in real time. However, this often requires the introduction of complex control systems and actuator mechanisms, which must be highly reliable and stable. Furthermore, additional energy consumption is unavoidable to drive the actuators and control systems. These factors increase the design, manufacturing, and maintenance costs of the aircraft, making the overall cost prohibitive.

[0007] Another approach, using a suction and blow device at the leading edge of the wing, can effectively control flow separation on the wing surface, thereby suppressing large-scale vibrations. However, this device consumes additional energy to generate high-momentum airflow and release it onto the wing surface to control flow separation. The convergence time of the controlled flow field is usually long, and the energy provided by the blowing and its range of action are limited, which limits the ability to control flow separation. Therefore, this type of leading edge blowing device has certain limitations in terms of control. Summary of the Invention

[0008] The purpose of the present invention is to provide a flexible wing structure based on multi-stable plates to passively suppress flutter. It does not require additional sensors and controllers, has a fast response speed, is easy to operate, and can effectively ensure the stability of the wing structure in complex airflow environments, thereby ensuring the flight safety of high-altitude, long-endurance solar-powered aircraft.

[0009] To achieve the above-mentioned objectives, the present invention provides a flexible wing structure for passively suppressing flutter based on a multi-stable plate, comprising a first wing shell and a second wing shell, and is characterized in that it also includes an I-beam for connecting the first wing shell and the second wing shell; and a multi-stable thin plate, which is arranged on the I-beam and located in the first wing shell.

[0010] Preferably, one side of the multistable thin plate is provided with a threaded hole corresponding to the I-beam, and the surface of the other side is provided with a plurality of circular bistable areas.

[0011] Preferably, suction cups are provided on the surfaces of the circular bistable areas, and the suction cups are connected to an air source through an air source pipeline.

[0012] Preferably, the first wing case includes a first wing case front portion and a first wing case rear portion.

[0013] Preferably, a rectangular through groove for embedding the I-beam is provided in the middle of the front portion of the first wing shell; and a gap for fixing the multi-stable thin plate is provided in the middle of the rear portion of the first wing shell.

[0014] Preferably, the multistable thin plate is fixed to the inner side of the rear portion of the first wing shell by bonding and is connected to the I-beam accordingly.

[0015] Preferably, the I-beam and the multistable thin plate are connected by bolts.

[0016] Preferably, the second wing shell is an integrated structure, and a through groove corresponding to the I-beam is provided inside the second wing shell.

[0017] Preferably, the material of the I-beam is 45 steel, and the material of the multi-stable thin plate is 304 stainless steel thin plate.

[0018] The present invention also provides a method for preparing a bistable region, comprising the following steps:

[0019] S1, the surface of the thin plate is processed by nanomechanical abrasion to form several circular areas;

[0020] S2. Accelerate multiple stainless steel balls using an ultrasonic transducer to collide with the circular area obtained in step S1 at high speed to form a circular bistable area.

[0021] Therefore, the present invention is a flexible wing structure that adopts the above structure and passively suppresses flutter based on a multi-stable plate, and its beneficial effects are as follows:

[0022] (1) When the wing is subjected to large-scale vibration, the multistable thin plate will passively switch to another stable geometric structure, thereby changing the shape of the wing trailing edge and reducing the fluctuation of the aerodynamic load on the wing surface;

[0023] (2) There is no need to change the mass of the wing structure, nor to add additional sensors and controllers. It has the advantages of fast response speed and easy operation, and solves the problem of large-scale vibration caused by aeroelastic instability of large aspect ratio flexible wing structures.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall appearance of a flexible wing structure that passively suppresses flutter based on multi-stable panels;

[0026] Figure 2 It is a cross-sectional view of a flexible wing structure based on a multistable plate for passive flutter suppression;

[0027] Figure 3 This is a schematic diagram of the connection between a multi-stable thin plate and an I-beam in a flexible wing structure based on a multi-stable plate for passive flutter suppression;

[0028] Figure 4Schematic diagram of the first wing shell structure of a flexible wing structure for passive flutter suppression based on a multistable plate, wherein (a) is a front view, (b) is a side view, (c) is a front view of the connection between the first wing shell, beam, and multistable thin plate (including suction cup), and (d) is a side view of the connection between the first wing shell, beam, and multistable thin plate;

[0029] Figure 5 It is a schematic diagram of the second wing shell structure of a flexible wing structure based on a multi-stable plate to passively suppress flutter;

[0030] Figure 6 Schematic diagram of a multistable thin plate structure for passive flutter suppression of a flexible wing structure based on a multistable plate, wherein (a) is a front view and a side view of the multistable thin plate, (b) is a front view and a side view of the multistable thin plate (including the suction cup), (c) is a schematic diagram of the initial stable state of the multistable thin plate, and (d) is a schematic diagram of the stable state of the multistable thin plate after deformation;

[0031] Figure 7 The present invention is a schematic diagram of a wing structure state of a flexible wing structure based on a multistable plate for passive flutter suppression, wherein (a) is a schematic diagram of an initial stable state of the multistable thin plate wing structure and a side view thereof, and a schematic diagram of an initial stable state of a bistable region; (b) is a schematic diagram of a stable state after deformation of the multistable thin plate wing structure and a side view thereof, and a schematic diagram of a stable state after deformation of the bistable region;

[0032] Figure 8 The diagram is a schematic diagram of the wing control process of a flexible wing structure based on a multistable thin plate to passively suppress flutter.

[0033] Reference numerals

[0034] 1. First wing shell; 2. Second wing shell; 3. I-beam; 4. Threaded hole; 5. Multistable thin plate; 6. Front part of first wing shell; 7. Rear part of first wing shell; 8. Bistable area; 9. Suction cup. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0036] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0037] like Figures 1 to 3 As shown, a flexible wing structure for passively suppressing flutter based on a multistable plate has an initial shape adopting a NACA0012 airfoil design, including a first wing shell 1, a second wing shell 2, an I-beam 3 and a multistable thin plate 5. The I-beam 3 is made of 45 steel to ensure the strength of the overall wing structure. A threaded hole 4 is provided at one end thereof, which penetrates and connects the first wing shell 1 and the second wing shell 2 as a whole. The multistable thin plate 5 is provided on the I-beam 3 through the threaded hole 4 by bolts and is located inside the first wing shell.

[0038] like Figures 4 to 6 As shown, the first wing shell 1 is divided into a first wing shell front part 6 and a first wing shell rear part 7, and the whole presents an asymmetric thickness structure.

[0039] A through groove corresponding to the I-beam is provided inside the front part 6 of the first wing shell, which is directly embedded in the I-beam 3, with a gap left on one side of the plane; the rear part 7 of the first wing shell is wedge-shaped, with a gap in the middle connected to the multistable thin plate 5.

[0040] The second wing shell 2 is an integrated structure with an asymmetric thickness structure. A through groove corresponding to the I-beam is provided inside, and is directly embedded in the I-beam 3, ensuring the position of the second wing shell 2 on the beam and fixing it.

[0041] The multi-stable thin plate 5 is made of 304 stainless steel and has a T-shaped cross section. A threaded hole 4 is provided at one end of the T-shape, corresponding to the threaded hole 4 at one end of the I-beam 3, and is fixed by bolts. The other end of the multi-stable thin plate 5 is fixed to the interior of the rear portion 7 of the first wing shell by adhesive fixing.

[0042] The surface of the multistable thin plate 5 is processed by nanomechanical abrasion to form circular areas arranged in a 1x3 pattern. Multiple stainless steel balls with a diameter of 2 mm are accelerated by an ultrasonic transducer to impact the circular area at high speed. The plastic deformation caused by the severe impact stretches the circular processed area under the constraint of the unprocessed area, forming compressive stress. When the compressive stress from the accumulated plastic deformation reaches a certain level, the circular area will exhibit bistability characteristics, forming a bistable region 8.

[0043] The bistable region 8 has two states and does not require additional energy to maintain the two states. Figure 6 As shown in (c) in FIG. 8 , “+” indicates the first initial stable state of the bistable region 8, as shown in FIG. Figure 6 As shown in (d), “-” indicates the second stable state after deformation of the bistable region 8. When the wing vibrates on a large scale, that is, is subjected to a large external load, the three bistable regions 8 of the multistable thin plate 5 will directly change from the “+” first stable state to the “-” second stable state. Therefore, the multistable thin plate 5 changes from Figure 6 The stable state shown in (c) is transformed into Figure 6 The stable state shown in (d) in the figure eventually leads to the passive Figure 7 The stable state shown in (a) becomes Figure 7 The stable state is shown in (b).

[0044] Suction cups 9 are respectively installed in the three bistable areas 8 on the multistable thin plate 5. The suction cups 9 are connected to air source pipelines. The air source pipelines pass through the second wing shell 2 along the I-beam 3 and are connected to the air source at the wing root.

[0045] The suction cup 9 can actively adjust the state of the bistable region 8. When the wing changes to a large-scale vibration state and returns to a stable state, the suction cup 9 is controlled to suck air, and the internal air pressure is reduced under the action of the suction, and the deformed multi-stable thin plate is actively Figure 6 The stable state shown in (d) is transformed into Figure 6 The stable state shown in (c) in FIG, thereby adjusting the state of the bistable region 8, and ultimately causing the wing structure to passively Figure 7 The stable state shown in (b) becomes Figure 7 The stable state shown in (a) above ensures the stable flight of the aircraft.

[0046] The specific working principle of the present invention is as follows: Figure 8As shown in the figure, when no flutter occurs, the multistable plate is in the initial stable state A. When the wing flutters due to a harsh external environment, the sudden increase in external loads causes the wing to vibrate on a large scale. When the load caused by the vibration is greater than the threshold of the multistable plate deformation, the multistable plate will rapidly deform, causing the wing to change from state A to state B. At the same time, the deformation of the wing's trailing edge can control flow separation, prevent large-scale vortex shedding caused by dynamic stall, stabilize the flow above the wing surface, reduce the fluctuation of the wing surface aerodynamic load, and thus help the wing to recover from the large-scale vibration state and restore stability. Finally, after the flight stabilizes, the multistable plate can be adjusted back to the initial stable state A by actively adjusting the suction cup.

[0047] Therefore, the present invention provides a flexible wing structure for passively suppressing flutter based on a multi-stable plate, which can passively deform when the wing undergoes large-scale vibration, change the aerodynamic shape of the local wing, reduce the aerodynamic load fluctuations on the wing surface, and thus suppress the large-scale vibration problem of the wing. This structural design does not require changing the mass of the wing structure, nor does it require additional sensors and controllers. It has the advantages of fast response speed and easy operation, and has excellent flight performance in complex airflow environments.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A flexible wing structure for passively suppressing flutter based on a multi-stable plate, comprising a first wing shell and a second wing shell, characterized in that: Also includes: an I-beam, used for penetrating and connecting the first wing shell and the second wing shell; a multistable thin plate disposed on the I-beam and located within the first wing shell; One side of the multistable thin plate is provided with threaded holes corresponding to the I-beams, and the surface of the other side is provided with a plurality of circular bistable areas; Suction cups are provided on the surfaces of the circular bistable areas, and the suction cups are connected to an air source through an air source pipeline.

2. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 1, characterized in that: The first wing case includes a first wing case front portion and a first wing case rear portion.

3. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 2, characterized in that: A rectangular through groove for embedding the I-beam is provided in the middle of the front portion of the first wing shell; a gap for fixing the multi-stable thin plate is provided in the middle of the rear portion of the first wing shell.

4. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 3, characterized in that: The multistable thin plate is fixed to the inner side of the rear portion of the first wing shell by bonding and is connected to the I-beam accordingly.

5. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 4, characterized in that: The I-beam and the multistable thin plate are connected via bolts.

6. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 1, characterized in that: The second wing shell is an integrated structure, and a through groove corresponding to the I-beam is provided inside the second wing shell.

7. The flexible wing structure for passive flutter suppression based on multistable panels according to claim 5, characterized in that: The material of the I-beam is 45 steel, and the material of the multi-stable thin plate is 304 stainless steel thin plate.

8. A method for preparing a flexible wing structure for passive flutter suppression based on a multistable plate according to any one of claims 1 to 7, characterized in that: The steps for preparing the bistable region are as follows: S1, the surface of the thin plate is processed by nanomechanical abrasion to form several circular areas; S2. Accelerate multiple stainless steel balls using an ultrasonic transducer to collide with the circular area obtained in step S1 at high speed to form a circular bistable region.

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