A support device for a volumetric flutter model with decoupled floating and pitch degrees of freedom.

Abstract

This invention provides a support device for a flutter model with decoupled heave and pitch degrees of freedom, comprising a crossbeam, a rotating bearing, a sliding mechanism, a steel shaft, and a set of displacement limiters. It ensures that the relative rotation between the sliding mechanism and the model remains unaffected, while simultaneously releasing the heave and pitch degrees of freedom. It has the advantages of small footprint, ease of implementation, and minimal impact on the model's aerodynamic shape, and avoids the influence of support stiffness introduced by support springs on the test results. The designed support device can simulate the real flight state of a flying wing to the greatest extent possible and can reduce test errors caused by frictional drag.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, specifically relating to a flutter model support device for decoupling the degrees of freedom of heave and pitch. Background Technology

[0002] Body flutter of a flying wing is an aeroelastic phenomenon involving the interaction between structural vibrations and aerodynamic forces during flight. Body flutter occurs when the rigid body pitch mode of an aircraft couples with the symmetrical wing bending mode under specific flight conditions. This phenomenon can lead to structural instability and damage, posing a threat to flight safety.

[0003] In recent years, most researchers have used half-wingspan models for ground vibration and wind tunnel tests of flying wing flutter models. To simulate flight conditions, the model is typically suspended by a pitch / huff elastic support with balancing weights. This design effectively decouples the suspension support stiffness in the pitch and huff directions, thus facilitating accurate vibration analysis of the model.

[0004] However, this suspension method is not suitable for suspending full-span flying wing wind tunnel test models. Some researchers have used guide rails to mount half-models of the flying wing at the bottom or sidewalls of the wind tunnel, releasing the buoyancy and pitch degrees of freedom of the flying wing configuration model through the guide rails, thus approximately simulating a "free-free" state. Furthermore, some researchers, based on free-flight models, have used active control systems to drive the control surfaces, thereby achieving wing balance and eliminating the potential influence of elastic suspension or support stiffness on the inherent modes. However, the introduction of active control systems may introduce new aerodynamic servoelasticity problems. These problems may have complex effects on the flutter characteristics of the aircraft, thus increasing the complexity and uncertainty of flutter testing.

[0005] Therefore, it is necessary to develop a body-degree-of-freedom flutter model support device that decouples the buoyancy and pitch degrees of freedom. Summary of the Invention

[0006] This invention provides a support device for a body-degree-of-freedom flutter model that decouples the buoyancy and pitch degrees of freedom. This device minimizes the impact of the support stiffness introduced by the support system on the body-degree-of-freedom flutter wind tunnel test results of the flying wing layout model. At the same time, it can approximate the "free flight" state of the model, thereby ensuring the safety and validity of the test results. It also helps to reduce or eliminate the influence of various factors (friction, suspension stiffness, etc.) on the test results of body-degree-of-freedom flutter characteristics.

[0007] This invention provides a support device for a body-degree-of-freedom flutter model with decoupled floating and pitch degrees of freedom. The body-degree-of-freedom flutter model 1 includes: a flying wing fuselage, a cross-shaped connecting beam, two wings, and an outer shell; the flying wing fuselage has a boat-shaped structure with a rectangular through hole at the tail, and the outer shell is fitted onto the outside of the flying wing fuselage; the two wings are connected to the flying wing fuselage through the cross-shaped connecting beam and are transitionally connected to the outer shell; the support device includes: a crossbeam 2, a rotary bearing, a sliding mechanism 3, a steel shaft 4, and two displacement limiters 5;

[0008] One end of each of the two crossbeams 2 is connected to a wing via a bearing, and the other end is connected to a sliding mechanism 3;

[0009] The sliding mechanism 3 includes a box and steel balls. A circular cavity is provided inside the box. A central through hole is provided on the upper and lower surfaces of the box. The steel shaft 4 passes through the central through hole of the box. The steel balls are arranged in the circular cavity and surround the steel shaft 4. The center of the box is located at the center of mass of the body degree of freedom flutter model 1.

[0010] The steel shaft 4 is also located inside the rectangular through hole;

[0011] The steel shaft 4 is connected to the top and bottom of the wind tunnel at both ends, and two displacement limiters 5 are also installed at both ends of the steel shaft 4.

[0012] Optionally, the crossbeam 2 is a carbon fiber tube.

[0013] Optionally, the axis of the beam 2 passes through the center of mass of the flutter model 1.

[0014] Optionally, the cross-shaped connecting beam is set parallel to the crossbeam 2.

[0015] Optionally, the crossbeam is inserted into the box and adhesive is applied to the contact surface.

[0016] Optionally, the steel shaft 4 is inserted through the center of the rectangular through hole, and the length of the rectangular through hole along the flight direction is 5-8cm.

[0017] Optionally, the steel shaft 4 is in contact with all the steel balls.

[0018] Optionally, the two displacement limiters 5 are spaced 50cm apart.

[0019] Optionally, the two displacement limiters 5 are made of rubber or foam.

[0020] This invention provides a support device for a body-degree-of-freedom flutter model that decouples the heave and pitch degrees of freedom. Since the body-degree-of-freedom flutter of a flying wing model is caused by the coupling of its rigid body mode pitch mode with the lower-order elastic bending mode of the wing, significant pitch / heave motion phenomena occur when body-degree-of-freedom flutter occurs. To ensure that the body-degree-of-freedom flutter characteristics of the model obtained in wind tunnel tests are more realistic and reliable, the support device must be able to release the pitch and heave degrees of freedom of the model, thereby simulating free flight in the air. This invention proposes a body-degree-of-freedom flutter model support device that decouples the buoyancy and pitch degrees of freedom. It uses carbon fiber tubes and rotating bearings to connect the flying wing and sliding mechanism, ensuring that the entire decoupling device remains at the model's center of mass. This reduces frictional drag, eliminates the need for a separate support spring, and allows for simultaneous release of both buoyancy and pitch degrees of freedom. It offers advantages such as small footprint, ease of implementation, minimal impact on the model's aerodynamic shape, and avoids the influence of support stiffness introduced by support springs on experimental results. The designed support device can simulate the actual flight state of the flying wing to the maximum extent and reduces experimental errors caused by frictional drag. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a basic diagram of the support device for a body-degree-of-freedom flutter model with decoupled floating and pitch degrees of freedom;

[0023] Figure 2 This is a detailed view of the horizontal axis;

[0024] Figure 3 This is a detailed diagram of the sliding mechanism;

[0025] Figure 4 This is a schematic diagram of the implementation of a flutter model support device for body degrees of freedom that decouples the degrees of freedom of buoyancy and pitch.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1- Flying wing layout model;

[0028] 2-Crossbeam;

[0029] 3-Sliding mechanism;

[0030] 4-Steel shaft;

[0031] 5-Displacement limiter. Detailed Implementation

[0032] The following is a detailed description of the body degree-of-freedom flutter model support device with decoupled buoyancy and pitch degrees of freedom provided by the present invention, with reference to the accompanying drawings.

[0033] like Figure 1-4 As shown, the present invention provides a body freedom flutter model support device with decoupled floating and pitch degrees of freedom, including a crossbeam 2, a rotating bearing, a sliding mechanism 3, a steel shaft 4 and a set of displacement limiters 5;

[0034] The crossbeam consists of two spanwise carbon fiber tubes arranged in the cavity in the middle of the fuselage of the flying wing layout model. The axis of the carbon fiber tubes passes through the center of mass of the flying wing, and both ends are fixedly connected to the internal structure of the flying wing layout model through rotating bearings. The cavity is used to house the free-flight support device.

[0035] The sliding mechanism includes a box and several steel balls placed inside the box; the box is arranged perpendicular to the plane of the model in the cavity in the middle of the model body, wherein the crossbeam and the sliding mechanism are connected by adhesive, and the center of the box is located at the center of mass of the flying wing.

[0036] The steel shaft passes through the central gap of the sliding mechanism and is in contact with all the steel balls inside the sliding mechanism, enabling the entire sliding mechanism to slide stably up and down on the steel shaft; the steel shaft is connected to the top and bottom of the wind tunnel. The flying wing fuselage has a boat-shaped structure with a rectangular through hole at the tail, and the steel shaft 4 is also located in the rectangular through hole; the steel shaft 4 passes through the center of the rectangular through hole, and the length of the rectangular through hole along the flight direction is 5-8 cm.

[0037] The sliding mechanism is located above the rectangular through hole. During the test, when the model undergoes pitching motion, it can prevent the rigid shaft from interfering with the boat-shaped structure.

[0038] The displacement limiter is mounted on a steel shaft at a certain distance above and below the sliding mechanism, and is made of rubber or foam.

[0039] For example, the diameter of the crossbeam provided by the present invention can be 5mm, and the corresponding diameter of the steel shaft can be 10mm.

[0040] The present invention proposes a body freedom flutter model support device with decoupled floating and pitch degrees of freedom, including a crossbeam 2, a rotating bearing, a sliding mechanism 3, a steel shaft 4 and a set of displacement limiters 5.

[0041] At the center of mass of the flying wing model, the model and the sliding mechanism are connected by two horizontal shafts (carbon fiber tubes). The horizontal shafts and the sliding mechanism are connected by blind holes and glued together. The horizontal shafts and the model are connected by a rotating bearing, so as to ensure that the relative rotation between the sliding mechanism and the model is not affected, thereby releasing the pitch degree of freedom of the flying wing model during the test.

[0042] The sliding mechanism includes a box and several steel balls placed inside the box. The horizontal axis is glued to the sliding mechanism through blind holes. The box has a central hole, through which the steel axis passes and contacts both the steel balls, allowing the sliding mechanism to slide stably up and down along the steel axis, thereby releasing the buoyancy freedom of the flying wing layout model.

[0043] To ensure the model moves within a defined area, the device also incorporates a set of displacement limiters mounted on a steel shaft at a certain distance above and below the sliding mechanism. These limit the amplitude of the buoyancy motion to guarantee the safe operation of the entire system. The steel shaft is connected to the top and bottom of the wind tunnel via flanges.

[0044] This flutter test support device for the flying wing model is highly flexible and easy to adjust. By adjusting the longitudinal position of the upper and lower limiters, the flutter pitch motion amplitude of the flying wing model can be controlled under certain conditions. At the same time, this design avoids unnecessary rigid or elastic constraints, thus ensuring that the test results more closely resemble real free flight.

[0045] When the incoming flow velocity approaches the flutter critical point, the flying wing layout model is excited by controlling the movement of the control surfaces, causing the wing to bend and drive the entire flying wing to pitch around the carbon fiber centerline. The signal attenuation is observed, and relevant data are recorded in detail for subsequent analysis and evaluation.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A body-degree-of-freedom flutter model support device with decoupled buoyancy and pitch degrees of freedom, characterized in that, The flutter model (1) includes: a flying wing fuselage, a cross-shaped connecting beam, two wings, and an outer shell; the flying wing fuselage is a boat-shaped structure with a rectangular through hole at the tail, the outer shell is fitted on the outside of the flying wing fuselage, and the two wings are connected to the flying wing fuselage through the cross-shaped connecting beam and are transitionally connected to the outer shell; the support device includes: a crossbeam (2), a rotary bearing, a sliding mechanism (3), a steel shaft (4), and two displacement limiters (5); One end of each of the two crossbeams (2) is connected to a wing via a bearing, and the other end is connected to a sliding mechanism (3); The sliding mechanism (3) includes a box and steel balls. A circular cavity is provided inside the box. A central through hole is provided on the upper and lower surfaces of the box. A steel shaft (4) passes through the central through hole of the box. The steel balls are arranged in the circular cavity and surround the steel shaft (4). The center of the box is located at the center of mass of the body degree of freedom flutter model (1). The steel shaft (4) is also located inside the rectangular through hole; The steel shaft (4) is connected to the top and bottom of the wind tunnel at both ends, and two displacement limiters (5) are also provided at both ends of the steel shaft (4).

2. The body freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The crossbeam (2) is a carbon fiber tube.

3. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 2, characterized in that, The axis of the beam (2) passes through the center of mass of the flutter model (1) of the body degrees of freedom.

4. The body freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The cross-shaped connecting beam is set parallel to the crossbeam (2).

5. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The crossbeam is inserted into the box and glue is applied to the contact surface.

6. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The steel shaft (4) is inserted through the center of the rectangular through hole, and the length of the rectangular through hole along the flight direction is 5-8cm.

7. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The steel shaft (4) is in contact with all the steel balls.

8. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The two displacement limiters (5) are spaced 50cm apart.

9. The body-degree-of-freedom flutter model support device with decoupled heave and pitch degrees of freedom according to claim 1, characterized in that, The two displacement limiters (5) are made of rubber or foam.

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