Body degree-of-freedom flutter model supporting device with sinking and floating degree-of-freedom and pitching degree-of-freedom decoupling

Abstract

The invention provides a body degree-of-freedom flutter model supporting device for sinking and floating and pitching degree-of-freedom decoupling. The body degree-of-freedom flutter model supporting device comprises a cross beam, a rotating bearing, a sliding mechanism, a steel shaft and a group of displacement limiters. It can be guaranteed that relative rotation between the sliding mechanism and the model is not affected, and meanwhile the sinking and floating degree of freedom and the pitching degree of freedom are released. The device has the advantages of being small in occupied space, easy to implement and small in influence on the aerodynamic configuration of the model, and the influence of supporting rigidity introduced by a supporting spring on a test result is avoided; the designed supporting device can simulate the real flight state of the flying wing to the maximum extent, and test errors caused by frictional resistance can be reduced.

Description

Technical Field

[0001] The invention belongs to the field of aviation technology, and in particular relates to a body freedom flutter model supporting device with decoupled heave and pitch freedom. Background Art

[0002] The body-freedom flutter of a flying wing is an aeroelastic phenomenon involving the interaction between structural vibration and aerodynamic forces during flight. Body-freedom flutter occurs when the rigid body pitch mode of the aircraft is coupled with the symmetric wing bending mode under specific flight conditions. This phenomenon may lead to instability and destruction of the aircraft structure, posing a threat to flight safety.

[0003] In recent years, most researchers have used half-span models for ground vibration tests and wind tunnel tests on flying wing body flutter models. In order to simulate flight conditions, the model is usually suspended by a pitch / float elastic support with a counterweight. This design method can effectively decouple the suspension support stiffness in the pitch and float directions, making it easier to perform accurate vibration analysis on the model.

[0004] However, this suspension method is not suitable for the suspension of full-span flying wing wind tunnel test models. Some scholars also use rails to install the flying wing half model on the bottom or side wall of the wind tunnel, and release the heave and pitch freedom of the flying wing layout model through the rails, thereby approximately simulating the "free-free" state. In addition, some scholars use active control systems to drive the rudders based on the free flight model to achieve the balance of the flying wing and eliminate the potential influence of elastic suspension or support stiffness on the inherent mode. However, after the introduction of active control systems, new aerodynamic servoelastic problems may arise. These problems may have a complex impact on the flutter characteristics of the aircraft, thereby increasing the complexity and uncertainty of flutter testing.

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

[0006] The present invention provides a body freedom flutter model support device with decoupled heave and pitch freedom, which minimizes the influence of support stiffness introduced by a support system on the body freedom flutter wind tunnel test results of a flying wing layout model, and can approximately simulate the "free flight" state of the model, thereby ensuring the safety of the test and the validity of the results, and helping to reduce or eliminate the influence of various factors (friction, suspension stiffness, etc.) on the body freedom flutter characteristic test results.

[0007] The present invention provides a body freedom flutter model support device with decoupled heave and pitch freedom. The body freedom flutter model 1 comprises: a flying wing fuselage, a cross-shaped connecting beam, two wings, and an outer shell; the flying wing fuselage is a boat-shaped structure, a rectangular through hole is arranged at the tail, the outer shell is sleeved on the outer side of the flying wing fuselage, the two wings are connected to the flying wing fuselage through a cross-shaped connecting beam, and are transitionally connected with the outer shell; the support device comprises: a crossbeam 2, a rotating bearing, a sliding mechanism 3, a steel shaft 4 and two displacement limiters 5;

[0008] One end of the two cross beams 2 is connected to a wing through a bearing, and the other end is connected to the sliding mechanism 3;

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

[0010] The steel shaft 4 is also arranged in the rectangular through hole;

[0011] Both ends of the steel shaft 4 are connected to the top and bottom of the wind tunnel, and two displacement limiters 5 are also arranged 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 body freedom flutter model 1.

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

[0015] Optionally, the crossbeam is inserted into the box body and glue is applied on the contact surface.

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

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

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

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

[0020] The present invention provides a body freedom flutter model support device with decoupled heave and pitch freedom. Since the body freedom flutter of the flying wing layout model is caused by the coupling of its rigid body mode pitch mode with the low-order elastic bending mode of the wing, when the body freedom flutter occurs, it will be accompanied by obvious pitch / heave motion phenomenon. In order to make the body freedom flutter characteristics of the model obtained in the wind tunnel test more realistic and reliable, the support device must be able to release the pitch and heave freedom of the model, so as to simulate the free flight state in the air. The present invention proposes a body freedom flutter model supporting device with decoupled heave and pitch freedom, which adopts carbon fiber tubes and rotating bearings to connect the flying wing and the sliding mechanism, so as to ensure that the entire heave and pitch freedom decoupling device is always at the center of mass of the model, and at the same time reduces the friction resistance, does not need to design supporting springs separately, can release the heave and pitch freedom at the same time, has the advantages of small space occupation, easy implementation and little influence on the aerodynamic shape of the model, and avoids the influence of the supporting stiffness introduced by the supporting spring on the test results; the designed supporting device can simulate the real flight state of the flying wing to the maximum extent, and can reduce the test error caused by friction resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. It is obvious that 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 work.

[0022] Figure 1 It is a basic composition diagram of the body freedom flutter model support device with decoupled heave and pitch freedom;

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

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

[0025] Figure 4 It is a schematic diagram of the implementation of a body freedom flutter model support device with decoupled heave and pitch freedom;

[0026] Description of reference numerals:

[0027] 1- Flying wing layout model;

[0028] 2- beam;

[0029] 3- Sliding mechanism;

[0030] 4-Steel shaft;

[0031] 5- Displacement limiter. DETAILED DESCRIPTION

[0032] The body freedom flutter model supporting device with decoupled heave and pitch freedom provided by the present invention will be described in detail below 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 heave and pitch freedom, comprising a crossbeam 2, a rotary bearing, a sliding mechanism 3, a steel shaft 4 and a set of displacement limiters 5;

[0034] The crossbeam is a carbon fiber tube arranged in two sections along the span direction in the cavity in the middle of the flying wing layout model fuselage, and the axis of the carbon fiber tube passes through the center of mass of the flying wing, and the two ends are fixedly connected to the internal structure of the flying wing layout model through a rotating bearing; the cavity is used to arrange a free flight support device;

[0035] The sliding mechanism comprises a box body and a plurality of steel balls arranged in the box body; the box body is arranged in the middle cavity of the model fuselage perpendicular to the model plane, wherein the cross beam is connected to the sliding mechanism by gluing, and the center of the box body is at the center of mass of the flying wing.

[0036] The steel shaft passes through the gap in the center of the sliding mechanism and contacts all the steel balls inside the sliding mechanism, so that the entire sliding mechanism can stably slide 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 is a boat-shaped structure, with a rectangular through hole at the tail, and the steel shaft 4 is also set in the rectangular through hole; the steel shaft 4 is passed through the center of the rectangular through hole, and the length of the rectangular through hole along the heading direction is 5-8cm.

[0037] The sliding mechanism is located above the rectangular through hole, and during the test, when the model undergoes pitching motion, interference between the rigid axis and the boat-shaped structure can be avoided.

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

[0039] Exemplarily, the diameter of the crossbeam provided by the present invention may be 5 mm, and correspondingly, the diameter of the steel shaft may be 10 mm.

[0040] The present invention provides a body freedom flutter model support device with decoupled heave and pitch freedom, comprising a crossbeam 2, a rotary bearing, a sliding mechanism 3, a steel shaft 4 and a group of displacement limiters 5.

[0041] The model and the sliding mechanism are connected at the center of mass of the flying wing layout model through two transverse axes (carbon fiber tubes). The transverse axes and the sliding mechanism are connected by blind hole gluing. The transverse axes and the model are connected by rotating bearings to ensure that the relative rotation between the sliding mechanism and the model is not affected, thereby releasing the pitch freedom of the flying wing layout model during the test.

[0042] The sliding mechanism includes a box body and a number of steel balls placed in the box body, in which the horizontal axis and the sliding mechanism are connected by blind hole gluing. A hole is opened in the center of the box body, and the steel axis passes through the hole of the box body and contacts the steel balls, so that the sliding mechanism can slide up and down stably along the steel axis, thereby releasing the sinking and floating freedom of the flying wing layout model.

[0043] In order to make the whole model move within a limited area, the device also designed a set of displacement limiters, which were installed on the steel shaft and located a certain distance above and below the sliding mechanism. By limiting the amplitude of the sinking and floating movement, the whole system can operate safely. The steel shaft is connected to the top and bottom of the wind tunnel through flanges.

[0044] The flying wing layout model body freedom flutter test support device is highly flexible and easy to adjust. By adjusting the longitudinal positions of the upper and lower limiters, the flutter pitch motion amplitude of the flying wing layout model can be controlled under certain conditions. At the same time, this design avoids unnecessary rigid or elastic constraints, thereby ensuring that the test results can be closer to the real free flight state.

[0045] When the incoming flow velocity approaches the flutter critical point, the flying wing layout model is stimulated by controlling the movement of the control surface, so that the wing bends and drives the entire flying wing to pitch around the centerline of the carbon tube. The attenuation of the signal is observed and the relevant data is 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 technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A body freedom flutter model support device with decoupled heave and pitch freedom, characterized in that: The body freedom flutter model (1) comprises: a flying wing fuselage, a cross-shaped connecting beam, two wings, and an outer shell; the flying wing fuselage is a boat-shaped structure, a rectangular through hole is arranged at the tail, the outer shell is sleeved on the outer side 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 with the outer shell; the supporting device comprises: a crossbeam (2), a rotating bearing, a sliding mechanism (3), a steel shaft (4) and two displacement limiters (5); One end of the two cross beams (2) is connected to a wing through a bearing, and the other end is connected to a sliding mechanism (3); The sliding mechanism (3) comprises a box body and a steel ball. A circular cavity is arranged in the box body. A central through hole is arranged on the upper and lower surfaces of the box body. A steel shaft (4) passes through the central through hole of the box body. The steel ball is arranged in the circular cavity and surrounds the steel shaft (4). The center of the box body is located at the center of mass of the body freedom vibration model (1). The steel shaft (4) is also arranged in the rectangular through hole; The two ends of the steel shaft (4) are connected to the top and bottom of the wind tunnel, and two displacement limiters (5) are also arranged at the two ends of the steel shaft (4).

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

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

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

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

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

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

8. The body freedom flutter model support device with decoupled heave and pitch freedom according to claim 1, characterized in that: The distance between the two displacement limiters (5) is 50 cm.

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

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