CN108284943B - Mechanism for flexibly bending tail edge of wing - Google Patents

Abstract

The invention discloses a mechanism for flexible bending of the trailing edge of a wing, belonging to the field of near space aircraft, comprising two rotating triangles T1 and T2 located on the same horizontal plane, a horizontal actuating rod L1 and two plane connecting rods L2 , L3; the two rotating triangles pass through their respective vertex hinges; the rotating triangle T1 connects 1/3 of the plane link L2, while the two ends of the plane link L2 are hinged to the horizontal actuation link L1 and the plane link L3; the plane The other end of the link L3 hinges the vertex of the triangle T2. The degree of freedom of the horizontal actuating link L1 to act left/right along the X axis drives the two plane links L2 and L3 to rotate clockwise/counterclockwise, and at the same time rotate the triangle to form a secondary rotation to realize the flexibility of the aircraft skin. / Downward movement. The structure of the invention is simple, the inner space of the wing is efficiently utilized, and the continuous bending of the wing can be realized. Effectively improve lift coefficient and lift-drag ratio at small angle of attack.

Description

A mechanism for flexible bending of wing trailing edge

technical field

The invention belongs to the field of near space aircraft, in particular to a mechanism for flexible bending of the trailing edge of a wing.

Background technique

Since the birth of drones, they have played a very important role in many fields such as military, communication and rescue. In the 1990s, the United States successively developed the "Predator" and "Global Hawk" unmanned aerial vehicles. Various military missions such as reconnaissance and signal collection. As far as the current development trend is concerned, UAVs are developing in the direction of high altitude, long endurance and multi-purpose. However, due to technical limitations, the current UAVs cannot meet the engineering needs of high altitude and long endurance.

First of all, the high-altitude UAV needs to pass through the troposphere during the take-off stage. This area is greatly affected by weather and terrain, and the airflow is turbulent and unstable. However, the UAV has a relatively large splay during long flight and has poor anti-stall performance. It is necessary to improve the aircraft. The stall performance of the wing; the second point, when the high-altitude UAV completes the cruising operation in the adjacent space, the air is thin and the density is lower than that of the conventional flight conditions, and the corresponding Reynolds number is also low (Re≈2×10 ⁵ ) , so it is also crucial to improve the lift coefficient and lift-drag ratio of aircraft cruise.

SUMMARY OF THE INVENTION

The present invention is a mechanism for flexible bending of the trailing edge of the wing, which adopts a slider link mechanism to realize the flexible bending of the trailing edge of the wing, which can improve the lift coefficient and lift-drag ratio of aircraft cruise; and the components are completely in the wing. Internal, small size and simple structure;

The flexible bending mechanism for the trailing edge of the wing adopts a slider linkage mechanism, which consists of two rotating triangles, a horizontal actuating rod and two plane connecting rods in total, and the five components are located on the same horizontal plane.

The two rotating triangles are respectively the rotating triangle T1 and the rotating triangle T2; the vertices of the rotating triangle T1 are named clockwise: the first vertex, the second vertex and the third vertex; the vertices of the rotating triangle T2 are named clockwise: start vertex, middle vertex and end vertex;

The first vertex hinge is fixed on the inner spar of the wing, the second vertex hinge is connected to the starting vertex of the rotating triangle T2; the third vertex hinge is connected to 1/3 of a plane link L2. One end of the horizontal actuating link L1 is hinged, and L1 realizes the horizontal movement through the chute, and the chute is fixed on the spar inside the wing.

The other end of the plane link L2 is connected to another plane link L3 through a hinge; at the same time, the other end of the plane link L3 is hinged at the middle vertex of the rotating triangle T2.

The five components are connected by hinges to form five rotating pairs: the horizontal actuating rod L1 is hinged to connect the plane link L2; the plane link L2 is hinged to connect the plane link L3; the plane link L2 is hinged to connect the third vertex of the rotating triangle T1; The plane link L3 is hingedly connected to the middle vertex of the rotating triangle T2; the starting vertex of the rotating triangle T2 is hingedly connected to the second vertex of the rotating triangle T1;

At the same time, the hinge of the first vertex of the rotating triangle T1 is fixed on the inner spar of the wing to form a rotating pair; the horizontal actuating rod L1 is restricted to move in the horizontal direction and is determined as a sliding pair;

Therefore, the plane degree of freedom of the overall mechanism is F=5×3-6×2-1×2=1, which can realize bending with a single degree of freedom, and the motion trajectory is clear.

The push rods above and below the overall mechanism are connected to the aircraft skin through small stringers, and the push rods are connected to the sides of the rotating triangle through hinges;

The working principle of the flexible bending of the overall mechanism is as follows:

The active element of the overall mechanism is the horizontal actuating rod L1. When it moves left and right along the X direction, it drives the two plane links to make L2 and L3 to make plane movements. The rotating stages are connected and drive the two rotating stages to rotate, and finally achieve the goal of flexible bending of the skin.

details as follows:

The degree of freedom of the horizontal actuating rod L1 to move horizontally to the left along the X-axis, drives the plane link L2 to make a plane movement with a clockwise rotation direction, and drives the rotating triangle T1 to rotate clockwise to the first stage of rotation; Driven by the plane link L2, the rod L3 also performs a plane motion with a clockwise rotation direction, and drives the rotating triangle T2 to rotate clockwise to act as the second rotation stage; then the skin is connected to the two rotation stages through the stringers, Realize flexible downward deflection movement.

Similarly, when the horizontal actuating rod L1 moves to the right along the X-axis, the two rotating stages rotate counterclockwise under the driving of the plane links L2 and L3 to complete the flexible upward deflection movement of the skin.

The advantages of the present invention and the beneficial effects brought are:

1), a mechanism for flexible bending of the trailing edge of the wing, the mechanism is simple, the internal space of the wing is efficiently utilized, and the continuous bending of the wing can be realized.

2) A mechanism for flexible bending of the trailing edge of the wing, which can effectively improve the lift coefficient and the lift-drag ratio at a small angle of attack when the wing is bent down.

3) A mechanism for flexible bending of the trailing edge of the wing, which can improve the stall performance of the wing when the wing is bent upward.

4) A mechanism for flexible bending of the trailing edge of the wing, when dragging the skin to bend, the skin bears less stress and prolongs the service life of the skin.

Description of drawings

1 is a general schematic diagram of a mechanism for flexible bending of a wing trailing edge according to the present invention;

2 is a schematic diagram of the connection between a mechanism for flexible bending of the trailing edge of a wing and a skin of the present invention;

3 is a schematic diagram of two-stage triangular space positions in a mechanism for flexible bending of a wing trailing edge according to the present invention;

4 is a schematic diagram of the spatial position of a plane connecting rod in a mechanism for flexible bending of a wing trailing edge according to the present invention;

Fig. 5 is the state diagram before the invention adopts E387 low Reynolds number airfoil deformation;

Fig. 6 is the state diagram of the present invention after the flexible bending of the E387 low Reynolds number airfoil;

Fig. 7 is the variation diagram of the flight angle of attack with the lift coefficient when the flexibility is down by 10° in the embodiment of the present invention;

8 is a graph showing the variation of the flight angle of attack with the drag coefficient when the flexibility is downwardly offset by 10° in the embodiment of the present invention;

9 is a graph showing the variation of the flight angle of attack with the lift-drag ratio when the flexibility is downwardly offset by 10° in the embodiment of the present invention;

Fig. 10 is the variation diagram of the flight angle of attack with the lift coefficient when the flexibility is upwardly offset by 10° in the embodiment of the present invention;

Fig. 11 is the variation diagram of the flight angle of attack with the drag coefficient when the flexibility is upwardly offset by 10° in the embodiment of the present invention;

FIG. 12 is a graph showing the variation of the flight angle of attack with the lift-to-drag ratio when the flexibility is upwardly offset by 10° in the embodiment.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

The present invention changes the camber of the trailing edge of the aircraft wing by designing a connecting rod mechanism to improve the aerodynamic performance of the aircraft. As shown in FIG. 1 , the invention includes a horizontal actuating rod L1, two plane connecting rods L2, L3 and two Rotate triangles T1, T2. All rods and rotating triangles are located on the same horizontal plane, and the sides of all rods and rotating triangles are made of alloy steel with a section size of 10mm×10mm.

The two rotating triangles are composed of two rotating stages, and the vertices are named clockwise: the vertices of the rotating triangle T1 are named: the first vertex, the second vertex and the third vertex; the vertices of the rotating triangle T2 are named: start vertex, middle vertex and end vertex;

The mechanism is integrally fixed on the inner spar of the wing, and the position of the fixed point is the first vertex of the first rotation stage triangle T1. As shown in Figure 2, the push rods above and below the mechanism are connected to the aircraft skin through small stringers. , the position of the push rod is located at the midpoint of the side of the rotating triangle, and all parts of the mechanism are connected by hinges.

The second vertex of the first rotation-level triangle T1 is hingedly connected to the starting vertex of the rotation triangle T2; in this embodiment, the specific dimensions of the two-level rotation triangle are shown in Figure 3, wherein the length of the side L4 of the triangle T1 is 33mm, and the length of the side L4 of the triangle T1 is 33mm. The angle α1 in the vertical direction is 36°, the length of the side L5 is 235mm, and the angle α2 with the vertical direction is 81°; the length of the side L6 of the triangle T2 is 25mm, and the angle α3 with the vertical direction is 65°; The length of the side L7 is 187mm, and the angle α4 with the vertical direction is 86°;

The third vertex hinge of the first rotation stage triangle T1 is connected to 1/3 of a plane connecting rod L2; as shown in FIG. The included angle β is 60°. The horizontal actuating link L1 is hinged at one end of the plane link L2. The length of the link L1 is 50mm. The L1 moves horizontally through the chute, and the chute is fixed on the spar inside the wing. The other end of the plane link L2 is connected to another plane link L3 through a hinge; at the same time, the other end of the plane link L3 is hinged at the middle vertex of the rotating triangle T2.

All parts of the mechanism are connected by hinges to form five rotating pairs; at the same time, the entire mechanism is fixed on the wing spar through the first vertex of the first rotating triangle T1 to form a rotating pair; the horizontal actuating rod L1 can only move in the horizontal direction, A sliding pair is formed; therefore, the plane degree of freedom of the mechanism is F=5×3-6×2-1×2=1, which can realize bending with a single degree of freedom and meet the design requirements.

When the slider is restricted from moving, it drives the two connecting rods L2 and L3 to move in a plane. The two connecting rods are respectively connected with the first rotating stage T1 and the second rotating stage T2 through the hinge, and drive the two rotating stages to rotate.

The principle of flexible bending of the present invention is as follows: the active element of the mechanism is the horizontal actuating rod L1, which has only the degree of freedom to act horizontally along the X-axis. When it moves to the left along the X-axis, it drives the first plane link L2 to rotate It is a clockwise plane motion, and drives the first-stage rotating triangle T1 to rotate clockwise; the second plane link L3, driven by the plane link L2, also performs a clockwise plane motion, and drives the first plane link L3. The secondary rotating triangle T2 rotates, and then the skin is connected with the two rotating stages through the stringer to realize the flexible downward deflection movement.

Similarly, when the horizontal actuating rod L1 moves to the right along the X-axis, the two rotating stages rotate counterclockwise under the driving of the connecting rod to complete the flexible upward deflection movement of the skin.

The present invention takes the E387 low Reynolds number airfoil as an example to perform flexible deformation. As shown in Figure 5, the horizontal axis is the x coordinate value of the airfoil, and the vertical axis is the z coordinate value of the airfoil. The deformed airfoil is shown in Figure 6. CFD aerodynamic simulation calculation is performed on the deformed airfoil. The calculation results are shown in Figure 7, Figure 8 and Figure 9, where α represents the flight angle of attack, _CL represents the lift coefficient, CD represents the drag coefficient, and L/ _D represents the lift drag ratio, when the airfoil bends down, as shown in Figure 7, the lift coefficient of the airfoil increases significantly under the condition of medium and small angle of attack (0°~5°). The lift coefficient increased from 0.69 to 1.09, an increase of 57.97%, as shown in Figure 9, the lift-drag ratio increased from 57.98 to 69.43, an increase of 19.75%, and the aerodynamic performance was significantly improved.

When the airfoil deflects upward, as shown in Figure 10, Figure 11 and Figure 12, although the lift coefficient of the airfoil decreases, the stall angle of attack is delayed from 10° to 12°, an increase of about 2°, and the anti-stall performance is improved. And the drag of the upward-biased airfoil is significantly reduced at a large angle of attack. Taking the 10° angle of attack as an example, the airfoil drag is reduced from 0.038 to 0.027, a decrease of 28.95%.

When aircraft is manufactured, the skin is generally made of zinc-aluminum alloy. The yield strength of this material is 505MPa, the ultimate strength is 573MPa, and the shear strength is 295MPa. Since the skin is a plastic material and has a thin thickness, the fourth strength theory is adopted. After checking, the skin will deform elastically when the mechanism is actuated. The force analysis of the skin is carried out through ANSYS finite element analysis. The results are as follows:

Table 1

It can be seen that when the mechanism drags the skin to perform a flexible downward bending motion, the maximum stress of the skin is 101.23MPa, and when the mechanism drags the skin to perform an upward deflection motion, the maximum stress of the skin is 60.18MPa. It is smaller than the yield strength of the aluminum alloy skin, so the flexible bending of the trailing edge realized by the action of the mechanism can prolong the service life of the skin.

Claims (5)

1. A mechanism for flexibly bending the tail edge of a wing is characterized in that a sliding block connecting rod mechanism is adopted and comprises five parts, namely two rotating triangles, a horizontal actuating rod and two plane connecting rods, wherein the five parts are positioned on the same horizontal plane;

the two rotating triangles are respectively a rotating triangle T1 and a rotating triangle T2; the vertexes of the rotating triangle T1 are named as follows: a first vertex, a second vertex and a third vertex; the vertexes of the rotating triangle T2 are named as follows: a start vertex, a middle vertex and an end vertex;

the wing is fixed on the wing internal wing spar through a first vertex hinge, and a second vertex hinge is connected with the initial vertex of the rotating triangle T2; the third vertex is hinged with a plane connecting rod L2 at the position 1/3, one end of the plane connecting rod L2 is hinged with a horizontal actuating rod L1, the horizontal actuating rod L1 realizes horizontal movement through a sliding groove, and the sliding groove is fixed on a wing beam in the wing;

the other end of the plane connecting rod L2 is connected with another plane connecting rod L3 through a hinge; meanwhile, the other end of the plane connecting rod L3 is hinged at the middle vertex of the rotating triangle T2;

push rods above and below the integral mechanism are connected with the aircraft skin through small stringers, and the push rods are connected to the edges of the rotating triangle through hinges.

2. The mechanism for flexibly bending the tail edge of the wing as claimed in claim 1, wherein the five components are connected through hinges to form five revolute pairs, specifically: the horizontal actuating rod L1 is hinged with the plane connecting rod L2; the plane connecting rod L2 is hinged with the plane connecting rod L3; the plane connecting rod L2 is hinged with the third vertex of the rotating triangle T1; the plane connecting rod L3 is hinged with the middle vertex of the rotating triangle T2; the initial vertex of the rotating triangle T2 is hinged with the second vertex of the rotating triangle T1; the first vertex of the rotating triangle T1 is hinged and fixed on the wing internal wing spar to form a revolute pair; the horizontal actuating rod L1 is restricted from moving in the horizontal direction and defines a sliding pair.

3. The mechanism for flexibly bending the tail edge of the wing as claimed in claim 1, wherein the planar degree of freedom F of the mechanism is 5 x 3-6 x 2-1 x 1, so that bending with a single degree of freedom is realized, and the motion track is clear.

4. A mechanism for flexible bending of a trailing edge of a wing according to claim 1, wherein the mechanism operates according to the following principle:

the driving element of the whole mechanism is a horizontal actuating rod L1, when the horizontal actuating rod moves left and right along the X direction, the horizontal actuating rod drives two plane connecting rods to do plane motion with L2 and L3, the two plane connecting rods are respectively connected with a rotating stage formed by a rotating triangle T1 and a rotating triangle T2 through hinges and drive the two rotating stages to rotate, and finally the aim of flexible bending of the skin is achieved; the method comprises the following specific steps:

the horizontal actuating rod L1 has a degree of freedom of horizontal actuation to the left along the X axis, drives the plane connecting rod L2 to do plane motion with a clockwise rotation direction, and drives the rotation triangle T1 to rotate clockwise to act a first-stage rotation stage; the plane connecting rod L3 is driven by the plane connecting rod L2 to do plane motion with clockwise rotation direction, and drives the rotation triangle T2 to rotate clockwise to act a second-stage rotation stage; then the skin is connected with the two rotating stages through stringers to realize flexible downward deflection motion;

similarly, when the horizontal actuating rod L1 moves to the right along the X axis, the two rotating stages rotate counterclockwise under the driving of the planar connecting rods L2 and L3, and the flexible upward-biased movement of the skin is completed.

5. A mechanism for flexible bending of a trailing edge of a wing according to claim 1, wherein the two pivoting triangles and one of the horizontal actuator rods are made of alloy steel having cross-sectional dimensions of 10mm x 10 mm.

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