A full-activity airfoil low-speed wind tunnel flutter test model with nonlinear characteristics

Abstract

The application belongs to the field of aircraft aeroelasticity, and relates to a full-actuated airfoil low-speed wind tunnel flutter test model with nonlinear characteristics, which comprises a fairing model, a supporting device, an airfoil model and a gap generating device. One end of the gap generating device is fixedly connected with the supporting device, and the other end is fixedly connected with the airfoil model. The gap generating device comprises a gap pin and a thimble, the thimble is connected with the supporting device, and the thimble can be matched with the gap pin to generate different gaps. When the low-speed wind tunnel flutter test is carried out, the airflow is transmitted to the airfoil model after being rectified by the fairing model, the airfoil model is deformed and vibrated according to the aerodynamic force, the gap generating device is replaced with different gap pins to generate different matching gaps, the airfoil model generates different vibrations under different gaps to generate different nonlinear characteristics, and the low-speed wind tunnel flutter test under the nonlinear characteristics is completed by recording the airfoil model under different matching gaps and different postures.

Description

Technical Field

[0001] This application belongs to the field of aircraft aeroelasticity, and specifically relates to a low-speed wind tunnel flutter test model for an all-moving airfoil with nonlinear characteristics. Background Technology

[0002] During flight, the all-moving wing surfaces of an aircraft need to perform frequent movements to maintain or change the aircraft's attitude. As the aircraft's flight time accumulates, mechanical wear will occur inside the all-moving wing surface control mechanism. This situation will cause gaps to appear inside the rotating components of the all-moving wing surface. As the value of these gaps increases, the nonlinear characteristics of the aircraft system become more and more obvious. In severe cases, it will affect the flutter characteristics of the aircraft body and thus endanger the safety of aircraft operation.

[0003] To clarify the influence of all-moving airfoil clearance on its flutter characteristics, necessary physical experiments are required for verification. Conventional flutter test models are mainly used to study test objects under linear assumptions, but are not applicable to test objects under nonlinear assumptions. To solve this technical problem, it is necessary to find an all-moving airfoil flutter model that can be used to study nonlinear flutter characteristics. Summary of the Invention

[0004] The purpose of this application is to provide a low-speed wind tunnel flutter test model for all-moving airfoils with nonlinear characteristics, in order to solve the problem that it is difficult to test the nonlinear flutter characteristics of aircraft systems in the prior art.

[0005] The technical solution of this application is: a low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil, comprising a rectification model, a support device, an airfoil model, and a gap generating device; the rectification model and the airfoil model do not contact each other, the length of the rectification model is greater than the chord length of the airfoil model, a cavity is formed inside the rectification model, the support device is located in the cavity, one end of the support device is rotatably connected to the airfoil model, and the other end is fixedly connected to the rectification model; one end of the gap generating device is fixedly connected to the support device, and the other end is fixedly connected to the airfoil model; the gap generating device includes a gap pin and a pin, the gap pin has a stepped structure with a gradually increasing diameter from the head to the end, the pin is connected to the support device, and the pin can produce different gap fits with the gap pin.

[0006] Preferably, the gap generating device further includes a pin seat and a screw. The pin seat is fixedly connected to the wing model. The pin seat has a U-shaped structure with slits on both sides. The pin seat has a pin hole corresponding to the gap pin direction, and a first pin hole and a second pin hole are formed on both sides of the pin seat respectively. The pin seat has a screw hole corresponding to the ejector pin direction. The slits are connected to the pin hole and the screw hole. The gap pin is inserted into the pin hole, and the screw is threaded into the screw hole. The gap pin has a stepped structure with a gradually increasing diameter from the head to the end. One end of the ejector pin has a through hole. The diameters of the first pin hole, the through hole, and the second pin hole increase sequentially. The gap pin is inserted into the through hole.

[0007] Preferably, the wing model includes an aluminum alloy beam frame and at least one set of dimensional frames, the dimensional frames being connected to the wing model, with gaps between any adjacent dimensional frames, and each dimensional frame having a skin covering its upper and lower surfaces.

[0008] Preferably, each of the three-dimensional frames is connected to the aluminum alloy beam frame at a single point.

[0009] Preferably, the support device includes a support plate, a rotating shaft, a bearing seat, and a spring plate; the support plate is fixedly connected to the cavity of the rectifier model, the bearing seat is disposed on the support plate, the bearing seat contains a bearing, one end of the rotating shaft is connected to the bearing in the bearing seat, and the other end is rotatably connected to the airfoil model; the spring plate is fixedly connected between the gap generating device and the support plate.

[0010] Preferably, the rectifier model includes a main frame and a cover. The main frame is located below the airfoil model. The side wall of the main frame has a streamlined structure. The cavity is opened in the middle of the main frame. The cover is connected to one side of the cavity by screws and can close the cavity.

[0011] This application discloses a low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil, comprising a rectification model, a support device, an airfoil model, and a gap generating device. One end of the gap generating device is fixedly connected to the support device, and the other end is fixedly connected to the airfoil model. The gap generating device includes a gap pin and a pin, the pin being connected to the support device and capable of different gap fits with the gap pin. During the low-speed wind tunnel flutter test, the airflow is first rectified by the rectification model and then transmitted to the airfoil model. The airfoil model deforms and vibrates according to aerodynamic forces. By changing different gap pins, the gap generating device generates different fit gaps, resulting in different vibrations in the airfoil model under different gaps, thus producing different nonlinear characteristics. By recording the airfoil model under different fit gaps and attitudes, the low-speed wind tunnel flutter test under nonlinear characteristics is completed. Attached Figure Description

[0012] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0013] Figure 1 This is a schematic diagram of the overall structure of this application;

[0014] Figure 2 This is a schematic diagram of the connection structure between the supporting device and the gap generating device in this application;

[0015] Figure 3 This is a schematic diagram of the gap generating device of this application;

[0016] Figure 4 This is a schematic diagram of the wing surface model structure of this application;

[0017] Figure 5 This is a schematic diagram of the free clearance of the all-moving airfoil in this application.

[0018] 1. Rectifier model; 2. Support device; 3. Cover; 4. Airfoil model; 5. Aluminum alloy beam frame; 6. Shaped frame; 7. Support plate; 8. Rotating shaft; 9. Bearing seat; 10. Spring plate; 11. Gap generating device; 12. Gap pin; 13. Pin seat; 14. Screw; 15. Ejector pin; 16. First pin hole; 17. Second pin hole; 18. Through hole; 19. Positioning plate; 20. Cut slit. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0020] A low-speed wind tunnel flutter test model for an all-moving airfoil with nonlinear characteristics, such as... Figure 1 , Figure 2 As shown, it includes a rectification model 1, a support device 2, an airfoil model 4, and a gap generating device 11.

[0021] The rectifying model 1 and the airfoil model 4 do not contact each other. The length of the rectifying model 1 is greater than the chord length of the airfoil model 4. A cavity is opened inside the rectifying model 1, and the support device 2 is located in the cavity. One end of the support device 2 is rotatably connected to the airfoil model 4, and the other end is fixedly connected to the rectifying model 1. One end of the gap generating device 11 is fixedly connected to the support device 2, and the other end is fixedly connected to the airfoil model 4. The gap generating device 11 includes a gap pin 12 and a pin 15. The gap pin 12 has a stepped structure with a gradually increasing diameter from the head to the end. The pin 15 is connected to the support device 2 and can be connected to different stepped positions of the gap pin 12.

[0022] During the low-speed wind tunnel flutter test, the airflow is first rectified by the rectifier model 1 and then transmitted to the airfoil model 4. The airfoil model 4 will deform and vibrate according to the aerodynamic force. The gap generating device 11 generates different fitting gaps by changing different gap pins 12. The airfoil model 4 produces different vibrations under different gaps, thus producing different nonlinear characteristics. By recording the airfoil model 4 under different fitting gaps and different attitudes, the low-speed wind tunnel flutter test under nonlinear characteristics is completed.

[0023] like Figure 3 As shown, preferably, the gap generating device 11 further includes a pin seat 13 and a screw 14. The pin seat 13 is fixedly connected to the wing model 4. The pin seat 13 has a U-shaped structure with slits 20 on both sides. The pin seat 13 has pin holes corresponding to the direction of the gap pin 12. The two pin holes are a first pin hole 16 and a second pin hole 17. The second pin hole 17 is located on the side of the pin seat 13 near the end of the gap pin 12. The pin seat 13 has a screw hole corresponding to the direction of the ejector pin 15. The slits 20 communicate with the pin holes and the screw holes. The gap pin 12 is inserted into the second pin hole 17 and the first pin hole 16 in sequence. The screw 14 is threaded into the screw hole. By slitting 20 in the stepped hole of the pin seat 13, the structure can undergo slight deformation when the bolt is tightened, thereby fixing the gap pin 12, and there is no need to worry about unexpected gaps occurring in this connection link. One side of the ejector pin 15 is a screw for connecting to the support device 2; the other end of the ejector pin 15 is designed with a through hole 18, and the end of the ejector pin 15 with the through hole 18 is inserted into the U-shaped opening of the pin seat 13. The diameters of the first pin hole 16, the through hole 18 and the second pin hole 17 increase sequentially. The diameter and tolerance of each hole are given according to the design and are used to cooperate with the clearance pin 12.

[0024] By replacing the clearance pin 12 with different tolerances, the clearance between the clearance pin 12 and the pin seat 13 remains unchanged, while the clearance between the clearance pin 12 and the ejector pin 15 changes, achieving precise manual control of the clearance. Because the clearance pin 12 employs a stepped structure, it can still be stably installed with the pin seat 13 and the ejector pin 15 even when the clearance between the clearance pin 12 and the through hole 18 changes.

[0025] like Figure 4As shown, preferably, the wing model 4 includes an aluminum alloy beam frame 5 and at least one set of three-dimensional frames 6. The aluminum alloy frames are composed of multiple rectangular beams with different cross-sectional dimensions. The design parameters of their cross-sectional dimensions are obtained by calculating the stiffness of the aircraft components based on the dynamic similarity ratio. The aluminum alloy frames serve as the main load-bearing structure of the wing model 4. By dividing the actual wing shape into multiple regions, each region is designed with at least one three-dimensional frame 6. The combination of three-dimensional frames 6 achieves an approximate simulation of the wing shape. After installation, the three-dimensional frames 6 cover the aluminum alloy beam frame. The upper and lower surfaces of each three-dimensional frame 6 are designed as curved surfaces to conform to the wing shape. The three-dimensional frames 6 will deform under the action of aerodynamic forces. Lightweight thin skins are also laid on the upper and lower surfaces of the three-dimensional frames 6, so that the aerodynamic forces of the three-dimensional frames 6 can be applied to the upper and lower surfaces of the three-dimensional frames 6, and the three-dimensional frames 6 can then transfer the aerodynamic forces to the aluminum alloy beam frame 5.

[0026] Each U-shaped frame 6 is connected to the aluminum alloy beam 5 at a single point, specifically by means of adhesive bonding. The U-shaped frame 6 transmits the aerodynamic force it bears to the aluminum alloy frame through the connection point. By using a single-point connection, the U-shaped frame 6 transmits the aerodynamic force without transmitting its own stiffness to the aluminum alloy beam 5, thus not affecting the measurement results.

[0027] The wing model 4 will undergo significant deformation during vibration. To avoid interference between the three-dimensional frames 6, any adjacent three-dimensional frames 6 will not contact each other, and there will be a gap between any adjacent three-dimensional frames 6. The gap can be 3mm or 5mm, etc. In this way, any adjacent three-dimensional frames 6 will maintain an appropriate distance and will not interfere with each other.

[0028] like Figure 2 As shown, preferably, the support device 2 includes a support plate 7, a rotating shaft 8, a bearing seat 9, and a spring plate 10. The support plate 7 is fixedly connected to the cavity of the rectifying model 1. The support plate 7 has an L-shaped or T-shaped structure and is made of steel. The support plate 7 is bolted to the cavity of the supporting model. The bearing seat 9 is vertically connected to the support plate 7. Two bearings are arranged vertically inside the bearing seat 9. One end of the rotating shaft 8 is connected to the two bearings inside the bearing seat 9, and the other end is rotatably connected to the aluminum alloy beam frame to support the aluminum alloy beam frame. After the rotating shaft 8 and the bearing seat 9 are installed, the rotating shaft 8 can rotate freely without any rotational clearance. Spring plate 10 is fixedly connected between gap generating device 11 and support plate 7, and can simulate the operating stiffness of the actuator of the all-moving airfoil. Since the stiffness of the actuator is actually transmitted through hydraulic pressure, if steel is used for connection, the stiffness will be too large, which will cause the airfoil model 4 to be unable to move. For different stiffness test requirements, different spring plates 10 can be selected and installed to replace them. The diameter of the rotating shaft 8 and the thickness of the spring plate 10 are obtained through stiffness equivalence and simulation calculation.

[0029] To ensure stable force transmission, an inner groove is provided at one end of the spring plate 10, and a positioning piece 19 is provided near one end of the ejector pin 15. The width of the positioning piece 19 is the same as that of the inner groove. After the ejector pin 15 is fixed with the spring plate 10, the positioning piece 19 is pulled into the inner groove to ensure that the spring plate 10 and the ejector pin 15 are installed stably.

[0030] like Figure 1 As shown, preferably, the rectifier model 1 includes a main frame and a cover 3. The main frame is located below the airfoil model 4. The side walls of the main frame have a streamlined structure, and a cavity is opened in the middle of the main frame. The front and rear sides of the main frame are made of pine wood. The cover 3 is connected to one side of the cavity by screws 14 and can close the cavity. The cover 3 is removable. When it is necessary to replace the spring plate 10, clearance pin 12, and other parts inside the cavity, the cover 3 is opened; after the replacement is completed, the cover 3 is closed, so that the outer surface of the rectifier model 1 maintains a streamlined structure.

[0031] like Figure 5 As shown, where Figure 5 The middle position is the pivot point 8, and the two sides are the airfoil positions. After the entire nonlinear characteristic low-speed wind tunnel flutter test model of the all-moving airfoil is manufactured, it is necessary to calibrate the tolerance value of the clearance pin 12 and the free deflection angle θ of the all-moving airfoil, establish the correspondence between the tolerance value of the clearance pin 12 and the free deflection angle θ of the airfoil, and achieve the purpose of accurate quantification of the rotation clearance.

[0032] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A low-speed wind tunnel flutter test model for an all-moving airfoil with nonlinear characteristics, characterized in that: The system includes a rectification model (1), a support device (2), an airfoil model (4), and a gap generating device (11). The rectification model (1) and the airfoil model (4) do not contact each other. The length of the rectification model (1) is greater than the chord length of the airfoil model (4). The rectification model (1) has a cavity inside. The support device (2) is located in the cavity. One end of the support device (2) is rotatably connected to the airfoil model (4), and the other end is fixedly connected to the rectification model (1). One end of the gap generating device (11) is fixedly connected to the support device (2), and the other end is fixedly connected to the airfoil model (4). The gap generating device (11) includes a gap pin (12) and a push pin (15). The push pin (15) is connected to the support device (2). The push pin (15) can produce different gap fits with the gap pin (12). The gap generating device (11) also includes a pin seat (13) and a screw (14). The pin seat (13) is fixedly connected to the wing model (4). The pin seat (13) has a U-shaped structure with slits (20) on both sides. The pin seat (13) has a pin hole corresponding to the gap pin (12), and a first pin hole (16) and a second pin hole (17) are formed on both sides of the pin seat (13). The pin seat (13) has a screw hole corresponding to the ejector pin (15). The slit (20) is connected to the pin hole and the screw hole. The gap pin (12) is inserted into the pin hole, and the screw (14) is threaded into the screw hole. The gap pin (12) has a stepped structure with a gradually increasing diameter from the head to the end. One end of the ejector pin (15) is provided with a through hole (18). The diameters of the first pin hole (16), the through hole (18), and the second pin hole (17) increase sequentially. The gap pin (12) is inserted into the through hole (18).

2. The low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil as described in claim 1, characterized in that: The wing model (4) includes an aluminum alloy beam frame (5) and at least one set of shaped frames (6). The shaped frames (6) are connected to the wing model (4), and there is a gap between any adjacent shaped frames (6). The upper and lower surfaces of each shaped frame (6) are covered with skin.

3. The low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil as described in claim 2, characterized in that: Each of the aforementioned shaped frames (6) is connected at a single point to the aluminum alloy beam frame (5).

4. The low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil as described in claim 1, characterized in that: The support device (2) includes a support plate (7), a rotating shaft (8), a bearing seat (9), and a spring plate (10); the support plate (7) is fixedly connected to the cavity of the rectifier model (1), the bearing seat (9) is provided on the support plate (7), the bearing seat (9) is provided with a bearing, one end of the rotating shaft (8) is connected to the bearing in the bearing seat (9), and the other end is rotatably connected to the airfoil model (4); the spring plate (10) is fixedly connected between the gap generating device (11) and the support plate (7).

5. The low-speed wind tunnel flutter test model with nonlinear characteristics for an all-moving airfoil as described in claim 1, characterized in that: The rectification model (1) includes a main frame and a cover (3). The main frame is located below the wing model (4). The side wall of the main frame has a streamlined structure. The cavity is opened in the middle of the main frame. The cover (3) is connected to one side of the cavity by screws (14) and can close the cavity.

Images