A precession simulation device for a screw oscillation wind tunnel test

Abstract

The present application belongs to the technical field of wind tunnel test, and particularly relates to a precession simulation device for a helical flutter wind tunnel test. The present application solves the problem of designing a helical flutter wind tunnel test device for a rotorcraft, and studies key influencing parameters and influencing rules of the helical flutter of the rotorcraft by designing a precession motion simulation device for the rotorcraft. The present application can realize the rotation of the rotor in the wind tunnel, and adjust the rotation speed of the rotor through a motor. Meanwhile, the precession system realizes the decoupling of the pitch and yaw modes of the rotation shaft, and the pitch and yaw mode frequencies are independently adjustable. Meanwhile, the axes of the pitch and yaw axes coincide, so that the precession motion of the pitch and yaw degrees of freedom can be realized under the action of the gyroscopic moment. Meanwhile, the adjustment of the rotation inertia of the nacelle rotating mass, the weight and the center of mass of the nacelle can be realized. Finally, the rotation speed of the rotating mass such as the rotor and the hub can be adjusted through the speed regulation motor, so as to ensure the matching of the rotation speed and the incoming flow speed, and achieve the helical flutter state.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, specifically relating to a spiral precession simulation device for helical flutter wind tunnel testing. Background Technology

[0002] Whirl flutter, also known as gyroscopic flutter, is an aeroelastic divergence phenomenon commonly encountered in propeller-powered aircraft such as tiltrotor aircraft and fixed-wing propeller aircraft. It involves the interaction of aerodynamic forces, elastic restoring forces, and inertial forces on the flexibly mounted engine nacelle and rotor system. Under specific rotational and flight speed conditions, this results in coupled pitch and yaw precession of the engine nacelle, accompanied by bending and torsion of the wing and rotor, leading to aeroelastic divergence. This phenomenon can cause structural instability and damage to the aircraft, seriously threatening flight safety. Currently, the phenomenon of whirl flutter is difficult to predict accurately through theoretical modeling and simulation analysis; wind tunnel testing is an important technical means for studying whirl flutter. However, there is a lack of whirl flutter wind tunnel test model devices designed domestically.

[0003] Patent CN202411438538 discloses a nacelle wind tunnel test model and simulation verification method for gyroscopic flutter analysis; however, it does not address the adjustment of parameters such as nacelle support stiffness, weight parameters, and rotational speed. Patent CN202410487340 discloses a method and device for measuring the gyroscopic flutter boundary of a tiltrotor aircraft, but it does not involve the wind tunnel test model for the tested gyroscopic flutter. Patent CN202411434304 discloses a method for calculating the gyroscopic flutter damping of a tiltrotor aircraft based on CAMRAD software, but it does not involve a wind tunnel test model or method for gyroscopic flutter. Patent CN202410092465 discloses a ground-based integrated test device and method for a rotor nacelle, but it does not involve wind tunnel testing. Patent CN202311507788 discloses a wind tunnel test method and test system for a scaled-down model of a tiltrotor aircraft gyroscopic flutter, but it does not involve structural details or the design of adjustment devices for parameters such as stiffness and mass. Patent CN202311507788 discloses a rotor blade configuration design to suppress gyroscopic flutter in tiltrotor aircraft. It only concerns the blades and does not involve the design of key components such as the nacelle and wing that are prone to gyroscopic flutter.

[0004] There is a lack of wind tunnel simulation equipment for helical flutter, a lack of simulation equipment for the precession motion when helical flutter occurs, a lack of decoupling devices for nacelle pitch and yaw motion and devices for independent adjustment of pitch and yaw stiffness, and a lack of wind tunnel test model equipment for helical flutter with adjustable nacelle weight and center of gravity parameters. Summary of the Invention

[0005] The unique characteristic of helical flutter lies in the fact that the precession of the rotating body is caused by the gyroscopic effect. Under the gyroscopic torque generated by the gyroscopic effect, the out-of-plane motion of the rotating body will induce a torque perpendicular to the direction of motion, thereby coupling the pitch and yaw modes to form a gyroscopic mode, also known as precession. Therefore, the wind tunnel test setup for helical flutter needs to achieve adjustable stiffness in both pitch and yaw degrees of freedom, while also enabling the coupling of pitch and yaw to form a gyroscopic mode.

[0006] Taking Figure 7 as an example, the rotor system includes a rotating shaft and rotating blades. When not rotating, its motion can be represented by two degrees of freedom: pitch θ about the y-axis and yaw ψ about the z-axis. The support stiffness coefficients for these two degrees of freedom are K. θ K ψ The stiffness coefficient is derived from the wing, engine nacelle pylons, etc. When the propeller is stationary and the airflow velocity is zero, the nacelle-propeller system exhibits two independent vibration modes, with the modal frequency about the y-axis being ω. θ The modal frequency about the z-axis is ω ψ .

[0007] When considering a propeller rotational speed of Ω, the gyroscopic effect causes the two independent modes to couple into a whirlmotion, as shown in Figure 8. This is due to the angular velocity ω about the z-axis. ψ This causes a rotational torque relative to the y-axis, and vice versa, ultimately resulting in the propeller shaft's motion becoming an elliptical gyroscope motion.

[0008] Consider a propeller rotational speed of Ω and an incoming flow velocity of V. ∞ The described gyro mode shapes cause variations in the propeller blade angle of attack, generating unsteady aerodynamics that can lead to flutter instability under certain conditions. From the perspective of flight stability, the critical flutter velocity is denoted by V. FL As shown in Figure 9. When the incoming flow velocity V ∞ <V FL The motion is stable, and the rotation of the axis converges towards the center, as shown in Figure 9(a); when V ∞ >V FL At this time, the motion is divergent, and the amplitude of the rotation axis becomes larger and larger, as shown in Figure 9(b), which will eventually lead to structural instability and failure.

[0009] This invention provides a precession simulation device for helical flutter wind tunnel testing, solving the design problem of helical flutter wind tunnel tests for rotorcraft rotating bodies. By simulating the precession motion mode caused by the gyroscopic effect, it obtains key influencing parameters of the aircraft's helical flutter characteristics and studies the impact of these key parameters on the aircraft's helical flutter boundary velocity V. FLThe technical solution provided by this invention patent can simulate the free rotation of an aircraft's rotating system (including engine rotor, shaft, rotor, etc.) in a wind tunnel, and adjust the rotational speed of the rotating body through a motor. Simultaneously, the pitch and yaw degrees of freedom of the rotating system's shaft are released, allowing it to rotate around the pitch and yaw axes, with the axes of the pitch and yaw axes coinciding. Thus, under the action of gyroscopic torque, the rotating body can achieve coupled pitch and yaw precession motion. Furthermore, the pitch and yaw degrees of freedom of the shaft are each supported by unidirectional spring plates and decoupling pins, enabling adjustable modal frequencies for each degree of freedom. This allows for the rational design of the rotating body's support stiffness and the study of the influence of support stiffness on the spiral flutter boundary. A counterweight is designed to adjust the nacelle weight and center of gravity position to study the influence of weight and center of gravity position factors on the spiral flutter boundary velocity.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A spiral flutter wind tunnel test simulation device includes: a speed-regulating motor, a coupling, a rotating shaft, a bearing housing, a propeller hub, a pitch shaft, a yaw shaft, a pitch spring, a yaw spring, a pitch decoupling pin, a yaw decoupling pin, a propeller hub limiter, a counterweight, and a blade clamp.

[0012] Figure 1 In this configuration, the speed-regulating motor is fixed on the tray, and its output shaft is connected to a coupling. The coupling connects the motor's output shaft and the rotating shaft. The rotating shaft is fixed to the tray via two bearing seats, transmitting the force and torque of the rotating body to the tray. The rotating body includes a rotating shaft, a hub, blade clamps, and a rotor.

[0013] The end of the shaft is connected to the hub, the hub is connected to three blade clamps, and the three blade clamps are connected to three blades respectively. The angle between each pair of blade clamps is 120°. The hub is fixed to the shaft by a hub limiter.

[0014] The rotor hub is detachable, and after disassembly, the angle of the blade clamp can be adjusted, thereby adjusting the rotor blade pitch.

[0015] Figure 2 In this configuration, the tray is responsible for securing the motor and rotating system, and bears the forces and torques from the motor and rotating body via bearing seats. The tray is connected to the yaw bracket via pitch axes on its left and right sides. When the yaw bracket is fixed, the tray, along with the motor and rotating body fixed on it, can rotate freely around the pitch axis.

[0016] Figure 3In this design, the left and right sides of the yaw support are pitch axes, while the upper and lower ends are designed with yaw axes. The yaw axes are connected to the nacelle cage via bearings. When the nacelle cage is fixed, the yaw support, along with the tray, can rotate freely around the yaw axes. The axes of the yaw and pitch axes coincide at a point P. This design ensures that the rotational motion of the rotating body around the pitch and yaw axes is coupled into a vortex motion around P.

[0017] Figure 3 The midpoint A of the upper beam of the yaw support and Figure 4 Point C of the pitch spring is connected, and the pitch spring is fixed perpendicularly to the pitch decoupling pin. The other end of the pitch decoupling pin is fixed to the tail end shaft of the tray. When the tray rotates around the pitch axis, it is restricted by the pitch decoupling pin and the pitch spring. Since the pitch decoupling pin has a small diameter, it can only transmit axial tension and compression, not bending moment. Therefore, the support stiffness of the pitch degree of freedom is only affected by the thickness of the pitch spring. By adjusting the thickness of the pitch spring, the pitch frequency can be independently adjusted without significantly affecting the yaw frequency.

[0018] Figure 3 In this configuration, the yaw support is a frame structure with fixed planes on both sides and upper and lower beams at the top and bottom, respectively. A yaw axis is vertically mounted at the center of each beam, with the axes coinciding. The other end of the yaw axis is connected to the nacelle cage via bearings, and the nacelle cage is bolted to the wing. When the nacelle cage is fixed, the yaw support can rotate around the yaw axis. Similar to the pitch degree of freedom, the yaw spring and yaw decoupling pin are vertically fixed and form the support structure for the yaw degree of freedom. By adjusting the thickness of the yaw spring, the yaw frequency of the rotating body can be changed.

[0019] The axes of the yaw and pitch axes coincide at a point P, ensuring that the rotating body can generate a precession motion around point P under the action of the gyroscopic effect when rotating.

[0020] Figure 1 In the middle, a counterweight is designed on the tail shaft of the tray. The size and position of the counterweight are adjustable, which can realize the adjustment of the nacelle weight and center of gravity, so as to study the influence of the nacelle weight factor on the boundary velocity of the propeller flutter.

[0021] Figure 5 shows the overall installation diagram of the rotary simulation device. Figure 6 As shown in Figure 5, the nacelle cage suspends the nacelle simulation device via a yaw axis and is fixed to the wing with bolts. Figure 6The tiltrotor aircraft spiral flutter wind tunnel test model device is shown, including a rigid wing, a flexible wing, a nacelle cage and a precession simulation device. The nacelle cage is bolted to the flexible wing, which is fixed to the wind tunnel wall. The rigid fuselage is also fixed to the wind tunnel wall, and the fuselage is only responsible for maintaining its aerodynamic shape.

[0022] A further improvement of this invention lies in the decoupled design of the pitch and yaw modes of the nacelle and rotor. The pitch freedom of the nacelle is achieved through rotation about the pitch axis, and the yaw freedom of the nacelle is achieved through rotation about the yaw axis. The modal frequencies of the pitch and yaw degrees of freedom are independently adjustable by adjusting the thickness of the pitch and yaw springs, allowing for changes in the pitch and yaw frequency parameters of the nacelle during wind tunnel testing. The axes of the pitch and yaw are aligned at a single point, ensuring that the pitch and yaw motions can be coupled into precession motion under the action of gyroscopic torque.

[0023] A further improvement of the present invention is that the rotor speed can be adjusted by a speed-regulating motor and a coupling system, and the rotor speed is independent of the wind tunnel inflow velocity, thus enabling the change of speed parameters during wind tunnel testing.

[0024] A further improvement of the present invention is that the weight and center of gravity of the nacelle can be adjusted by the counterweight, thereby enabling changes in the mass and center of gravity parameters of the rotating mass during wind tunnel testing.

[0025] A method for using a precession simulation device for helical flutter wind tunnel testing, comprising the following steps:

[0026] Step 1: The speed-regulating motor is fixed on the tray, and its output shaft is connected to the coupling. The coupling connects the motor's output shaft and the rotating shaft. The rotating shaft is fixed on the tray through two bearing seats, transmitting the force and torque of the rotating body to the tray. The end of the rotating shaft is connected to the rotor hub, which is connected to three blade clamps. Each of the three blade clamps is connected to one of the three rotor blades. The rotor hub is responsible for adjusting the rotor pitch.

[0027] Step 2: The tray is responsible for securing the motor and rotating system, and bears the forces and torques from the motor and rotating body through the bearing housings. The tray is connected to the yaw bracket via its left and right pitch axes. When the yaw bracket is fixed, the tray, along with the motor and rotating system fixed on it, can rotate freely around the pitch axis.

[0028] Step 3: The left and right pitch axes of the yaw support have yaw axes at their upper and lower ends. The yaw axes are connected to the nacelle cage via bearings. When the nacelle cage is fixed, the yaw support, along with the tray, can rotate freely around the yaw axes. Note: The axes of the yaw and pitch axes coincide at a point P. This design ensures that the rotational motion of the rotating body around the pitch and yaw axes can be coupled into a vortex motion around P.

[0029] Step 4: Connect the midpoint A of the upper beam of the yaw support to point Z of the pitch spring plate. The pitch spring plate is connected to the pitch decoupling pin, which is connected to the tail shaft of the tray. When the tray rotates around the pitch axis, it is restricted by the pitch decoupling pin and the pitch spring plate. Since the pitch decoupling pin has a small diameter, it can only transmit axial tension and compression, not bending moment. Therefore, the support stiffness of the pitch degree of freedom is only affected by the thickness of the pitch spring plate. By adjusting the thickness of the pitch spring plate, the pitch frequency can be independently adjusted without significantly affecting the yaw frequency.

[0030] Step 5: The upper and lower beam ends of the yaw support are also designed with yaw axes. The yaw axes are connected to the nacelle cage via bearings, and the nacelle cage is connected to the wing via bolts. The yaw support can rotate around the yaw axis relative to the nacelle cage. Similar to the pitch degree of freedom, the yaw spring and yaw decoupling pin support the yaw degree of freedom, and adjusting the thickness of the yaw spring does not significantly affect the pitch frequency.

[0031] Step 6: The axes of the yaw axis and the pitch axis coincide at a point P, ensuring that the rotating body can generate a precession motion around point A under the action of the gyroscopic effect when rotating.

[0032] Step 7: A counterweight is designed on the tail shaft of the tray. The size and position of the counterweight are adjustable, which can adjust the weight and center of gravity of the nacelle to study the influence of the nacelle weight factor on the boundary velocity of the propeller flutter.

[0033] Step 8: Overall installation diagram of the rotation simulation device as shown in the figure. Figure 2 and Figure 3 As shown, the yaw simulation device is mounted on the nacelle cage via a yaw axis. The nacelle cage is bolted to the wing, which is fixed to the wind tunnel wall. The rigid fuselage is only responsible for maintaining the shape.

[0034] Compared with existing technologies, the present invention has the following advantages:

[0035] This invention solves the problem of experimental prediction of the spiral flutter boundary of tiltrotor aircraft, and obtains the key influencing parameters and their influence laws for the spiral flutter characteristics of tiltrotor aircraft. This invention enables decoupling of the nacelle pitch and yaw modes, with independent adjustable frequencies for both modes. Simultaneously, it allows adjustment of the nacelle's rotating mass moment of inertia, weight, and center of mass position. Finally, through a speed-regulating motor, the rotational speed of the rotor, hub, and other rotating masses can be adjusted to ensure matching between the rotational speed and the incoming flow velocity, achieving a spiral flutter state. This effectively supports the development of tiltrotor aircraft models. Attached Figure Description

[0036] Figure 1 Diagram of a nacelle spin-up motion simulation device;

[0037] Figure 2 A diagram of the nacelle tray and rotating body;

[0038] Figure 3 Yaw support diagram;

[0039] Figure 4 Detailed schematic diagram of pitch and yaw springs and decoupling pins;

[0040] Figure 5(a) Three-dimensional view of the nacelle structure;

[0041] Figure 5(b) Front view of the nacelle structure;

[0042] Figure 6 Schematic diagram of a wind tunnel test model for tiltrotor aircraft spiral flutter.

[0043] Figure 7(a) Schematic diagram of pitch motion;

[0044] Figure 7(b) Schematic diagram of yaw motion;

[0045] Figure 8(a) Schematic diagram of backward vortex motion during precession;

[0046] Figure 8(b) Schematic diagram of forward vortex motion during precession;

[0047] Figure 9(a)V <V FL Schematic diagram of convergence and divergence of helical flutter;

[0048] Figure 9(b) V>V FL Schematic diagram of convergence and divergence of helical flutter.

[0049] In the diagram: 1. Fuselage; 2. Flexible wing; 2(a) Flexible wing spars; 2(b) Flexible wing ribs; 3. Nacelle cage; 4. Nacelle; 5. Rotor; 7. Speed-regulating motor; 8. Coupling; 9. Shaft; 10. Bearing housing; 11. Rotor hub; 12. Pitch shaft; 13. Yaw shaft; 14. Pitch spring; 15. Yaw spring; 16. Pitch decoupling pin; 17. Yaw decoupling pin; 18. Rotor hub limiter; 19. Counterweight; 21. Blade clamp; 22. Tray; 23. Yaw support. Detailed Implementation

[0050] Example 1:

[0051] This invention provides a precession simulation device for helical flutter wind tunnel testing, such as... Figure 1 As shown, it includes: a speed regulating motor 7, a coupling 8, a rotating shaft 9, a bearing housing 10, a propeller hub 11, a pitch shaft 12, a yaw shaft 13, a pitch spring plate 14, a yaw spring plate 15, a pitch decoupling pin 16, a yaw decoupling pin 17, a propeller hub limiter 18, a counterweight block 19, and a blade clamp 21.

[0052] Figure 1In this configuration, the speed-regulating motor 7 is fixed on the tray 22, and its output shaft is connected to the coupling 8. The coupling 8 connects the output shaft of the motor 7 and the rotating shaft 9. The rotating shaft 9 is fixed on the tray 22 through two bearing seats 10, transmitting the force and torque of the rotating body to the tray 22. The rotating body includes the rotating shaft 9, the hub 11, the blade clamp 21, and the rotor 5.

[0053] The end of the rotating shaft 9 is connected to the hub 11, the hub 11 is connected to three blade clamps 21, the three blade clamps 21 are connected to three blades respectively, the angle between each pair of blade clamps 21 is 120°, and the hub 11 is fixed on the rotating shaft 9 by the hub limiter 18.

[0054] The rotor hub 11 is detachable, and after disassembly, the angle of the blade clamp can be adjusted, thereby adjusting the pitch of the rotor blades.

[0055] Figure 2 In this configuration, the tray 22 is responsible for fixing the motor 7 and the rotation system, and bears the forces and torques from the motor and the rotating body through the bearing housing 10. The tray 22 is connected to the yaw support 23 through the pitch axes 12 on its left and right sides. When the yaw support 23 is fixed, the tray 22, together with the motor 7 and the rotating body fixed on it, can rotate freely around the pitch axis 12.

[0056] Figure 3 In the design, the yaw support 23 has pitch axes 12 on its left and right sides, and yaw axes 13 at its upper and lower ends. The yaw axes 13 are connected to the nacelle cage 3 via bearings. When the nacelle cage 3 is fixed, the yaw support 23, together with the tray 22, can rotate freely around the yaw axes 13. The axes of the yaw axes 13 and the pitch axes 12 coincide at a point P. This design ensures that the rotational motion of the rotating body around the pitch axes 12 and the yaw axes 13 is coupled into a vortex motion around P.

[0057] Figure 3 The midpoint A of the upper beam of the yaw support 23 and Figure 4 Point C of the pitch spring plate 14 is connected, and the pitch spring plate 14 is fixed perpendicularly to the pitch decoupling pin 16. The other end of the pitch decoupling pin 16 is fixed to the tail end shaft of the tray 22. When the tray 22 rotates around the pitch axis 12, it is restricted by the pitch decoupling pin 16 and the pitch spring plate 14. Since the pitch decoupling pin 16 has a small diameter, it can only transmit axial tension and compression, but not bending moment. Therefore, the support stiffness of the pitch degree of freedom is only affected by the thickness of the pitch spring plate. By adjusting the thickness of the pitch spring plate 14, the pitch frequency can be independently adjusted without significantly affecting the yaw frequency.

[0058] Figure 3In the configuration, the yaw support 23 is a frame structure with fixed planes on both sides and an upper and lower beam at the top and bottom, respectively. A yaw axis 13 is vertically mounted at the center of each of the upper and lower beams, with the axes of the yaw axes 13 coinciding. The other end of the yaw axis 13 is connected to the nacelle cage 3 via a bearing, and the nacelle cage 3 is bolted to the wing 2. When the nacelle cage 3 is fixed, the yaw support 23 can rotate around the yaw axis 13. Similar to the pitch degree of freedom, the yaw spring plate 15 and the yaw decoupling pin 17 are vertically fixed and form the support structure for the yaw degree of freedom. By adjusting the thickness of the yaw spring plate 15, the yaw frequency of the rotating body can be changed.

[0059] The axes of yaw axis 12 and pitch axis 13 coincide at a point P, ensuring that the rotating body can generate a precession motion around point P under the action of the gyroscopic effect when rotating.

[0060] Figure 1 In the middle, a counterweight 19 is designed on the tail shaft of the tray. The size and position of the counterweight are adjustable, which can realize the adjustment of the nacelle weight and center of gravity, so as to study the influence of the nacelle weight factor on the boundary velocity of the propeller flutter.

[0061] Figure 5 shows the overall installation diagram of the rotary simulation device. Figure 6 As shown in Figure 5, the spin-up simulation device is installed on the nacelle cage 3. The nacelle cage 3 suspends the spin-up simulation device via the yaw axis 13 and is fixed to the wing 2 with bolts. Figure 6 The tiltrotor aircraft spiral flutter wind tunnel test model device is shown, including a rigid wing 1, an elastic wing 2, a nacelle cage 3, and a spiral simulation device. The nacelle cage 3 is bolted to the elastic wing 2, the elastic wing 2 is fixed to the wind tunnel wall, and the rigid fuselage 1 is also fixed to the wind tunnel wall. The fuselage is only responsible for maintaining its aerodynamic shape.

[0062] The pitch and yaw modes of the nacelle 4 and rotor 5 are designed to be decoupled. The pitch freedom of the nacelle 4 is achieved by rotation about the pitch axis 12, and the yaw freedom of the nacelle is achieved by rotation about the yaw axis 13. The modal frequencies of the pitch and yaw freedom are independently adjustable by adjusting the thickness of the pitch spring plate 14 and the yaw spring plate 15, allowing for changes in the pitch and yaw frequency parameters of the nacelle during wind tunnel testing. The axes of the pitch axis 12 and the yaw axis 13 are aligned at a single point, ensuring that the pitch and yaw motions can be coupled into precession motion under the action of gyroscopic torque.

[0063] The rotational speed of rotor 5 can be adjusted by a speed-regulating motor and coupling system. The rotational speed of rotor 5 is independent of the wind tunnel inflow velocity, and the rotational speed parameter can be changed during wind tunnel testing.

[0064] The weight and center of gravity of the nacelle can be adjusted by using counterweights, which can change the mass and center of gravity parameters of the rotating mass during wind tunnel testing.

[0065] Example 2:

[0066] A method for using a precession simulation device for helical flutter wind tunnel testing, comprising the following steps:

[0067] Step 1: The speed-regulating motor 7 is fixed on the tray 22, and its output shaft is connected to the coupling 8. The coupling 8 connects the output shaft of the motor 7 to the rotating shaft 9. The rotating shaft 9 is fixed on the tray 22 through two bearing seats 10, transmitting the force and torque of the rotating body to the tray 22. The end of the rotating shaft is connected to the rotor hub 11, which is connected to three blade clamps 21. The three blade clamps 21 are connected to three blades respectively. The rotor hub 11 is responsible for adjusting the rotor pitch.

[0068] Step 2: The tray 22 is responsible for fixing the motor 7 and the rotating system, and bears the forces and torques from the motor and the rotating body through the bearing housing 10. The tray 22 is connected to the yaw support 23 through the pitch axes 12 on its left and right sides. When the yaw support 23 is fixed, the tray 22, together with the motor 7 and the rotating system fixed on it, can rotate freely around the pitch axis 12.

[0069] Step 3: The left and right pitch axes 12 of the yaw support 23 are designed with yaw axes 13 at their upper and lower ends. The yaw axes 13 are connected to the nacelle cage 3 through bearings. When the nacelle cage 3 is fixed, the yaw support 23, together with the tray 22, can rotate freely around the yaw axis 13. Note: The axes of the yaw axis 13 and the pitch axis 12 coincide at a point P. This design ensures that the rotational motion of the rotating body around the pitch axis 12 and the yaw axis 13 can be coupled into a vortex about P.

[0070] Step 4: The midpoint A of the upper beam of the yaw support 23 is connected to point Z of the pitch spring plate 14. The pitch spring plate 14 is connected to the pitch decoupling pin 16, which is connected to the tail shaft of the tray 22. When the tray 22 rotates around the pitch axis 12, it is restricted by the pitch decoupling pin 16 and the pitch spring plate 12. Since the pitch decoupling pin 16 has a small diameter, it can only transmit axial tension and compression, not bending moment. Therefore, the support stiffness of the pitch degree of freedom is only affected by the thickness of the pitch spring plate. By adjusting the thickness of the pitch spring plate 14, the pitch frequency can be independently adjusted without significantly affecting the yaw frequency.

[0071] Step 5: The upper and lower beam ends of the yaw support 23 are also designed with yaw shafts 13. The yaw shafts 13 are connected to the nacelle cage 3 via bearings, and the nacelle cage 3 is connected to the wing 2 via bolts. The yaw support 23 can rotate around the yaw shaft 13 relative to the nacelle cage 3. Similar to the pitch degree of freedom, the yaw spring plate 15 and the yaw decoupling pin 17 support the yaw degree of freedom, and adjusting the thickness of the yaw spring plate 15 will not significantly affect the pitch frequency.

[0072] Step 6: The axes of yaw axis 12 and pitch axis 13 coincide at a point P, ensuring that the rotating body can generate a precession motion around point A under the action of the gyro effect when rotating.

[0073] Step 7: A counterweight 19 is designed on the tail shaft of the tray. The size and position of the counterweight are adjustable, which can adjust the weight and center of gravity of the nacelle to study the influence of the nacelle weight factor on the boundary velocity of the propeller flutter.

[0074] Step 8: Overall installation diagram of the rotation simulation device as shown in the figure. Figure 2 and Figure 3 As shown, the yaw simulation device is mounted on the nacelle cage 3 via the yaw axis 13. The nacelle cage 3 is bolted to the wing 1. The wing is fixed to the wind tunnel wall, and the rigid fuselage is only responsible for maintaining the shape.

Claims

1. A precession simulation device for use in a screw oscillation wind tunnel test, characterized by, The short nose (4), the speed regulating motor (7), the shaft coupling (8), the rotating shaft (9), the bearing seat (10), the hub (11), the pitch shaft (12), the yaw shaft (13), the pitch spring piece (14), the yaw spring piece (15), the pitch decoupling needle (16), the yaw decoupling needle (17), the hub limiter (18), the counterweight (19) and the blade clamp (21); The speed regulating motor (7) is fixed on the tray (22), the output shaft is connected with the shaft coupling (8), the shaft coupling (8) is responsible for connecting the output shaft of the motor (7) and the rotating shaft (9), the rotating shaft (9) is fixed on the tray (22) through two bearing seats (10), and the force and torque of the rotating body are transmitted to the tray (22); The rotating body includes the rotating shaft (9), the hub (11), the blade clamp (21) and the rotor (5); the end of the rotating shaft (9) is connected with the hub (11), and the hub (11) is connected with three blade clamps (21); The tray (22) is connected with the yaw support (23) through the pitch shaft (12) on the left and right sides; when the yaw support (23) is fixed, the tray (22) can rotate freely around the pitch shaft (12) together with the motor (7) and the rotating body fixed thereon. The left and right sides of the yaw support (23) are the pitch shaft (12), and the upper and lower ends are designed with the yaw shaft (13), the yaw shaft (13) is connected with the short nose cage (3) through a bearing, when the short nose cage (3) is fixed, the yaw support (23) can rotate freely around the yaw shaft (13) together with the tray (22); the axes of the yaw shaft (13) and the pitch shaft (12) coincide at a point P, and the design can ensure that the rotating motion of the rotating body around the pitch shaft (12) and the yaw shaft (13) is coupled into the whirling motion around P; The yaw support (23) is a frame structure, the two sides are fixed planes, and the upper and lower parts are the upper beam and the lower beam of the yaw support (23); the central positions of the upper beam and the lower beam of the yaw support (23) are vertically provided with the yaw shaft (13), and the axes of the yaw shaft (13) of the upper beam and the lower beam coincide; the other end of the yaw shaft (13) is connected with the short nose cage (3) through a bearing, and the short nose cage (3) is connected with the wing (2) through a bolt; when the short nose cage (3) is fixed, the yaw support (23) can rotate around the yaw shaft (13); the midpoint A of the upper beam of the yaw support (23) is connected with the C point of the pitch spring piece (14), the pitch spring piece (14) is fixed vertically with the pitch decoupling needle (16), the other end of the pitch decoupling needle (16) is fixed with the tail end shaft of the tray (22); similar to the pitch freedom degree, the yaw spring piece (15) and the yaw decoupling needle (17) are fixed vertically and constitute the support structure of the yaw freedom degree, and the yaw frequency of the rotating body can be changed by adjusting the thickness of the yaw spring piece (15); The axes of the yaw shaft (13) and the pitch shaft (12) coincide at a point P, so that the rotating body can produce the precession motion around the point P under the action of the gyro effect when rotating.

2. A precession simulation device for use in a screw oscillation wind tunnel test as defined in claim 1, characterized in that The three blade clamps (21) are connected with three blades respectively, the angle between every two blade clamps (21) is 120°, the hub (11) is fixed on the rotating shaft (9) through the hub limiter (18).

3. A precession simulation device for use in a screw oscillation wind tunnel test as defined in claim 1, characterized in that The hub (11) is detachable, after being disassembled, the angle of the blade clamp can be adjusted, and then the pitch of the rotor blade is adjusted.

4. A precession simulation apparatus for use in a screw oscillation wind tunnel test as defined in claim 1, wherein The tail shaft of the tray (22) is designed with a counterweight (19), the size and the front and back position of the counterweight can be adjusted, and the weight and the gravity center of the nacelle can be adjusted.

5. A precession simulation apparatus for use in a screw oscillation wind tunnel test as defined in claim 1, wherein The nacelle cage (3) is hung by the yaw shaft (13) and is fixed with the wing (2) through bolts.

6. A precession simulation apparatus for use in a screw oscillation wind tunnel test as defined in claim 1, wherein The pitch and yaw modes of the nacelle (4) and the rotor (5) are designed to be decoupled, the pitch freedom of the nacelle (4) is realized by rotating around the pitch shaft (12), the yaw freedom of the nacelle is realized by rotating around the yaw shaft (13), the modal frequency of the pitch and yaw freedom is independently adjustable by adjusting the thickness of the pitch spring sheet (14) and the yaw spring sheet (15), the axis of the pitch shaft (12) and the yaw shaft (13) is compared with a point, which ensures that the pitch and yaw movements can be coupled into the precession movement under the action of the gyroscopic moment.

7. A precession simulation apparatus for use in a screw oscillation wind tunnel test as defined in claim 1, wherein The rotating speed of the rotor (5) is adjusted through the speed regulation motor and the coupling system, the rotating speed of the rotor (5) is not dependent on the wind tunnel flow speed, and the rotating speed parameter change in the wind tunnel test can be realized.

8. A precession simulation apparatus for use in a screw oscillation wind tunnel test as defined in claim 1, wherein The weight and the gravity center position of the nacelle (4) can be adjusted through the counterweight, and the mass and the mass center position of the rotating mass in the wind tunnel test can be changed.

9. A method of using a precession simulation device for a screw-augmenting wind tunnel test according to any one of claims 1 to 8, characterized in that, The steps are as follows: First step: the speed regulation motor (7) is fixed on the tray (22), the output shaft is connected with the coupling (8), the coupling (8) is responsible for connecting the output shaft of the motor (7) and the rotating shaft (9), the rotating shaft (9) is fixed on the tray (22) through two bearing seats (10), the force and the torque of the rotating body are transmitted to the tray (22), the end of the rotating shaft is connected with the hub (11), the hub (11) is connected with three blade clamps (21), the three blade clamps (21) are connected with three blades respectively, the hub (11) is responsible for adjusting the pitch of the rotor; Second step: the tray (22) is responsible for fixing the motor (7) and the rotating system, and bears the force and the torque from the motor and the rotating body through the bearing seat (10); the tray (22) is connected with the yaw support (23) through the pitch shaft (12) on the left and right sides; when the yaw support (23) is fixed, the tray (22) together with the fixed motor (7) and the rotating system can freely rotate around the pitch shaft (12); Third step: the pitch shaft (12) on the left and right sides of the yaw support (23) is designed with the yaw shaft (13) on the upper and lower ends, the yaw shaft (13) is connected with the nacelle cage (3) through the bearing, when the nacelle cage (3) is fixed, the yaw support (23) together with the tray (22) can freely rotate around the yaw shaft (13); Fourth step: the pitch spring sheet (14) is connected with the pitch decoupling needle (16), the pitch decoupling needle (16) is connected with the tail shaft of the tray (22). The fifth step: the upper and lower beam ends of the yaw support (23) are designed with a yaw shaft (13), the yaw shaft (13) is connected with the nacelle cage (3) through a bearing, and the nacelle cage (3) is connected with the wing (2) through a bolt; The sixth step: the axes of the yaw shaft (13) and the pitch shaft (12) coincide at a point P, which ensures that the rotating body can produce a precession motion around the point P under the action of the gyro effect when the rotating body rotates; The seventh step: a counterweight (19) is designed on the tail shaft of the tray, and the weight and the front and rear positions of the counterweight are adjustable; The eighth step: the precession simulation device is installed on the nacelle cage (3) through the yaw shaft (13), the nacelle cage (3) is installed on the wing (2) through a bolt, the wing is fixed on the wall of the wind tunnel, and the rigid fuselage is only responsible for maintaining the shape.

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