A method of suppressing flutter of a control surface by limiting rotational movement

Abstract

The application discloses a method for inhibiting aircraft control surface flutter, and belongs to the technical field of wing dynamics coupling test, which comprises the following steps: in a wind tunnel test, the wing control surface vibration condition is observed, and vibration response data analysis results are used as auxiliary determination standards; when it is confirmed that the wing control surface vibration amplitude is increased, the control surface inhibition device is started, and the wind tunnel is directly stopped to avoid flutter; in a flutter flight test, data collected by a sensor are analyzed to determine the vibration condition of the aircraft; after vibration response data signals collected are processed, parameters of aircraft control surface rotation mode are obtained, damping and amplitude changes of the control surface rotation mode are observed, when the damping tends to zero and the amplitude is divergently increased, it is considered that the control surface flutter is about to occur, the inhibitor device is started to inhibit the control surface rotation movement, and the flight speed of the aircraft is reduced, so that the control surface flutter is avoided, the state of the control surface support system is determined, and a continue-to-fly strategy is determined.

Description

Technical Field

[0001] This invention belongs to the field of wing dynamics coupling test technology, specifically relating to a method for suppressing flutter on the control surfaces of an aircraft wing model. Background Technology

[0002] During flutter flight tests, when the flight speed exceeds a critical point, the energy gained from the airflow by the aircraft's structural system within one vibration cycle exceeds the energy dissipated by internal damping. This causes a divergent increase in the vibration amplitude of local structures, potentially damaging the aircraft structure—a phenomenon known as flutter. Control surface flutter is caused by the coupling of the control surface's rotational mode with other structural modes. Therefore, suppressing the control surface's rotational motion can suppress control surface rotational flutter. While flutter protection can be achieved in wind tunnel tests using safety ropes, this invention can suppress control surface rotational motion to avoid control surface flutter when it's inconvenient to install such ropes at the test site. The device and method provided by this invention can limit the rotational motion of control surfaces when control surface flutter is imminent, thus avoiding flutter and better protecting the aircraft structure. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention discloses a method for suppressing control surface flutter by limiting rotational motion. This method can suppress the rotational motion of the control surface to avoid control surface flutter. It can limit the rotational motion of the control surface when the aircraft is about to experience control surface flutter, thereby avoiding flutter and better protecting the aircraft structure.

[0004] This invention is implemented as follows:

[0005] A method for suppressing control surface flutter by limiting rotational motion, characterized in that the method comprises:

[0006] 1) Determine if flutter is occurring on the control surface;

[0007] 2) During wind tunnel testing, visually observe the vibration of the wing control surfaces. The primary criterion is the visually observed wing vibration, supplemented by vibration response data analysis. When the amplitude of the wing control surface vibration increases and is confirmed as control surface flutter, activate the control surface suppression device and simultaneously reduce or stop the wind tunnel's airflow. (There is no clear standard for visually confirmed flutter; if data analysis is used, the damping of the control surface rotation mode is used as the standard. When the damping decreases and approaches zero, it is determined that flutter is likely to occur in this mode.)

[0008] 3) During flutter flight tests, the condition of the aircraft cannot be visually confirmed. Data collected by sensors installed on the aircraft is analyzed to determine the vibration status of the aircraft. The analysis method is as follows: data analysis is performed using spectrum analysis, random subspace identification, and matrix beam parameter identification.

[0009] 4) After analyzing and processing the collected vibration response data signals, the parameters of multiple structural modes of the aircraft are obtained, and the structural modal parameters of the corresponding control surfaces are found based on the ground test results.

[0010] 5) Observe the changes in damping and amplitude of the control surface rotation mode. When the damping gradually approaches zero and the amplitude increases divergently, that is, when the vibration amplitude tends to increase, it is considered that control surface flutter is about to occur. At this time, activate the suppressor device to suppress the rotational motion of the control surface, and at the same time reduce the flight speed of the aircraft to avoid control surface flutter. (Here, "reducing" only needs to be slightly lower than the speed at which flutter occurs. To ensure safety, it is stipulated to be lower than the flutter speed by 10%).

[0011] Furthermore, when control surface flutter occurs, after the suppressor device suppresses the flutter, it determines the current control surface status; if there is no fault in the aircraft system, it reduces the aircraft airspeed to below the flutter speed, manipulates the suppressor device to restore the control surface, cancels the control surface rotation restriction, and at this time the control surface continues to work normally, and the aircraft can continue to fly.

[0012] When a malfunction in the control surface system causes a decrease in control surface stiffness, a suppressor device is used to maintain normal control stiffness. In this situation, the control surface cannot deflect, and the aircraft's handling performance is weakened. With the suppressor device activated, the aircraft gradually reduces its speed to complete a landing. (Normal control stiffness refers to the force applied to the control surface by the control surface system when it is functioning correctly, ensuring that the control surface itself does not rotate arbitrarily; when the control surface system malfunctions, the suppressor device takes over to maintain control surface stiffness, preventing the control surface from rotating arbitrarily during flight.)

[0013] Furthermore, the suppressor device sequentially includes a support arm, a drive rod, a support frame, a limiting rod, a limiting block, and a rudder surface shaft; the limiting rod is mounted on the rudder surface shaft, as well as the limiting block on the same axis as the limiting rod; the limiting block, the limiting rod, and the drive rod are on the same axis;

[0014] The support frame, support arm, and pivot bracket are all fixed to the rear wall of the wing via the support arm, and the control surface pivot is fixed via the pivot bracket. The support frame is a square frame with a support arm, and the limiting block is located in the square frame. There are ribs on the inner surfaces of the upper and lower sides of the square frame, parallel to the axis of the control surface pivot, and the limiting block can slide in the square frame.

[0015] Furthermore, one end of the limiting rod is a cylinder with an internal hexagonal recess, and the other end is a square cross-section rod; the limiting block has a groove inside, corresponding to the square cross-section rod at the front end of the limiting rod.

[0016] Furthermore, the drive rod is a tubular structure; the outside of the tube has multiple parallel ribs forming a gear-shaped cross-section, and the inside has threads; one end of the drive rod is connected to the limiting block through a pin, so that the two translate at the same amplitude on the axis of rotation; the outer ribs of the drive rod mesh with a gear driven by a motor, and the motor is mounted on the support arm through a support arm, with the motor axis parallel to the axis of the threaded rod; when the motor starts, the drive rod rotates under the drive of the gear, and completes the translational movement on the axis of rotation through the threaded post on the support arm, thereby driving the limiting block to hold or release the limiting rod.

[0017] Furthermore, when the suppressor device is activated, the limiting block contains the limiting rod; when the suppressor device is reset, the limiting block separates from the limiting rod.

[0018] When the motor starts, the limiting block will move along the axis of rotation toward the limiting rod; as the limiting block moves and holds the limiting rod, the rotation angle of the limiting rod (rudder surface) gradually decreases until it stops rotating;

[0019] Aircraft control surface flutter is caused by the coupling of the control surface rotation mode with other modes of the structure. Suppressing the control surface rotation mode can suppress the aircraft's control surface rotation flutter.

[0020] The vibration response signal of the aircraft is analyzed to obtain the parameters of the control surface rotation mode, and the changes in the parameters are observed to determine whether control surface flutter has occurred.

[0021] The advantages of this invention compared to the prior art are as follows:

[0022] Aircraft control surface flutter is caused by the coupling of the control surface's rotational mode with other modes of the structure. Control surface rotational flutter is suppressed by inhibiting the control surface's rotational mode. The vibration response signal of the aircraft is analyzed to obtain the parameters of the control surface rotational mode, and changes in these parameters are observed to determine whether control surface flutter has occurred. This invention can be used to suppress wing control surface flutter during aircraft flutter tests. When the control surface system is operating normally, the flight speed can be reduced, the suppression device restored, and the aircraft can continue flying normally. However, when a control surface malfunction causes a decrease in control surface operating stiffness, this invention can be used to maintain control surface stiffness, helping the aircraft continue flying and land safely.

[0023] This invention provides a method for suppressing the rotational motion of wing control surfaces to avoid flutter, which is used in flutter flight tests and flutter wind tunnel tests to suppress the rotation of aircraft wing control surfaces and thus avoid control surface flutter induced by it. Attached Figure Description

[0024] Figure 1 This invention relates to a method for suppressing control surface flutter by limiting rotational motion, specifically an airfoil with a suppressor.

[0025] Figure 2 This is a planar cross-section of the suppressor AA in a method for suppressing rudder flutter by limiting rotational motion according to the present invention;

[0026] Figure 3 This is a cross-sectional view of the suppressor BB in a method for suppressing rudder flutter by limiting rotational motion according to the present invention.

[0027] Figure 4 This is a flowchart illustrating the flutter suppression process in a method for suppressing flutter by limiting rotational motion, as described in this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following examples provide a more detailed description of the invention. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0029] like Figure 1 The diagram shows a top view of the suppressor device and the wing control surface. The suppressor device includes a support frame, a limiting block, a limiting rod, a drive rod, a control motor, and a support arm. The support frame, support arm, and pivot support are all fixed to the rear wall of the wing via the support arm. The limiting block has a groove inside, corresponding to the square cross-section rod at the front end of the limiting rod. The support frame is a square frame with a support arm. The inner surfaces of the top and bottom sides of the square frame have ribs parallel to the axis of rotation of the control surface, allowing the limiting block to slide within the square frame. The drive rod is a tubular structure. The tube has ribs on the outside, forming a gear-shaped cross-section, and internal threads. One end of the drive rod is connected to the limiting block via a pin, allowing both to translate at the same amplitude along the axis of rotation. The outer ribs of the drive rod mesh with a gear driven by a motor, which is mounted on the support arm, with its axis parallel to the axis of the threaded rod. The limiting block, limiting rod, and drive rod are all on the same axis. When the motor starts, the drive rod rotates under the drive of the gear, and completes the translational movement on the axis of rotation through the threaded column, thereby driving the limiting block to hold or release the limiting rod.

[0030] like Figure 2 , 3 The image shows cross-sections of the suppressor from different directions. The limiting rod rotates with the shaft at the end of the shaft, while the limiting block remains in the same direction and can move along the shaft. Figure 3As can be seen, the groove in the limiting block has slopes on both sides. The maximum width of the slope is greater than the maximum rotation angle of the limiting rod (set to 30 degrees in this example). The angle of the slope is consistent with the slope of the generatrix of the limiting rod. As the limiting rod is gradually contained by the groove of the limiting block, its rotation direction is constrained and the rotation angle gradually decreases until the two are engaged. The limiting rod and the shaft stop rotating, thus achieving the purpose of suppressing the flutter of the control surface.

[0031] like Figure 4 As shown, whether and when to activate the suppressor device is determined by the on-site testing personnel. Taking wind tunnel testing as an example, the testing personnel can visually observe the vibration of the wing control surfaces. In this case, the visually observed vibration of the wing control surfaces is taken as the standard, while the vibration response data analysis results are used as an auxiliary judgment criterion. When it is confirmed that the amplitude of the wing control surface vibration has increased, the control surface suppression device is activated, and the testing personnel immediately stop the wind tunnel to avoid flutter.

[0032] In flutter flight tests, the aircraft's condition cannot be visually confirmed. Therefore, data collected by sensors installed on the aircraft is analyzed to determine its vibration status. Methods such as spectral analysis, random subspace identification, and matrix-beam parameter identification are used for data analysis. After processing the collected vibration response data signals, parameters for multiple structural modes of the aircraft are obtained. Based on ground test results, the structural modal parameters of the corresponding control surfaces are identified. The damping and amplitude changes of the control surface rotational modes are observed. When the damping gradually approaches zero and the amplitude increases divergently, control surface flutter is considered imminent. At this point, the suppressor device is activated to suppress the control surface rotational motion, and the aircraft's flight speed is reduced to avoid control surface flutter.

[0033] The device provided by this invention, when control surface flutter occurs, suppresses the flutter and then determines the current control surface state. If the aircraft system is not faulty, the aircraft airspeed is reduced to move away from the flutter speed, the control suppressor device is restored, and the control surface rotation restriction is lifted. At this time, the control surface can continue to work normally, and the aircraft can continue to fly. However, when a control surface system malfunction causes a reduction in control surface stiffness, the device maintains normal control stiffness. In this case, the control surface cannot deflect, and the aircraft's handling performance will be affected. The aircraft can gradually reduce its speed to complete a landing while the device is activated.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for suppressing control surface flutter by limiting rotational motion, characterized in that, The method is as follows: 1) Determine if flutter is occurring on the control surfaces; 2) During wind tunnel testing, visually observe the vibration of the wing control surfaces. At this time, the direct visual observation of the wing vibration is the primary standard, supplemented by the vibration response data analysis results. When the amplitude of the wing control surface vibration increases and it is confirmed to be control surface flutter, activate the control surface suppression device and simultaneously reduce the wind tunnel blowing speed or stop the wind tunnel blowing. 3) During flutter flight tests, the condition of the aircraft cannot be visually confirmed. Data collected by sensors installed on the aircraft is analyzed to determine the vibration status of the aircraft. The analysis method is as follows: corresponding data analysis is performed using spectrum analysis, random subspace identification, and matrix beam parameter identification. 4) After analyzing and processing the collected vibration response data signals, the parameters of multiple structural modes of the aircraft are obtained, and the structural modal parameters of the corresponding control surfaces are found based on the ground test results. 5) Observe the changes in damping and amplitude of the control surface rotation mode. When the damping gradually approaches zero and the amplitude increases divergently, that is, when the vibration amplitude becomes larger and larger, it is considered that control surface flutter is about to occur. At this time, the suppressor device is activated to suppress the rotation of the control surface and the flight speed of the aircraft is reduced to avoid control surface flutter. 6) Assess the status of the control surface support system and determine the flight strategy; When control surface flutter occurs, the suppressor device suppresses the flutter and then determines the current control surface status. If there is no fault in the aircraft system, the aircraft airspeed is reduced to below the flutter speed, the suppressor device is manipulated to restore the control surface, the control surface rotation restriction is lifted, and the control surface continues to work normally, and the aircraft continues to fly. When a malfunction in the control surface system causes a decrease in control surface stiffness, a suppressor device is used to maintain normal control stiffness. At this time, the control surface cannot be deflected, the aircraft's control performance is weakened, and the aircraft's landing is completed by gradually reducing the flight speed when the device is activated. The suppressor device comprises, in sequence, a support arm, a drive rod, a support frame, a limiting rod, a limiting block, and a control surface shaft. A limiting rod and a limiting block coaxial with the limiting rod are mounted on the control surface shaft. The limiting block, limiting rod, and drive rod are on the same axis. The support frame, support arm, and shaft support are all fixed to the rear wall of the wing via the support arm, and the control surface shaft is fixed via the shaft support. The support frame is a square frame with a support arm, and the limiting block is located within the square frame. Ribs are present on the inner surfaces of the upper and lower sides of the square frame, parallel to the axis of the control surface shaft, allowing the limiting block to slide within the square frame. One end of the limiting rod is a cylinder with an internal hexagonal recess, and the other end is a square-section rod. The limiting block has a groove inside, corresponding to the square-section rod at the front end of the limiting rod.

2. The method for suppressing control surface flutter by limiting rotational motion according to claim 1, characterized in that, The drive rod is a tubular structure; the outside of the tube has multiple parallel ribs forming a gear-shaped cross-section, and the inside has threads; one end of the drive rod is connected to the limiting block by a pin, so that the two can translate at the same amplitude on the axis of rotation; the outer ribs of the drive rod mesh with a gear driven by a motor, and the motor is mounted on the support arm through a support arm, with the motor axis parallel to the axis of the threaded rod; when the motor starts, the drive rod rotates under the drive of the gear, and completes the translational movement on the axis of rotation through the threaded post on the support arm, thereby driving the limiting block to hold or release the limiting rod.

3. The method for suppressing control surface flutter by limiting rotational motion according to claim 1, characterized in that, When the suppressor device is activated, the limiting block holds the limiting rod; when the suppressor device is deactivated, the limiting block separates from the limiting rod. When the motor starts, the limiting block will move along the axis of rotation toward the limiting rod; as the limiting block moves and holds the limiting rod, the rotation angle of the limiting rod gradually decreases until it stops rotating. Aircraft control surface flutter is caused by the coupling of the control surface rotation mode with other modes of the structure. Suppressing the control surface rotation mode can suppress the aircraft's control surface rotation flutter. The vibration response signal of the aircraft is analyzed to obtain the parameters of the control surface rotation mode, and the changes in the parameters are observed to determine whether control surface flutter has occurred.

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