A device and method for low-speed wind tunnel gust or flutter half-model test

Abstract

A device and method for a low-speed wind tunnel gust or flutter half-model test, belonging to the field of wind tunnel testing, the present invention is to solve the problem that the existing gust or flutter half-model test device cannot achieve the complete release of the heave and pitch degrees of freedom, and the device is difficult to achieve the common use of the two tests. The device includes an integral frame, the integral frame is installed in the wind tunnel test section, two slide rails are vertically arranged on the front end surface of the integral frame, two groups of slider groups are arranged on the left and right on the rear end surface of the pulley, the two groups of slider groups are slidably matched with the two groups of slide rails in a one-to-one correspondence, two spring seats are arranged at the top of the integral frame, the spring seat is provided with a horizontal axis, the inner ring ends of the two springs are connected to the horizontal axes of the two spring seats in a one-to-one correspondence, the outer ring ends of the two springs are respectively drooped and connected to the pulley, the model mounting seat is cylindrical, and the model mounting seat is rotatably matched with the pulley; the present invention can be used for both gust load mitigation tests and body freedom flutter tests, and the two tests can be shared.

Description

Technical Field

[0001] The invention belongs to the field of wind tunnel tests, and in particular relates to a device and method for low-speed wind tunnel gust or flutter half-mold tests. Background Art

[0002] During the flight of an aircraft, its structure undergoes elastic deformation due to the action of aerodynamic forces, and the elastic deformation of the structure causes changes in the distribution and magnitude of the aerodynamic loads. This change in aerodynamic loads will cause new elastic deformations of the structure. The mutual coupling between the above-mentioned aerodynamic changes and structural elastic deformations is called aeroelasticity. The aeroelastic phenomenon involves the coupling between aerodynamic forces, elastic forces, and inertial forces. Aeroelastic problems can change the equilibrium state of the aircraft and even cause structural fatigue, leading to the destruction of the aircraft. At present, the most concerned dynamic aeroelastic problems are mainly of two categories: one is the aeroelastic dynamic response problem, such as maneuvering load reduction; the other is the aeroelastic dynamic stability problem, such as flutter.

[0003] In modern aircraft design, in order to pursue high-speed, high-maneuverability and other flight performance, lightweight and flexible materials are usually used, which makes the aeroelastic problem more prominent. Especially for flying wing layout aircraft, the aircraft wing load is small and the structure is flexible. When encountering strong gusts, it will cause drastic changes in attitude and center of mass acceleration, and induce elastic movement of the flexible wing, resulting in increased wing root bending moment and excessive wing tip vibration, affecting the completion of the flight mission and endangering flight safety; the elastic modal frequency of the flexible wing structure is close to the rigid body modal frequency of the aircraft, and it will also bring about a special body freedom flutter phenomenon; in addition, the aircraft gust response and body freedom flutter phenomenon involve the coupling problem of the elastic mode and rigid body mode of the model.

[0004] At present, the research on gust load mitigation and body freedom flutter of aircraft is mostly carried out by wind tunnel test methods. The existing half-model wind tunnel test system for gust or flutter cannot achieve the complete release of heave and pitch freedom, cannot decouple the rigid body mode of the elastic model from the elastic body mode, and is difficult to achieve the common use of gust and flutter tests. The weight of the pulley used to achieve heave movement cannot be constantly offset, and thus the model cannot move freely. The model cannot achieve a wide range of pitch angle adjustment, and the system has large damping, which affects the accuracy of the test results. There is a lack of reliable safety protection measures, and it is difficult to provide protection in multiple dimensions. The device lacks deflectors or the deflectors are small in size and cannot be extended. The device can only be installed on the side wall of the wind tunnel for use. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for gust or flutter half-model test in a low-speed wind tunnel, so as to solve the problems that the existing gust or flutter half-model wind tunnel test system cannot fully release the heave and pitch degrees of freedom, and it is difficult to achieve the common use of gust and flutter tests. The technical solutions adopted by the present invention are as follows:

[0006] An apparatus for low-speed wind tunnel gust or flutter half-model testing, comprising an integral frame, a spring, a trolley and a model mounting seat;

[0007] The rear end of the overall frame is connected to the side wall of the wind tunnel test section, the lower end of the overall frame is connected to the bottom wall of the wind tunnel test section, two slide rails are vertically arranged on the front end surface of the overall frame, and two sets of slider groups are arranged on the left and right sides of the rear end surface of the pulley. The two sets of slider groups are slidably matched with the two sets of slide rails in a one-to-one correspondence. The top of the overall frame is provided with two spring seats, and the spring seats are provided with horizontal axes. The inner ring ends of the two springs are connected to the horizontal axes of the two spring seats in a one-to-one correspondence. The outer ring ends of the two springs are respectively drooped and connected to the pulley. The model mounting seat is cylindrical, and the model mounting seat is rotatably matched with the pulley.

[0008] The test model is an elastic wing half model, the wing root of the test model is connected to the front end of the model mounting seat, the trailing edge of the test model is provided with ailerons and flaps, the driving devices of the ailerons and flaps are respectively electrically connected to the model control system, and the combined force of the elastic forces of the two springs is based on the weight and setting of the test model, the model mounting seat, the two slider groups and the pulley;

[0009] The pitch protection system includes a dual-axis cylinder and a limit block. A limit plane is provided at the rear end of the model mounting seat, and the limit plane is parallel to the axis of the model mounting seat. The limit block is a wedge-shaped block. The dual-axis cylinder is horizontally arranged, and the output end of the dual-axis cylinder faces the limit plane. The wedge surface on one side of the limit block is abutted and connected with the output end of the dual-axis cylinder, and the wedge surface on the other side of the limit block limits the rotation of the limit plane.

[0010] Furthermore, protective dampers are provided at the upper and lower ends of the slide rail, and the buffer heads of the protective dampers face the corresponding slider groups.

[0011] Furthermore, adjusting nuts are provided at the four corners of the bottom of the overall frame, and four vertically arranged adjusting screws are threadably matched with the four adjusting nuts in a one-to-one correspondence, and a movable roller is provided at the bottom of the adjusting screws.

[0012] Furthermore, there are a plurality of limit blocks, and the wedge angles of the limit blocks vary from 0° to 45° in sequence at intervals of 5°.

[0013] Furthermore, a plurality of side wall mounting seats are provided at the rear end of the overall frame, a plurality of mounting holes are provided at the lower end of the overall frame, the overall frame is connected to the side wall of the wind tunnel test section through the plurality of side wall mounting seats, and the overall frame is connected to the bottom wall of the wind tunnel test section through the plurality of mounting holes.

[0014] Furthermore, a plurality of guide plate mounting seats are provided on the front end surface of the overall frame, the guide plates are fixed on the plurality of guide plate mounting seats, a long hole is vertically provided on the guide plate, and the front end of the model mounting seat passes through the long hole.

[0015] Furthermore, two linear guide clamps are arranged on the left and right sides of the pulley, and the two linear guide clamps are slidably matched or locked with the two slide rails in a one-to-one correspondence.

[0016] The present invention also provides a method for low-speed wind tunnel gust test, which is implemented based on the above-mentioned device for low-speed wind tunnel gust or flutter half-mold test, and includes the following steps:

[0017] Step 1: For the gust test, install the gust generator at the entrance of the wind tunnel and connect the drive device of the gust generator to the model control system;

[0018] Step 2: Connect the overall frame to the side walls and bottom wall of the wind tunnel test section;

[0019] Step 3: Connect the test model to the model mounting base;

[0020] Step 4: For the gust test, an inclination sensor and an angular rate gyroscope are installed at the center of gravity of the test model, the pitch angle of the test model is measured by the inclination sensor, and the pitch angle rate of the test model is measured by the angular rate gyroscope;

[0021] Step 5: Select the corresponding limit block according to the test requirements, and adjust the extension of the dual-axis cylinder piston rod according to the pitch angle range of the test model;

[0022] Step 6: Install an acceleration sensor at the wing tip of the test model, paste a strain gauge for measuring the wing root bending moment at the wing root of the test model, arrange an optical fiber for measuring the wing deformation on the wing beam of the test model, fix a pull-rope displacement sensor on the test model, connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signal is normal;

[0023] Step 7: Conduct frequency sweep tests on the aileron and flap of the test model with and without incoming flow to obtain the frequency response characteristics of the model;

[0024] Step 8: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed;

[0025] Step 9: When the gust spoiler reaches the test model, the vibration response signal of the test model is measured by the acceleration sensor, and the pitch angular rate of the test model is measured by the angular rate gyroscope. The vibration response signal and the pitch angular rate are solved by the data acquisition and processing system to obtain the disturbance amount of the gust, and then the disturbance amount is transmitted to the model control system. The model control system drives the flap to move, generating a force in the opposite direction to the aerodynamic force brought by the gust, so as to achieve the pitch attitude control effect, that is, the inner loop control, and realizes the load reduction of the elastic body;

[0026] Step 10: While the inner loop control is being performed in step 9, the displacement change of the test model heave motion is first measured by the displacement sensor, and the signal data is sent to the data acquisition and processing system for solution, and then the solved displacement change is transmitted to the model control system, and the model control system drives the flap movement to keep the test model at the set height, that is, the outer loop control, to achieve the reduction of the rigid body load;

[0027] Step 11. For the gust test, comprehensively compare the wing tip acceleration, wing root strain and heave range of the test model before and after flap and aileron control in steps 7 and 8, and compare with the case without control. If the wing tip acceleration and wing root strain values ​​after control are lower than 20% of those without control, and the heave range of the test model is stable within the predetermined range, it means that the load mitigation effect of this train test meets the standard, and this train test is terminated and the next train test is carried out. Otherwise, continue to adjust the flap and aileron parameters until the load mitigation effect meets the standard.

[0028] Step 12: Set ±0.3m of the initial height of the test model as the set threshold for the heave movement. During the test, if the heave movement amplitude of the test model exceeds the set threshold, start the linear guide clamp for locking protection.

[0029] Furthermore, in step seven, according to the deflection of the flap control surface, direct lift is generated to offset the aerodynamic force and torque increment generated by the gust, and the gust load mitigation equation established is as follows:

[0030]

[0031] Where, L α is the derivative of lift with respect to angle of attack, L q is the derivative of lift with respect to pitch rate, L f is the flap lift increment, δ f is the flap deflection angle, V is the incoming wind speed, w g is the vertical gust speed at the reference point (the aerodynamic center of the wing), is the rate of change of gust wind speed at the reference point, M α is the derivative of the pitching moment with respect to the angle of attack, M q is the derivative of the pitch moment with respect to the pitch angular rate, M fis the flap pitch moment increment;

[0032] Since the flap is arranged near the reference point, the pitching moment caused by the rudder deflection can be ignored, that is:

[0033] M f δ f ≈0(2)

[0034] The conventional layout models used in the present invention are:

[0035] L q ≈0(3)

[0036] Combining equation (2) and equation (3), we can get the relationship between the rudder deflection angle and the gust disturbance:

[0037] δ f =K1w g (4)

[0038] In formula (4), K1 is the gain from the open-loop gust mitigation controller, the gust amplitude to the flap deflection, and its specific expression is as follows:

[0039]

[0040] The present invention also provides a method for flutter half-mold testing, which is implemented based on the above-mentioned device for low-speed wind tunnel gust or flutter half-mold testing, and includes the following steps:

[0041] Step 1: Connect the overall frame to the side wall and bottom wall of the wind tunnel test section;

[0042] Step 2: Connect the test model to the model mounting base;

[0043] Step 3: Select the corresponding limit block according to the test requirements, and adjust the extension of the dual-axis cylinder piston rod according to the pitch angle range of the test model;

[0044] Step 4: Install an acceleration sensor at the wing tip of the test model, paste a strain gauge for measuring the wing root bending moment at the wing root of the test model, arrange an optical fiber for measuring the wing deformation on the wing beam of the test model, fix a pull-rope displacement sensor on the test model, connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signal is normal;

[0045] Step 5: Perform frequency sweep tests on the aileron and flap of the test model with and without incoming flow to obtain the frequency response characteristics of the model;

[0046] Step 6: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed;

[0047] Step 7: Obtain the flutter velocity boundary of the test model according to the wing tip acceleration or the wing root strain value;

[0048] Step 8: Set ±0.3m of the initial height of the test model as the set threshold for the heave movement. During the test, if the heave movement amplitude of the test model exceeds the set threshold, the linear guide clamp is activated for locking protection.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention adopts an elastic wing half model for testing, which can reduce the number of sensors arranged, save the processing cost of the test model, reduce the disassembly and assembly time of the test model, improve the test efficiency, and can completely release the heave and pitch freedom, decouple the rigid body mode of the elastic wing half model from the elastic body mode, and realize the gust mitigation control mode of the test model rigid body mode, elastic body mode, and rigid-elastic mixed mode; the present invention can be used for both gust load mitigation test and body freedom flutter test, and adopts multiple sets of protection measures to timely and efficiently protect the test model in both heave and pitch directions, thereby ensuring the safety of the test model. A large range of movement of the pitch angle of the test model can be achieved, and the pitch angle can be adjusted by selecting different limit blocks. The pulley reduces the damping of the test model through the lifting and sliding mode of the double slide rails. The spring spring is a constant force spring, which can continuously offset the additional mass brought to the test model by the device, ensure that the test model is evenly stressed and moves freely during the test, more realistically simulate the flight state of the aircraft, and improve the accuracy of test data acquisition. The opening scale of the guide plate is small, which has little effect on the model flow field. The guide plate is extensible and suitable for test models of different sizes. In the gust test, the device of the present invention can be installed on the side wall of the wind tunnel test section, using a horizontally designed gust generator for gust test, and can also be installed on the bottom wall of the wind tunnel test section, using a vertically designed gust generator for gust test. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is an axonometric view of the device of the present invention without the guide plate;

[0052] Figure 2 is an axonometric view of the device of the present invention;

[0053] Figure 3 yes Figure 1 A magnified image of point A;

[0054] Figure 4 yes Figure 1 The enlarged view of point B;

[0055] Figure 5 It is a schematic diagram of the coordination between the pulley and the slide rail;

[0056] Figure 6 It is a schematic diagram of the coordination of the pulley and the slide rail parts from a rear view perspective;

[0057] Figure 7 It is a schematic diagram of the frequency response curve of the test model;

[0058] Figure 8 is the inner loop schematic diagram of the model control system;

[0059] Fig. 9 is the schematic diagram of the outer loop of the model control system;

[0060] Fig.10 is a schematic diagram of the flutter velocity boundary of the test model;

[0061] Fig.11 This is the effect diagram of the wing root bending moment mitigation test;

[0062] Fig.12 It is a schematic diagram of the test model installed on the device of the present invention.

[0063] In the figure, 1. overall frame, 2. slide rail, 3. pulley, 4. model mounting seat, 5. side wall mounting seat, 6. spring, 7. deflector, 8. long hole, 9. protective damper, 10. spring seat, 11. adjusting screw, 12. adjusting nut, 13. moving roller, 14. slider group, 15. linear guide clamp, 16. dual-axis cylinder, 17. limit block, 18. test model, 19. aileron, 20. flap. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0065] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as bolt connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can be found in the existing connection methods to achieve the function, and those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and bolt connection is selected for detachable connection.

[0066] The present invention will be further described in detail below in conjunction with the accompanying drawings. The following embodiments are provided to explain the present invention, but the present invention is not limited to the following embodiments.

[0067] Embodiment 1: Figure 1 to Figure 6 , Fig.12 As shown, a device for low-speed wind tunnel gust or flutter half-model test includes an overall frame 1, a spring 6, a pulley 3 and a model mounting seat 4;

[0068] The rear end of the overall frame 1 is connected to the side wall of the wind tunnel test section, the lower end of the overall frame 1 is connected to the bottom wall of the wind tunnel test section, two slide rails 2 are vertically arranged on the front end surface of the overall frame 1, and two groups of slider groups 14 are arranged on the left and right sides of the rear end surface of the pulley 3. The two groups of slider groups 14 are slidably matched with the two groups of slide rails 2 in a one-to-one correspondence. The top of the overall frame 1 is provided with two spring seats 10, and the spring seats 10 are provided with horizontal axes. The inner ring ends of the two springs 6 are connected to the horizontal axes of the two spring seats 10 in a one-to-one correspondence. The outer ring ends of the two springs 6 are respectively drooped and connected to the pulley 3. The model mounting seat 4 is cylindrical, and the model mounting seat 4 is rotatably matched with the pulley 3.

[0069] The test model 18 is a half model of an elastic wing, the wing root of the test model 18 is connected to the front end of the model mounting seat 4, the trailing edge of the test model 18 is provided with an aileron 19 and a flap 20, the driving devices of the aileron 19 and the flap 20 are respectively electrically connected to the model control system, and the combined force of the elastic force of the two spring springs 6 is based on the weight and setting of the test model 18, the model mounting seat 4, the two slider groups 14 and the pulley 3;

[0070] The pitch protection system includes a dual-axis cylinder 16 and a limit block 17. A limit plane is provided at the rear end of the model mounting seat 4, and the limit plane is parallel to the axis of the model mounting seat 4. The limit block 17 is a wedge-shaped block. The dual-axis cylinder 16 is horizontally arranged, and the output end of the dual-axis cylinder 16 faces the limit plane. One side wedge surface of the limit block 17 is abutted and connected with the output end of the dual-axis cylinder 16, and the other side wedge surface of the limit block 17 limits the rotation of the limit plane.

[0071] The upper and lower ends of the slide rail 2 are both provided with protective dampers 9 , and the buffer heads of the protective dampers 9 face the corresponding slider groups 14 .

[0072] Adjustment nuts 12 are provided at the four corners of the bottom of the overall frame 1 , and four vertically arranged adjustment screws 11 are threadedly matched with the four adjustment nuts 12 in a one-to-one correspondence, and a moving roller 13 is provided at the bottom of the adjustment screw 11 .

[0073] There are a plurality of limit blocks 17, and the wedge angles of the limit blocks 17 vary from 0° to 45° at intervals of 5°.

[0074] The rear end of the overall frame 1 is provided with a plurality of side wall mounting seats 5, the lower end of the overall frame 1 is provided with a plurality of mounting holes, the overall frame 1 is connected to the side wall of the wind tunnel test section through the plurality of side wall mounting seats 5, and the overall frame 1 is connected to the bottom wall of the wind tunnel test section through the plurality of mounting holes.

[0075] A plurality of guide plate 7 mounting seats are provided on the front end surface of the overall frame 1 , and the guide plate 7 is fixed on the plurality of guide plate 7 mounting seats. A long hole 8 is vertically provided on the guide plate 7 , and the front end of the model mounting seat 4 passes through the long hole 8 .

[0076] Two linear guide clamps 15 are arranged on the left and right sides of the pulley 3 , and the two linear guide clamps 15 are slidably matched or locked with the two slide rails 2 in a one-to-one correspondence.

[0077] The test model 18 is connected to the pulley 3 through the model mounting seat 4. Under the action of the disturbed aerodynamic force formed by the gust generator, the test model 18 performs heave and sink motion along the slide rail 2. The pulley 3 is equipped with a double-axis cylinder 16 and a linear guide clamp 15, which can limit the range of the test model 18's heave and pitch motion, and play a role in protecting the test model 18. During the test, the linear guide clamp 15 can be used to limit the heave and float motion of the test model 18 as needed, and the pitch angle of the test model 18 can be adjusted by installing a limit block 17 with different wedge angles. When the pitch angle of the test model 18 is large, the double-axis cylinder 16 can be started to drive the limit block 17 to fix the model mounting seat 5.

[0078] The present invention uses an elastic wing half model for testing, which can reduce the number of sensors arranged, save the processing cost of the test model 18, reduce the time for disassembly and assembly of the test model 18, and improve the test efficiency. It can completely release the heave and pitch freedom, decouple the rigid body mode of the elastic wing half model from the elastic body mode, and realize the gust mitigation control mode of the rigid body mode, elastic body mode, and rigid-elastic mixed mode of the test model 18; the present invention can be used for both gust load mitigation tests and body freedom flutter tests, and adopts multiple sets of protection measures to timely and efficiently protect the test model 18 in both heave and pitch directions, thereby ensuring the safety of the test model 18. A large range of movement of the pitch angle of the test model 18 can be achieved, and the pitch angle can be adjusted by selecting different limit blocks. The pulley 3 reduces the damping of the test model 18 through the lifting and sliding mode of the double slide rails 2. The clockwork spring 6 is a constant force spring, which can continuously offset the additional mass brought by the device to the test model 18, ensuring that the test model 18 is evenly stressed and moves freely during the test, more realistically simulating the flight state of the aircraft, and improving the accuracy of test data collection. The opening scale of the guide plate 7 is small, which has little effect on the model flow field. The guide plate 7 is extensible and suitable for models of different sizes. In the gust test, the device of the present invention can be installed on the side wall of the wind tunnel test section, using a horizontally designed gust generator for gust tests, and can also be installed on the bottom wall of the wind tunnel test section, using a vertically designed gust generator for gust tests.

[0079] Embodiment 2: Figures 1 to 9 , Fig.11 , Fig.12 As shown, a method for a low-speed wind tunnel gust test is implemented based on a device for a low-speed wind tunnel gust or flutter half-mold test as described in Example 1, and includes the following steps:

[0080] Step 1: For the gust test, install the gust generator at the entrance of the wind tunnel and connect the drive device of the gust generator to the model control system;

[0081] Step 2: Connect the overall frame 1 to the side wall and bottom wall of the wind tunnel test section;

[0082] Step 3: Connect the test model 18 to the model mounting base 4;

[0083] Step 4: For the gust test, an inclination sensor and an angular rate gyroscope are installed at the center of gravity of the test model 18, and the pitch angle of the test model 18 is measured by the inclination sensor, and the pitch angle rate of the test model 18 is measured by the angular rate gyroscope;

[0084] Step 5: Select the corresponding limit block according to the test requirements, and adjust the extension of the piston rod of the dual-axis cylinder 16 according to the pitch angle range of the test model 18;

[0085] Step 6: Install an acceleration sensor at the wing tip of the test model 18, paste a strain gauge for measuring the wing root bending moment at the wing root of the test model 18, arrange an optical fiber for measuring the wing deformation on the wing beam of the test model 18, fix a pull-rope displacement sensor on the test model 18, connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signal is normal;

[0086] Step 7: Perform frequency sweep tests on the aileron 19 and flap 20 of the test model 18 under the condition of oncoming flow and without oncoming flow, respectively, to obtain the frequency response characteristics of the model;

[0087] Step 8: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed;

[0088] Step nine, when the gust spoiler reaches the test model 18, the vibration response signal of the test model 18 is measured by the acceleration sensor, and the pitch angular rate of the test model 18 is measured by the angular rate gyroscope. The vibration response signal and the pitch angular rate are solved by the data acquisition and processing system to obtain the disturbance amount of the gust, and then the disturbance amount is transmitted to the model control system. The model control system drives the flap to move, generating a force in the opposite direction to the aerodynamic force brought by the gust, so as to achieve the pitch attitude control effect, that is, the inner loop control, and realizes the reduction of the elastic body load;

[0089] Step 10: While the inner loop control is being performed in step 9, the displacement change of the heave motion of the test model 18 is first measured by the displacement sensor, and the signal data is sent to the data acquisition and processing system for solution, and then the solved displacement change is transmitted to the model control system, and the model control system drives the flap 20 to move so that the test model 18 maintains the set height, that is, the outer loop control, and the rigid body load is reduced;

[0090] Step 11: For the gust test, comprehensively compare the wing tip acceleration, wing root strain and heave range of the test model 18 before and after the flap 20 and aileron 19 are controlled in steps 7 and 8, and compare with the case where no control is applied. If the wing tip acceleration and wing root strain values ​​after the control are lower than 20% of those without control, and the heave range of the test model 18 is stable within a predetermined range, it means that the load mitigation effect of this train test meets the standard, and this train test is terminated and the next train test is carried out. Otherwise, continue to adjust the parameters of the flap 20 and aileron 19 until the load mitigation effect meets the standard.

[0091] Step 12: Set ±0.3m of the initial height of the test model 18 as the set threshold of the heave movement. During the test, if the heave movement amplitude of the test model 18 exceeds the set threshold, start the linear guide clamp 15 for locking protection.

[0092] In step 7, according to the deflection of the flap 20 control surface, direct lift is generated to offset the aerodynamic force and torque increment generated by the gust, and the gust load mitigation equation established is as follows:

[0093]

[0094] Where, L α is the derivative of lift with respect to angle of attack, L q is the derivative of lift with respect to pitch rate, L f is the flap lift increment, δ f is the flap deflection angle, V is the incoming wind speed, w g is the vertical gust speed at the reference point (the aerodynamic center of the wing), is the rate of change of gust wind speed at the reference point, M α is the derivative of the pitching moment with respect to the angle of attack, M q is the derivative of the pitch moment with respect to the pitch angular rate, M f is the flap pitch moment increment;

[0095] Since the flap is arranged near the reference point, the pitching moment caused by the rudder deflection can be ignored, that is:

[0096] M f δ f ≈0(2)

[0097] The conventional layout models used in the present invention are:

[0098] L q ≈0(3)

[0099] Combining equation (2) and equation (3), we can get the relationship between the rudder deflection angle and the gust disturbance:

[0100] δ f =K1w g (4)

[0101] In formula (4), K1 is the gain of the open-loop gust mitigation controller from the gust amplitude to the flap deflection, and the specific expression is as follows:

[0102]

[0103] The present invention installs the test device in the wind tunnel test section. For the gust test, the gust generator is installed at the entrance of the wind tunnel, the test model 18 is installed on the model mounting seat 4, and the acceleration sensor, strain gauge, displacement sensor, gyroscope and other sensors arranged on the test model 18 are connected to the data acquisition and processing system, and then the linear guide clamp 15 and the double-axis cylinder 16 are connected to the air supply pump and the 24V DC power supply. Then the wind tunnel starts to blow, and after reaching the predetermined wind speed, the gust generator is controlled to move according to the set swing frequency and swing amplitude. Under the action of the disturbed aerodynamic force generated by the gust generator, the test model 18 performs heave motion on the pulley 3. The model control system drives the flap deflection according to the feedback signal of the displacement sensor to achieve the comprehensive load reduction of the rigid body, elastic body and rigid-elastic coupling mode of the test model 18. If the heave motion or pitch motion of the test model 18 exceeds the set threshold, the displacement sensor triggers the protection system to ensure the safety of the test model 18. After the test, the accelerometer signals at the wing tip and center of gravity of the model, the strain gauge signals at the wing root, the model motion signals measured by the displacement sensor and other data were processed to obtain comparative data before and after the gust mitigation control was applied and not applied, and the value of the gust load mitigation was obtained.

[0104] like Fig.11 The figure shows the effect of the wing root bending moment mitigation test. When the control law is turned on and the model rudder is deflected, the gust load suffered by the model is effectively reduced. At the key frequency of 3.5Hz, the gust load mitigation amount reaches more than 55%, which quickly and efficiently reduces the gust load and has a significant mitigation control effect.

[0105] Embodiment 3: Figure 1 to Figure 7 , Fig.10 , Fig.12 As shown, a method for flutter half-mold test is implemented based on the device for low-speed wind tunnel gust or flutter half-mold test described in Example 1, and includes the following steps:

[0106] Step 1: Connect the overall frame 1 to the side wall and bottom wall of the wind tunnel test section;

[0107] Step 2: Connect the test model 18 to the model mounting base 4;

[0108] Step 3: Select the corresponding limit block according to the test requirements, and adjust the extension of the piston rod of the dual-axis cylinder 16 according to the pitch angle range of the test model 18;

[0109] Step 4: Install an acceleration sensor at the wing tip of the test model 18, paste a strain gauge for measuring the wing root bending moment at the wing root of the test model 18, arrange an optical fiber for measuring the wing deformation on the wing beam of the test model 18, fix a pull-rope displacement sensor on the test model 18, connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signal is normal;

[0110] Step 5: Perform frequency sweep tests on the aileron 19 and flap 20 of the test model 18 under the condition of oncoming flow and without oncoming flow, respectively, to obtain the frequency response characteristics of the model;

[0111] Step 6: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed;

[0112] Step 7: Obtain the flutter velocity boundary of the test model 18 according to the wing tip acceleration or the wing root strain value;

[0113] Step 8: Set ±0.3m of the initial height of the test model 18 as the set threshold of the heave movement. During the test, if the heave movement amplitude of the test model 18 exceeds the set threshold, start the linear guide clamp 15 for locking protection.

[0114] like Fig.10 As shown in the figure, for the flutter test, there is no need to install a generator device. It is only necessary to use the vibration response of the accelerometer and strain gauge and the wing root bending moment. The model flutter boundary is obtained by processing and analyzing the acceleration and strain data values. The protection measures are the same as those for the gust test.

[0115] The above embodiments are merely exemplary descriptions of the present invention and do not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit of the present invention.

Claims

1. A device for low-speed wind tunnel gust or flutter half-mold testing, characterized in that: It comprises an overall frame (1), a spring (6), a pulley (3) and a model mounting seat (4); The rear end of the overall frame (1) is connected to the side wall of the wind tunnel test section, the lower end of the overall frame (1) is connected to the bottom wall of the wind tunnel test section, two slide rails (2) are vertically arranged on the front end surface of the overall frame (1), and two groups of slider groups (14) are arranged on the left and right sides of the rear end surface of the pulley (3), and the two groups of slider groups (14) are slidably matched with the two groups of slide rails (2) in a one-to-one correspondence, and the top of the overall frame (1) is provided with two spring seats (10), and the spring seats (10) are provided with a horizontal axis, the inner ring ends of the two spring springs (6) are connected to the horizontal axes of the two spring seats (10) in a one-to-one correspondence, and the outer ring ends of the two spring springs (6) are respectively drooped and connected to the pulley (3), and the model mounting seat (4) is cylindrical, and the model mounting seat (4) is rotationally matched with the pulley (3); The test model (18) is a semi-model of an elastic wing. The wing root of the test model (18) is connected to the front end of the model mounting seat (4). The trailing edge of the test model (18) is provided with an aileron (19) and a flap (20). The driving devices of the aileron (19) and the flap (20) are respectively electrically connected to the model control system. The combined force of the elastic force of the two spring springs (6) is based on the weight and setting of the test model (18), the model mounting seat (4), the two slider groups (14) and the pulley (3). The pitch protection system comprises a dual-axis cylinder (16) and a limit block (17); a limit plane is provided at the rear end of the model mounting seat (4); the limit plane is parallel to the axis of the model mounting seat (4); the limit block (17) is a wedge-shaped block; the dual-axis cylinder (16) is horizontally arranged; the output end of the dual-axis cylinder (16) faces the limit plane; a wedge surface on one side of the limit block (17) is abutted and connected to the output end of the dual-axis cylinder (16); and a wedge surface on the other side of the limit block (17) limits the rotation of the limit plane.

2. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 1, characterized in that: The upper end and the lower end of the slide rail (2) are both provided with a protective damper (9), and the buffer head of the protective damper (9) faces the corresponding slider group (14).

3. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 2, characterized in that: The four corners of the bottom of the overall frame (1) are each provided with an adjusting nut (12), four vertically arranged adjusting screws (11) are threadably matched with the four adjusting nuts (12) in a one-to-one correspondence, and a movable roller (13) is provided at the bottom of the adjusting screw (11).

4. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 3, characterized in that: There are a plurality of limit blocks (17), and the wedge angles of the limit blocks (17) are changed in sequence from 0° to 45° at intervals of 5°.

5. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 4, characterized in that: A plurality of side wall mounting seats (5) are provided at the rear end of the overall frame (1), a plurality of mounting holes are provided at the lower end of the overall frame (1), the overall frame (1) is connected to the side wall of the wind tunnel test section via the plurality of side wall mounting seats (5), and the overall frame (1) is connected to the bottom wall of the wind tunnel test section via the plurality of mounting holes.

6. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 5, characterized in that: A plurality of guide plate (7) mounting seats are provided on the front end surface of the overall frame (1), the guide plates (7) are fixed on the plurality of guide plate (7) mounting seats, a long hole (8) is vertically provided on the guide plate (7), and the front end of the model mounting seat (4) passes through the long hole (8).

7. The device for low-speed wind tunnel gust or flutter half-mold test according to claim 6, characterized in that: Two linear guide rail clamps (15) are arranged on the left and right sides of the pulley (3), and the two linear guide rail clamps (15) are slidably matched or locked with the two slide rails (2) in a one-to-one correspondence.

8. A method for low-speed wind tunnel gust test, implemented by relying on the device for low-speed wind tunnel gust or flutter half-mold test according to claim 7, characterized in that: The following steps are involved: Step 1: Install the gust generator at the entrance of the wind tunnel and connect the driving device of the gust generator with the model control system; Step 2: Connect the overall frame (1) to the side wall and bottom wall of the wind tunnel test section; Step 3: Connect the test model (18) to the model mounting base (4); Step 4: Install an inclination sensor and an angular rate gyroscope at the center of gravity of the test model (18), measure the pitch angle of the test model (18) by the inclination sensor, and measure the pitch angle rate of the test model (18) by the angular rate gyroscope; Step 5: Select the corresponding limit block according to the test requirements, and adjust the extension amount of the piston rod of the dual-axis cylinder (16) according to the pitch angle range of the test model (18); Step 6: Install an acceleration sensor at the wing tip of the test model (18), affix a strain gauge for measuring the wing root bending moment at the wing root of the test model (18), arrange an optical fiber for measuring the wing deformation on the wing beam of the test model (18), fix a pull-rope type displacement sensor on the test model (18), connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signals are normal; Step 7: Perform frequency sweep tests on the aileron (19) and flap (20) of the test model (18) with and without incoming flow, respectively, to obtain the frequency response characteristics of the model; Step 8: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed; Step nine, when the gust of wind reaches the test model (18), the vibration response signal of the test model (18) is measured by the acceleration sensor, and the pitch angular rate of the test model (18) is measured by the angular rate gyroscope. The vibration response signal and the pitch angular rate are solved by the data acquisition and processing system to obtain the disturbance amount of the gust of wind, and then the disturbance amount is transmitted to the model control system. The model control system drives the flap (20) to move, generating a force in the opposite direction to the aerodynamic force brought by the gust of wind, so as to achieve the pitch attitude control effect, that is, the inner loop control, and realizes the reduction of the elastic body load; Step 10: While the inner loop control is being performed in step 9, the displacement change of the heave motion of the test model (18) is first measured by the displacement sensor, and the signal data is sent to the data acquisition and processing system for solution, and then the solved displacement change is transmitted to the model control system, and the model control system drives the aileron (19) to move so that the test model (18) maintains the set height, that is, the outer loop control, to achieve the reduction of the rigid body load; Step 11: comprehensively compare the wing tip acceleration, wing root strain and heave range of the test model (18) before and after the flap (20) and aileron (19) are controlled in Step 7 and Step 8, and compare with the case where no control is applied. If the wing tip acceleration and wing root strain values ​​after the control are less than 20% of those without control, and the heave range of the test model (18) is stable within a predetermined range, it means that the load mitigation effect of this train test has met the standard, and this train test is terminated and the next train test is carried out. Otherwise, continue to adjust the parameters of the flap (20) and aileron (19) until the load mitigation effect meets the standard. Step 12: Set ±0.3m of the initial height of the test model (18) as the set threshold of the heave movement. During the test, if the heave movement amplitude of the test model (18) exceeds the set threshold, start the linear guide clamp (15) for locking protection.

9. A method for low-speed wind tunnel gust test according to claim 8, characterized in that: In step 7, according to the deflection of the flap (20) control surface, direct lift is generated to offset the aerodynamic force and torque increment generated by the gust, and the gust load mitigation equation established is as follows: （1） In the formula, is the derivative of lift with respect to the angle of elevation, is the derivative of lift with respect to pitch rate, is the lift increment of flap (20), is the flap (20) deflection angle, is the incoming wind speed, is the vertical gust speed at the reference point, is the rate of change of gust wind speed at the reference point, is the derivative of the pitching moment with respect to the angle of attack, is the derivative of the pitch moment with respect to the pitch angular rate, is the pitch moment increment of the flap (20); The flap (20) is arranged near the reference point, and the pitching moment generated by its rudder deflection is: （2） In the conventional layout model: （3） Combining equation (2) and equation (3), we can get the relationship between the flap (20) deflection angle and the gust disturbance: （4） In formula (4), is the gain from the open loop gust mitigation controller, gust amplitude to flap (20) deflection, and is expressed as follows: （5）。 10. A method for flutter half-mold testing, implemented by relying on the device for low-speed wind tunnel gust or flutter half-mold testing according to claim 7, characterized in that: The following steps are involved: Step 1: Connect the overall frame (1) to the side wall and bottom wall of the wind tunnel test section; Step 2: Connect the test model (18) to the model mounting base (4); Step 3: Select the corresponding limit block according to the test requirements, and adjust the extension amount of the piston rod of the dual-axis cylinder (16) according to the pitch angle range of the test model (18); Step 4: Install an acceleration sensor at the wing tip of the test model (18), affix a strain gauge for measuring the wing root bending moment at the wing root of the test model (18), arrange an optical fiber for measuring the wing deformation on the wing beam of the test model (18), fix a pull-rope type displacement sensor on the test model (18), connect the pull rope of the displacement sensor vertically to the top wall or bottom wall of the wind tunnel test section, connect the acceleration sensor, strain gauge, displacement sensor and optical fiber to the data acquisition and processing system respectively, and ensure that the collected signals are normal; Step 5: Perform frequency sweep tests on the aileron (19) and flap (20) of the test model (18) with and without incoming flow, respectively, to obtain the frequency response characteristics of the model; Step 6: Before the gust test, the wind speed of the wind tunnel is made to reach a preset value, and then the gust generator is turned on to make the blades of the gust generator move according to the specified swing angle, swing frequency and waveform; before the flutter half-model test, the wind speed of the wind tunnel is first started to make the wind speed of the wind tunnel reach a preset value, and then the incoming wind speed is gradually increased until the incoming wind speed reaches the model flutter speed; Step 7, obtaining the flutter velocity boundary of the test model (18) under zero damping according to the wing tip acceleration or the wing root strain value; Step 8: Set ±0.3m of the initial height of the test model (18) as a set threshold for the heave movement. During the test, if the heave movement amplitude of the test model (18) exceeds the set threshold, start the linear guide clamp (15) for locking protection.

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