An experimental device for simulating the attitude of an aircraft with wind perturbations

Abstract

The application discloses an experimental device for simulating the attitude of an aircraft with wind disturbance, and relates to the technical field of aircraft testing devices.The device comprises a support holder, a ring-shaped frame, a fixed mounting frame and a near-interface simulation plate.The support holder is used for placing the aircraft.The ring-shaped frame is arranged around the support holder.The fixed mounting frame is arranged outside the support holder and the ring-shaped frame.A connecting platform is arranged on the fixed mounting frame.The top surface of the ring-shaped frame is connected with the connecting platform through a plurality of telescopic driving elements, so that the ring-shaped frame can be lifted and deflected relative to the support holder.A plurality of telescopic air pipes are arranged on the ring-shaped frame at intervals.The air outlet end of each telescopic air pipe is directed towards the center of the ring-shaped frame.The near-interface simulation plate is arranged below the support holder and can be deflected relative to the support holder.The upper surface of the near-interface simulation plate is used for mounting different interface templates, so as to simulate different wind field interfaces.The application has the effect of improving the authenticity of the simulated wind field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aircraft test devices, and particularly relates to an experimental device for simulating an aircraft attitude with wind disturbance. BACKGROUND

[0002] In aircraft design, "wind disturbance resistance" is a classic and important problem. The wind in the real world is complex and changeable (such as sustained wind, gust, wind shear, turbulence, etc.), and the test mode of directly taking off the aircraft in the air for actual test has high cost, high risk, and non-reproducible conditions. Therefore, experimental equipment is generally set up on the ground to simulate the real wind disturbance environment. The ground equipment simulation is much safer than the real flight test, and can accurately and repeatedly apply the same wind disturbance, which is crucial for comparing the advantages and disadvantages of different design schemes or algorithms, which cannot be achieved by field test. It can also independently change the type, intensity and direction of wind disturbance for "separated variable" scientific research.

[0003] The current experimental device usually adopts the form of fan array or wind tunnel to provide the airflow for test by the equipment fixed around the position. The patent document with the authorization announcement number CN211766379U discloses a quadrotor aircraft attitude experiment device with wind disturbance, which comprises an experimental table, a support unit arranged on the experimental table, a lifting unit arranged on the support unit, a aircraft mounting unit arranged on the lifting unit, and a wind disturbance unit arranged corresponding to the mounting position of the quadrotor aircraft. The aircraft mounting unit is used for mounting the quadrotor aircraft and making the attitude of the quadrotor aircraft variable. The wind disturbance unit is used for providing a wind environment for the quadrotor aircraft. The lifting unit is used for adjusting the height of the aircraft mounting unit to adjust the height of the quadrotor aircraft. When the wind disturbance unit supplies wind, the attitude experiment of the quadrotor aircraft with wind disturbance can be carried out. When the wind disturbance unit does not supply wind, the attitude experiment of the quadrotor aircraft without wind disturbance can be carried out. Thus, the attitude experiment of the quadrotor aircraft with and without wind disturbance can be carried out indoors, the external interference can be reduced, the data precision of measurement can be improved, the structure is simple, the installation and disassembly are convenient, the operation is simple, and the cost is low.

[0004] However, the above experimental device can only simulate relatively uniform stable wind or simple sinusoidal or step gust. However, the wind disturbance in the real world has high non-uniformity, non-constancy, and four-dimensional characteristics in space and time. It is not a wind, but a three-dimensional dynamic "field" containing small vortex, sudden wind shear and complex flow structure. The above experimental device is difficult to generate such a complex wind field with high resolution, dynamic evolution and spatial heterogeneity in a small range. Therefore, the actual wind field that can be simulated is very limited. SUMMARY

[0005] In order to improve the existing aircraft wind disturbance experimental device which can simulate a very limited and unrealistic wind field, the application provides an experimental device for simulating the attitude change of an aircraft with wind disturbance.

[0006] The application provides an experimental device for simulating the attitude change of an aircraft with wind disturbance, which adopts the following technical scheme:

[0007] An experimental device for simulating the attitude change of an aircraft with wind disturbance comprises

[0008] A support holder is configured as a three-degree-of-freedom spherical holder containing sensors for detecting the attitude change of the aircraft under the disturbance of air flow.

[0009] A ring-shaped frame is arranged around the support holder.

[0010] A fixed mounting frame is arranged outside the support holder and the ring-shaped frame, and a connecting platform is arranged on the fixed mounting frame. The top surface of the ring-shaped frame is connected to the connecting platform through a plurality of telescopic driving members. The ring-shaped frame and the telescopic driving members form a Stewart platform, so that the ring-shaped frame can be lifted and deflected relative to the support holder. A plurality of telescopic air pipes are arranged on the ring-shaped frame at intervals. The air outlet ends of each telescopic air pipe are directed towards the center of the ring-shaped frame, and the air inlet ends are connected to a wind supply device. A control unit is further arranged on the fixed mounting frame. The support holder and the telescopic driving members are electrically connected to the control unit.

[0011] A near-interface simulation board is arranged below the support holder and can be deflected relative to the support holder. The upper surface of the near-interface simulation board is used to install different interface modules to simulate different wind field interfaces.

[0012] Optionally, the ring-shaped frame comprises at least two layers arranged at intervals. Adjacent two ring-shaped frames are connected as a whole through connecting rods. The top surface of the uppermost ring-shaped frame is connected to the telescopic driving members. All ring-shaped frames are movably provided with telescopic air pipes. The positions of the telescopic air pipes on adjacent two ring-shaped frames correspond to each other. In the vertical direction, at least one ring-shaped frame is used to correspond to the position of the upper half of the fuselage and the rotor of the aircraft, and at least one ring-shaped frame is used to correspond to the position of the lower half of the fuselage and the landing gear of the aircraft.

[0013] Optionally, the telescopic air pipes of each layer of the ring-shaped frame cover at least the front, rear, left and right four directions on the horizontal plane where the aircraft is located. Each layer of the ring-shaped frame is provided with at least one telescopic air pipe corresponding to the front, rear, left and right four directions on the horizontal plane where the aircraft is located, so as to improve the resolution of the simulated wind field. The ring-shaped frame is configured as a frame with a circular horizontal cross section.

[0014] Optionally, each of the telescopic air ducts is rotationally connected to the annular frame, and an axis of rotation of each telescopic air duct coincides with or is parallel to a tangent direction at the hinged position of the telescopic air duct and the annular frame; the annular frame is provided with a rotation driving assembly corresponding to each telescopic air duct, for driving the corresponding telescopic air duct to rotate; and an outer wall of each telescopic air duct is provided with a telescopic driving assembly corresponding thereto, for driving the corresponding telescopic air duct to telescope.

[0015] Optionally, an outer wall of the air outlet end of each telescopic air duct is provided with a distance measuring element, an emitting end of the distance measuring element faces a center direction of the annular frame, and the distance measuring element is used to detect a distance between the air outlet end of the telescopic air duct and the aircraft.

[0016] Optionally, the air outlet end of each telescopic air duct is detachably connected with a fairing, for providing a stable simulated air flow.

[0017] Optionally, the connecting platform is connected with the fixed mounting frame through a first adjusting assembly and a second adjusting assembly, the first adjusting assembly comprises a first moving seat, the second adjusting assembly comprises a second moving seat, a bottom of the first moving seat is connected with a top of the connecting platform, the first moving seat is horizontally slidably connected to a bottom of the second moving seat, the second moving seat is horizontally slidably connected to the fixed mounting frame, and a sliding direction of the first moving seat is perpendicular to a sliding direction of the second moving seat.

[0018] Optionally, a lifting element is arranged at a bottom of the supporting holder, and the lifting element is used to drive the supporting holder to vertically lift.

[0019] In summary, the present application has at least one of the following beneficial effects:

[0020] 1. By setting a support holder in the center of the fixed mounting frame, and setting a ring-shaped frame around the support holder, a plurality of telescopic air pipes are installed on the ring-shaped frame, the telescopic air pipes are also arranged around the support holder, all the telescopic air pipes are directed to the support holder corresponding to the ring-shaped frame, the support holder can be installed and placed for the experimental aircraft, and the support holder is a three-degree-of-freedom spherical holder containing sensors, which can realize extremely low friction and effectively reduce the influence of the holder itself on the aircraft experiment, the rotors of the aircraft can not rotate or be replaced by a prosthesis to exclude the influence of power, and the aerodynamic attitude of the aircraft is purely researched, when the aircraft is placed on the support holder, the sensors inside the support holder can monitor the key attitude signals of the three degrees of freedom of the aircraft pitch, roll and yaw in real time, the plurality of telescopic air pipes around the aircraft can at least spray simulated air flow to the aircraft from the front, back, left and right of the aircraft, and the ring-shaped frame and the telescopic driving member form a Stewart platform, when all the telescopic driving members are synchronously telescoped, the ring-shaped frame can be driven to ascend and descend as a whole while keeping its own attitude unchanged, when the telescopic driving member on one side is elongated and the telescopic driving member on the other side is correspondingly elongated, the ring-shaped frame can be driven to deflect to one side by a certain amplitude, and the blowing angle of each telescopic air pipe to the aircraft can be indirectly adjusted by changing the position or deflection angle of the ring-shaped frame, so that the aircraft can be simulated in various wind field scenarios, from the traditional wind tunnel "global uniform wind" to the "local, dynamic, high-resolution vector wind field" which can be arbitrarily shaped and moved in space, instead of "one fan" beside "one platform", the platform itself has the ability to generate controllable wind field;

[0021] 2. The adjustment of the simulated wind field is more convenient and flexible, by setting a first adjustment assembly and a second adjustment assembly above the ring-shaped frame and the telescopic driving member, the first adjustment assembly includes a first moving seat, the second adjustment assembly includes a second moving seat, the top of the first moving seat is connected with the bottom of the connecting platform, the first moving seat is horizontally slidably connected to the bottom of the second moving seat, the second moving seat is horizontally slidably connected to the fixed mounting frame, and the sliding direction of the first moving seat is perpendicular to the sliding direction of the second moving seat, the ring-shaped frame can slide along the second moving seat in a horizontal direction by the connecting platform following the first moving seat, and when the first moving seat slides along the second moving seat in another horizontal direction along the fixed mounting frame, the ring-shaped frame also moves following the first moving seat, and the moving directions of the two are perpendicular to each other, when the ring-shaped frame needs to translate in the horizontal plane where it is located, the relative position between the ring-shaped frame and the aircraft can be further finely adjusted by adjusting the first moving seat and the second moving seat in two orthogonal directions respectively;

[0022] 3. By setting a near-interface simulation plate below the support gimbal, the upper surface of the near-interface simulation plate can be used to install different interface modules, and the near-interface simulation plate is a test plate that can be electrically adjusted in height and inclination angle. The near-interface simulation plate can install ground modules, building modules, or water surface modules, and other different interface modules, which are respectively used to simulate different scenarios that the aircraft may encounter in actual flight, such as near-ground take-off, building flow effect, or coupling of the downward shock wave and the “water surface effect”. The combination of the annular frame and the near-interface simulation plate can realize the coupled attitude disturbance simulation of the aircraft under the dual action of wind disturbance and near-interface, further unlock more complex wind field scenarios, and change the experimental device from simulating isolated “wind disturbance” or “interface effect” to simulating more realistic secondary complex disturbance generated after strong coupling of “wind and interface”, and directly measuring the attitude response of the aircraft to this;

[0023] 4. By installing the telescopic wind pipes on the annular frame, and the annular frame being movably installed on the fixed mounting frame as a Stewart platform, the entire experimental device is more compact under the premise of meeting various test functions. The telescopic wind pipes on the annular frame can simulate various complex wind field scenarios for the aircraft on the support gimbal in a relatively limited space, and each independent telescopic wind pipe can be telescoped and deflected relative to the annular frame, so that the distance between the air outlet end of each telescopic wind pipe and the aircraft can be independently adjusted, thereby accurately controlling the effect and influence of each airflow forming a wind field on the aircraft. Compared with other wind field simulation devices, the combination of the annular frame and multiple independent telescopic wind pipes can greatly reduce the demand for fans, effectively reduce the demand for equipment such as fans under the premise of being able to realize various complex wind fields, and can also flexibly adjust the angle, position of the annular frame relative to the aircraft, and the angle and position of the airflow exerted by each air outlet end on the aircraft, so that the entire experimental device is more intelligent and efficient;

[0024] 5. By setting two or more annular frames, the aircraft can be fully surrounded in the vertical direction. The telescopic wind pipes on each annular frame can correspond to different height positions of the aircraft, so as to divide the wind field and perform partitioned blowing action on the aircraft, so that the wind field can blow the corresponding position of the aircraft in multiple regions in the vertical direction, thereby being able to simulate more realistic wind field scenarios and simulate complex wind fields more realistically. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the entire experimental device according to an embodiment of the present application;

[0026] Figure 2 is a structural schematic diagram of the inside of the fixed mounting frame according to an embodiment of the present application;

[0027] Figure 3 is a partial schematic view of a support holder structure according to an embodiment of the present application;

[0028] Figure 4 is a partial schematic view of a ring frame structure according to an embodiment of the present application;

[0029] Figure 5 is a top view schematic view of a ring frame and an aircraft structure according to an embodiment of the present application;

[0030] Figure 6 is Figure 5 an enlarged schematic view at A.

[0031] Legend: 1, support holder; 11, spherical universal joint; 12, clamping frame; 13, lifting member; 2, ring frame; 21, telescopic air pipe; 211, distance measuring member; 212, fairing; 22, connecting rod; 23, driven gear; 24, rotary driving member; 25, driving gear; 26, air pipe telescopic member; 27, telescopic driving member; 3, fixed mounting frame; 31, support leg; 32, top frame; 33, control unit; 34, connecting platform; 35, first moving seat; 36, second moving seat; 4, near interface simulation board; 41, interface module; 5, aircraft. DETAILED DESCRIPTION

[0032] The following will be described in detail with reference to the accompanying drawings. Figures 1-6 The present application will be further described in detail.

[0033] An experimental device for simulating the attitude of an aircraft with wind disturbance is disclosed according to an embodiment of the present application, with reference to Figures 1 to 3The experimental device for simulating the attitude of an aircraft with wind disturbance includes a support holder 1, a ring-shaped frame 2, a fixed mounting frame 3 and a near-interface simulation plate 4. The support holder 1 is used to place the aircraft 5, and the support holder 1 is placed on the ground through a tripod support at the bottom, so that the support holder 1 is away from the working ground. The fixed mounting frame 3 is a frame assembled and spliced by a plurality of fixed frames. The fixed mounting frame 3 is placed on the ground at the working position through four supporting legs 31 of the same length. The four supporting legs 31 are fixed with a horizontal top frame 32 above, and the two supporting legs 31 adjacent to each other among the four supporting legs 31 are connected and fixed through the cross-shaped reinforcing rib plate, so that the four supporting legs 31 and the top frame 32 form a hollow and vertically placed frame cover. The support holder 1, the ring-shaped frame 2 and the near-interface simulation plate 4 are arranged in the frame cover of the fixed mounting frame 3. The fixed mounting frame 3 is also fixed with a control unit 33, and the panel of the control unit 33 can be used by the experimenters to adjust various experimental parameters. In order to facilitate the disassembly and assembly of the fixed mounting frame 3, the supporting legs 31, the top frame 32 and the reinforcing rib plate can be detachably connected through fastening bolts. In order to facilitate the disassembly and adjustment of the aircraft 5 by the experimenters, no reinforcing rib plate is arranged between the two supporting legs 31, and the space formed between the two supporting legs 31 can be used by the experimenters to enter and exit the fixed mounting frame 3, and the stability of the fixed mounting frame 3 is not affected.

[0034] Referring to Figure 3 and Figure 4In the embodiment of the present application, the support holder 1 is configured as a three-degree-of-freedom spherical holder containing sensors, and includes a high-precision spherical joint 11 at the center. A clamping frame 12 is fixed to the top of the spherical joint 11, and the clamping frame 12 can be used to clamp and fix the aircraft 5. In order to reduce the friction between the spherical joint 11 and the support holder 1 itself, the spherical joint 11 can be provided as a hollow sphere, and a smooth coating such as a high-density polyethylene coating or a ceramic coating is sprayed on the surface of the spherical joint 11, or the spherical joint 11 is directly selected as a magnetic suspension joint or an air suspension joint, so as to realize extremely low friction and reduce the influence of the friction of the spherical joint 11 on the experimental results. The position corresponding to the spherical joint 11 of the support holder 1 is integrated with three orthogonal optical encoders (not shown), which are used to non-contact and high-precision real-time measurement of the pitch, roll and yaw angles of the aircraft 5 model, and output the final experimental signal. The three orthogonal optical encoders are electrically connected with the control unit 33. The pitch angle encoder should be installed on the transverse axis of the spherical joint 11 (i.e. the horizontal axis of the left-right direction of the unmanned aerial vehicle), which is used to detect the rotation angle of the unmanned aerial vehicle around the axis. The position needs to ensure that the rotation axis of the encoder is completely aligned with the pitch axis of the joint, so as to capture the pitch direction deviation caused by the air flow disturbance. The pitch angle encoder needs to be integrated at the root of the rotation axis of the spherical joint 11 or near the bearing, so as to directly capture the axial rotation angle. The roll angle encoder needs to be installed on the longitudinal axis of the spherical joint 11 (i.e. the horizontal axis of the front-back direction of the unmanned aerial vehicle), which is used to measure the roll angle of the unmanned aerial vehicle around the axis. The axis should be perpendicular to the pitch axis and as close as possible to the geometric center of the joint, so as to reduce the measurement error caused by the gravity center deviation. The roll angle encoder can also be integrated at the root of the rotation axis of the spherical joint 11 or near the bearing. The yaw angle encoder should be arranged on the vertical axis of the spherical joint 11 (i.e. the rotation axis penetrating up and down), which is used to monitor the rotation of the unmanned aerial vehicle around the vertical axis. The rotation axis of the yaw angle encoder should coincide with the geometric center of the spherical joint 11, so as to avoid the measurement error caused by the gravity center deviation. The position needs to ensure that the encoder axis coincides with the yaw axis of the joint, while avoiding the coupling interference with the pitch and roll axes.

[0035] The rotation axes of the three encoders must be strictly perpendicular to each other, so as to ensure the independent measurement of each degree of freedom and avoid angle coupling. Meanwhile, the geometric center of the spherical joint 11 should coincide with the gravity center of the aircraft 5, otherwise the air flow disturbance may generate additional moment due to the gravity center deviation, which affects the attitude measurement accuracy. The specific selection of the support holder 1 can be made according to the actual experimental requirements. The holder is a very mature existing technology, as long as it can meet the high-precision attitude monitoring of the aircraft 5 under wind disturbance, and details are not described herein.

[0036] Further, the annular frame 2 is arranged around the support holder 1 as a whole, in the embodiment of the present application, the annular frame 2 is preferably a ring-shaped frame with a circular horizontal section, in the initial state, the annular frame 2 is horizontally placed, and the support holder 1 is located at the center position inside the annular frame 2, in order to reduce the weight of the annular frame 2, the annular frame 2 can be preferably made of carbon fiber composite material pipe, so that the annular frame 2 has very high specific strength and specific stiffness, and is light in weight, which can reduce the load of the components supporting the annular frame 2 and the motion inertia of the whole system, and realize faster dynamic response. A plurality of telescopic air pipes 21 are arranged on the annular frame 2 at intervals, the telescopic air pipes 21 can be made of light aluminum alloy or carbon fiber material, which effectively reduces the weight of the telescopic air pipes 21, and the telescopic air pipes 21 can be made of a plurality of sections of air pipes connected end to end and sleeved layer by layer, and each section of independent air pipe in the same telescopic air pipe 21 is in sliding connection with the adjacent independent air pipe, so that the length of each telescopic air pipe 21 can be freely adjusted. The air outlet end of each telescopic air pipe 21 is directed to the center of the annular frame 2, that is, to the direction of the support holder 1, and the air inlet end of each telescopic air pipe 21 can be connected with a high-pressure centrifugal fan or other air supply equipment, and each telescopic air pipe 21 is connected with an independent air supply equipment, so that each telescopic air pipe 21 has the ability to independently provide test airflow. Because the circular frame has perfect 360-degree symmetry, when simulating airflow from any direction, the interference of the annular frame 2 itself to the airflow is consistent, and no additional deviation caused by shape asymmetry is introduced, which is crucial for obtaining pure test data; and when simulating rotating wind field or rotating the frame itself, the control algorithm of the circular frame is simpler and more intuitive; at the same time, the stress distribution of the circular structure is more uniform when bearing the force from the inside (reaction force of the telescopic air pipe 21) and the outside.

[0037] Referring to Figure 4 and Figure 5, the telescopic air pipes 21 on the annular frame 2 cover at least four directions of front, back, left and right on the horizontal plane where the aircraft 5 is located, so as to simulate the airflow from the four directions of front, back, left and right blowing to the aircraft 5. In order to simulate the wind from any direction, form a rotating airflow and simulate the narrow pipe effect, at least four orthogonal directions (front, back, left and right) and four oblique directions (front left, front right, back left and back right) control capabilities are required on the horizontal plane where the aircraft 5 is located, therefore, eight simulation air pipes are required in the horizontal direction, but considering the overall size of the annular frame 2, in the embodiment of the present application, the telescopic air pipes 21 on the same annular frame 2 are preferably six, if the nose direction of the aircraft 5 is 0 degrees, then the six telescopic air pipes 21 on the same annular frame 2 are respectively located at 0° (front), 60°, 120°, 180° (back), 240° and 300° positions, that is, the six telescopic air pipes 21 are distributed at the positions of the six corners of the inscribed hexagon of the annular frame 2, the oblique airflows blown by the telescopic air pipes 21 located on the left and right sides of the aircraft 5 can be blown to the side of the aircraft 5 after forming a confluence, or can act on the side of the aircraft 5 respectively with oblique airflows. In other embodiments of the present application, in order to ensure that the left and right sides of the aircraft 5 can be subjected to the airflow blown from the left and right directions, a telescopic air pipe 21 in the forward direction can be added between the two oblique telescopic air pipes 21 on the left and right sides respectively, so that the resolution of the simulated wind field is higher and the simulation effect is more realistic.

[0038] To further improve the resolution of the simulated wind field, the annular frame 2 comprises at least two layers and is spaced apart in the vertical direction, and the adjacent two annular frames 2 are connected as a whole by the connecting rod 22. In the embodiment of the present application, the annular frame 2 is preferably two layers distributed in the vertical direction, and six telescopic air pipes 21 are installed on each layer of the annular frame 2, and the telescopic air pipes 21 on the upper and lower annular frames 2 are one-to-one corresponding in the vertical direction. In the vertical direction, the annular frame 2 in the upper layer corresponds to the position of the upper half of the fuselage and the rotor of the aircraft 5, and the six telescopic air pipes 21 on the upper annular frame 2 are mainly responsible for simulating the high-altitude airflow, the sinking airflow, and the disturbance to the upper half of the aircraft 5; the annular frame 2 in the lower layer corresponds to the position of the lower half of the fuselage and the landing gear, and the six telescopic air pipes 21 on the lower annular frame 2 are mainly responsible for simulating the ground wind, the rising airflow, and the disturbance to the lower half of the aircraft 5 and the landing gear. This "double-layer six-pipe" layout provides strong three-dimensional wind field shaping capability and can meet most complex wind field scenarios. In other embodiments of the present application, the number of layers of the annular frame 2 in the vertical direction can also be increased according to the specific size of the aircraft 5 participating in the experiment, so that in the vertical direction, at least one annular frame 2 corresponds to the position of the upper half of the fuselage and the rotor of the aircraft 5, and at least one annular frame 2 corresponds to the position of the lower half of the fuselage and the landing gear of the aircraft 5, so that the three-dimensional wind field formed by all the telescopic air pipes 21 on the annular frame 2 can completely surround the aircraft 5 to be tested, and the full surrounding of the aircraft 5 in the vertical direction can be realized, and the telescopic air pipes 21 on each layer of the annular frame 2 can correspond to different height positions of the aircraft 5 respectively, so that the wind field can be partitioned and the aircraft 5 can be partitioned and blown, so that the wind field can blow the corresponding position of the aircraft 5 in multiple areas in the vertical direction, thereby being able to simulate more realistic wind field scenarios and more realistically simulate complex wind fields.

[0039] Further, with reference to Figure 5 and Figure 6In order to improve the flexibility of the telescopic air duct 21, each telescopic air duct 21 is rotatably connected to the annular frame 2 through a rotating shaft, the rotating shaft is distributed on both sides of the telescopic air duct 21, one end of the rotating shaft is fixed on the annular frame 2, and the other end is rotatably connected to the side wall of the telescopic air duct 21, or one end of the rotating shaft is fixed on the side wall of the telescopic air duct 21, and the other end is rotatably connected to the annular frame 2, so that the telescopic air duct 21 can rotate relative to the annular frame 2, and the rotating axis of each telescopic air duct 21 coincides with or is parallel to the tangent direction of the hinge position of itself and the annular frame 2, so that the telescopic air duct 21 can still face the aircraft 5 when the pitch angle is adjusted. The telescopic air duct 21 divides the complete annular frame 2 into multiple sections, each section of the annular frame 2 can be fixed as a whole through a fixed connection frame, or can be directly connected as a whole by the telescopic air duct 21, as long as the annular frame 2 is a horizontal section in the form of a circular frame. In order to drive the telescopic air duct 21 to rotate, a driven gear 23 is coaxially fixed on the rotating shaft on one side of the telescopic air duct 21, and a rotating drive 24 is fixed at a position corresponding to each telescopic air duct 21 of the annular frame 2. The rotating drive 24 is preferably a micro servo motor, and all rotating drives 24 are electrically connected to the control unit 33. A drive gear 25 is coaxially fixed on the output shaft of the rotating drive 24, the drive gear 25 corresponds to and engages with the driven gear 23, the rotating drive 24 can drive the corresponding telescopic air duct 21 to rotate through the engaged drive gear 25 and driven gear 23, thereby flexibly adjusting the pitch angle of the telescopic air duct 21. At the same time, an air duct telescopic member 26 is fixed on the outer wall of each telescopic air duct 21, the air duct telescopic member 26 is preferably a micro electric cylinder, and is electrically connected to the control unit 33. The output shaft of the air duct telescopic member 26 is parallel to the length direction of the corresponding telescopic air duct 21, the body of the air duct telescopic member 26 is fixed to the outer wall of the independent single-section air duct hinged to the annular frame 2, and the output shaft end of the air duct telescopic member 26 is fixed to the outer wall of the smallest diameter independent air duct of the telescopic air duct 21 through a connecting block. When the output shaft of the air duct telescopic member 26 telescopes, it can drive the corresponding telescopic air duct 21 to telescope.

[0040] When simulating different wind field scenarios, the distance between the air outlet end of each telescopic air duct 21 and the aircraft 5 can be different. To more accurately adjust the actual distance between the air outlet end of each telescopic air duct 21 and the aircraft 5, the outer wall of the air outlet end of each telescopic air duct 21 is fixed with a distance measuring piece 211, which is preferably a micro laser distance measuring module. The emission end of the distance measuring piece 211 is oriented in the same direction as the air outlet end of the corresponding telescopic air duct 21, i.e., towards the center of the annular frame 2. The distance measuring piece 211 is electrically connected to the control unit 33. The distance measuring piece 211 can monitor the distance between the air outlet end of the corresponding telescopic air duct 21 and the aircraft 5 in real time through laser ranging principle, and feed back real-time signals to the control unit 33. The control unit 33 automatically adjusts the length of the corresponding telescopic air duct 21 according to the distance signal, in combination with the characteristics of the wind field to be simulated. Meanwhile, the air outlet end of each telescopic air duct 21 is detachably connected with a fairing 212. The detachable connection can be preferably a clamping connection. To facilitate the simulation of different air flows, the fairing 212 can be designed with air outlets of various sizes and shapes, such as flared, constricted or straight, etc. so that the air flow becomes more stable after passing through the fairing 212. Of course, the fairing 212 can also make the passing air flow become more turbulent, which can be achieved by changing the shape of the fairing 212. To be able to dynamically control the orientation of the air outlet end of each telescopic air duct 21 in real time through the algorithm software pre-written in the control unit 33, a micro camera is fixed on the outer wall of the end corresponding to the distance measuring piece 211 of each telescopic air duct 21. The camera is also electrically connected to the control unit 33. The orientation of the camera is consistent with the air outlet orientation of the telescopic air duct 21. The camera transmits the real-time images monitored to the control unit 33 for analysis. The control unit 33 adjusts the air outlet orientation of each telescopic air duct 21 according to the preset algorithm software, and further adjusts the orientation and telescopic length of the telescopic air duct 21 in combination with the real-time images of the air outlet end direction of the corresponding telescopic air duct 21 monitored by the camera. The specific control logic is not described here.

[0041] Referring to Figures 2 to 5The connecting platform 34 is arranged on the top frame 32, the top surface of the annular frame 2 in the uppermost layer is connected with the connecting platform 34 through a plurality of telescopic driving members 27, the telescopic driving members 27 are preferably telescopic electric cylinders, the bodies of all the telescopic driving members 27 are hinged with the connecting platform 34, the output shafts of the telescopic driving members 27 are hinged with the top surface of the annular frame 2, in the embodiment, the number of the telescopic driving members 27 is preferably 6, the annular frame 2 and the six telescopic driving members 27 jointly constitute an inverted “Stewart platform”, the six telescopic driving members 27 are electrically connected with the control unit 33, through the mutual telescopic cooperation between the six telescopic driving members 27, the annular frame 2 can be driven to ascend and descend relative to the supporting holder 1 and to deflect, and can also be horizontally translated in a small range, thereby a more complex wind field scene can be simulated.

[0042] In the actual experiment process, the rotor of the aircraft 5 can not rotate or directly replace the aircraft 5 with a prosthesis to exclude the power impact, and purely study the aerodynamic attitude of the aircraft 5. When the aircraft 5 is clamped on the support holder 1, the sensors inside the support holder 1 can monitor the key attitude signals of the aircraft 5 in three degrees of freedom of pitch, roll and yaw in real time. The multiple telescopic air pipes 21 around the aircraft 5 can at least spray simulated air flow to the aircraft 5 from multiple directions such as front, back, left and right of the aircraft 5, and the annular frame 2 and the telescopic drive 27 together form a Stewart platform. When all the telescopic drives 27 are synchronously telescoped, the annular frame 2 can be driven to ascend and descend as a whole while keeping its own attitude unchanged. When the telescopic drive 27 on one side is elongated and the corresponding telescopic drive 27 on the other side is elongated, the annular frame 2 can be driven to deflect to one side by a certain amplitude. Both of them can indirectly adjust the blowing angle of each telescopic air pipe 21 to the aircraft 5 by changing the position or deflection angle of the annular frame 2, so as to simulate various wind field scenes for the aircraft 5. From the traditional wind tunnel "global uniform wind", it is upgraded to "local, dynamic, high-resolution vector wind field" which can be arbitrarily shaped and moved in space. Instead of "one fan" beside "one platform", the annular frame 2 itself has the ability to generate controllable wind field. The telescopic air pipes 21 are concentratedly installed on the annular frame 2, and the annular frame 2 as a Stewart platform is movably installed on the fixed mounting frame 3, so that the whole experimental device is more compact in structure under the premise of meeting various test functions. The telescopic air pipes 21 on the annular frame 2 can simulate various complex wind field scenes for the aircraft 5 on the support holder 1 in a relatively limited space, and each independent telescopic air pipe 21 can be telescoped and deflected relative to the annular frame 2, so that the distance between the air outlet end of each telescopic air pipe 21 and the aircraft 5 can be adjusted independently, thereby accurately controlling the effect and influence of each air flow forming the wind field on the aircraft 5. Compared with other wind field simulation devices, the annular frame 2 combined with multiple independent telescopic air pipes 21 can greatly reduce the demand for fans. Under the premise of being able to realize various complex wind fields, the demand for fans and other equipment can be effectively reduced. Moreover, according to the actual experimental requirements, the angle, position of the annular frame 2 relative to the aircraft 5 and the angle and position of each air outlet end exerting the air flow on the aircraft 5 can be flexibly adjusted, so that the whole experimental device is more intelligent and efficient.

[0043] Further, the connecting platform 34 is connected with the fixed mounting frame 3 through a first adjusting assembly and a second adjusting assembly, wherein the first adjusting assembly comprises a first moving seat 35 and a pair of ball screw assemblies, the ball screw assemblies corresponding to the first moving seat 35 are arranged in the first moving seat 35, the second adjusting assembly comprises a second moving seat 36 and another pair of ball screw assemblies, the ball screw assemblies corresponding to the second moving seat 36 are arranged in the second moving seat 36, and the two pairs of ball screw assemblies are respectively driven to rotate by a high-precision servo motor, and the two high-precision servo motors are electrically connected with the control unit 33. The bottom of the first moving seat 35 is fixed with the top of the connecting platform 34, the first moving seat 35 is horizontally slidably connected with the bottom of the second moving seat 36, the second moving seat 36 is horizontally slidably connected with the bottom of the top frame 32, and the sliding direction of the first moving seat 35 is perpendicular to the sliding direction of the second moving seat 36, the first moving seat 35 and the second moving seat 36 are respectively driven to move by the corresponding ball screw assemblies, and the combination of the ball screw assembly and the screw block is the most common mechanical structure, which is used to drive the first moving seat 35 and the second moving seat 36 to horizontally slide in the perpendicular directions, and the detailed structure is not described here. When the first moving seat 35 slides relative to the second moving seat 36, the first moving seat 35 can drive the annular frame 2 to translate in the horizontal direction through the connecting platform 34 and the telescopic driving piece 27; when the second moving seat 36 moves relative to the top frame 32, the second moving seat 36 can drive the annular frame 2 to translate in the horizontal direction through the first moving seat 35, and the direction is perpendicular to the direction when the first moving seat 35 slides relative to the second moving seat 36, when the first moving seat 35 and the second moving seat 36 move simultaneously, the annular frame 2 can be driven to move in any direction in the horizontal direction, further improving the flexibility of the annular frame 2.

[0044] In order to make the adjustment of the whole simulated wind field more convenient and flexible, the top of the first moving seat 35 is connected with the bottom of the connecting platform 34, the first moving seat 35 is horizontally slidably connected with the bottom of the second moving seat 36, the second moving seat 36 is horizontally slidably connected with the fixed mounting frame 3, and the sliding direction of the first moving seat 35 is perpendicular to the sliding direction of the second moving seat 36, the annular frame 2 can slide along the second moving seat 36 in a horizontal direction through the connecting platform 34 and the first moving seat 35, and when the first moving seat 35 slides along the second moving seat 36 in another horizontal direction through the fixed mounting frame 3, the annular frame 2 also moves along the first moving seat 35, and the moving directions of the two are perpendicular to each other, when the annular frame 2 needs to translate in the horizontal plane where it is located, it can be adjusted in two orthogonal directions respectively through the first moving seat 35 and the second moving seat 36, and the relative position between the annular frame 2 and the aircraft 5 can be further finely adjusted.

[0045] "interface" refers to the boundary between two different media or regions of different physical properties, in the embodiments of the present application, "near-interface" specifically refers to the region where the aircraft 5 flies very close to a macroscopic physical interface, such as the solid surface of an airport runway, grassland, mountain slope, urban street, building roof, etc., or the liquid surface of the sea, lake, river, reservoir, etc., or the discontinuous and non-smooth surface of the forest canopy, large recycling net, etc.

[0046] The existence of "near-interface" will change the basic aerodynamic characteristics, for example, the classic ground effect: when the aircraft 5 is close to the interface, the air pressure below it (especially the rotor downwash or the wing lower surface) will increase significantly, forming an "air cushion", which will make the aircraft 5 obtain additional lift, with the same thrust, the aircraft will "float" higher, when there is a crosswind, the "air cushion" will be blown asymmetrically, the air cushion effect on the windward side will be weakened, and the air cushion effect on the leeward side will be enhanced, which will directly generate a rolling moment, even without other disturbances, the aircraft 5 must tilt at an angle to balance, so the experiment is to accurately measure the inherent rolling moment generated by the coupling of "wind + ground effect". The existence of "near-interface" will change the structure of the wind field itself, in the open sky, the wind may be relatively uniform, but when this wind blows to the near-interface region, it will change dramatically, for example, the wind speed close to the ground is zero, gradually increasing upwards, forming a wind speed gradient (wind shear), the upper and lower parts of the aircraft 5 will receive different wind speeds, which will generate a pitching moment, or the wind encounters obstacles such as hills, buildings, etc., generating rising airflows, descending airflows, vortices, acceleration zones, etc., once the aircraft 5 enters these areas, it will no longer be subjected to uniform wind, but highly distorted and unstable local wind field, which will cause severe attitude changes. The existence of "near-interface" will induce secondary effect physical phenomena, the strong downwash airflow of the aircraft 5 (especially the rotor) impacting the interface, such as the reverse vortex ring generated by impacting the water surface, will seriously damage the airflow stability of the rotor disc, leading to severe lift pulsation and attitude instability. The existence of "near-interface" will also change the dynamic response characteristics of the aircraft 5, in the near-interface region, the "viscosity" and "compressibility" of the air are more pronounced, when the aircraft 5 makes rapid attitude changes, the air between the aircraft body and the interface will be "squeezed" and "sucked", generating additional air damping moments, which will make the attitude response of the aircraft 5 in the near-interface region more "sluggish" or "heavy" than in the high altitude.

[0047] Therefore, in order to simulate the "near interface" effect, the near interface simulation plate 4 is correspondingly arranged below the support holder 1. The bottom of the near interface simulation plate 4 is provided with two pairs of telescopic cylinders. The two telescopic cylinders of the same pair support the near interface simulation plate 4 in an "eight" shape and are electrically connected with the control unit 33. The top of the two telescopic cylinders is hinged with the near interface simulation plate 4, and the bottom is hinged with a fixing seat which is in contact with the ground. The two telescopic cylinders can drive the near interface simulation plate 4 to deflect and lift relative to the support holder 1 in the process of telescoping. The upper surface of the near interface simulation plate 4 is a flat plane, which can be used to install different interface modules 41, such as a ground module for simulating the ground, a water surface module for simulating the water surface, or a floor module for simulating the floor, which are used to correspondingly simulate different wind field interfaces. These different interface modules 41 can be manufactured according to the actual needs of the experimental site. The floor module can be made of plastic material, which effectively reduces the load of the near interface simulation plate 4. Correspondingly, the upper surface of the near interface simulation plate 4 is provided with a clamping piece for clamping each type of interface module 41. The clamping piece can be a limiting plate with a corresponding shape, which is then fixedly connected through a fastening bolt. The clamping method of the clamping piece to the interface module 41 is not fixed, as long as it can meet the requirements of fixing the interface module 41 and facilitating the disassembly and assembly of the interface module 41. In order to cooperate with the movement of the near interface simulation plate 4, the bottom of the support holder 1 is connected with a lifting piece 13. The lifting piece 13 can also be preferably a telescopic cylinder. The lifting piece 13 can drive the support holder 1 to vertically lift. The lifting piece 13 is also electrically connected with the control unit 33. In the embodiment of the present application, the support rod below the support holder 1 penetrates the near interface simulation plate 4. The position of the support rod below the support holder 1 corresponding to the near interface simulation plate 4 can be provided with a through hole with a proper size, so that the near interface simulation plate 4 will not interfere with the support rod below the support holder 1 when lifting or small deflection, and at the same time, the near interface simulation plate 4 can simulate the near interface effect. In other embodiments of the present application, the support rod below the support holder 1 can be changed from the vertical state to the inclined state diverging towards the periphery of the support holder 1. At this time, the support rod below the support holder 1 is no longer connected with the lifting piece 13 downward, but is directly diverged to the periphery and is fixedly connected with the four supporting legs 31, so that the support rod below the support holder 1 no longer penetrates the near interface simulation plate 4. At this time, the near interface simulation plate 4 does not need to be perforated, and the integrity of the near interface simulation plate 4 can be maintained. The support rod below the support holder 1 can be changed to a telescopic sleeve rod with a locking structure, thereby realizing the lifting function of the support holder 1.

[0048] By setting the near-interface simulation board 4 below the supporting gimbal 1, the upper surface of the near-interface simulation board 4 can be used to install different interface modules 41, and the near-interface simulation board 4 is a test board that can be electrically adjusted in height and inclination angle. The near-interface simulation board 4 can be installed with ground modules, building modules or water surface modules and other different interface modules 41, which are respectively used to simulate different scenarios that the aircraft 5 may encounter in actual flight, such as near-ground take-off, building flow effect, or coupling of the downwash shock wave and the “water surface effect”. The annular frame 2 and the near-interface simulation board 4 in combination can realize the coupled attitude disturbance simulation of the aircraft 5 under the dual action of wind disturbance and near-interface, further unlock more complex wind field scenarios, so that the experimental device changes from simulating isolated “wind disturbance” or “interface effect” to simulating more realistic secondary complex disturbance generated after strong coupling of “wind and interface”, and directly measuring the attitude response of the aircraft 5 to it.

[0049] In order to show the cooperation between the components of the experimental device in the embodiments of the present application under different simulated wind field scenarios, the following selects several typical wind field scenarios for demonstration:

[0050] A typical small and medium-sized unmanned aerial vehicle (wheelbase 450mm, rotor diameter about 25cm) is taken as an experimental object (i.e. the aircraft 5) to set and determine the basic specifications of the entire system.

[0051] First, the diameter of the annular frame 1 is 2.5 m, and the size of the annular frame 1 is large enough to ensure that the outlet end of the telescopic air duct 21 has sufficient safety and flow field development distance (about 1 m) from the measured aircraft 5 (about 0.5 m wide) in the contracted state, while not making the entire device too large, which is convenient for indoor installation. The stroke of the six telescopic driving members 27 is 1 m, the maximum thrust is 5000 N, and the highest push speed is 0.5 m / s, which ensures that there is enough stroke and speed to achieve a large range and high dynamic attitude and position simulation. The stroke of the first moving seat 35 corresponding to the ball screw pair is ±1 m, and the stroke of the second moving seat 36 corresponding to the ball screw pair is also ±1 m, which can realize the large range horizontal translation of the annular frame 2, and is used for simulating the aircraft maneuvering scene. The telescopic stroke of each telescopic air duct 21 is 0.5 m, and the diameter of the air outlet end of the telescopic air duct 21 is 150 mm. The independent fan corresponding to each telescopic air duct 21 is a high-pressure centrifugal fan, the maximum power of the independent fan is 2.2 kW, and the maximum wind speed (at the air outlet) is 40 m / s. The high-pressure centrifugal fan can provide concentrated and high-pressure airflow with strong penetration and is suitable for accurate shaping of airflow. The power and wind speed are sufficient to simulate the wind speed in extreme weather. The size of the near-interface simulation plate 4 is a square platform of 3 m*3 m, the lifting stroke of the near-interface simulation plate 4 is 1.5 m, the deflection angle is ±30°, and the near-interface simulation plate 4 is made of a steel structure base plus replaceable aluminum alloy or composite material panel. Similarly, with the nose direction of the aircraft 5 as 0 degrees, the six telescopic air ducts 21 on the same annular frame 2 are located at 0° (front), 60° (left front), 120° (left rear), 180° (rear), 240° (right rear), and 300° (right front), i.e. the six telescopic air ducts 21 are distributed at the six corners of the inscribed hexagon in the annular frame 2.

[0052] The vertical distance between the upper and lower annular frames 2 is 0.6 m, which ensures that the airflow of the telescopic air duct 21 on the upper annular frame 2 mainly impacts the wing, the upper surface of the fuselage, and the area above the rotor disc of the aircraft 5; and the airflow of the telescopic air duct 21 on the lower annular frame 2 mainly impacts the lower part of the fuselage, the landing gear, and the area below the rotor disc. The reserved distance between the upper and lower annular frames 2 can provide a certain independent development space for the airflow ejected by each layer of telescopic air duct 21, avoiding excessive mixing of the upper and lower airflows before reaching the aircraft 5, so as to independently control the aerodynamic force applied to the upper and lower parts of the aircraft 5, which is the basis for realizing the vertical wind shear effect. The reserved space makes it easy to set a significant wind speed difference (for example, 20 m / s for the upper layer and 10 m / s for the lower layer) within this distance, forming a clear vertical wind shear profile, and the spacing between the upper and lower annular frames 2 also reserves sufficient space for attitude changes of the aircraft 5.

[0053] About distance correction: the distance measuring element 211 corresponding to the outflow end of each telescopic air duct 21 is used for real-time monitoring, and the target of the control system is not "to extend XX millimeters", but "to maintain the distance between the outflow end of the telescopic air duct 21 and the aircraft 5 as XX millimeters". When the ring frame 2 moves, the telescopic air duct 21 will automatically extend or retract to compensate for the change in position, and always maintain the set relative distance.

[0054] About wind speed correction: a hot-wire anemometer (not shown) is installed on the outer wall of the outflow end of each telescopic air duct 21, and the target of the control system is not "fan power XX%", but "to maintain the wind speed of the outflow end of the telescopic air duct 21 as XX meters per second", which can compensate for the change in pressure loss caused by the telescopic air duct 21.

[0055] Before entering the specific simulation wind field scene, a general PID feedback correction controller formula is defined, which will be used as the basis for "real-time feedback corrector" in all scenarios. For any controlled quantity (such as wind speed, position), its control output u(t) is determined by the following formula:

[0056]

[0057] Where, : the output of the controller at time t (for example, the voltage increment of the fan motor);

[0058] : the error at time t, which is the difference between the target value and the actual value; : proportional gain coefficient, which determines the response strength to the current error; : integral gain coefficient, used to eliminate steady-state error; : differential gain coefficient, used to predict future errors and suppress system oscillation.

[0059] Simulation of basic steady wind field and unsteady wind field (single wind field action):

[0060] The annular frame 2 is stationary in the center position, the height is flush with the aircraft 5, the aircraft 5 is located between the upper and lower annular frames 2, the near interface simulation board 4 is lowered to the lowest position and kept horizontal, and all the telescopic wind pipes 21 on the upper and lower annular frames 2 are kept in a horizontal posture with a pitch angle of 0°. When simulating a left constant wind field, the telescopic wind pipes 21 at positions of 60° (left front) and 120° (left rear) in the upper and lower telescopic wind pipes 21 blow wind to the aircraft 5 at a wind speed of 20 m / s, and the corresponding outflow ends are extended to 0.8 m away from the left wing or fuselage surface of the aircraft 5, at this time, the independent fan power is about 60%, other wind pipes do not blow wind and are kept in a contracted state. When simulating an unsteady wind field, a gust is set to appear in front while the left constant wind field exists, at this time, the left constant wind field is kept, at the same time, the telescopic wind pipe 21 at a position of 0° (directly in front) blows wind, the outflow end is also 0.8 m away from the nose, and the wind speed is linearly increased from 0 m / s to 30 m / s within 0.2 s, maintained for 0.8 s, and then decreased to 0 m / s within 0.2 s, and the cycle is repeated.

[0061] Corresponding target trajectory generation under unsteady wind field (gust velocity profile):

[0062]

[0063] wherein, : target wind speed at time t; V2: peak value of gust (for example, 30 m / s); : duration of gust (for example, 1.2 s). Thus, a smooth "bell-shaped" velocity curve starting from 0, reaching the peak value and returning to 0 can be generated, avoiding infinite acceleration caused by ideal step and being more in line with physical reality.

[0064] Corresponding fan power control formula under unsteady wind field (with feedforward):

[0065]

[0066] wherein, : final power applied to the fan motor; : a lookup table or a polynomial function, which gives a basic steady-state power value according to the target wind speed The table is obtained by pre-experimental calibration; : equivalent rotational inertia coefficient of the fan; : acceleration of the target wind speed; : output of the PID feedback corrector, used to compensate for model inaccuracy and external disturbance.

[0067] Simulation of atmospheric turbulent field (single wind field action):

[0068] The annular frame 2 is subjected to random motion in X, Y, Z directions with a frequency of 5 Hz and an amplitude of ±5 cm, while the near-field simulation board 4 is lowered to the lowest position and kept horizontal, all the 12 telescopic wind pipes 21 in the upper and lower layers are subjected to high-frequency (e.g. 5-10 Hz) random fluctuation with an average wind speed (e.g. 10 m / s) as the center and according to a preset turbulent energy spectrum, and the angles and telescopic distances of all the 12 telescopic wind pipes 21 are also subjected to small-range, non-synchronous random disturbance around the initial set values, for example, ±5° and ±10 cm random disturbance around the initial set values (horizontal, 1 m).

[0069] The formula for generating corresponding turbulent wind speed under atmospheric turbulent field (harmonic synthesis method based on the spectrum of Dryden):

[0070]

[0071] wherein, : the turbulent fluctuation velocity component generated at time t; : the amplitude of the nth harmonic, which is determined by the Dryden turbulent energy spectrum density function, , : the Dryden spectrum formula, : the frequency of the nth harmonic; : a random phase uniformly distributed in the interval [0, ]. The controller independently runs this formula for each of the 12 telescopic wind pipes (uses different random phases φ n ), thereby synthesizing a spatially correlated and temporally random three-dimensional turbulent field.

[0072] Simulation of extreme meteorological dynamic process under downburst (single wind field action):

[0073] At T=0s, the annular frame 2 is located 1m in front of the aircraft. At T=2s, it moves to 1m directly above the aircraft 5. At T=4s, it moves to 1m behind the aircraft 5. The near-interface simulation plate 4 remains at its lowest position and horizontal. At this time, the near-interface simulation plate 4 does not participate in the simulation. The relevant parameters of the telescopic duct 21 are as follows: During T=0-2s, the simulation encounters a headwind. At this time, the annular frame 2 is located in front of the aircraft 5. The three sets of telescopic ducts 21 located at 0° (directly in front), 60° (left in front), and 300° (right in front) in the upper and lower layers of telescopic ducts 21 blow horizontally towards the aircraft 5 with a strong wind of 35m / s. During T=2-4s, the simulation enters the sinking zone. At this time, the annular frame 2 quickly rises to directly above the aircraft 5. All telescopic ducts 21 in the upper layer... All elements deflect downwards by 60°, simultaneously blowing a strong wind of 40 m / s downwards towards the upper part of the aircraft 5. At this time, all telescopic ducts 21 located on the lower layer are closed. Within T=4-6s, a tailwind is simulated. At this time, the annular frame 2 quickly moves to the rear of the aircraft 5. Three sets of telescopic ducts 21 on the upper and lower layers, located at 120° (left rear), 180° (direct rear), and 240° (right rear), blow a strong wind of 35 m / s horizontally towards the aircraft 5 from the rear. This simulates an extreme wind field scenario under a downburst. The core control logic needs to be solved using inverse kinematics on the Stewart platform.

[0074] The formula for calculating the length of the six telescopic drive components corresponding to the downward burst is as follows:

[0075]

[0076] in, : No. The target length of the root telescopic drive 27 at time t; : The 4x4 homogeneous transformation matrix of the ring frame 2 at time t. This matrix is ​​calculated in real time by the target trajectory generator based on the translation (x,y,z) and rotation (Euler angles α,β,γ) of the ring frame 2. : No. The coordinate vector of the connection point of the root telescopic drive component 27 in the coordinate system of the annular frame 2; : No. The coordinate vector of the connection point of the root telescopic drive component 27 in the coordinate system of the fixed mounting bracket 3; : indicates the calculation of the Euclidean norm (i.e., length) of a vector.

[0077] Simulated flight vehicle 5's own maneuver relative to the wind field (single wind field effect):

[0078] Set aircraft 5 to turn left, speed 20 m / s, turn radius 50 m, at this moment the ring frame 2 as a whole translates 0.5 m to the right, 0.2 m backward, and rotates 10° clockwise relative to the aircraft 5, the near-interface simulation board 4 is still lowered to the lowest position and remains horizontal, at this moment the near-interface simulation board 4 does not participate in simulation. The ring frame 2 as a whole translates to the right and rear of the aircraft 5, and rotates clockwise, the two groups of telescopic air pipes 21 at 60° (left front) and 120° (left rear) positions of the upper and lower telescopic air pipes 21 blow to the side of the aircraft 5 at a medium wind speed of 20 m / s, these two groups of telescopic air pipes 21 remain horizontal and automatically adjust the telescopic amount through the range finder 211 to maintain the new "left front" surface distance of 0.8 m from the aircraft 5, and other telescopic air pipes 21 are closed.

[0079] The relative wind vector corresponding to the aircraft 5 self-manipulation relative to the wind field is calculated as follows:

[0080]

[0081] Wherein, : the relative wind speed vector perceived by the aircraft 5, : the environmental wind vector (in this scenario, [0, 0, 0]); : the speed vector of the virtual aircraft 5 at time t.

[0082] The wind pipe wind speed distribution formula corresponding to the aircraft 5 self-manipulation relative to the wind field is as follows:

[0083]

[0084] Wherein, : a column vector containing 12 target wind speeds of telescopic air pipes 21; : the pseudo-inverse matrix of a 12x3 weight matrix, which describes the contribution of each telescopic air pipe 21 to the wind speed vector of the center point at a unit wind speed, and is determined by the position and direction of each telescopic air pipe 21. The contribution of each telescopic air pipe 21 to the wind speed vector of the center point at a unit wind speed is described, which is determined by the position and direction of each telescopic air pipe 21. According to the desired wind speed vector at the center point, vector, the contribution of each telescopic air pipe 21 to the wind speed is inversely calculated.

[0085] The following is the wind field scenario after the simulation wind field interacts with the interface. This type of wind field scenario requires the cooperation of telescopic air pipes 21 and near-interface simulation board 4.

[0086] Simulation of terrain wind when the wind blows on a hillside (strong coupling effect between wind field and interface):

[0087] When the annular frame 2 is at the center position, the upper surface of the near-interface simulation board 4 is fixedly installed with hard slope modules for simulating the flight or landing of the aircraft 5 close to a slope with a certain inclination angle, and the near-interface simulation board 4 is raised upward so that the closest distance between the aircraft 5 and the slope is 0.5 m, and the slope is inclined by 20°. At this time, the wind needs to be simulated to blow from below the slope, and the four groups of telescopic wind pipes 21 located at the lower layer and at positions of 60° (left front), 120° (left rear), 180° (directly rear) and 240° (right rear) blow wind at a medium wind speed of 15 m / s, and the four groups of telescopic wind pipes 21 are parallel to the slope at an elevation angle of 20°, simulating the wind climbing along the slope, and the air outlet ends of the four groups of telescopic wind pipes 21 are all extended to a distance of 0.7 m below the aircraft 5, simulating the interaction of the wind and the slope, forming an upward airflow on the windward side of the aircraft 5 and a sinking and backflow on the leeward side, and the attitude of the aircraft 5 will change in pitch and roll.

[0088] Simulation of building or urban environment around flow similar to building side hovering (strong coupling effect of wind field and interface):

[0089] When the annular frame 2 is at the center position, the upper surface of the near-interface simulation board 4 is fixedly installed with urban building group modules, and a "building" with a height of 1.5 m is located at the left side of the aircraft 5 at a distance of 0.5 m, and each "building" of the urban building group modules can be made of plastic material to reduce the pressure of the urban building group modules on the near-interface simulation board 4, and the near-interface simulation board 4 needs to be raised to the top of the "building" to be flush with the aircraft 5. Three groups of telescopic wind pipes 21 located at 0° (directly front), 60° (left front) and 300° (right front) of the upper and lower layers of telescopic wind pipes 21 blow wind to the aircraft 5 at a medium wind speed of 15 m / s, simulating the wind blowing from the front, and the telescopic wind pipe 21 located at 180° (directly rear) of the upper and lower layers of telescopic wind pipes 21 rotates the air outlet end to the horizontal reverse direction and blows wind at a low wind speed of 5 m / s, simulating backflow. After the wind flows through the "building" on the left side, a complex around flow and vortex is formed on the left side of the aircraft 5, causing irregular lateral force, and the aircraft 5 will produce roll and yaw oscillation, and the experimental device monitors the roll and yaw oscillation parameters of the aircraft 5 at this time.

[0090] Simulation of downwash flow similar to sleep vortex ring and interface interaction effect (strong coupling effect of wind field and interface):

[0091] The annular frame 2 is stationary in the center position, at which time the upper surface of the near-interface simulation board 4 is fixedly installed with a water tank module, and water is injected into the water tank until the water depth is 0.2 m, the near-interface simulation board 4 is kept horizontal and raised to a distance of 0.3 m from the bottom of the aircraft 5. All the lower-layer telescopic air pipes 21 blow downward at an extremely strong wind speed of 40 m / s, and are all deflected downward by 60°, and the feedback signal of the range finder 211 is used to adjust the air outlet end of all the lower-layer telescopic air pipes 21 to a position 0.5 m above the water surface, all the upward air pipes are closed, and the airflow is converged directly below the aircraft 5 to simulate a strong downward washing flow.

[0092] Taking the water surface vortex ring as an example, the reverse airflow pulse prediction formula is:

[0093]

[0094] wherein, : the predicted upward washing airflow speed generated by the water surface reflection; : the reflection coefficient, a dimensionless parameter related to the water surface characteristics and the impact angle, calibrated by experiments (for example, 0.1-0.3); : the downward impact downward washing flow speed (for example, 40 m / s); : the impact delay, that is, the time for the airflow to reach the water surface and return; : the attenuation coefficient, which describes the dissipation speed of the reverse airflow pulse. The control unit 33 uses this formula to predict the upcoming upward disturbance, and can command the upper-layer telescopic air pipe 21 to perform feedforward compensation to offset this undesirable secondary effect, so as to ensure the purity of the experimental conditions.

[0095] Simulation of crossing the edge of a forest fire (strong coupling effect of wind field and interface):

[0096] The annular frame 2 as a whole translates backward at a slow speed of 0.5 m / s to simulate the slow forward flight of the aircraft 5, at this time the upper surface of the near-interface simulation board 4 is fixedly installed with a forest canopy module (not shown), the forest canopy module includes simulated branches with a height of 0.5 m, and the near-interface simulation board 4 remains horizontal while being raised to the top of the branches at a distance of 0.2 m from the landing gear of the aircraft 5. Two groups of telescopic air pipes 21 located at positions of 60° (left front) and 120° (left rear) in the upper and lower two layers of telescopic air pipes 21 blow air to the aircraft 5, and small electric heating wires are connected between the two groups of telescopic air pipes 21 and the corresponding independent air blower, the electric heating wires heat the air flow blown out by the two groups of telescopic air pipes 21, so that the outlet end air temperature is 50°C higher than the environment, the air flow blown out by the two groups of telescopic air pipes 21 is irregularly pulsed between 15 m / s to 35 m / s, and the outlet end is randomly disturbed between ± 15° and 0.7-0.9 m, thereby blowing out a random pulsed air flow with high temperature and irregular wind speed. The other two groups of telescopic air pipes 21 corresponding to positions of 240° (right rear) and 300° (right front) on the other side blow horizontally to the side of the aircraft 5 at a low wind speed of 5 m / s. The telescopic air pipes 21 at the remaining other positions are all closed, simulating that the aircraft 5 is threatened by thermal buoyancy, strong turbulence, normal wind and potential scraping from below vertically, and the attitude of the aircraft 5 is monitored.

[0097] The vertical wind speed component estimation formula corresponding to the thermal buoyancy when crossing the forest fire edge:

[0098]

[0099] wherein, : the additional vertical upward wind speed generated by thermal buoyancy;

[0100] : the acceleration of gravity (take 9.8 m / s²); : the effective height of the thermal plume; : the absolute temperature of the thermal air flow; : the absolute temperature of the environment air. When setting the wind speed of the telescopic air pipe 21 blowing out the thermal air flow, the control unit 33 will vectorially combine the horizontal wind speed component and the calculated vertical wind speed component, thereby generating a more realistic thermal plume with both horizontal speed and strong upward trend, and this will also be superimposed into the turbulence model to increase the vertical direction pulse intensity.

[0101] The implementation principle of the experimental device for simulating the attitude of an aircraft under wind disturbance is as follows: the aircraft 5 is clamped and fixed on the support holder 1, the sensors inside the support holder 1 can monitor the key attitude signals of the aircraft 5 in three degrees of freedom of pitch, roll and yaw in real time, the plurality of telescopic air pipes 21 surrounding the aircraft 5 can at least spray simulated air flow to the aircraft 5 from multiple directions such as front, back, left and right of the aircraft, and the annular frame 2 and the telescopic driving member 27 together form a Stewart platform, when all the telescopic driving members 27 are synchronously telescoped, the annular frame 2 can be driven to ascend and descend as a whole while keeping its own attitude unchanged, when the telescopic driving member 27 on one side is elongated and the telescopic driving member 27 on the other side is correspondingly elongated, the annular frame 2 can be driven to deflect to one side by a certain amplitude, and the blowing angle of each telescopic air pipe 21 to the aircraft 5 can be indirectly adjusted by changing the position or deflection angle of the annular frame 2, so that the aircraft 5 can be simulated in various wind field scenarios, from the traditional wind tunnel "global uniform wind" to the "local, dynamic, high-resolution vector wind field" which can be arbitrarily shaped and moved in space, instead of "one fan" beside "one platform", the annular frame 2 itself has the ability to generate a controllable wind field, and each independent telescopic air pipe 21 can be telescoped and deflected relative to the annular frame 2, so that the distance between the air outlet end of each telescopic air pipe 21 and the aircraft 5 can be independently adjusted, thereby accurately controlling the effect and influence of each air flow forming the wind field on the aircraft 5, and different interface modules 41 such as ground modules, building modules or water surface modules can be installed on the near-interface simulation plate 4 to simulate different scenarios that the aircraft 5 may encounter in actual flight, such as take-off near the ground, building flow effect, or coupling of "water surface effect" with the "washing shock wave", the annular frame 2 and the near-interface simulation plate 4 can realize the coupled attitude disturbance simulation of the aircraft 5 under the action of wind disturbance and near-interface, and further unlock more complex wind field scenarios.

[0102] The above are preferred embodiments of the present application, but do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. An experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance, characterized in that: include Support gimbal (1) is used to place the aircraft (5). The support gimbal (1) is configured as a three-degree-of-freedom spherical gimbal containing sensors to detect the attitude changes of the aircraft (5) under airflow disturbance. A ring frame (2) is set around the supporting gimbal (1); A fixed mounting bracket (3) is installed outside the support gimbal (1) and the ring frame (2). A connecting platform (34) is provided on the fixed mounting bracket (3). The top surface of the ring frame (2) is connected to the connecting platform (34) through multiple telescopic drive components (27). The ring frame (2) and the telescopic drive components (27) form a Stuart platform so that the ring frame (2) can be raised and deflected relative to the support gimbal (1). Multiple telescopic air ducts (21) are installed at intervals on the ring frame (2). The air outlet of each telescopic air duct (21) faces the center of the ring frame (2), and the air inlet is used to connect to external air supply equipment. A control unit (33) is also provided on the fixed mounting bracket (3). The support gimbal (1) and the telescopic drive components (27) are electrically connected to the control unit (33). The near-interface simulation board (4) is set below the support gimbal (1) and can be adjusted in height and tilt angle relative to the support gimbal (1). The upper surface of the near-interface simulation board (4) is used to install different interface modules (41) to realize the simulation of coupled attitude disturbance of the aircraft under the dual action of wind disturbance and near-interface. The ring frame (2) includes at least two layers, which are distributed vertically and horizontally. Adjacent ring frames (2) are connected as a whole by connecting rods (22). The top surface of the ring frame (2) at the top layer is connected to the telescopic drive component (27). All ring frames (2) are movably equipped with telescopic air ducts (21), and the telescopic air ducts (21) on adjacent ring frames (2) are in corresponding positions. In the vertical direction, at least one ring frame (2) is used to correspond to the position of the upper fuselage and rotor of the aircraft (5), and at least one ring frame (2) is used to correspond to the position of the lower fuselage and landing gear of the aircraft (5). Each of the telescopic ducts (21) is rotatably connected to the annular frame (2), and the rotation axis of each telescopic duct (21) coincides with or is parallel to the tangent direction of its own hinge position and the annular frame (2). The annular frame (2) is provided with a rotation drive assembly corresponding to each telescopic duct (21) to drive the corresponding telescopic duct (21) to rotate. The outer wall of each telescopic duct (21) is provided with a telescopic drive assembly to drive the corresponding telescopic duct (21) to extend or retract. Each telescopic duct (21) is connected to an independent air supply device.

2. The experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance as described in claim 1, characterized in that: The telescopic duct (21) of each layer of the annular frame (2) covers at least the front, back, left and right directions of the aircraft (5) on the horizontal plane. Each layer of the annular frame (2) is provided with at least one telescopic duct (21) corresponding to the front, back, left and right directions of the aircraft (5) on the horizontal plane to improve the resolution of the simulated wind field. The annular frame (2) is configured as a frame with a circular horizontal cross section.

3. The experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance as described in claim 1, characterized in that: Each of the telescopic ducts (21) is provided with a distance measuring device (211) on the outer wall of the corresponding air outlet end. The transmitting end of the distance measuring device (211) faces the center direction of the annular frame (2) and is used to detect the distance between the air outlet end of the telescopic duct (21) and the aircraft (5).

4. The experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance as described in claim 3, characterized in that: Each of the telescopic ducts (21) has a detachable shroud (212) at its outlet end for providing a stable simulated airflow.

5. The experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance as described in claim 1, characterized in that: The connecting platform (34) is connected to the fixed mounting frame (3) through a first adjustment component and a second adjustment component. The first adjustment component includes a first movable seat (35), and the second adjustment component includes a second movable seat (36). The bottom of the first movable seat (35) is connected to the top of the connecting platform (34), and the first movable seat (35) is horizontally slidably connected to the bottom of the second movable seat (36). The second movable seat (36) is horizontally slidably connected to the fixed mounting frame (3), and the sliding direction of the first movable seat (35) is perpendicular to the sliding direction of the second movable seat (36).

6. The experimental apparatus for simulating the attitude change of an aircraft (5) under wind disturbance as described in claim 1, characterized in that: The bottom of the support gimbal (1) is provided with a lifting component (13), which is used to drive the support gimbal (1) to rise and fall vertically.

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