Small-sized electric direct-driven variable-total-pitch rotor wind tunnel test bench and test method

Abstract

The invention provides a small-sized electric direct-driven variable-total-pitch rotor wind tunnel test bench and a test method. A rotor test system test device in the test bench is arranged on a mounting rack; the rotor wing test system testing device comprises a rotor wing, a propeller hub central piece and the like, the rotor wing is fixedly connected with a propeller clamp assembly of the pitch changing mechanism through a blade pin screw and then connected with the propeller hub central piece, and the propeller clamp assembly is coaxially connected with the propeller hub central piece; the propeller hub central part and a rotor part of the motor are coaxially and vertically installed, a stator part of the motor is fixedly connected with the upper end of the steering engine installation frame, the lower end of the steering engine installation frame is fixedly connected with the upper end of the six-component balance, the lower end of the six-component balance is fixedly connected with the adapter, and a photoelectric sensor is arranged on the tilting mechanism fixed installation panel. The polarized light is vertically emitted upwards, and reflective stickers are pasted on the lower end surfaces of the paddles; and the device can be adapted to small unmanned helicopters and eVTOL rotors.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology for rotor performance of small unmanned helicopters, and particularly relates to a small electric direct-drive variable collective pitch rotor wind tunnel test rig and test method. Background Technology

[0002] The helicopter rotor system is the most distinctive system of a helicopter. The relative motion between the rotor and the air generates lift, enabling it to fly in the air. Rotor performance is one of the key factors affecting its flight. Wind tunnel testing is an economical and efficient means of understanding and mastering the aerodynamic performance of rotors. Rotor wind tunnel test rigs are core equipment for studying the aerodynamic characteristics of rotorcraft such as helicopters. By conducting simulated flight tests within the wind tunnel's flow field, it can be used to verify and solve problems related to rotor aerodynamic performance, dynamics, and flight mechanics, providing precise experimental data support for model development, performance optimization, and safety verification. Specifically, this includes three aspects: First, solving the challenge of testing complex rotor aerodynamic forces, obtaining key parameters such as aerodynamic forces, torque, and pressure distribution under different Mach numbers, angles of attack, and wind speeds, and clarifying the mechanisms of complex aerodynamic phenomena such as propeller-vortex interference and dynamic stall; Second, developing the feasibility of rotor system design schemes, conducting tests on aeroelastic stability, vibration characteristics, and noise levels by comparing scaled-down or full-size rotor models, and proactively addressing and mitigating potential structural safety risks such as gyroscopic flutter; Third, supporting the research and iteration of new rotor configurations, calibrating aerodynamic simulation models through experimental data, shortening the aircraft's development cycle, and reducing development costs. With the development of helicopter technology, small unmanned aerial vehicles (UAVs) and vertical takeoff and landing (VTOL) aircraft are developing rapidly. Therefore, it is crucial to verify their rotor performance in a low-cost, rapid, and effective manner. Thus, it is essential to provide a test device capable of simulating rotor flight, equipped with corresponding test methods, to reduce research costs and risks.

[0003] Currently, traditional rotor test benches include large rotor test benches, as seen in patent documents CN113335563A and CN119460161B. These benches have complex structures, numerous systems, high prices, and require auxiliary systems such as lubrication and cooling. They are suitable for rotor testing of larger blades with higher power. However, due to the presence of the gearbox, large rotor test benches are bulky and have low rotor speeds, making them unsuitable for rotor testing of small rotorcraft drones. Their compatibility with the small size and low power rotors of drones is also low.

[0004] To adapt to small unmanned helicopters and eVTOL rotors, this invention provides a small electric direct-drive variable collective pitch rotor wind tunnel test rig and test method. Summary of the Invention

[0005] To adapt to small unmanned helicopters and eVTOL rotors, this invention provides a small electric direct-drive variable collective pitch rotor wind tunnel test rig and test method. It is low-cost, flexibly disassembled, and can conduct hovering and wind tunnel tests on variable collective pitch rotors under different speeds, wind speeds, and angles of attack. The technical solution is as follows: In a first aspect, a small electric direct-drive variable collective pitch rotor wind tunnel test rig is provided, comprising: a rotor test system testing device 2, the rotor test system testing device 2 including a rotor 3, a rotor hub central component 4, a variable pitch mechanism 5, a motor 6, a servo mounting bracket 7, a six-component balance 8, an adapter 9, and a tilting mechanism 10. The rotor 3 is fixedly connected to the rotor clamp assembly 12 of the pitch mechanism 5, and then connected to the rotor hub central component 4; the rotor hub central component 4 is coaxially and vertically installed with the rotor component of the motor 6; the stator component of the motor 6 is fixedly connected to the upper end of the servo mounting bracket 7; the lower end of the servo mounting bracket 7 is fixedly connected to the upper end of the six-component balance 8; the lower end of the six-component balance 8 is fixedly connected to the adapter 9; and the adapter 9 is fixedly connected to the tilting mechanism 10.

[0006] Furthermore, the rotor test system test device 2 is set on the mounting platform 30 and located at the wind tunnel inlet, with the rotor at the center of the wind tunnel flow path.

[0007] Furthermore, a photoelectric sensor 11 is provided on the fixed mounting panel of the tilting mechanism 10, which emits polarized light vertically upward. A reflective sticker is attached to the area on the lower end surface of the rotor 3 opposite to the light emission position of the photoelectric sensor 11. When the rotor rotates to the appropriate position, the polarized light emitted by the photoelectric sensor 11 is reflected by the reflective sticker on the lower end surface of the rotor to the receiving module of the photoelectric sensor 11.

[0008] Optionally, the rotor 3 and the blade clamp assembly 12 of the pitch mechanism 5 are fixedly connected by blade pin screws, and the blade clamp assembly 12 is coaxially connected to the central part of the blade hub 4. The rotor 3 and the blade clamp assembly 12 are arranged symmetrically.

[0009] Furthermore, the rotor test system test device 2 also includes: a first vibration sensor 28 and a second vibration sensor 29. The first vibration sensor 28 is installed on the lower end face of the servo mounting bracket 7, and the second vibration sensor 29 is installed on the fixed mounting panel of the tilting mechanism 10, for monitoring the vibration value of the test bench.

[0010] Optionally, the pitch control mechanism 5 includes: a propeller clamp assembly 12, a propeller rod 13, a pitch control lever 14, a dynamic-to-static conversion assembly 15, a stationary ring rod 16, a servo arm 17, a servo 18, and a servo frame assembly 19. The rotor hub central member 4 has a rotor clamp assembly 12 on each of its left and right sides. The rotor clamp assembly 12 is pressed into the rotor hub central member 4 by bearings and can rotate around the rotor hub central member 4 along its central axis. Two rotor blade tie rods 13 are symmetrically arranged about the pitch control lever 14. The rotor blade tie rods 13 and the pitch control lever 14 are connected. The pitch control lever 14 passes coaxially through the bearing at the axial center of the rotor hub central member 4. The bottom of the pitch control lever 14 is connected to a dynamic-static conversion assembly 15. The dynamic-static conversion assembly 15 is connected to the servo frame assembly 19 and the stationary ring tie rod 16. The stationary ring tie rod 16 is connected to the servo arm 17 through a ball joint bearing. The servo arm 17 is connected to the servo 18. The servo 18 is fixedly mounted on the servo frame assembly 19.

[0011] Optionally, the dynamic-static conversion assembly 15 has two bearings installed inside. The inner wall of the bearing is a rotating part, and the outer end is a non-rotating fixed ring 20. An anti-torsion shaft 21 is connected to one side of the fixed ring 20. The end of the anti-torsion shaft 21 is inserted into the slide groove of the servo frame assembly 19. The anti-torsion shaft 21 can only move vertically along the slide groove. The other side of the fixed ring 20 is connected to the fixed ring tie rod 16 through a ball joint bearing.

[0012] Optionally, the blade linkage 13 and the pitch control lever 14 are connected by a fork-shaped component, and the servo arm 17 is fixedly connected to the servo 18 by screws.

[0013] Optionally, during the rotation of the motor 6, the central component 4 of the rotor hub rotates synchronously. The central component 4 of the rotor hub drives the rotor clamp assembly 12 and the rotor 3 to rotate synchronously. When the rotor clamp assembly 12 rotates, it drives the blade tie rod 13 and the pitch control lever 14 to rotate synchronously along the intermediate bearing of the central component 4 of the rotor hub and the bearing of the dynamic-static conversion assembly 15. When the rotor 3 needs to control the collective pitch change, a control signal is sent to the servo motor 18. The internal gear of the servo motor 18 rotates, which drives the servo arm 17 to rotate. The servo arm 17 drives the stationary ring tie rod 16 to perform displacement change movement. The stationary ring tie rod 16 drives the stationary ring 20 to perform vertical displacement change. During the vertical displacement, the stationary ring 20 drives the anti-torsion shaft 21 to perform vertical displacement along the slide groove of the servo frame assembly 19. As the stationary ring 20 moves vertically, it drives the pitch control lever 14 to move synchronously. The pitch control lever 14 then drives the blade tie rod 13 to extend and retract. The blade tie rod 13 drives the blade clamp assembly 12 to rotate along its axial direction. The rotation of the blade clamp assembly 12 drives the rotor 3 to rotate, thus causing a change in the collective pitch of the rotor 3. Since all the above connecting parts are connected by ball joint bearings, displacement changes in other directions can be effectively eliminated.

[0014] Optionally, the tilting mechanism 10 includes: a mounting panel 22, a lower base plate 23, a drive arm 24, a linear guide rail 25, a drive motor 26, and a linear displacement groove 27. The upper end of the tilting mechanism 10 is fixedly connected to the adapter 9 via the mounting panel 22, and the lower end is fixedly connected to the mounting frame 30 via the lower base plate 23. The front end of the mounting panel 22 is connected to the fork lugs of the lower base plate 23 via connecting pins. The rear end of the mounting panel 22 is connected to one end of each of the two drive arms 24 via connecting pins. The other end of each drive arm 24 is connected to a linear displacement groove 27 via connecting pins. A transverse sliding groove is provided in the middle of both sides of the linear displacement groove 27. The connecting pins are used to fix the drive arms 24 to the drive motor 26 via the sliding groove. The drive motor 26 is installed in the linear displacement groove 27 and fixed by a linear guide rail 25. The drive motor 26 can only move along the axial direction of the linear guide rail 25. Through the reasonable design of the linear displacement groove 27, the rotor angle of attack can be changed from negative angle of attack to positive angle of attack.

[0015] Optionally, the front end of the mounting panel 22 is connected to the fork lug of the lower base plate 23 via two fork lugs through a connecting pin, and the rear end of the mounting panel 22 is connected to one end of each of the two drive arms 24 via a connecting pin, and the other end of the drive arm 24 is connected to the linear displacement groove 27 via a connecting pin.

[0016] Optionally, during the test, when the rotor 3 needs to change its angle of attack, the drive motor 26 moves unidirectionally along the linear guide rail 25. During the movement, the drive motor 26 drives the drive arm 24 to move. The drive arm 24 drives the mounting panel 22 to rotate axially along its front connecting pin. The mounting panel 22 drives the adapter 9 and all components above the adapter 9 to rotate, thereby causing the rotor angle of attack to change.

[0017] In a second aspect, a test method is provided for a small electric direct-drive variable collective pitch rotor wind tunnel test rig as described in any of the first aspects, comprising: Step 1: After the motor 6 is powered on, the six-component balance 8 collects initial data, and at the same time, the environmental parameters at the rotor position are recorded and stored through a handheld atmospheric weather station. Step 2: Control the test bench speed to the preset value through motor 6, check the operating status and communication status of the other equipment, and check whether the rotor speed and direction are correct. If all are normal, proceed to step 3. Step 3: After the test bench runs at the preset speed for a preset time, check the operating status of each device. If the operation is normal, set the speed of the test bench to the test speed through the photoelectric sensor 11, start the wind tunnel, run for a preset time, check the communication status, and if it is normal, proceed to step 4. Step 4: Conduct the experiment according to the experimental state table and obtain steady-state data for each state.

[0018] Optionally, environmental parameters include atmospheric pressure, temperature, and humidity.

[0019] Furthermore, prior to step 1, the method further includes: conducting a hovering test, specifically: After step 2, the test bench operates at a preset speed for a preset time. Then, the tilting mechanism 10 is used to make the angle of attack of the test bench 0°. The operating status of each device is checked. If the operation is normal, the speed of the test bench is set to the first test speed. After the speed stabilizes, the servo motor 18 is operated according to the test status table to change the rotor collective pitch. The operation is carried out for a preset time. During the operation, the test data is recorded and stored in real time. The communication status is checked. If it is normal, the next step is executed. Enter the second test speed test state. Use motor 6 to stabilize the rotor speed to the second test speed test state. After the speed stabilizes, operate the servo control system according to the test state table to change the rotor collective pitch. Run for a preset time. Record and store test data in real time during the operation. Check the communication status. If it is normal, proceed to the next step. Repeat the previous step until data from all experimental states have been collected.

[0020] Optionally, the test data includes: rotor speed collected by a six-component balance 8 and photoelectric sensor 11, test bench vibration values ​​collected by a first vibration sensor 28 and a second vibration sensor 29, and control angle values ​​collected by a servo motor 18.

[0021] Furthermore, the method also includes: Determine the operating status of the six-component balance 8, motor 6, photoelectric sensor 11, servo motor 18, first vibration sensor 28, second vibration sensor 29, and tilting mechanism 10. If the operating status is abnormal, troubleshoot first, and then execute step 1.

[0022] The beneficial effects of this invention are at least as follows: 1. The device of this invention has a simple structure, is less expensive than traditional rotor test benches, can be flexibly disassembled, has an overall height of less than 2.5 meters, and is easy to install and move; 2. The device of the present invention can perform hovering and wind tunnel tests on variable collective pitch rotors under different rotational speeds, wind speeds and angles of attack. It can test the rotor's collective pitch, rotor speed, wind speed, angle of attack, rotor's six force elements, and test bench vibration data, thereby enabling data analysis of rotor performance. 3. Most small unmanned helicopters and eVTOL rotors adopt constant collective pitch variable speed or constant speed with only variable collective pitch and no periodic pitch. The device of this invention is well suited to their test requirements. 4. The rotor, hub assembly, motor, tilt servo, tilt mechanism, six-component balance, and other components of the device of this invention are highly replaceable and can be flexibly modified according to different test purposes and needs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 Overall view of a small electric direct-drive variable collective pitch rotor wind tunnel test rig; Figure 2 This is a schematic diagram of the test device for the rotor test system; Figure 3 This is a front view of the pitch mechanism; Figure 4 Right view of the pitch mechanism; Figure 5 This is a front view of the tilting mechanism; Figure 6 This is an axis view of the tilting mechanism; Figure 7 Diagram showing the rotor angle of attack at +20°; Figure 8 This is a diagram showing the rotor at 0° angle of attack.

[0025] Figure 9 This is a diagram showing the rotor at an angle of attack of -5°. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0028] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] This invention relates to a small-scale electric direct-drive variable collective pitch rotor wind tunnel test rig, which mainly consists of a test rig frame, a test component system (rotor and hub), a power system (motor and speed control system), a servo control system (servo motor, pitch mechanism, and servo motor host controller), a data acquisition system (six-component balance, speed sensor, vibration sensor, data acquisition software and equipment), and a tilt control system (tilt mechanism and tilt controller). The test rig can conduct hovering and wind tunnel tests on variable collective pitch rotors under different speeds, wind speeds, and angles of attack. It can test the rotor's collective pitch, rotor speed, wind speed, angle of attack, rotor six forces, and test rig vibration data, thereby enabling data analysis of rotor performance. The collective pitch control of the servo control system and the angle of attack control of the tilt control system of this invention can be continuously varied, and through reasonable design, can be steplessly varied from negative to positive angles. The rotor, hub assembly, motor, tilt servo motor, tilt mechanism, six-component balance, and other components of this invention are highly replaceable and can be flexibly modified according to different test purposes and requirements.

[0031] The overall installation of the small electric direct-drive variable collective pitch rotor wind tunnel test rig is as follows: Figure 1 As shown, the test bench includes a rotor test system testing device 2 and a mounting frame 30. The rotor test system testing device 2 is mounted on the mounting frame 30 and located at the wind tunnel inlet 1, with the rotor positioned at the exact center of the wind tunnel flow path. The rotor is 2.5 meters above the ground.

[0032] The rotor test system test device 2 includes: rotor 3, rotor hub central component 4, pitch mechanism 5, electric motor 6, servo mounting bracket 7, six-component balance 8, adapter 9, tilting mechanism 10, photoelectric sensor 11, first vibration sensor 28, and second vibration sensor 29.

[0033] See Figure 2 and Figure 3The rotor 3 and the blade clamp assembly 12 of the pitch mechanism 5 are fixedly connected by blade pin screws, and then connected to the central part of the blade hub 4. The blade clamp assembly 12 and the central part of the blade hub 4 are coaxially connected, and the rotor 3 and the blade clamp assembly 12 are arranged symmetrically. The rotor hub central component 4 is vertically mounted coaxially with the rotor component of the motor 6. The stator component of the motor 6 is fixedly connected to the upper end of the servo mounting bracket 7. The lower end of the servo mounting bracket 7 is fixedly connected to the upper end of the six-component balance 8. The lower end of the six-component balance 8 is fixedly connected to the adapter 9. The adapter 9 is fixedly connected to the tilting mechanism 10. A photoelectric sensor 11 is installed on the fixed mounting panel of the tilting mechanism 10. Its polarized light is emitted vertically upward. A reflective sticker is attached to a suitable position on the lower end surface of the blade 3 (opposite to the light emission position of the photoelectric sensor 11). When the blade rotates to the suitable position, the polarized light emitted by the photoelectric sensor 11 is reflected by the reflective sticker on the lower end surface of the blade 3 to the receiving module of the photoelectric sensor 11. Based on the transmission and reception time of multiple revolutions, the rotor speed can be calculated. A first vibration sensor 28 is installed on the lower end surface of the servo mounting bracket 7, and a second vibration sensor 29 is installed on the fixed mounting panel of the tilting mechanism 10 to monitor the vibration value of the test bench.

[0034] For example, based on the transmission and reception times over multiple revolutions, the rotor speed is calculated as follows: Assume the photoelectric sensor 11 receives the signal for the first time at time t1, the second time at time t2, the third time at time t3, and so on, with the 11th reception time being t11. Therefore, the rotor speed in the first revolution is... The rotor speed on the second revolution is [speed value] / [speed value]. Rotation speed per second, and so on, the rotor speed at the tenth revolution is... The revolutions per second (rpm) are used to calculate the average rotational speed, with 10 revolutions per complete cycle. Revolves per second.

[0035] To better explain the principle and implementation method of the variable pitch mechanism 5, the following will be combined with... Figure 3 and Figure 4 It will be explained in detail.

[0036] The pitch control mechanism 5 specifically includes: a propeller clamp assembly 12, a propeller rod 13, a pitch control lever 14, a dynamic-to-static conversion assembly 15, a stationary ring rod 16, a servo arm 17, a servo 18, a servo frame assembly 19, a stationary ring 20, and an anti-torsion shaft 21.

[0037] The propeller clamp assembly 12 is pressed together with the propeller hub center piece 4 through bearings. The propeller clamp assembly 12 can rotate around the propeller hub center piece 4 along the central axis. One propeller clamp assembly 12 is arranged on each of the left and right sides of the propeller hub center piece 4, but when it moves, its rotation direction is synchronously upward or downward. Two blade tie rods 13 are symmetrically arranged about the pitch control lever 14. The blade tie rods 13 and the pitch control lever 14 are connected by a fork-shaped component. The pitch control lever 14 passes coaxially through the bearing at the center of the rotor hub central component 4. A dynamic-static conversion assembly 15 is connected to the bottom of the pitch control lever 14. Two bearings are installed inside the dynamic-static conversion assembly 15. The inner wall of the bearing is a rotating part, and the outer end is a non-rotating fixed ring 20. An anti-torsion shaft 21 is connected to one side of the fixed ring 20. The end of the anti-torsion shaft 21 is inserted into the slide groove of the servo frame assembly 19. The anti-torsion shaft 21 can only move vertically along the slide groove, thereby preventing torsion. The other side of the fixed ring 20 is connected to the fixed ring tie rod 16 through a ball joint bearing. The fixed ring tie rod 16 is connected to the servo arm 17 through the ball joint bearing. The servo arm 17 is fixedly connected to the servo 18 by screws. The servo 18 is fixedly mounted on the servo frame assembly 19.

[0038] The working principle of the pitch-changing mechanism 5 is as follows: First, during the rotation of the motor 6, the central component 4 of the rotor hub rotates synchronously. The central component 4 of the rotor hub drives the rotor clamp assembly 12 and the rotor 3 to rotate synchronously. When the rotor clamp assembly 12 rotates, it drives the blade tie rod 13 and the pitch control lever 14 to rotate synchronously along the intermediate bearing of the central component 4 of the rotor hub and the bearing of the dynamic-static conversion assembly 15. When the rotor 3 needs to control the collective pitch change, a control signal is sent to the servo motor 18 through a control command. The internal gear of the servo motor 18 rotates, driving the servo arm 17 to rotate. The servo arm 17 drives the stationary ring tie rod 16 to move forward. The stationary ring 20 undergoes vertical displacement due to the vertical displacement of the stationary ring 16. During this vertical displacement, the stationary ring 20 drives the anti-torsion shaft 21 to move vertically along the groove of the servo frame assembly 19. As the stationary ring 20 moves vertically, it synchronously moves the pitch control lever 14, which in turn drives the blade tie rod 13 to extend and retract. The blade tie rod 13 then drives the blade clamp assembly 12 to rotate along its axial direction. This rotation of the blade clamp assembly 12 causes the rotor 3 to rotate, resulting in a change in the collective pitch of the rotor 3. Since all the connecting parts are connected via ball joint bearings, displacement changes in other directions can be effectively eliminated.

[0039] To better explain the principle and implementation method of the tilting mechanism 10, combined with Figure 5 and Figure 6 It will be explained in detail.

[0040] The tilting mechanism 10 includes: a mounting panel 22, a lower base plate 23, a drive arm 24, a linear guide rail 25, a drive motor 26, and a linear displacement groove 27.

[0041] The upper end face of the tilting mechanism 10 is fixedly connected to the adapter 9 via the mounting panel 22, and the lower end face is fixedly connected to the mounting frame 30 via the lower base plate 23. The front end of the mounting panel 22 is connected to the fork lugs of the lower base plate 23 via connecting pins. The two fork lugs at the rear end of the mounting panel 22 are respectively connected to one end of the two drive arms 24 via connecting pins. The other end of the drive arm 24 is connected to the linear displacement groove 27 via connecting pins. A transverse sliding groove is provided in the middle of both sides of the linear displacement groove 27. The connecting pins are used to fix the drive arm 24 to the drive motor 26 via the sliding groove. The drive motor 26 is installed in the linear displacement groove 27 and fixed by the linear guide rail 25. The drive motor 26 can only move along the axial direction of the linear guide rail 25.

[0042] The working principle of the tilting mechanism 10 is as follows: During the test, when the rotor 3 needs to change its angle of attack, the drive motor 26 moves unidirectionally along the linear guide rail 25. During the displacement, the drive motor 26 drives the drive arm 24 to move. The drive arm 24 drives the mounting panel 22 to rotate axially along its front connecting pin. The mounting panel 22 drives the adapter 9 and all components above the adapter 9 to rotate, thereby changing the rotor's angle of attack. Through the reasonable design of the linear displacement groove 27, the rotor's angle of attack can be changed from a negative angle of attack to a positive angle of attack. Figure 7 , Figure 8 and Figure 9 This is a diagram showing the working status of the test bench with three different rotor angles of attack.

[0043] In one embodiment, the present invention provides a hovering test method for a small electric direct-drive variable collective pitch rotor wind tunnel test rig, the specific steps of which are as follows: 1. Before the test begins, confirm the operating status of the six-component balance 8 and its matching measurement and acquisition equipment, the motor 6 and its matching speed control system, the photoelectric sensor 11 and its matching acquisition equipment, the servo motor 18 and its matching control system 2, the first vibration sensor 28 and the second vibration sensor 29 and their matching vibration monitoring system, and the tilting mechanism 10 and its matching control system. If any of these devices are not operating normally, troubleshooting must be completed before proceeding to the next step. 2. Notify all personnel at the test positions to begin the test. After the motor 6 and its matching speed control system are powered on, the six-component balance 8 and its matching measurement and acquisition equipment collect the initial readings. At the same time, use a handheld atmospheric weather station to record and store the atmospheric pressure, temperature and humidity at the rotor position. 3. After the initial readings are collected, the motor 6 and its matching speed control system control the test bench speed to 50 rpm. Check the operating status and communication status of the other equipment, and whether the rotor speed direction is correct. If it is not normal, stop the machine and return to step 1. 4. After the test bench runs at 50 rpm for 30 seconds, check the operating status of each system. The tilting mechanism 10 and its supporting control system ensure that the angle of attack of the test bench is 0°. If each system is operating normally, after the test bench speed is set to the first test speed and the speed stabilizes, operate the servo motor 18 and its supporting control system in sequence according to the test status table to change the rotor collective pitch. Run for 30 seconds. During the operation, record and store in real time the rotor speed, the test bench vibration value collected by the six-component balance 8 and its supporting measurement and acquisition equipment, the photoelectric sensor 11 and its supporting acquisition equipment, the test bench vibration value collected by the first vibration sensor 28 and the second vibration sensor 29 and the supporting vibration monitoring system, the control angle value collected by the servo motor 18 and its supporting control system, and other parameters. Check the communication status. If it is abnormal, stop the machine and return to step 1. 5. Next, the second test speed test state will be carried out. The motor 6 and its matching speed control system will control and stabilize the rotor speed to the second test speed test state. After the speed stabilizes, the servo control system will be operated in sequence according to the test state table to change the rotor collective pitch. The operation will last for 30 seconds. During the operation, the parameters collected in step d will be recorded and stored in real time. The communication status will be checked. If it is abnormal, the machine will be stopped and the process will return to step 1. 6. Repeat the previous step until all test states have been collected. After all test states have been collected, or considering the issue of motor cooling due to prolonged test bench operation time and test repeatability, stop the test bench according to the normal shutdown procedure and check the test bench. 7. After the test bench inspection is completed, the inspector reports to the on-site commander. If the status is normal, steps 1 to 5 can be repeated to proceed to the next status table test or the current test status table content can continue. The test must be a repeatability test according to the task requirements to verify the repeatability accuracy of the test.

[0044] In one embodiment, the present invention provides a wind tunnel testing method for a small electric direct-drive variable collective pitch rotor wind tunnel test rig, the specific steps of which are as follows: 1. Before the test begins, confirm the operating status of the six-component balance 8 and its matching measurement and acquisition equipment, the motor 6 and its matching speed control system, the photoelectric sensor 11 and its matching acquisition equipment, the servo motor 18 and its matching control system 2, the first vibration sensor 28 and the second vibration sensor 29 and their matching vibration monitoring system, and the tilting mechanism 10 and its matching control system. If any of these devices are not operating normally, troubleshooting must be completed before proceeding to the next step. 2. Notify all personnel at the test positions to begin the test. After the motor 6 and its matching speed control system are powered on, the six-component balance 8 and its matching measurement and acquisition equipment system collect the initial readings. At the same time, use a handheld atmospheric weather station to record and store the atmospheric pressure, temperature and humidity at the rotor position. 3. After the initial readings are collected, the motor 6 and its matching speed control system control the test bench speed to 50 rpm. Check the operating status of the other equipment, the communication status, and whether the rotor speed direction is correct. If not, stop the machine and return to step 1. 4. After the test bench runs at 50 rpm for 30 seconds, check the operating status of each system. If each system is operating normally, the test bench speed is set to the test speed through photoelectric sensor 11 and its matching acquisition equipment. The wind tunnel starts blowing at 5 m / s and runs for 30 seconds. Check the communication status. If it is not normal, stop the machine and return to step 1. 5. Conduct the tests in the following order: first, stabilize the wind speed; then, test the motor 6 and its associated speed control system, the servo motor 18 and its associated control system, and finally, the tilting mechanism 10 and its associated control system, according to the test state table. Ensure that 10 seconds of steady-state data is obtained in each state. Closely monitor each monitoring value during the test. In case of any abnormal situation during the test, follow the emergency response plan. 6. After all test conditions are completed, or considering the issues of motor cooling due to prolonged test bench operation time and test repeatability, stop the test bench according to the normal shutdown procedure and inspect it. 7. After the test bench inspection is completed, the inspector shall report to the test site commander. If the status is normal, steps 1 to 5 can be repeated to proceed to the next status table test or continue the contents of the current test status table.

[0045] This invention provides a rotor test bench designed for small unmanned aerial vehicles (UAVs) and eVTOL rotors. It can be used in a wind tunnel environment to test the aerodynamic performance data and test bench vibration data of the rotor at different speeds and collective pitches while hovering. It can also be used to conduct wind tunnel tests to test the aerodynamic performance data and test bench vibration data of the rotor at different speeds, collective pitches, and angles of attack, thereby verifying the rotor's design specifications and obtaining its hovering and forward flight efficiency.

[0046] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A small-scale electric direct-drive variable collective pitch rotor wind tunnel test rig, characterized in that, include: The rotor test system test device (2) includes a rotor (3), a hub central component (4), a pitch mechanism (5), a motor (6), a servo mounting bracket (7), a six-component balance (8), a connector (9), and a tilting mechanism (10). The rotor (3) is fixedly connected to the blade clamp assembly (12) of the pitch mechanism (5), and then connected to the hub center component (4); the hub center component (4) is coaxially and vertically installed with the rotor component of the motor (6); the stator component of the motor (6) is fixedly connected to the upper end of the servo mounting bracket (7); the lower end of the servo mounting bracket (7) is fixedly connected to the upper end of the six-component balance (8); the lower end of the six-component balance (8) is fixedly connected to the adapter (9); and the adapter (9) is fixedly connected to the tilting mechanism (10).

2. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 1, characterized in that, The rotor test system test device (2) is set on the mounting platform (30) and located at the wind tunnel inlet, with the rotor at the center of the wind tunnel flow.

3. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 1, characterized in that, A photoelectric sensor (11) is installed on the fixed mounting panel of the tilting mechanism (10). Its polarized light is emitted vertically upward. A reflective sticker is attached to the area on the lower end surface of the rotor (3) opposite to the light emission position of the photoelectric sensor (11). When the rotor rotates to the appropriate position, the polarized light emitted by the photoelectric sensor (11) is reflected by the reflective sticker on the lower end surface of the rotor to the receiving module of the photoelectric sensor (11).

4. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 1, characterized in that, The rotor (3) and the blade clamp assembly (12) of the pitch mechanism (5) are fixedly connected by blade pin screws. The blade clamp assembly (12) is coaxially connected with the central part of the blade hub (4). The rotor (3) and the blade clamp assembly (12) are arranged symmetrically.

5. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 1, characterized in that, The rotor test system test device (2) also includes: a first vibration sensor (28) and a second vibration sensor (29). The first vibration sensor (28) is installed on the lower end face of the servo mounting bracket (7), and the second vibration sensor (29) is installed on the fixed mounting panel of the tilting mechanism (10) to monitor the vibration value of the test bench.

6. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 1, characterized in that, The pitch control mechanism (5) includes: a propeller clamp assembly (12), a blade tie rod (13), a pitch control lever (14), a dynamic-to-static conversion assembly (15), a stationary ring tie rod (16), a servo arm (17), a servo (18), and a servo frame assembly (19). Among them, a propeller clamp assembly (12) is set on each of the left and right sides of the propeller hub central part (4). The propeller clamp assembly (12) is pressed with the propeller hub central part (4) through a bearing. The propeller clamp assembly (12) can rotate around the propeller hub central part (4) along the central axis. Two propeller rods (13) are symmetrically arranged about the pitch control lever (14). The propeller rods (13) and the pitch control lever (14) are connected. The pitch control lever (14) passes through the bearing at the axial center of the propeller hub central part (4) on the same axis. The bottom end of the pitch control lever (14) is connected to the dynamic-static conversion assembly (15). The dynamic-static conversion assembly (15) is connected to the servo frame assembly (19) and the stationary ring rod (16). The stationary ring rod (16) is connected to the servo arm (17) through a ball joint bearing. The servo arm (17) is connected to the servo (18). The servo (18) is fixedly installed on the servo frame assembly (19).

7. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 6, characterized in that, The dynamic-static conversion assembly (15) has two bearings installed inside. The inner wall of the bearing is a rotating part, and the outer end is a non-rotating fixed ring (20). An anti-torsion shaft (21) is connected to one side of the fixed ring (20). The end of the anti-torsion shaft (21) is inserted into the slide groove of the servo frame assembly (19). The anti-torsion shaft (21) can only move vertically along the slide groove. The other side of the fixed ring (20) is connected to the fixed ring tie rod (16) through a ball joint bearing.

8. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 6, characterized in that, The blade lever (13) and the pitch control lever (14) are connected by a fork, and the servo arm (17) is fixedly connected to the servo (18) by screws.

9. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 7, characterized in that, During the rotation of the motor (6), the central component (4) of the rotor hub rotates synchronously. The central component (4) of the rotor hub drives the rotor clamp assembly (12) and the rotor (3) to rotate synchronously. When the rotor clamp assembly (12) rotates, it drives the blade tie rod (13) and the pitch control lever (14) to rotate synchronously along the intermediate bearing of the central component (4) of the rotor hub and the bearing of the dynamic-static conversion assembly (15). When the rotor (3) needs to control the collective pitch change, it sends a control signal to the servo motor (18). The internal gear of the servo motor (18) rotates, which drives the servo arm (17) to rotate. The servo arm (17) drives the stationary ring tie rod (16) to perform displacement change. The stationary ring tie rod (16) drives the stationary ring (20) to perform vertical displacement change. During the vertical displacement, the stationary ring (20) drives the anti-torsion shaft (21) to perform vertical displacement along the slide of the servo frame assembly (19).

10. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 2, characterized in that, The tilting mechanism (10) includes: a mounting panel (22), a lower base plate (23), a drive arm (24), a linear guide rail (25), a drive motor (26), and a linear displacement groove (27). The upper end of the tilting mechanism (10) is fixedly connected to the adapter (9) through the mounting panel (22), and the lower end is fixedly connected to the mounting frame (30) through the bottom plate (23). The front end of the mounting panel (22) is connected to the fork of the bottom plate (23) through the connecting pin through two fork lugs. The rear end of the mounting panel (22) is connected to one end of each of the two drive arms (24) through the connecting pin. The other end of the drive arm (24) is connected to the linear displacement groove (27) through the connecting pin. A transverse sliding groove is provided in the middle of both sides of the linear displacement groove (27). The connecting pin is used to fix the drive arm (24) to the drive motor (26) through the sliding groove. The drive motor (26) is installed in the linear displacement groove (27) and fixed through the linear guide rail (25). The drive motor (26) can only move along the axial direction of the linear guide rail (25).

11. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 10, characterized in that, The front end of the mounting panel (22) is connected to the fork lug of the bottom plate (23) through a connecting pin via two fork lugs. The two fork lugs at the rear end of the mounting panel (22) are connected to one end of the two drive arms (24) through a connecting pin, and the other end of the drive arm (24) is connected to the linear displacement groove (27) through a connecting pin.

12. The small electric direct-drive variable collective pitch rotor wind tunnel test rig according to claim 11, characterized in that, During the test, when the rotor (3) needs to change its angle of attack, the drive motor (26) moves in one direction along the linear guide rail (25). During the movement, the drive motor (26) drives the drive arm (24) to move. The drive arm (24) drives the mounting panel (22) to rotate along the axial direction of its front connecting pin. The mounting panel (22) drives the adapter (9) and all the components above the adapter (9) to rotate, thereby causing the rotor angle of attack to change.

13. A test method for a small electric direct-drive variable collective pitch rotor wind tunnel test rig as described in any one of claims 1 to 12, characterized in that, include: Step 1: After the motor (6) is powered on, the six-component balance (8) collects the initial data, and at the same time, the environmental parameters at the rotor position are recorded and stored by the handheld atmospheric weather station. Step 2: Control the test bench speed to the preset value through the motor (6), check the operating status and communication status of the other equipment, and check whether the rotor speed direction is correct. If all are normal, proceed to step 3. Step 3: After the test bench runs at the preset speed for a preset time, check the operating status of each device. If the operation is normal, set the speed of the test bench to the test speed through the photoelectric sensor (11), then the wind tunnel starts to blow and runs for a preset time. Check the communication status. If it is normal, execute step 4. Step 4: Conduct the experiment according to the experimental state table and obtain steady-state data for each state.

14. The method according to claim 13, characterized in that, Environmental parameters include atmospheric pressure, temperature, and humidity.

15. The method according to claim 13, characterized in that, Before step 1, the method further includes: conducting a hovering test, specifically: After step 2, the test bench runs at a preset speed for a preset time. Then, the tilting mechanism (10) makes the angle of attack of the test bench 0°. The operating status of each device is checked. If the operation is normal, the speed of the test bench is set to the first test speed. After the speed stabilizes, the servo motor (18) is operated according to the test status table to change the rotor collective pitch. The operation is for a preset time. During the operation, the test data is recorded and stored in real time. The communication status is checked. If it is normal, the next step is executed. Enter the second test speed test state, stabilize the rotor speed to the second test speed test state through the motor (6), and after the speed is stabilized, operate the servo control system according to the test state table to change the rotor collective pitch. Run for a preset time, record and store test data in real time during the operation, check the communication status, and if it is normal, proceed to the next step. Repeat the previous step until data from all experimental states have been collected.

16. The method according to claim 15, characterized in that, The test data include: rotor speed collected by a six-component balance (8) and photoelectric sensor (11), test bench vibration value collected by a first vibration sensor (28) and a second vibration sensor (29), and control angle value collected by a servo motor (18).

17. The method according to claim 13, characterized in that, The method further includes: Determine the operating status of the six-component balance (8), motor (6), photoelectric sensor (11), servo motor (18), first vibration sensor (28), second vibration sensor (29), and tilting mechanism (10). If the operating status is abnormal, troubleshoot first, and then execute step 1.

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