A small-volume rotor test bench and parameter matching method and control angle calculation method

Abstract

A small-volume rotor test bench and a parameter matching method and a control angle solution method belong to the technical field of aviation aerodynamic wind tunnel test. The present invention is to solve the problems existing in the existing small-volume rotor test bench. The test bench includes a main shaft tilt system, which includes a base, a tilt electric cylinder, a rotating shaft seat, a tilt table and an inclination sensor. Two rotating shaft seats are respectively arranged on the left and right sides of the base, and shaft heads are respectively arranged on the left and right sides of the tilt table. The two coaxial shaft heads are respectively rotated in correspondence with the two rotating shaft seats. The rear cylinder cover of the tilt electric cylinder is hinged to the front side of the base, and the piston rod of the tilt electric cylinder is arranged upward and hinged to the front side of the tilt table. An inclination sensor is arranged on the tilt table. The test rotor is connected to the power transmission system, and the power transmission system is connected to the tilt table. The present invention can provide technical support for the measurement of the rotor performance, blade surface pressure and blade bending moment load of a small unmanned aerial vehicle.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation aerodynamic wind tunnel test, and in particular relates to a small-volume rotor test bench and a parameter matching method and a control angle solution method. Background Art

[0002] The popularity of low-altitude economy continues to rise, and EVTOL and small rotor-type UAVs have become the current research hotspots. Similar to single-rotor helicopters, the rotor aerodynamic characteristics of rotor-type UAVs are complex. Wind tunnel tests are still an important means to conduct research and verification of the aerodynamic characteristics of such rotors. In order to understand the flow phenomena and vibration characteristics on the rotor blade surface and their influence on the rotor performance, it is necessary to conduct rotor blade bending moment and surface pressure measurements. The rotor wind tunnel test uses the rotor test bench to conduct tests such as rotor performance, rotor blade surface pressure and blade bending moment load measurement. The traditional large rotor test bench is equipped with a transmission shaft bottom A slip ring is installed, and the slip ring cable is connected to the rotation signal line on the blade through a hollow transmission shaft to realize the transmission of the rotation signal. However, the traditional large rotor platform is large in size and has insufficient rotor speed due to the presence of a reduction gearbox, etc., and is not suitable for rotor testing of small rotor UAVs. The existing small rotor platform has a thin transmission shaft and cannot realize the transmission of rotation signals through a hollow shaft. It can often only measure the overall performance of the rotor, but not the rotation signal on the rotor blade, which does not meet the refined measurement needs of the rotor of small rotor UAVs. It is necessary to design a small-volume rotor test bench that can measure rotation signals. Summary of the invention

[0003] The purpose of the present invention is to provide a small-volume rotor test bench and a parameter matching method and a control angle calculation method to solve the problems existing in the existing small-volume rotor test bench. The technical solution adopted by the present invention is as follows:

[0004] A small-volume rotor test bench includes a main shaft tilting system, a torque measuring device, a power transmission system, a rotor balance, a control system and a slip ring;

[0005] The main shaft tilting system includes a base, a tilting electric cylinder, a rotating shaft seat, a tilting platform and an inclination sensor. Two rotating shaft seats are respectively arranged on the base on the left and right sides. The left and right sides of the tilting platform are respectively provided with shaft heads. The two coaxial shaft heads are respectively rotated in correspondence with the two rotating shaft seats. The rear cylinder cover of the tilting electric cylinder is hinged to the front side of the base. The piston rod of the tilting electric cylinder is arranged upward and is hinged to the front side of the tilting platform. The tilting platform is provided with an inclination sensor.

[0006] The torque measuring device includes a torque sensor, and the power transmission system includes a motor, a transition sleeve, a transmission shaft, a rotor shaft, a transition connection seat, a transmission sleeve and a balance fixing seat. The transition connection seat is fixed on the tilting platform, and the rotor balance, the balance fixing seat, the transmission sleeve and the transition connection seat are sequentially connected from top to bottom. The torque sensor includes a first rotor and a first stator that are rotatably sleeved inside and outside. The first stator is fixed on the transition connection seat through a sensor mounting seat. The motor is fixed on the tilting platform, and the output shaft of the motor extends into the transition connection seat. The rotor shaft, the transmission shaft, the first rotor, the transition sleeve and the output shaft of the motor are sequentially connected from top to bottom. The transmission shaft passes through the transmission sleeve, and the two ends of the transmission sleeve are respectively matched with the transmission shaft for rotation.

[0007] The control system includes a control electric cylinder seat, a control electric cylinder, an automatic tilt device, a guide cylinder and a П-shaped key. The slip ring includes a second rotor and a second stator that are matched for internal and external rotation. The second stator, the guide cylinder and the control electric cylinder seat are connected in sequence from top to bottom. A plurality of control electric cylinders are arranged around the control electric cylinder seat. A plurality of П-shaped keys are arranged on the outer periphery of the guide cylinder. The inner ring of the automatic tilt device slides along the axial direction of the guide cylinder, and the inner ring of the automatic tilt device and the guide cylinder are matched circumferentially through the П-shaped key. The piston rods of the plurality of control electric cylinders are arranged upward and are respectively hinged to the outer ring of the automatic tilt device. The lower ends of the plurality of pitch-changing pull rods are respectively hinged to the outer ring of the automatic tilt device. The rotor shaft passes through the rotor balance and the guide cylinder. The second rotor is sleeved on the rotor shaft. The two ends of the guide cylinder are respectively matched for rotation with the rotor shaft. The bearing at the top of the guide cylinder is a deep groove ball bearing, and the bearing at the bottom of the guide cylinder is a double-row angular contact bearing. The load on the rotor shaft is transmitted to the rotor balance through the two bearings.

[0008] The control electric cylinder seat is connected to the upper end of the rotor balance, the upper end of the rotor shaft is connected to the hub of the test rotor, and the upper ends of a plurality of pitch-changing pull rods are hinged to the leading edge sides of the blades of a plurality of test rotors in a one-to-one correspondence.

[0009] Furthermore, two tilt limit blocks are arranged front and rear on the end surface of the rotating shaft seat facing the tilting platform, and limit blocks are arranged on the left and right sides of the tilting platform respectively, and the limit blocks swing between the two tilt limit blocks on the same side.

[0010] Furthermore, a through groove opened along the length direction is provided on the end face of the I-shaped key facing the guide tube. The I-shaped key and the guide tube cooperate to form a lead hole for the cable of the slip ring to pass through. The cable of the second rotor is connected to the blade surface pressure and bending moment load measurement cable of the test rotor, and rotates synchronously with the test rotor.

[0011] Furthermore, the lower end of the first rotor is connected to the transition sleeve through a single diaphragm coupling, the transition sleeve is connected to the output shaft of the motor through a flat key, the upper end of the first rotor is connected to the lower end of the transmission shaft through another single diaphragm coupling, and the other end of the transmission shaft is connected to the rotor shaft through a double diaphragm coupling.

[0012] Furthermore, it also includes a plurality of anti-torsion arms, the lower ends of which are respectively hinged to the outer ring of the automatic tilt device, and the upper ends of which are respectively connected to the hub of the test rotor.

[0013] Furthermore, the shaft head is rotatably connected to the corresponding rotating shaft seat through a bearing.

[0014] Furthermore, it also includes a data acquisition trigger device and a data acquisition system. The data acquisition trigger device includes a code disk, a photoelectric switch mounting seat, a first photoelectric switch and a second photoelectric switch. The code disk is sleeved on the transition sleeve. A number of pulse holes and a zero position reference hole are evenly arranged on the circumference of the code disk. The two photoelectric switch mounting seats are respectively fixed on the transition connecting seat. The first photoelectric switch and the second photoelectric switch are respectively arranged on the two photoelectric switch mounting seats in a one-to-one correspondence. When the first photoelectric switch is aligned with the zero position reference hole, the second photoelectric switch is aligned with the pulse hole farthest from the zero position reference hole. The first photoelectric switch and the second photoelectric switch are respectively electrically connected to the data acquisition system.

[0015] The present invention also provides a small-volume rotor test bench parameter matching method, which is based on the above-mentioned small-volume rotor test bench to achieve:

[0016] definition O 1 is the left-view projection of the axis of the shaft head, the tilt table and the motor constitute the lower assembly, the part of the power transmission system above the tilt table, the torque measuring device, the rotor balance, the control system, the slip ring and the test rotor constitute the upper assembly, O 3 is the left-side projection of the piston rod of the tilt electric cylinder and the axis of the hinge axis of the tilt table. O 3 to O The distance of 1 is L 1. The center of gravity of the lower assembly is O The distance of 1 is L 3. The center of gravity of the upper assembly is O The distance of 1 is L 4. Test rotor hub center to O The distance of 1 is L 5, then:

[0017] Thrust of tilting electric cylinder F 1 satisfies the following formula:

[0018] ;

[0019] Where: F 2 is the wind load on the test rotor, M z is the pitch moment measured by the rotor balance, G 1 is the gravity exerted on the upper component, G 2 is the gravity exerted on the lower component,α is the tilt angle of the rotor shaft. When the rotor shaft is vertical in the initial state, α The value is zero, β It is the angle between the upper end surface of the tilt table and the piston rod of the tilt electric cylinder. s is the safety factor;

[0020] Will α When the value is zero, the extended length of the piston rod of the tilting electric cylinder is marked as L , and define the length L As the reference length, the piston rod of the tilt electric cylinder extends out compared to the reference length, and the rotor shaft tilts backward. The piston rod of the tilt electric cylinder retracts compared to the reference length, and the rotor shaft tilts forward. The forward tilt of the rotor shaft is defined as positive, and the backward tilt of the rotor shaft is defined as negative. When the rotor shaft tilts backward to the limit angle, α The value is the smallest, and the rotor axis tilts forward to the limit angle. α The value is the largest;

[0021] Define the left-view projection of the axis of the rear cylinder cover of the tilt electric cylinder and the hinge axis on the end surface of the tilt table as O 2, O 1 and O The horizontal distance of 2 is L 6. O 1 and O The vertical distance of 2 is L 7, γ The upper surface of the tilting table O 1The angle between the upper vertical direction, is the extension and contraction change of the piston rod of the tilting electric cylinder compared to the reference length, then γ and Satisfies the following relationship:

[0022] ;

[0023] set up α When the maximum value is taken, Value is , α When taking the minimum value, Value is :

[0024] The total length of the piston rod of the tilting electric cylinder is S 1 satisfies the following formula:

[0025] ;

[0026] Angle γ Satisfy the following formula:

[0027] ;

[0028] Where: δ is the angle between the rotor shaft and the upper end surface of the tilt table;

[0029] L 6 is calculated by the following formula:

[0030] ;

[0031] Where: θ The piston rod of the tilting electric cylinder O 2The angle between the left horizontal direction; L 2 for O 3 to O 2 distance;

[0032] L 7 is calculated by the following formula:

[0033] ;

[0034] Angle θ Satisfy the following formula:

[0035] ;

[0036] Hover pull T 0 is calculated by the following formula:

[0037] ;

[0038] Where: ρ is the air density, is the blade tip loss coefficient, π is the circumference of a circle, R is the rotor radius, is the hovering induced speed;

[0039] Hovering power P 0 is calculated by the following formula:

[0040] ;

[0041] Where: J 0 is the induced power correction coefficient, is the resistance power correction factor, c x is the airfoil drag coefficient, b is the blade chord length of the test rotor, is the rotation speed of the test rotor, N is the number of blades of the test rotor, is the slope of the airfoil lift line, is the collective pitch of the test rotor;

[0042] Hover induced speedv 0 is calculated by the following formula:

[0043] ;

[0044] Test rotor torque Calculated by the following formula:

[0045] ;

[0046] When flying forward, the model's maximum backward force is H Calculated by the following formula:

[0047] ;

[0048] Where: A 1 is the longitudinal periodic pitch variation, T is the maximum pulling force during forward flight;

[0049] When flying forward, the model's maximum lateral force is S Calculated by the following formula:

[0050] ;

[0051] Where: B 1 is the longitudinal periodic pitch variation;

[0052] Maximum pulling force in forward flight T Calculated by the following formula:

[0053] ;

[0054] Hub torque of the test rotor M G Calculated by the following formula:

[0055] ;

[0056] Where: e To test the rotor's flapping hinge displacement, S e is the mass static distance of the blade of the test rotor about the flapping hinge, β 1 is the blade cyclic flapping angle of the test rotor;

[0057] The calculation formula of the six-component load of the rotor balance is as follows:

[0058] ;

[0059] Where: Y is the pulling force measured by the rotor balance, X is the drag measured by the rotor balance, Z is the side force measured by the rotor balance, My is the yaw moment measured by the rotor balance, M z is the pitch moment measured by the rotor balance, M x are the rolling moments measured by the rotor balance, s 3 is the design safety factor of the rotor balance, l 8 is the distance from the hub center of the test rotor to the calibration center of the rotor balance;

[0060] Torque load on rotor balance M k Calculated by the following formula:

[0061] ;

[0062] Where: M k is the torque balance load of the rotor balance;

[0063] Motor power P Calculated by the following formula:

[0064] .

[0065] The present invention also provides a control angle calculation method, which is implemented based on the above-mentioned small-volume rotor test bench:

[0066] Calculate the extension and contraction change of the piston rod of the electric cylinder based on the control angle of the test rotor m The formula is as follows:

[0067] ;

[0068] Where: d is the distance between the hinged shafts at both ends of the pitch rod. M is the transformation matrix, M -1 is a matrix M's Generalized inverse matrix;

[0069] Control the extension and contraction of the piston rod of the electric cylinder m Calculated by the following formula:

[0070] ;

[0071] in m 1. m 2 and m 3 is the expansion and contraction variation of the piston rods of the three operating electric cylinders;

[0072] Transformation Matrix M Calculated by the following formula:

[0073] ;

[0074] d Calculated by the following formula:

[0075] ;

[0076] Where: d 1. d 2. d 3 and d 4 are the axial displacements of the four variable pitch tie rods, L c is the length of the pitch rod

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] 1. The purpose of the present invention is to provide a small-volume rotor test bench that can measure rotation signals. The test rotor is directly driven by a motor without a reduction gearbox, which reduces the volume of the rotor test bench, has a compact structure, and reduces the blockage of the rotor test bench. At the same time, a through-hole slip ring is installed under the hub of the test rotor to avoid the long-distance transmission of the slip ring cable of the traditional rotor test bench. The present invention can provide technical support for the measurement of rotor performance, blade surface pressure and blade bending moment load of small UAVs.

[0079] 2. The ultimate goal of the parameter matching method of the present invention is to determine the thrust of the tilting electric cylinder F 1Conditions to be met: The piston rod extension and contraction change of the tilting electric cylinder ∆ L Conditions to be met, motor power P Conditions to be met, six-component calculation formula for rotor balance, and torque load of rotor balance M k Through the parameter matching method, the design parameters of the rotor platform can be quickly obtained through key parameters such as the tilt electric cylinder, the motor, and the rotor balance, while improving the matching degree of each system of the rotor platform.

[0080] 3. According to the desired test rotor control angle, the corresponding telescopic change of the piston rod of the control electric cylinder is calculated through the matrix, and the desired test rotor control angle can be obtained by controlling the telescopic change of the piston rod of the control electric cylinder. The test rotor collective pitch and cyclic pitch control can be realized without on-site calibration. The rotor test bench can provide technical support for the measurement of small UAV rotor performance, blade surface pressure and blade bending moment load. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a structural schematic diagram of the test bench of the present invention;

[0082] Figure 2is a left sectional view of the test bench of the present invention;

[0083] Figure 3 It is a structural schematic diagram of the spindle tilting system;

[0084] Figure 4 It is a schematic diagram of the structure where the rotor shaft is connected to the motor;

[0085] Figure 5 It is a schematic diagram of the connection between the control system and the power transmission system;

[0086] Figure 6 It is a schematic diagram of the connection between the rotor balance and the power transmission system;

[0087] Figure 7 It is a schematic diagram of the structure of the control system;

[0088] Figure 8 It is a schematic diagram of the coordination between the data acquisition trigger device and the torque measurement device and the power transmission system;

[0089] Fig. 9 It is a structural diagram of a data acquisition trigger device;

[0090] Fig.10 It is a schematic diagram of the coordination between the rotor shaft and the guide cylinder;

[0091] Fig.11 It is a schematic diagram of the matching of the transmission shaft and the transmission sleeve;

[0092] Fig.12 It is a schematic diagram of some parameters in the parameter matching method of the present invention;

[0093] Fig.13 It is another part of the parameter schematic diagram in the parameter matching method of the present invention;

[0094] Fig.14 It is a schematic diagram of the solution method of the present invention.

[0095] 1. Spindle tilt system, 11. Base, 12. Tilt electric cylinder, 13. Rotating shaft seat, 14. Tilt table, 15. Tilt sensor, 16. Tilt stop block, 2. Data acquisition trigger device, 21. Code disk, 22. Photoelectric switch mounting seat, 23. First photoelectric switch, 24. Second photoelectric switch, 3. Torque measuring device, 31. Torque sensor, 32. Sensor mounting seat, 4. Power transmission system, 41. Motor, 42. Transition sleeve, 43. Single diaphragm coupling, 44. Transmission shaft, 45. Double diaphragm coupling, 46. Rotor shaft, 47. Transition connection seat, 48. Transmission sleeve, 49. Balance fixing seat, 5. Rotor balance, 6. Control system, 61. Control electric cylinder seat, 62. Control electric cylinder, 63. Automatic tilter, 64. Guide cylinder, 65. Π-shaped key, 66. Anti-torsion arm, 67. Pitch rod, 7. Slip ring, 8. Test rotor. DETAILED DESCRIPTION

[0096] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0097] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as bolt connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can be found in the existing connection methods to achieve the function, and those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and bolt connection is selected for detachable connection.

[0098] The present invention will be further described in detail below in conjunction with the accompanying drawings. The following embodiments are provided to explain the present invention, but the present invention is not limited to the following embodiments.

[0099] Embodiment 1: Figure 1 to Figure 14 As shown, a small-volume rotor test bench includes a main shaft tilting system 1, a torque measuring device 3, a power transmission system 4, a rotor balance 5, a control system 6 and a slip ring 7;

[0100] The main shaft tilting system 1 comprises a base 11, a tilting electric cylinder 12, a rotating shaft seat 13, a tilting platform 14 and an inclination sensor 15. Two rotating shaft seats 13 are respectively arranged on the base 11 on the left and right sides. The tilting platform 14 is respectively provided with shaft heads on the left and right sides. The two coaxial shaft heads are respectively rotated in correspondence with the two rotating shaft seats 13. The rear cylinder cover of the tilting electric cylinder 12 is hinged to the front side of the base 11. The piston rod of the tilting electric cylinder 12 is arranged upward and hinged to the front side of the tilting platform 14. The tilting platform 14 is provided with an inclination sensor 15.

[0101] The torque measuring device 3 includes a torque sensor 31, and the power transmission system 4 includes a motor 41, a transition sleeve 42, a transmission shaft 44, a rotor shaft 46, a transition connection seat 47, a transmission sleeve 48 and a balance fixing seat 49. The transition connection seat 47 is fixed on the tilting platform 14, and the rotor balance 5, the balance fixing seat 49, the transmission sleeve 48 and the transition connection seat 47 are sequentially connected from top to bottom. The torque sensor 31 includes a first rotor and a first stator that are rotatably sleeved inside and outside. The first stator is fixed on the transition connection seat 47 through the sensor mounting seat 32. The motor 41 is fixed on the tilting platform 14, and the output shaft of the motor 41 extends into the transition connection seat 47. The rotor shaft 46, the transmission shaft 44, the first rotor, the transition sleeve 42 and the output shaft of the motor 41 are sequentially connected from top to bottom. The transmission shaft 44 passes through the transmission sleeve 48, and the two ends of the transmission sleeve 48 are respectively rotatably matched with the transmission shaft 44;

[0102] The operating system 6 includes an operating electric cylinder seat 61, an operating electric cylinder 62, an automatic tilter 63, a guide cylinder 64 and a П-shaped key 65. The slip ring 7 includes a second rotor and a second stator that are rotated together inside and outside. The second stator, the guide cylinder 64 and the operating electric cylinder seat 61 are connected in sequence from top to bottom. A plurality of operating electric cylinders 62 are arranged around the operating electric cylinder seat 61. A plurality of П-shaped keys 65 are arranged on the outer periphery of the guide cylinder 64. The inner ring of the automatic tilter 63 slides along the axial direction of the guide cylinder 64, and the inner ring of the automatic tilter 63 and the guide cylinder 64 are circumferentially connected through the П-shaped key 65. The piston rods of the plurality of operating electric cylinders 62 are arranged upward and are respectively hinged to the outer rings of the automatic tilting device 63. The lower ends of the plurality of pitch-changing pull rods 67 are respectively hinged to the outer rings of the automatic tilting device 63. The rotor shaft 46 passes through the rotor balance 5 and the guide cylinder 64. The second rotor is sleeved on the rotor shaft 46. The two ends of the guide cylinder 64 are respectively rotatably matched with the rotor shaft 46. The bearing at the top of the guide cylinder 64 is a deep groove ball bearing, and the bearing at the bottom of the guide cylinder 64 is a double-row angular contact bearing. The load on the rotor shaft 46 is transmitted to the rotor balance 5 through the two bearings.

[0103] The control electric cylinder seat 61 is connected to the upper end of the rotor balance 5, the upper end of the rotor shaft 46 is connected to the hub of the test rotor 8, and the upper ends of a plurality of pitch-changing pull rods 67 are hinged to the leading edge sides of the blades of a plurality of test rotors 8 in a one-to-one correspondence.

[0104] The main shaft tilt system 1 can adjust the tilt attitude of the test rotor 8, so as to meet the simulation requirements of different forward flight attitudes of the test rotor 8. The base 11 is used to support the entire rotor test bench. The tilt table 14 is rotatably mounted on the base 11 through the rotating shaft seat 13. The rear cylinder head end of the tilt electric cylinder 12 is hinged to the base 11, and the telescopic end of the tilt electric cylinder 12 is connected to the front side of the tilt table 14 through a joint bearing. The tilt table 14 can be driven to tilt by the telescopic movement of the piston rod of the tilt electric cylinder 12. The tilt angle sensor 15 is used to measure the tilt angle of the rotor shaft 46.

[0105] The rotor balance 5 is used to measure the force and torque generated by the test rotor 8. A fixed frame is provided at the lower end of the rotor balance 5, and a floating frame is provided at the upper end of the rotor balance 5. The fixed frame and the balance fixing seat 49 are positioned by a stopper and connected by bolts. The floating frame supports the control system 6 and the test rotor 8. The rotor balance 5 is used to measure the force and torque of the test rotor 8. There is a circular hole in the center of the rotor balance 5, and the rotor shaft 46 passes through the circular hole, and a gap is provided between the rotor shaft 46 and the rotor balance 5.

[0106] The control system 6 is used to adjust the blade pitch angle of the test rotor 8. The control electric cylinder seat 61 is connected to the floating frame of the rotor balance 5 by bolts. There are three control electric cylinders 62, which are evenly arranged around the axis of the rotor shaft 46. The rear cylinder cover end of the control electric cylinder 62 is hinged to the control electric cylinder seat 61. The piston rod of the control electric cylinder 62 is hinged to the outer ring of the automatic tilt device 63 through a joint bearing. The automatic tilt device 63 can be raised and lowered by extending and retracting the piston rod of the control electric cylinder 62, thereby realizing the variable pitch control of the test rotor 8 at different angles.

[0107] The purpose of the present invention is to provide a small-volume rotor test bench that can measure rotation signals. The test rotor 8 is directly driven by a motor 41 without a reduction gearbox, which reduces the volume of the rotor test bench, has a compact structure, and reduces the blockage of the rotor test bench. At the same time, the through-hole slip ring 7 is installed under the hub of the test rotor 8 to avoid the long-distance transmission of the slip ring cable of the traditional rotor test bench. The present invention can provide technical support for the measurement of the rotor performance, blade surface pressure and blade bending moment load of a small unmanned aerial vehicle.

[0108] Two tilt limit blocks 16 are arranged at the front and rear ends of the rotating shaft seat 13 on one side end surface facing the tilt platform 14, and limit blocks are respectively arranged on the left and right sides of the tilt platform 14. The limit block swings between the two tilt limit blocks 16 on the same side. If the piston rod of the tilt electric cylinder 12 fails to be connected to the tilt platform 14 and separates, the limit block will be offset and limited by any tilt limit block 16 on the same side to avoid accidents caused by failure of the tilt electric cylinder 12.

[0109] A through groove opened along the length direction is provided on the end face of the I-shaped key 65 facing the guide cylinder 64. The I-shaped key 65 cooperates with the guide cylinder 64 to form a lead hole for the cable of the slip ring 7 to pass through. The cable of the second rotor is connected to the blade surface pressure and bending moment load measurement cable of the test rotor 8, and rotates synchronously with the test rotor 8, thereby realizing the collection of rotation signals.

[0110] The lower end of the first rotor is connected to the transition sleeve 42 through a single diaphragm coupling 43, and the transition sleeve 42 is connected to the output shaft of the motor 41 through a flat key. The upper end of the first rotor is connected to the lower end of the transmission shaft 44 through another single diaphragm coupling 43, and the other end of the transmission shaft 44 is connected to the rotor shaft 46 through a double diaphragm coupling 45. The power transmission system 4 realizes the rotation of the test rotor 8 by the rotation of the motor 41 through the above structure, and only transmits torque without transmitting axial force by connecting the single diaphragm coupling 43 and the double diaphragm coupling 45 in series, thereby realizing the decoupling of the aerodynamic measurement of the rotor balance.

[0111] It also includes a plurality of anti-torsion arms 66 , the lower ends of which are respectively hinged to the outer ring of the automatic tilt device 63 , and the upper ends of which are respectively connected to the hub of the test rotor 8 .

[0112] The shaft head is rotatably connected to the corresponding shaft seat 13 via a bearing.

[0113] The data acquisition trigger device 2 and the data acquisition system are also included. The data acquisition trigger device 2 includes a code disk 21, a photoelectric switch mounting seat 22, a first photoelectric switch 23 and a second photoelectric switch 24. The code disk 21 is sleeved on the transition shaft sleeve 42. A plurality of pulse holes and a zero position reference hole are evenly arranged on the circumference of the code disk 21. The two photoelectric switch mounting seats 22 are respectively fixed on the transition connecting seat 47. The first photoelectric switch 23 and the second photoelectric switch 24 are respectively arranged on the two photoelectric switch mounting seats 22 in a one-to-one correspondence. When the first photoelectric switch 23 is aligned with the zero position reference hole, the second photoelectric switch 24 is aligned with the pulse hole farthest from the zero position reference hole. The first photoelectric switch 23 The second photoelectric switch 24 is electrically connected to the data acquisition system respectively. When the first photoelectric switch 23 is aligned with the zero-position reference hole, the first photoelectric switch 23 sends out a zero-position pulse signal, and the data acquisition system starts to collect the strain load data of the rotor balance 5. At the same time, the second photoelectric switch 24 starts to send out an equi-azimuth pulse signal when it is aligned with any pulse hole. One rotation of the code disk 21 is a measurement cycle. When the first photoelectric switch 23 is aligned with the zero-position reference hole again, the first photoelectric switch 23 sends out a zero-position pulse signal again to perform zero-position calibration. After the second photoelectric switch 24 outputs eight cycles of equi-azimuth pulse signals, the strain load measurement of the rotor balance 5 is completed.

[0114] Embodiment 2: Figure 1 to Figure 14As shown, a parameter matching method for a small-volume rotor test bench is implemented based on a small-volume rotor test bench described in Example 1:

[0115] definition O 1 is the left-view projection of the axis of the shaft head, the tilting platform 14 and the motor 41 constitute the lower assembly, the part of the power transmission system 4 located above the tilting platform 14, the torque measuring device 3, the rotor balance 5, the control system 6, the slip ring 7 and the test rotor 8 constitute the upper assembly, O 3 is a left-side projection of the piston rod of the tilt electric cylinder 12 and the articulation axis of the tilt table 14. O 3 to O The distance of 1 is L 1. The center of gravity of the lower assembly is O The distance of 1 is L 3. The center of gravity of the upper assembly is O The distance of 1 is L 4. Test rotor 8 from the hub center to O The distance of 1 is L 5, then:

[0116] Thrust of the tilting electric cylinder 12 F 1 satisfies the following formula:

[0117] ;

[0118] Where: F 2 is the wind load on the test rotor 8, M z is the pitch moment measured by the rotor balance 5, G 1 is the gravity exerted on the upper component, G 2 is the gravity exerted on the lower component, α is the tilt angle of the rotor shaft 46. In the initial state, the rotor shaft 46 is vertical. α The value is zero, β is the angle between the upper end surface of the tilting table 14 and the piston rod of the tilting electric cylinder 12, s is the safety factor;

[0119] Will α When the value is zero, the extended length of the piston rod of the tilting electric cylinder 12 is marked as L , and define the length L As the reference length, the piston rod of the tilt electric cylinder 12 extends out compared to the reference length, and the rotor shaft 46 tilts backward. As the piston rod of the tilt electric cylinder 12 retracts compared to the reference length, the rotor shaft 46 tilts forward. The forward tilt of the rotor shaft 46 is defined as the positive direction, and the backward tilt of the rotor shaft 46 is defined as the negative direction. When the rotor shaft 46 tilts backward to the limit angle, α The value is minimum, and the rotor shaft 46 tilts forward to the limit angle.α The value is the largest;

[0120] The left-view projection of the axis of the hinge axis between the rear cylinder cover of the tilt electric cylinder 12 and the upper end surface of the tilt table 14 is defined as O 2, O 1 and O The horizontal distance of 2 is L 6. O 1 and O The vertical distance of 2 is L 7, γ The upper end surface of the tilting platform 14 and O 1The angle between the upper vertical direction, is the extension and contraction change of the piston rod of the tilt electric cylinder 12 compared to the reference length, then γ and Satisfies the following relationship:

[0121] ;

[0122] set up α When the maximum value is taken, Value is , α When taking the minimum value, Value is :

[0123] The total length of the piston rod of the tilting electric cylinder 12 is S 1 satisfies the following formula:

[0124] ;

[0125] Angle γ Satisfy the following formula:

[0126] ;

[0127] Where: δ is the angle between the rotor shaft 46 and the upper end surface of the tilting platform 14;

[0128] L 6 is calculated by the following formula:

[0129] ;

[0130] Where: θ The piston rod of the tilt electric cylinder 12 and O 2The angle between the left horizontal direction; L 2 for O 3 to O 2 distance;

[0131] L 7 is calculated by the following formula:

[0132] ;

[0133] Angle θ Satisfy the following formula:

[0134] ;

[0135] Hover pull T 0 is calculated by the following formula:

[0136] ;

[0137] Where: ρ is the air density, is the blade tip loss coefficient, π is the circumference of a circle, R is the rotor radius, is the hovering induced speed;

[0138] Hovering power P 0 is calculated by the following formula:

[0139] ;

[0140] Where: J 0 is the induced power correction coefficient, is the resistance power correction factor, c x is the airfoil drag coefficient, b is the blade chord length of the test rotor 8, To test the rotation speed of rotor 8, N is the number of blades of the test rotor 8, is the slope of the airfoil lift line, is the collective pitch of the test rotor 8;

[0141] Hover induced speed v 0 is calculated by the following formula:

[0142] ;

[0143] Test rotor 8 torque Calculated by the following formula:

[0144] ;

[0145] When flying forward, the model's maximum backward force is H Calculated by the following formula:

[0146] ;

[0147] Where: A 1 is the longitudinal periodic pitch variation, Tis the maximum pulling force during forward flight;

[0148] When flying forward, the model's maximum lateral force is S Calculated by the following formula:

[0149] ;

[0150] Where: B 1 is the longitudinal periodic pitch variation;

[0151] Maximum pulling force in forward flight T Calculated by the following formula:

[0152] ;

[0153] Hub torque of test rotor 8 M G Calculated by the following formula:

[0154] ;

[0155] Where: e To test the flapping hinge outward displacement of rotor 8, S e is the mass static distance of the blade of the test rotor 8 around the flapping hinge, β 1 is the blade cyclic flapping angle of the test rotor 8;

[0156] The calculation formula of the six-component load of the rotor balance 5 is as follows:

[0157] ;

[0158] Where: Y is the pulling force measured by the rotor balance 5, X is the resistance measured by the rotor balance 5, Z is the side force measured by the rotor balance 5, M y is the yaw moment measured by the rotor balance 5, M z is the pitch moment measured by the rotor balance 5, M x are the rolling moments measured by the rotor balance 5, s 3 is the design safety factor of the rotor balance 5, l 8 is the distance from the hub center of the test rotor 8 to the calibration center of the rotor balance 5;

[0159] Torque load of rotor balance 5 M k Calculated by the following formula:

[0160] ;

[0161] Where: M k is the torque balance load of the rotor balance 5;

[0162] Power of motor 41 P Calculated by the following formula:

[0163] .

[0164] The ultimate purpose of the parameter matching method of the present invention is to determine the thrust of the tilting electric cylinder 12 F 1Conditions to be met: The extension and contraction amount of the piston rod of the tilting electric cylinder 12 ∆ L Conditions to be met, power of motor 41 P Conditions to be met, six-component calculation formula of rotor balance 5, and torque load of rotor balance 5 M k Through the parameter matching method, the design parameters of the rotor platform can be quickly obtained through key parameters such as the tilting electric cylinder 12, the motor 41, the rotor balance 5, etc., while improving the matching degree of each system of the rotor platform.

[0165] Embodiment 3: Figure 1 to Figure 14 As shown, a control angle solution method is implemented based on a small-volume rotor test bench described in Example 1:

[0166] The telescopic variation of the piston rod of the control electric cylinder 62 is calculated from the control angle of the test rotor 8 m The formula is as follows:

[0167] :

[0168] Where: d is the distance between the hinge shafts at both ends of the pitch-changing rod 67, M is the transformation matrix, M -1 is a matrix M's Generalized inverse matrix;

[0169] The expansion and contraction variation of the piston rod of the electric cylinder 62 m Calculated by the following formula:

[0170] ;

[0171] in m 1. m 2 and m 3 is the extension and contraction variation of the piston rods of the three operating electric cylinders 62;

[0172] Transformation Matrix M Calculated by the following formula:

[0173] ;

[0174] d Calculated by the following formula:

[0175] ;

[0176] Where: d 1. d 2. d 3 and d 4 are the axial displacements of the four variable pitch tie rods 67, L c is the length of the pitch-changing rod 67.

[0177] According to the desired control angle of the test rotor 8, the expansion and contraction variation of the piston rod of the corresponding control electric cylinder 62 is calculated through the matrix, and the desired control angle of the test rotor 8 can be obtained by controlling the expansion and contraction variation of the piston rod of the control electric cylinder 62. The total pitch and cyclic pitch control of the test rotor 8 can be realized without on-site calibration, and the rotor test bench can provide technical support for the measurement of rotor performance, blade surface pressure and blade bending moment load of small UAVs.

[0178] The above embodiments are merely exemplary descriptions of the present invention and do not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit of the present invention.

Claims

1. A small-volume rotor test bench, characterized in that: It comprises a main shaft tilting system (1), a torque measuring device (3), a power transmission system (4), a rotor balance (5), a control system (6) and a slip ring (7); The main shaft tilting system (1) comprises a base (11), a tilting electric cylinder (12), a rotating shaft seat (13), a tilting platform (14) and an inclination sensor (15); two rotating shaft seats (13) are respectively arranged on the base (11) on the left and right sides; shaft heads are respectively arranged on the left and right sides of the tilting platform (14); two coaxial shaft heads are respectively rotatably matched with the two rotating shaft seats (13); a rear cylinder cover of the tilting electric cylinder (12) is hinged to the front side of the base (11); a piston rod of the tilting electric cylinder (12) is arranged upward and hinged to the front side of the tilting platform (14); and an inclination sensor (15) is arranged on the tilting platform (14); The torque measuring device (3) comprises a torque sensor (31), the power transmission system (4) comprises a motor (41), a transition sleeve (42), a transmission shaft (44), a rotor shaft (46), a transition connection seat (47), a transmission sleeve (48) and a balance fixing seat (49), the transition connection seat (47) is fixed on the tilting table (14), the rotor balance (5), the balance fixing seat (49), the transmission sleeve (48) and the transition connection seat (47) are connected in sequence from top to bottom, and the torque sensor (31) comprises an inner and outer rotating sleeve A first rotor and a first stator, wherein the first stator is fixed to a transition connection seat (47) via a sensor mounting seat (32), the motor (41) is fixed to a tilting table (14), the output shaft of the motor (41) extends into the transition connection seat (47), the rotor shaft (46), the transmission shaft (44), the first rotor, the transition sleeve (42) and the output shaft of the motor (41) are connected in sequence from top to bottom, the transmission shaft (44) passes through a transmission sleeve (48), and both ends of the transmission sleeve (48) are respectively rotatably matched with the transmission shaft (44); The operating system (6) comprises an operating electric cylinder seat (61), an operating electric cylinder (62), an automatic tilter (63), a guide sleeve (64) and a П-shaped key (65); the slip ring (7) comprises a second rotor and a second stator which are matched for internal and external rotation; the second stator, the guide sleeve (64) and the operating electric cylinder seat (61) are connected in sequence from top to bottom; a plurality of operating electric cylinders (62) are arranged around the operating electric cylinder seat (61); a plurality of П-shaped keys (65) are arranged on the outer periphery of the guide sleeve (64); the inner ring of the automatic tilter (63) is arranged along the guide sleeve (64); The automatic tilting device (63) is axially slidable, and the inner ring of the automatic tilting device (63) and the guide sleeve (64) are circumferentially matched via a П-shaped key (65). The piston rods of the plurality of operating electric cylinders (62) are arranged upward and are respectively hinged to the outer ring of the automatic tilting device (63). The lower ends of the plurality of variable pitch pull rods (67) are respectively hinged to the outer ring of the automatic tilting device (63). The rotor shaft (46) passes through the rotor balance (5) and the guide sleeve (64). The second rotor is sleeved on the rotor shaft (46). The two ends of the guide sleeve (64) are respectively rotationally matched with the rotor shaft (46). The control electric cylinder seat (61) is connected to the upper end of the rotor balance (5), the upper end of the rotor shaft (46) is connected to the hub of the test rotor (8), and the upper ends of the plurality of pitch-changing pull rods (67) are hinged to the leading edge sides of the blades of the plurality of test rotors (8) in a one-to-one correspondence.

2. A small-volume rotor test bench according to claim 1, characterized in that: Two tilting limit blocks (16) are arranged front and rear on the end surface of one side of the rotating shaft seat (13) facing the tilting platform (14), and limit blocks are respectively arranged on the left and right sides of the tilting platform (14), and the limit blocks swing between the two tilting limit blocks (16) on the same side.

3. A small-volume rotor test bench according to claim 1, characterized in that: A through groove is provided on the end surface of the П-shaped key (65) facing the guide tube (64) along the length direction. The П-shaped key (65) cooperates with the guide tube (64) to form a lead hole through which the cable of the slip ring (7) can pass. The cable of the second rotor is connected to the blade surface pressure and bending moment load measurement cable of the test rotor (8), and rotates synchronously with the test rotor (8).

4. The small-volume rotor test bench according to claim 1, characterized in that: The lower end of the first rotor is connected to a transition sleeve (42) via a single diaphragm coupling (43); the transition sleeve (42) is connected to an output shaft of a motor (41) via a flat key; the upper end of the first rotor is connected to a lower end of a transmission shaft (44) via another single diaphragm coupling (43); the other end of the transmission shaft (44) is connected to a rotor shaft (46) via a double diaphragm coupling (45).

5. The small-volume rotor test bench according to claim 1, characterized in that: It also includes a plurality of anti-torsion arms (66), the lower ends of which are respectively hinged to the outer ring of the automatic tilt device (63), and the upper ends of which are respectively connected to the hub of the test rotor (8).

6. The small-volume rotor test bench according to claim 1, characterized in that: The shaft head is rotatably connected to the corresponding rotating shaft seat (13) via a bearing.

7. A small-volume rotor test bench according to any one of claims 1 to 6, characterized in that: It also includes a data acquisition trigger device (2) and a data acquisition system. The data acquisition trigger device (2) includes a code disk (21), a photoelectric switch mounting seat (22), a first photoelectric switch (23) and a second photoelectric switch (24). The code disk (21) is sleeved on a transition shaft sleeve (42). The code disk (21) is evenly provided with a plurality of pulse holes and a zero position reference hole on the circumference. The two photoelectric switch mounting seats (22) are respectively fixed on the transition connection seat (47). The first photoelectric switch (23) and the second photoelectric switch (24) are respectively provided on the two photoelectric switch mounting seats (22) in a one-to-one correspondence. When the first photoelectric switch (23) is aligned with the zero position reference hole, the second photoelectric switch (24) is aligned with the pulse hole farthest from the zero position reference hole. The first photoelectric switch (23) and the second photoelectric switch (24) are respectively electrically connected to the data acquisition system.

8. A parameter matching method for a small-volume rotor test bench, implemented by relying on a small-volume rotor test bench according to any one of claims 1 to 7, characterized in that: definition O 1 is a left-side projection of the axis of the shaft head, the tilting platform (14) and the motor (41) constitute a lower component, and the part of the power transmission system (4) located above the tilting platform (14), the torque measuring device (3), the rotor balance (5), the control system (6), the slip ring (7) and the test rotor (8) constitute an upper component. O 3 is a left-side projection of the piston rod of the tilt electric cylinder (12) and the axis of the articulation axis of the tilt table (14). O 3 to O The distance of 1 is L 1. The center of gravity of the lower assembly is O The distance of 1 is L 3. The center of gravity of the upper assembly is O The distance of 1 is L 4. The hub center of the test rotor (8) is O The distance of 1 is L 5, then: Thrust of the tilting electric cylinder (12) F 1 satisfies the following formula: ； Where: F 2 is the wind load on the test rotor (8), M z is the pitch moment measured by the rotor balance (5), G 1 is the gravity on the upper component, G 2 is the gravity exerted on the lower component, α is the tilt angle of the rotor shaft (46), when the rotor shaft (46) is vertical in the initial state, α The value is zero, β is the angle between the upper end surface of the tilting table (14) and the piston rod of the tilting electric cylinder (12), s is the safety factor; Will α When the value is zero, the extended length of the piston rod of the tilt electric cylinder (12) is marked as L , and define the length L When the piston rod of the tilt electric cylinder (12) is extended compared to the reference length, the rotor shaft (46) tilts backwards; when the piston rod of the tilt electric cylinder (12) is retracted compared to the reference length, the rotor shaft (46) tilts forwards. The forward tilt of the rotor shaft (46) is defined as a positive direction, and the backward tilt of the rotor shaft (46) is defined as a negative direction. When the rotor shaft (46) tilts backwards to a limit angle, α When the value is minimum and the rotor shaft (46) tilts forward to the limit angle, α The value is the largest; The left-view projection of the axis of the hinge axis between the rear cylinder cover of the tilting electric cylinder (12) and the upper end surface of the tilting table (14) is defined as: O 2, O 1 and O The horizontal distance of 2 is L 6. O 1 and O The vertical distance of 2 is L 7, γ The upper end surface of the tilting table (14) and O 1The angle between the upper vertical direction, is the extension and contraction change of the piston rod of the tilting electric cylinder (12) compared to the reference length, then γ and Satisfies the following relationship: ； set up α When the maximum value is taken, Value is , α When taking the minimum value, Value is : The total length of the piston rod of the tilting electric cylinder (12) is S 1 satisfies the following formula: ； Angle γ Satisfy the following formula: ； Where: δ is the angle between the rotor shaft (46) and the upper end surface of the tilting platform (14); L 6 is calculated by the following formula: ； Where: θ The piston rod of the tilt electric cylinder (12) and O 2The angle between the left horizontal direction; L 2 for O 3 to O 2 distance; L 7 is calculated by the following formula: ； Angle θ Satisfy the following formula: ； Hover pull T 0 is calculated by the following formula: ； Where: ρ is the air density, is the blade tip loss coefficient, π is the circumference of a circle, R is the rotor radius, is the hovering induced speed; Hovering power P 0 is calculated by the following formula: ； Where: J 0 is the induced power correction coefficient, is the resistance power correction factor, c x is the airfoil drag coefficient, b is the blade chord length of the test rotor (8), is the rotational speed of the test rotor (8), N is the number of blades of the test rotor (8), is the slope of the airfoil lift line, is the collective pitch of the test rotor (8); Hover induced speed v 0 is calculated by the following formula: ； Test rotor (8) torque Calculated by the following formula: ； When flying forward, the model's maximum backward force is H Calculated by the following formula: ； Where: A 1 is the longitudinal periodic pitch variation, T is the maximum pulling force during forward flight; When flying forward, the model's maximum lateral force is S Calculated by the following formula: ； Where: B 1 is the longitudinal periodic pitch variation; Maximum pulling force in forward flight T Calculated by the following formula: ； Hub moment of the test rotor (8) M G Calculated by the following formula: ； Where: e is the flapping hinge outward displacement of the test rotor (8), S e is the mass static distance of the blade of the test rotor (8) about the flapping hinge, β 1 is the blade cyclic flapping angle of the test rotor (8); The calculation formula of the six-component load of the rotor balance (5) is as follows: ； Where: Y is the tension measured by the rotor balance (5), X is the drag force measured by the rotor balance (5), Z is the side force measured by the rotor balance (5), M y is the yaw moment measured by the rotor balance (5), M z is the pitch moment measured by the rotor balance (5), M x are the rolling moments measured by the rotor balance (5), s 3 is the design safety factor of the rotor balance (5), l 8 is the distance from the hub center of the test rotor (8) to the calibration center of the rotor balance (5); Torque load of rotor balance (5) M k Calculated by the following formula: M k = M y ； Where: M k is the torque balance load of the rotor balance (5); Power of the motor (41) P Calculated by the following formula: 。 9. A control angle calculation method, implemented by relying on a small-volume rotor test bench as claimed in any one of claims 1 to 7, characterized in that: The telescopic change of the piston rod of the control electric cylinder (62) is calculated from the control angle of the test rotor (8). m The formula is as follows: ； Where: d is the distance between the hinge shafts at both ends of the pitch-changing tie rod (67), M is the transformation matrix, M -1 is a matrix M's Generalized inverse matrix; The extension and contraction variation of the piston rod of the electric cylinder (62) m Calculated by the following formula: ； in m 1. m 2 and m 3 is the extension and contraction variation of the piston rods of the three operating electric cylinders (62); Transformation Matrix M Calculated by the following formula: ； d Calculated by the following formula: ； Where: d 1. d 2. d 3 and d 4 are the axial displacements of the four variable pitch tie rods (67), L c is the length of the pitch-changing rod (67).

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