Ducted fan experimental measurement platform based on acoustic wind tunnel

Abstract

The invention discloses a ducted fan experimental measurement platform based on an acoustic wind tunnel, and belongs to the technical field of aviation power testing. The platform comprises a mounting base, an electric lifting platform is arranged on the mounting base, and a force transducer is mounted at the top of the electric lifting platform; a motor fixing support and a bearing fixing support are arranged above the force measuring sensor; a servo tilting motor is installed on the motor fixing support, the output end of the servo tilting motor is connected with a tilting shaft, and the tilting shaft is supported by the bearing fixing support. And a rectification clamp is fixed at the end part of the tilting shaft and comprises a wing-shaped shell and a clamping part for fixing a test object. By means of the structure, continuous and accurate tilting and high-precision measurement of a test object are achieved, and meanwhile interference of the supporting structure on a wind tunnel flow field and acoustic measurement is effectively reduced through the wing-shaped shell.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aviation power test, and particularly relates to a ducted fan experimental measurement platform based on an acoustic wind tunnel. BACKGROUND

[0002] With the rapid development of electric vertical take-off and landing aircraft (eVTOL), distributed tilt ducted fans have become a research hotspot due to their high thrust efficiency, low noise and high safety. However, the flow field structure of the ducted fan is complex during the tilt process from hovering to cruising, and the aerodynamic force shows strong unsteady characteristics, which brings challenges to the design and control of the aircraft.

[0003] At present, experimental researches on the ducted fan are mostly limited to fixed attack angle conditions. Although some experimental devices can realize tilting, the following defects are generally present: (1) lack of continuous and automatic tilting mechanism, which cannot simulate the real dynamic transition process; (2) insufficient rigidity of the support structure, which is easy to produce vibration under high-speed and high-thrust working conditions, affecting the accuracy of the force measurement; (3) the support and clamp are directly exposed in the flow field, which seriously interferes with the flow field quality and noise measurement, leading to data distortion; (4) single function, which is difficult to simultaneously perform high-precision aerodynamic force, flow field and acoustic measurement.

[0004] Therefore, there is an urgent need in the field for a special experimental platform capable of continuously tilting the ducted fan, high-precision force measurement and simultaneous acoustic and flow field measurement in an acoustic wind tunnel environment. SUMMARY

[0005] In order to solve the above technical problems, the application designs a ducted fan experimental measurement platform based on an acoustic wind tunnel to realize continuous and accurate tilting of the ducted fan or propeller in a large angle range, and simultaneously and accurately measure the unsteady aerodynamic characteristics, velocity field and acoustic characteristics of the ducted fan in a low-interference acoustic wind tunnel environment.

[0006] The ducted fan experimental measurement platform based on an acoustic wind tunnel of the application comprises a mounting base, two symmetrical electric lifting platforms mounted on the mounting base, force sensors mounted on the top of the electric lifting platforms, a motor fixing support mounted on one of the force sensors, and a bearing fixing support mounted on the other force sensor; a servo tilting motor is mounted on the motor fixing support, and a connecting bearing is mounted on the bearing fixing support; a tilting shaft is connected to the output end of the servo tilting motor and the connecting bearing, respectively, and a fairing clamp is fixed to the end of the tilting shaft.

[0007] The electric lifting platform comprises a support rod and a sleeve sleeve outside the support rod, and has a metal screw rod and a guide rail inside.

[0008] The motor fixing support is provided with a long strip-shaped counterbore groove, and the servo tilting motor is connected with the motor fixing support through fasteners penetrating through the counterbore groove.

[0009] The airfoil-shaped shell of the rectifying clamp is a symmetrical airfoil shape; and the clamping part is detachably connected with the airfoil-shaped shell through a quick-release pin.

[0010] The bearing fixing support is provided with at least two connecting bearings for supporting the tilting shaft.

[0011] The bottom of the mounting base is fixed with a support column for supporting the ground, and the four corners of the mounting base are provided with a moving mechanism including a threaded stud, a handle for rotating the threaded stud, and a universal wheel mounted at the bottom end of the threaded stud.

[0012] The force sensor is a six-component force sensor.

[0013] The application also provides a method for conducting a ducted fan experiment using the above experimental measurement platform, including the following steps: S1, mounting and fixing the ducted fan or propeller to be measured on the clamping part of the rectifying clamp, and adjusting the test object to the center height of the wind tunnel test section through the electric lifting platform; S2, controlling the servo tilting motor to drive the tilting shaft and the rectifying clamp to rotate the test object to the target tilting angle; S3, starting the wind tunnel and the test object, measuring the six-component force and torque of the test object through the force sensor, and synchronously collecting acoustic data and flow rate data.

[0014] The application has the following advantages: compared with the prior art, the application realizes continuous and accurate tilting of the test object by the design of the servo tilting motor driving combined with the airfoil-shaped rectifying clamp, significantly reduces the interference of the support structure on the wind tunnel flow field and acoustic measurement, the overall platform adopts a high-rigidity structure design and modular quick-release connection, effectively suppresses vibration under high-speed working conditions, and guarantees the accuracy and stability of unsteady aerodynamic force measurement; meanwhile, the integrated height adjustment, multi-dimensional force measurement and multi-physical quantity synchronous measurement functions enable the platform to efficiently and reliably obtain comprehensive experimental data of the ducted fan in the tilting transition stage, and provide strong experimental support for the design and optimization of the eVTOL power system. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following briefly introduces the drawings needed to be used in the embodiment description.

[0016] Figure 1 is the overall structure schematic diagram of the measurement platform in the embodiment.

[0017] Figure 2 is the upper structure schematic diagram of the measurement platform in the embodiment.

[0018] Figure 3 This is a schematic diagram of the rectifier fixture of the measurement platform in the embodiment.

[0019] Figure 4 This is an exploded view of the rectifier fixture of the measurement platform in the embodiment.

[0020] Figure 5 This is a schematic diagram of the mounting base structure of the measurement platform in the embodiment.

[0021] In the attached diagram, the structural names represented by each number are as follows: 1-Mounting base, 101-Support column, 102-Extension plate, 2-Electric lifting platform, 201-Support rod, 202-Outer sleeve, 3-Motor fixing support, 301-Counterhead groove, 4-Bearing fixing support, 5-Force sensor, 6-Servo tilt motor, 7-Connecting bearing, 8-Rectifying fixture, 801-Airfoil shell, 802-Tilting shaft, 803-Clamping part, 804-Quick release pin, 9-Stud, 10-Handle, 11-Universal wheel, 12-Test object. Detailed Implementation

[0022] 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, and not all embodiments. In addition, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0023] Example 1

[0024] like Figures 1 to 5 As shown in the figure, the ducted fan experimental measurement platform based on the acoustic wind tunnel in this embodiment mainly includes a mounting base 1, an electric lifting platform 2, a force sensor 5, a motor fixing support 3, a bearing fixing support 4, a servo tilt motor 6, a connecting bearing 7, and a rectifier fixture 8. Each component is modularly designed for rapid assembly and disassembly, and high-rigidity materials and precision structures ensure stability and measurement accuracy under high-speed and high-thrust conditions.

[0025] The mounting base 1 is a rectangular frame structure made of stainless steel sheet metal process to reduce the overall weight while ensuring structural strength. The four corners of the base are fixed with support columns 101 for stable support on the ground. The central base is welded with an expansion plate 102, which has multiple specifications of threaded holes for adapting to the installation of different test accessories. The four corners of the base are integrated with a moving mechanism, which includes a stud 9, a handle 10 and a universal wheel 11. The stud 9 is threadedly connected with the base, and the handle 10 is fixed on the top of the stud 9 for manual rotation of the stud. The universal wheel 11 is installed at the bottom end of the stud 9. When the handle 10 is rotated clockwise, the stud 9 drives the universal wheel 11 to descend, so that the support column 101 is separated from the ground, facilitating the movement of the platform; when it is rotated counterclockwise, the universal wheel 11 rises, and the support column 101 contacts the ground to achieve fixation. The four corners of the base are also welded with triangular reinforcing ribs to further improve the overall stiffness.

[0026] The electric lifting platform 2 is provided with two, symmetrically arranged on the mounting base 1. Each electric lifting platform includes a support rod 201 and an outer sleeve 202, the support rod 201 is sleeved in the outer sleeve 202, and the two are relatively moved through the internal precise metal screw and linear guide rail. The top and bottom ends of the support rod 201 and the outer sleeve 202 are provided with threaded holes, the top end of the support rod 201 is connected with the force sensor 5 through bolts, and the bottom end of the outer sleeve 202 is connected with the mounting base 1 through bolts. The electric lifting platform 2 is driven by a motor and can realize synchronous lifting to accurately adjust the height position of the test object 12 in the wind tunnel test section, ensuring the consistency of the measurement conditions under different tilt angles.

[0027] The force sensor 5 is a six-component force sensor fixed on the top end of the support rod 201 of the electric lifting platform 2. The sensor can measure the force and torque in three orthogonal directions (x, y, z) at the same time, and has three range settings: first gear 0-40N, second gear 0-400N, and third gear 0-4000N, with a measurement accuracy of 10 -4 N. The bottom of the force sensor 5 is provided with threaded holes, which are connected with the transition plate through countersunk screws, and the transition plate is fixed with the support rod 201. The sensor is connected with the external data acquisition system through a cable to realize real-time data transmission and processing.

[0028] The motor fixing support 3 and the bearing fixing support 4 are respectively installed on the two force sensors 5. The motor fixing support 3 is made of aluminum alloy, and a long slot 301 is formed on it for fixing the servo tilt motor 6 through fasteners (such as bolts). The slot 301 allows the servo tilt motor 6 to adjust the position along the support to adapt to different sizes of test objects 12. The bearing fixing support 4 is provided with two coaxial connecting bearings 7 for supporting the tilt shaft 802. The connecting bearings 7 are fixed through a bearing seat, and the bearing seat is connected with the force sensor 5 through a countersunk screw to ensure the stable rotation of the tilt shaft 802.

[0029] The servo tilt motor 6 is fixed on the motor fixing support 3, and the output end is connected with the tilt shaft 802 through a flat key, and a transition fit is adopted to suppress vibration. The servo tilt motor 6 is equipped with a planetary gear reducer to provide high torque output and realize accurate angle control. The motor is controlled by an external driver, and can be programmed to realize uniform or stepwise tilt movement, and the tilt angle range is ±90°. The relationship between the tilt angle θ and the step value Step is determined by the following formula: wherein, is the tilt angle, is the step value, is the number of runs.

[0030] The rectifying clamp 8 includes a wing-shaped shell 801 and a clamping part 803. The wing-shaped shell 801 adopts a NACA0018 symmetrical airfoil design to reduce the disturbance of the wind tunnel flow field and the interference of acoustic noise. The wing-shaped shell 801 is internally provided with a special-shaped groove for passing through the motor power line, and a circular hole is provided in the middle for mounting the tilt shaft 802, and the tilt shaft 802 and the circular hole adopt a gap fit. The clamping part 803 is composed of two upper and lower parts, the inner surface of which matches the outer contour of the ducted fan or propeller, and is fixed by screwing and nutting the ear pieces on both sides of the test object 12. The wing-shaped shell 801 and the clamping part 803 are connected by quick-release pins 804 for quick disassembly and replacement. The quick-release pins 804 pass through the corresponding hole positions of the wing-shaped shell 801 and the clamping part 803.

[0031] In addition, the experimental platform is designed as a multifunctional integrated system, and can also carry displacement sensors, acceleration sensors and hot-wire anemometers and other measuring elements to expand the vibration detection and flow field velocity measurement functions. The displacement sensor can be installed on the tilt shaft 802 or the rectifying clamp 8 to monitor the displacement change during tilting; the acceleration sensor can be installed on the test object 12 or the clamping part 803 to measure the vibration acceleration. The hot-wire anemometer can be installed in the wind tunnel test section through a special support and synchronized with the platform data acquisition system for high-precision measurement of flow field velocity distribution. The data of these sensors can be integrated and processed by the same acquisition system to realize synchronous measurement of multiple physical quantities.

[0032] The experimental platform assembly and operation process is as follows: (1) Assembly stage: place the installation base 1 on the horizontal ground, adjust the height of the universal wheel 11 by rotating the handle 10, and make the support column 101 stably contact the ground.

[0033] Fix the electric lifting platform 2 on the expansion plate 102 of the installation base 1 by bolts.

[0034] Install the force sensor 5 on the top end of the support rod 201 of the electric lifting platform 2, and connect it with the data acquisition system through a cable.

[0035] The motor fixing support 3 and the bearing fixing support 4 are fixed on the two force sensors 5 respectively.

[0036] The servo tilting motor 6 is installed on the motor fixing support 3 and is connected with the tilting shaft 802 through a flat key.

[0037] The other end of the tilting shaft 802 is inserted into the connecting bearing 7 to ensure coaxiality.

[0038] The airfoil shell 801 of the rectifying clamp 8 is fixed with the tilting shaft 802 through the quick release pin 804, then the clamping part 803 is installed and the test object 12 is fixed.

[0039] Optionally, the displacement sensor and the acceleration sensor are installed at the above specified positions and are connected to the data acquisition system; at the same time, the hot-wire anemometer is installed in the wind tunnel test section to ensure synchronization with the platform.

[0040] (2) Calibration and test phase: start the electric lifting platform 2, adjust the test object 12 to the center height of the wind tunnel test section.

[0041] Calibration of the force sensor 5: place a standard mass on the force sensor 5, open the force software, measure the six-component force of the force sensor under stable conditions, and calibrate the measurement results. The force measurement results of the force sensor and the stress conditions of the experimental target satisfy the following relationship: in the no-flow condition, , , , wherein , , and , , are the measurement results of the two force sensors, is the vertical distance from the vertical center of the force sensor to the tilting axis, is the pitching moment of the experimental target.

[0042] In the flow condition: , , is the tilting angle, is the thrust of the experimental target in the static state, and are the horizontal and vertical resistances of the experimental target, and are the horizontal and vertical resistances of the rectifying airfoil. Since the pitching moment of the symmetrical airfoil at the aerodynamic center is 0, the pitching moment calculation formula is equal to that in the no-flow condition.

[0043] The servo tilting motor 6 drives the test object 12 to the target tilting angle.

[0044] The wind tunnel and the test object 12 are started, six-component force and moment data are collected in real time through the force sensor 5, acoustic and flow velocity data are collected synchronously using a microphone array, a hot-wire anemometer and other auxiliary equipment, and vibration data are collected through a displacement sensor and an acceleration sensor, so that comprehensive measurement of aerodynamic, acoustic, flow field and vibration characteristics is realized.

[0045] The present embodiment effectively overcomes the defects of large vibration, strong flow field interference and single function in the prior art by means of high-rigidity structure design, modular quick-release connection and low-interference rectifying clamps, and realizes high-precision synchronous measurement of unsteady aerodynamic and acoustic characteristics of the ducted fan in the transition stage of tilting.

[0046] The preferred embodiments disclosed above are only used to help illustrate the present application. The preferred embodiments do not describe all the details and do not limit the present application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application.

Claims

1. An experimental measurement platform for ducted fans based on an acoustic wind tunnel, characterized in that, The device includes a mounting base (1), on which two symmetrical electric lifting platforms (2) are mounted. Force sensors (5) are mounted on the top of the electric lifting platforms (2). One force sensor (5) is mounted on a motor fixing support (3), and the other force sensor (5) is mounted on a bearing fixing support (4). A servo tilt motor (6) is mounted on the motor fixing support (3), and a connecting bearing (7) is mounted on the bearing fixing support (4). The output end of the servo tilt motor (6) and the connecting bearing (7) are respectively connected to a tilt shaft (802). A rectifier fixture (8) is fixed at the end of the tilt shaft (802). The rectifier fixture (8) includes an airfoil shell (801) and a clamping part (803) for fixing the test object (12).

2. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, The electric lifting platform (2) includes a support rod (201) and an outer sleeve (202) sleeved on the outside of it, and contains a metal screw and a guide rail inside.

3. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, The motor mounting bracket (3) has an elongated countersunk groove (301), and the servo tilt motor (6) is connected to the motor mounting bracket (3) through a fastener passing through the countersunk groove (301).

4. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, The airfoil shell (801) of the rectifier clamp (8) is a symmetrical airfoil; the clamping part (803) and the airfoil shell (801) are detachably connected by a quick-release pin (804).

5. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, At least two connecting bearings (7) for supporting the tilting shaft (802) are installed on the bearing fixing support (4).

6. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, The mounting base (1) has a support column fixed at the bottom to support it on the ground. The four corners of the mounting base (1) are provided with a moving mechanism, which includes a stud (9), a handle (10) for rotating the stud (9), and a caster wheel (11) installed at the bottom of the stud (9).

7. The ducted fan experimental measurement platform based on an acoustic wind tunnel according to claim 1, characterized in that, The force sensor (5) is a six-component force sensor.

8. A method for conducting ducted fan experiments using the experimental measurement platform as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Install and fix the ducted fan or propeller to be tested on the clamping part (803) of the rectifier fixture (8), and adjust the test object (12) to the center height of the wind tunnel test section by the electric lifting platform (2); S2. Control the servo tilt motor (6) to drive the tilt shaft (802) and the rectifier fixture (8) to make the test object (12) rotate to the target tilt angle; S3. Start the wind tunnel and the test object (12), measure the six components of force and torque of the test object (12) by the force sensor (5), and collect acoustic data and flow velocity data simultaneously.

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