CN112985750B - Air-floating type wind tunnel force measuring device - Google Patents
Air-floating type wind tunnel force measuring device Download PDFInfo
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- CN112985750B CN112985750B CN202011539279.2A CN202011539279A CN112985750B CN 112985750 B CN112985750 B CN 112985750B CN 202011539279 A CN202011539279 A CN 202011539279A CN 112985750 B CN112985750 B CN 112985750B
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- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/06—Measuring arrangements specially adapted for aerodynamic testing
- G01M9/062—Wind tunnel balances; Holding devices combined with measuring arrangements
Abstract
The invention relates to an air-floating wind tunnel force measuring device, which comprises: the device comprises a fixed frame (1), a floating frame (2), a high-precision force measuring sensor assembly (3), an air floatation supporting device (4), a protecting device (5), a calibrating device (6) and a supporting platform (8); according to the reading of the high-precision force-measuring sensor assembly (3) arranged in the axial direction of the measured object, the resistance F acting on the axial direction of the measured object is obtained, and the small-load force-measuring device can be applied to a low-speed wind tunnel force-measuring test, so that the problems of small load magnitude and high required precision are solved; the model has large scale, the gravity direction is loaded, the required response speed is high, and the test capability of the FD-09 wind tunnel in the aspects of large-scale models and small-load high-precision force measurement tests is effectively expanded.
Description
Technical Field
The invention relates to an air-floating type wind tunnel force measuring device, and belongs to the technical field of low-speed wind tunnel force measuring tests.
Background
With the rapid advance of the science and technology (2022) action plan, the concept of science and technology assistance is gradually deepened into the mind, and the competitive sports have been developed into high-tech competition in spite of the stage in the world of the contemporary competitive sports. Some racing sports such as yachts, skis, short track speed skis, etc., the gap in performance between high-level athletes is sometimes only on the order of milliseconds. The air resistance experienced by sports equipment and athletes in these sports has a non-negligible effect on athletic performance. The resistance is measured by means of a wind tunnel experiment, so that theoretical basis and data support can be provided for the appearance optimization of the instrument and the guidance of the training and competitive actions of athletes according to the test result, and the game achievement is finally improved.
The low-speed wind tunnel experiment resistance measurement data of sports equipment has high precision requirement, the load measurement range is small, the total weight of sports equipment and athletes is large, the requirements cannot be met by adopting conventional force measuring equipment, and a mature testing device does not exist in China.
Disclosure of Invention
The technical problem solved by the invention is as follows: the air-floating type wind tunnel force measuring device can be applied to small-load force measurement of a low-speed wind tunnel force measurement test, and solves the problems of small load magnitude and high required precision; the model has large scale, the gravity direction is heavy, the response speed is high, and the test capability of the FD-09 wind tunnel in the aspects of large-scale heavy model and small-load high-precision force measurement test is effectively expanded.
The technical scheme of the invention is as follows: an air-floating wind tunnel force measuring device comprises: the device comprises a fixed frame (1), a floating frame (2), a high-precision force measuring sensor assembly (3), an air floatation supporting device (4), a protecting device (5), a calibrating device (6) and a supporting platform (8);
calibration device (6) comprising: the weight scale comprises a wheel component (11), a steel wire rope (12), a weight tray (13) and weights (14);
the fixed frame (1) is fixed in the wind tunnel, the measured object is fixedly connected with the floating frame (2), the floating frame (2) is connected with the fixed frame (1) in the lifting force direction through the air-floating supporting device (4), when high-pressure air enters the air-floating supporting device (4), the floating frame (2) and the measured object can be suspended together, the suspension height is in the micron level, the floating frame (2) is not mechanically connected with the fixed frame (1) in the lifting force direction, the floating frame (2) is in a free state in the transverse direction, disturbance can enable the floating frame (2) to transversely move along with the force-bearing direction, and the weight of the measured object generates negligible friction resistance in the self axial direction and the self lateral direction; in the axial direction of a measured object, one end of a floating frame (2) is connected through a high-precision force-measuring sensor assembly (3), the other end of the floating frame (2) is connected with a steel wire rope (12), the steel wire rope (12) bypasses a pulley assembly (11) of a calibration device (6) and is connected with a weight tray (13), a weight (14) is placed on the weight tray (13) to serve as a balance weight, and pretightening force is applied to the high-precision force-measuring sensor assembly (3) corresponding to the axial direction of the measured object, so that the high-precision force-measuring sensor assembly (3) is always in a tension state; in the lateral direction of an object to be measured, four high-precision force-measuring sensor assemblies (3) are symmetrically arranged on the fixed frame (1) relative to the center of the fixed frame (1), and the four high-precision force-measuring sensor assemblies (3) are connected with the floating frame (2) and the fixed frame (1);
when no high-pressure air enters the air-floating supporting device (4), the air-floating supporting device (4) does not work, the bottom surface of the air-floating supporting device (4) is in contact with the supporting platform (8), and the weight of the object to be measured and the weight of the floating frame (2) are transmitted to the fixed frame (1) through the supporting platform (8); during a wind tunnel test, the air floating supporting device (4) works by introducing high-pressure air, the floating frame (2) is suspended in the air, the resistance of wind tunnel incoming flow acting on a measured object is directly transmitted to the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object through the floating frame (2), and the resistance acting on the axial direction of the measured object is obtained according to the reading of the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object.
Preferably, the floating frame (2) and the fixed frame (1) are connected by the air floatation supporting device (4) in the lifting direction, that is, the floating frame (2) and the fixed frame (1) are connected by the air floatation supporting device (4) in the vertical direction.
Preferably, the suspension height is in the micron order, meaning: the height from the bottom of the air floatation supporting device (4) to the supporting platform (8) is in micron level.
Preferably, the weight of the measured object in its own lateral direction is the direction perpendicular to the plane in which the axial direction and the vertical direction are located together.
Preferably, the resistance F acting on the axial direction of the measured object is obtained according to the reading of the high-precision load cell assembly (3) arranged in the axial direction of the measured object, and the specific steps are as follows:
when no incoming flow exists in the wind tunnel, the reading of a high-precision force measuring sensor component (3) arranged in the axial direction of a measured object is U1; during a wind tunnel test, incoming flow exists in a wind tunnel, the reading of a high-precision force measuring sensor assembly (3) arranged in the axial direction of a measured object is U2, and the change delta U of the reading is = U2-U1;
f = k Δ U; k is a set calibration coefficient.
Preferably, the calibration factor k is determined as follows:
and (4) carrying out weight loading through the calibration component (6) to obtain loading data, and calculating through the loading data to obtain the value of the calibration coefficient k.
Preferably, k is a set calibration coefficient and is 1.04kg/V.
Preferably, the fixing frame (1) is fixed to the lower wall of the test section in the wind tunnel.
Preferably, the four sensors corresponding to the lateral direction of the measured object output readings, and the lateral force and the yaw moment of the measured object with the sideslip angle are measured.
Compared with the prior art, the invention has the advantages that:
(1) The invention adopts a module assembly type, is convenient to install, has less processing amount and low cost;
(2) The wind tunnel balance in-situ calibration device is preferably provided with a calibration device, simulates a ground axis system loading mode of a wind tunnel balance, and carries out in-situ calibration on axial force, lateral force and yaw moment, so that the measurement accuracy is improved.
(3) The invention uses the air floatation support connection mode, realizes the non-mechanical connection in the gravity direction, eliminates the interference of other components on the resistance and improves the small resistance measurement precision of the measured object.
(4) The high-precision sensor assembly is replaceable, the measuring range of the force measuring device can be changed according to the actual measuring range, the measuring load is matched, and the application range is wide.
(5) The calibration device and the force measuring device are integrated, so that the space utilization rate is high;
(6) According to the invention, the fixed frame (1) and the floating frame (2) preferably adopt aluminum profiles with light weight as the frames, and compared with the frames welded by the section steel, the processing cost is reduced, the system response is improved, the design speed is accelerated, and the design freedom is increased.
(7) The invention effectively expands the test capability of the FD-09 wind tunnel.
Drawings
FIG. 1 is a schematic front view of a force measuring device according to the present invention;
FIG. 2 is a schematic top view of a force measuring device according to the present invention;
FIG. 3 is a schematic structural view of a preferred embodiment of the fixing frame of the present invention;
FIG. 4 is a schematic structural view of a preferred embodiment of the floating frame of the present invention;
FIG. 5 is a schematic structural diagram of a preferred embodiment of the calibration device of the present invention;
FIG. 6 is a schematic structural view of a preferred embodiment of the air floatation support device in the invention;
FIG. 7 is a schematic diagram of a triple repeat curve of the present invention;
Detailed Description
The invention is described in further detail below with reference to the figures and the specific embodiments.
The invention relates to an air-floating wind tunnel force measuring device, which comprises: the device comprises a fixed frame (1), a floating frame (2), a high-precision force measuring sensor assembly (3), an air floatation supporting device (4), a protecting device (5), a calibrating device (6) and a supporting platform (8); in the axial direction of a measured object, one end of a floating frame (2) is connected with a fixed frame (1) through a high-precision force-measuring sensor assembly (3), the other end of the floating frame (2) is connected with a steel wire rope (12), a weight disc (13) is connected with the other end of the steel wire rope (12), the steel wire rope (12) bypasses a pulley assembly (11) of a calibration device (6) and is connected with the weight disc (13), a weight (14) is placed on the weight disc (13) to serve as a balance weight, and pretightening force is applied to a sensor in the high-precision force-measuring sensor assembly (3) in the axial direction, so that the sensor is always in a tension state. (ii) a According to the reading of the high-precision force-measuring sensor assembly (3) arranged in the axial direction of the measured object, the resistance F acting on the axial direction of the measured object is obtained, and the small-load force-measuring device can be applied to a low-speed wind tunnel force-measuring test, so that the problems of small load magnitude and high required precision are solved; the model has large scale and is loaded in the gravity direction, and the required response speed is high. The test capability of the FD-09 wind tunnel in the aspects of large-scale models, small-load high-precision force measurement tests is effectively expanded.
The invention adopts an air-floating supporting mode, solves the problem of additional interference load caused by mechanical connection of the floating frame and the fixed frame, and improves the measurement precision; one is provided with in-situ calibration, so that interference errors caused by system installation can be eliminated, and the measurement precision is improved. The invention adopts a pre-tightening device, solves the problem that one end of the sensor is connected by a soft steel wire rope, only can generate force in a pulled state, and provides the sensor with a state of being always pulled.
The wind tunnel force measuring equipment preferably adopts a rod balance or a box balance, the model is a model obtained by scaling a real tester according to a certain proportion, the model is small in size, light in weight, large in load measuring range and matched with the scale range of the balance.
The wind tunnel test is one of three aerodynamic research means and plays an important role in the development process of the aircraft. The low-speed wind tunnel aerodynamic research and the national economy development and construction have closer relation, and can be widely applied to various aspects such as building design, transportation, sports competition and the like. Particularly, in the aspect of competitive sports, along with the rapid advance of a 'science and technology (2022) action plan', the concept of science and technology assistance is gradually deepened, and the competitive sports are developed into high-technology competition throughout the stage in the world of the contemporary competitive sports.
Taking the current potential advantage project racing boat in China as an example, the potential advantage project racing boat can obtain better ranking for many times in major competitions such as world championship and the like, shows higher competitive level, but has less times of entering the first three and even seizing gold medals, and the development of the potential advantage project racing boat can meet the bottleneck. Therefore, when the output power of athletes almost reaches the physiological capacity limit and the energy utilization rate almost reaches the extreme of the excellent racing boat technology, on the premise of ensuring that the gliding power is not influenced, the reduction of the aerodynamic drag is an important breakthrough point, and the wind tunnel experiment is one of very important means for researching the aerodynamic drag reduction.
The low-speed wind tunnel force test preferably adopts an integral multi-component rod or box type strain balance, and if the component measuring ranges of the balance are matched, the balance is reasonably designed, so that higher precision can be obtained, and the test requirements are met. In a conventional force measurement test of a low-speed wind tunnel, a test model is basically a model after scaling compared with a real aircraft, so that the model is not large in size and light in weight, loads acting on components of the model are matched relatively, the components do not greatly interfere with resistance, and the conventional force measurement balance is applied to basically meet test requirements.
The accuracy requirement of the low-speed wind tunnel experiment resistance measurement data of the sports equipment is high, the load measurement range is small, the size of sports equipment such as a racing boat or a ski with a rudder is large, the weight of athletes is added, the whole equipment is heavy, the total length of the racing boat is about 12 meters, the total weight sum of the racing boat and the athletes is about 430kg by taking four-person racing boats as an example, the requirements cannot be met by adopting conventional force measuring equipment, and at present, a mature force measuring device for wind tunnel force measurement of the sports equipment does not exist in China.
In order to meet the requirement of a large-scale model on a small-load low-speed wind tunnel force measurement test, overcome the interference of the weight of the model on small-load resistance and lateral force and bring larger interference error to small-load measurement, the invention develops the small-load device suitable for the low-speed wind tunnel force measurement test so as to expand the test capability of the low-speed wind tunnel. The invention adopts a split assembly mode, uses a low-friction support mode in the lifting force direction of a floating frame and a fixed frame, realizes no mechanical connection with a sensor in the lifting force direction, so that the output of the sensor transversely arranged is hardly influenced by the weight of a model.
The object to be tested is preferably a sports apparatus for sports competition, such as a four-player racing boat or a two-player ski with a rudder. The racing apparatus is preferably designed according to a streamline shape along the windward side, and aims to reduce the resistance, improve the speed and save the time for racing. In order to ensure the safety of the sports apparatus and the athletes, the overall strength of the sports apparatus is required to be high, in order to improve the response speed and reduce the weight of the sports apparatus when in competition, the sports apparatus for competition is preferably made of high-strength and light carbon fiber materials based on the two requirements.
As shown in fig. 1, the X direction points to the incoming flow direction of the wind tunnel, which is opposite to the airflow direction, the Y direction is vertically downward, the Z direction is determined according to the right-hand rule, and points upward in the top view;
the preferred scheme is as follows: the invention relates to an air-floating wind tunnel force measuring device, which comprises: the device comprises a fixed frame (1), a floating frame (2), a high-precision force measuring sensor assembly (3), an air floatation supporting device (4), a protecting device (5), a calibrating device (6) and a supporting platform (8);
calibration device (6) comprising: the weight scale comprises wheel components (11), steel wire ropes (12), weight plates (13) and weights (14);
the fixed frame (1) is fixed in the wind tunnel, the measured object is fixedly connected with the floating frame (2), the floating frame (2) is connected with the fixed frame (1) in the lifting force direction through the air-floating supporting device (4), when high-pressure air enters the air-floating supporting device (4), the floating frame (2) and the measured object can be suspended together, the suspension height is in the micron level (the height from the bottom of the air-floating supporting device (4) to the supporting platform (8) is in the micron level) (the height is invisible to naked eyes), the floating frame (2) is not mechanically connected with the fixed frame (1) in the lifting force direction, the floating frame (2) is in a free state in the transverse direction (namely the horizontal direction), (because the air friction coefficient is very small), the floating frame (2) can transversely move along with the stress direction, and the weight of the measured object generates negligible friction resistance in the self axial direction and the lateral direction (the lateral direction is the plane where the measured object is vertical direction together perpendicular to the axial direction and the vertical direction), so that the measurement accuracy is improved; in the axial direction of a measured object, one end of a floating frame (2) is connected through a high-precision force-measuring sensor assembly (3), the other end of the floating frame (2) is connected with a steel wire rope (12), the steel wire rope (12) bypasses a pulley assembly (11) of a calibration device (6) and is connected with a weight tray (13), a weight (14) is placed on the weight tray (13) to serve as a balance weight, and pretightening force is applied to the high-precision force-measuring sensor assembly (3) corresponding to the axial direction of the measured object, so that the high-precision force-measuring sensor assembly (3) is always in a tension state; in the lateral direction of a measured object, four high-precision force measuring sensor assemblies (3) are symmetrically arranged on the fixed frame (1) relative to the center of the fixed frame (1), and the four high-precision force measuring sensor assemblies (3) are connected with the floating frame (2) and the fixed frame (1);
the preferred scheme is as follows: and measuring the lateral force and the yaw moment of the measured object with a sideslip angle through different combinations of the four sensor output readings.
When no high-pressure air enters the air-floating supporting device (4), the air-floating supporting device (4) does not work, the bottom surface of the air-floating supporting device (4) is in contact with the supporting platform (8), and the weight of the object to be measured and the weight of the floating frame (2) are transmitted to the fixed frame (1) through the supporting platform (8); during a wind tunnel test, the air floating supporting device (4) works by introducing high-pressure air, the floating frame (2) is suspended in the air, the resistance of wind tunnel incoming flow acting on a measured object is directly transmitted to the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object through the floating frame (2), and the resistance acting on the axial direction of the measured object is obtained according to the reading of the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object.
According to the reading (U) of the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object, the resistance F acting on the axial direction of the measured object is obtained, and the method is as follows:
when no incoming flow exists in the wind tunnel, the reading of a high-precision force measuring sensor component (3) arranged in the axial direction of a measured object is U1; during a wind tunnel test, incoming flow exists in a wind tunnel, the reading of a high-precision force measuring sensor assembly (3) arranged in the axial direction of a measured object is U2, and the change delta U = U2-U1 of the reading;
f = k Δ U; k is a calibration coefficient and k is a calibration coefficient,
the calibration coefficient k is preferably set in the following manner: the loading is carried out by a calibration component (6) to obtain a series of loading data, and a calibration coefficient is calculated by the data. Or directly setting the value of K, wherein K is preferably 1.04kg/V
The fixed frame (1) is preferably fixed on the lower wall of a test section in a wind tunnel
In the lateral direction of the measured object, the four high-precision force-measuring sensor components (3) are used for: when the measured object has a sideslip angle, the lateral force and the yawing moment acting on the measured object are measured.
The wind tunnel force measuring device of the present invention preferably further comprises: the ground simulation frame plate (7) is connected to the fixed frame (1), and the ground simulation frame plate (7) is parallel to the lower surface of the fixed frame (1) and used for simulating a water surface or a skiing snow road;
the wind tunnel force measuring device of the present invention preferably further comprises: a calibration device (6) by which a calibration coefficient k can be obtained by the calibration device (6);
the preferable scheme of the calibration device (6) is as follows: as shown in fig. 5, the calibration device (6) comprises a pulley assembly (11), a steel cable (12), a weight tray (13) and a standard weight (14). The pulley assembly (11) comprises a pulley frame (111) and a fixed pulley (112). Pulley components (11) are fixedly connected with a fixed frame (1) through pulley frames (111), one end of a steel wire rope (12) is fixedly connected with a floating frame (2), the other end of the steel wire rope (12) bypasses fixed pulleys (112) to hang a weight plate (13), and a 1kg weight (14) is placed on the weight plate (13) to serve as a balance weight. In fig. 5, 11-pulley assembly 12-wire rope 13-weight tray 14-standard weight 111-pulley yoke 112-fixed pulley.
When the axial direction of a measured object is calibrated, the air floatation supporting device (4) is ventilated, the measured object and the floating frame (2) are suspended in the air and are in a balanced state, and an initial reading of a sensor of the high-precision force measuring sensor assembly (3) arranged in the axial direction is recorded as U0. According to the design range of the force measuring device, weights with the same weight are added on a weight tray (14) in an equal-step mode until the maximum load is reached, for example, the number of steps is 8, the weight load Y of the weights is respectively marked as Y1, Y2 \8230, 8230and Y8, corresponding sensors have corresponding reading output and are respectively marked as U1, U2 \8230, 8230and U8, the reading is sequentially increased to the maximum load, then the weights are sequentially unloaded to the initial state, the loading and unloading are repeated for more than three times, the recorded sensor reading output data and the applied load are fitted according to the least square method, namely, a linear relation between the load Y and the sensor reading, namely, a calibration formula Y = k.DELTA.U, and the calibration coefficient k of the force measuring device is obtained.
The preferable scheme of the fixed frame (1) is as follows: the aluminum profile is preferably formed by connecting aluminum profiles with each other through special angle braces of the aluminum profiles by screws, wherein the height of the cross section of the aluminum profile is 400mm, and the width of the aluminum profile is preferably 200 mm. The fixed frame is required to have high strength and large rigidity, and to have small deformation when bearing the weight of the object to be measured and the floating frame. As shown in fig. 3, the fixed frame (1) preferably comprises two outer main beams 101, a middle main beam 102, two main longitudinal beams 103, four auxiliary support longitudinal beams 104, two middle auxiliary beams 105 and four diagonal support beams 106, the middle of the fixed frame (1) is preferably rectangular, and the front end and the rear end of the fixed frame are preferably triangular. Four faces of the aluminum profile are preferably provided with T-shaped grooves for fixed installation.
The preferable scheme of the floating frame (2) is as follows: preferably, the aluminum profile is formed by connecting the aluminum profiles through angle braces for the aluminum profiles by screws, wherein the height of the cross section of the aluminum profile is 400mm, and the width of the aluminum profile is 200 mm. The floating frame (2) is preferably required to have high strength, high rigidity, and small deformation when subjected to the weight of an object to be measured. As shown in fig. 4, the floating frame (2) is preferably composed of three longitudinal main beams 201, two lateral main beams 202, and auxiliary support beams 203. The floating frame (2) is preferably rectangular in shape.
The preferable scheme of the high-precision force-measuring sensor component (3) is as follows: preferably consisting of a load cell shaped as a cylinder with internal threads at both ends, preferably with an accuracy of 0.02%, and a steel wire rope with a diameter of preferably 0.3 mm. The high-precision load cell assembly (3) is required to transmit only the load along the axial direction of the cell and generate inhibition effect on the loads in other directions.
As shown in fig. 6, the air-floating support device (4) preferably comprises: the air floatation device comprises an air floatation block (401), an air floatation screw rod (402), an air floatation nut (403), a supporting platform (8) and the like. The air-floating supporting device (4) requires to provide clean high-pressure air, the air-floating block (401) adopted by the device is in an oblate cylindrical shape, the contact surface of the air-floating block (401) and the supporting platform (8) requires high smoothness, no dust particles exist, and when the air-floating block enters from the high-pressure air, the air-floating block (401) can be suspended in the air and can freely move in a transverse plane. One end of the air floatation screw rod (402) is in a spherical hinge form and is fixed with the air floatation block (401), the other end of the air floatation screw rod is screwed with the air floatation nut (402), and the air floatation nut (402) is fixed with the floating frame (2) through a screw. In FIG. 6, 1-fixed frame, 2-floating frame, 401-floating block, 402-floating screw, 403-floating nut, 8-support platform;
the preferred scheme of protection device (5) specifically is spiral force-bearing device, preferably by the protection device base, the protection device screw rod, the protection device nut is constituteed, protection device screw rod lower extreme is fixed with the protection device base, protection device screw rod upper end can insert the downthehole that floating frame (2) reserved, screw rod upper end and the floating frame reserved hole periphery preferably keep 3-5mm clearance, the protection device nut requires can reciprocate along the screw rod axial, when the nut rebound, the upper surface of nut and the lower surface contact of floating frame (2), the upper surface is locked with another nut and is prevented lockingly. In a non-force-measuring state, the weight of the measured object and the floating frame can be transmitted to the fixed frame through the protection device (5), and the measured object is protected from being damaged when being subjected to abnormal force.
The preferable scheme of the supporting platform (8) is as follows: the device is high in rigidity and strength, can bear the whole weight of a measured object and the floating frame (2), provides a smooth plane with high finish and flatness for the air floating supporting device (4), and requires the supporting platform (8) to be provided with foundation bolts capable of adjusting the flatness of the upper surface of the platform. The supporting platform (8) is preferably made of marble in order to reach the surface finish degree required by suspension when the air floatation supporting device (4) can be communicated with high-pressure air, and the surface of the platform is manually polished to meet the requirement of the finish degree.
As shown in fig. 1 and fig. 2, the present invention is composed of a fixed frame 1, a floating frame 2, a high-precision load cell assembly 3, an air-floating support device 4, a protection device 5, a calibration device 6, etc. The fixed frame structure is shown in fig. 3, 101, an outer main beam 102, a middle main beam 103, a main longitudinal beam 104, an auxiliary support longitudinal beam 105, a middle auxiliary beam 106, and a diagonal support beam; in fig. 4, 201-longitudinal main beam 202-transverse main beam 203-auxiliary support beam; the floating frame structure is shown in fig. 4, the coordinate system is shown in fig. 1 and 2, the X direction points to the incoming flow direction of the wind tunnel and is opposite to the air flow direction, the Y direction is vertically downward, the Z direction is determined according to the right-hand rule, and the X direction points to the upper side in the plan view. The fixed frame 1 is fixedly connected with the ground of the wind tunnel through bolts in the wind tunnel, and the tested model is fixedly connected with the floating frame 2. The fixed frame 1 and the floating frame 2 are connected through four air-floating supporting devices 4 in the lifting direction. The device is connected by a group of high-precision force measuring sensor components 3 in the axial force direction and is used for measuring the resistance of wind tunnel incoming flow acting on a measured object in a wind tunnel test. Four groups of high-precision force measuring sensor assemblies 3 are symmetrically arranged in the lateral force direction and are used for measuring the positive and negative lateral forces and the yaw moment of a measured object through different combinations of the four sensors. In order to prevent the excessive impact of the weight of the installation model on the air floating device 4 and equipment during installation, the air floating device 4 and the equipment are damaged, four protection devices 5 are symmetrically arranged between the fixed frame 1 and the floating frame 2, the base of each protection device 5 is fixedly connected with the fixed frame 1 through bolts, the screw rods of the protection devices 5 penetrate through the unthreaded holes in the floating frame 2, gaps are reserved around the holes, and the floating frame is ensured not to touch the screw rods in the circumferential direction. When the force measurement is not carried out, the floating frame 2 is supported by the nut of the protection device 5, the bottom surface of the air floatation supporting device 4 is separated from the fixed frame 1, the model weight and the impact load are not transmitted to the fixed frame 1 through the air floatation device 4, but are transmitted to the protection device 5 through the floating frame 2, and the impact and the weight are borne by the protection device 5. When measuring the force, the nut of the protection device 5 is rotated reversely, the floating frame 2 is slowly dropped, and the lower bottom surface of the air floatation support device 4 is contacted with the fixed frame 1. The weight of the model is transmitted to the fixed frame 1 through the air-floating supporting device 4, and the nut of the protecting device 5 is continuously rotated, so that the nut is separated from the floating frame 2 by a certain distance and is not contacted, the force borne by the measured object is directly transmitted to the corresponding sensor through the floating frame 2 during force measurement, and the measured force is obtained by substituting the reading of the sensor into the corresponding calibration formula. In order to eliminate errors caused by system installation and obtain a real formula, the invention is provided with a calibration device 6, and the relation between the output signal of the sensor of the force measuring device and the actual load is obtained by an in-situ calibration method, namely the calibration formula. As shown in fig. 2, the calibration device 6 is composed of four pulley assemblies. One calibration device 6 is arranged in the axial force direction for applying axial forces and two calibration devices 6 are arranged in the positive lateral force direction for applying positive lateral forces and yaw moments. In the direction of the negative lateral force, in the position of the moment centre of the device, a calibration device 6 is arranged for applying the negative lateral force. And (4) loading according to the measuring range of each component of the force measuring device to obtain the reading output of the sensors. Through calculation, a calibration formula of each component is obtained, system errors are eliminated, and measurement accuracy is improved. As shown in fig. 2, the X direction points to the wind tunnel incoming flow direction, opposite to the air flow direction, the Y direction is vertically downward, the Z direction is determined according to the right-hand rule, and points upward in the top view of fig. 2;
the device is used for carrying out installation debugging and blowing tests in an FD-09 wind tunnel, three times of repeated measurement of three wind speeds (4 m/s, 5m/s and 6 m/s) is carried out in the tests, and the minimum value of resistance obtained by the measurement is 0.2957kg, and the maximum value is 0.59078kg. The triple-repeat curve is shown in FIG. 7.
Claims (8)
1. An air-floating type wind tunnel force measuring device is characterized by comprising: the device comprises a fixed frame (1), a floating frame (2), a high-precision force measuring sensor assembly (3), an air floatation supporting device (4), a protecting device (5), a calibrating device (6) and a supporting platform (8);
calibration device (6) comprising: pulley components (11), steel wire ropes (12), weight plates (13) and weights (14);
the fixed frame (1) is fixed in the wind tunnel, the measured object is fixedly connected with the floating frame (2), the floating frame (2) is connected with the fixed frame (1) in the lifting force direction through the air-floating supporting device (4), when high-pressure air enters the air-floating supporting device (4), the floating frame (2) and the measured object can be suspended together, the suspension height is in the micron level, the floating frame (2) is not mechanically connected with the fixed frame (1) in the lifting force direction, the floating frame (2) is in a free state in the transverse direction, disturbance can enable the floating frame (2) to transversely move along with the force-bearing direction, and the weight of the measured object generates negligible friction resistance in the self axial direction and the self lateral direction; in the axial direction of a measured object, one end of a floating frame (2) is connected through a high-precision force-measuring sensor assembly (3), the other end of the floating frame (2) is connected with a steel wire rope (12), the steel wire rope (12) bypasses a pulley assembly (11) of a calibration device (6) and is connected with a scale pan (13), a weight (14) is placed on the scale pan (13) to serve as a balance weight, pretightening force is applied to the high-precision force-measuring sensor assembly (3) corresponding to the axial direction of the measured object, and the high-precision force-measuring sensor assembly (3) is always in a tension state; in the lateral direction of an object to be measured, four high-precision force-measuring sensor assemblies (3) are symmetrically arranged on the fixed frame (1) relative to the center of the fixed frame (1), and the four high-precision force-measuring sensor assemblies (3) are connected with the floating frame (2) and the fixed frame (1);
when no high-pressure air enters the air-floating supporting device (4), the air-floating supporting device (4) does not work, the bottom surface of the air-floating supporting device (4) is in contact with the supporting platform (8), and the weight of the object to be measured and the weight of the floating frame (2) are transmitted to the fixed frame (1) through the supporting platform (8); during a wind tunnel test, the air-floating supporting device (4) works by introducing high-pressure air, the floating frame (2) is suspended in the air, the resistance of wind tunnel incoming flow acting on a measured object is directly transmitted to the high-precision force-measuring sensor assembly (3) arranged in the axial direction of the measured object through the floating frame (2), and the resistance acting on the axial direction of the measured object is obtained according to the reading of the high-precision force-measuring sensor assembly (3) arranged in the axial direction of the measured object;
the floating frame (2) is connected with the fixed frame (1) by the air floatation supporting device (4) in the lifting force direction, namely the floating frame (2) is connected with the fixed frame (1) by the air floatation supporting device (4) in the vertical direction;
the air floatation supporting device (4) comprises an air floatation block (401), an air floatation screw rod (402) and an air floatation nut (403); one end of the air floatation screw rod (402) is in a spherical hinge form and is fixed with the air floatation block (401), the other end of the air floatation screw rod is screwed with the air floatation nut (403), and the air floatation nut (403) is fixed with the floating frame (2) through a screw;
the protection device (5) comprises a protection device base, a protection device screw rod and a protection device nut, the lower end of the protection device screw rod is fixed with the protection device base, the upper end of the protection device screw rod can be inserted into a hole reserved in the floating frame (2), a gap of 3-5mm is kept between the upper end of the protection device screw rod and the periphery of the hole reserved in the floating frame, in a non-force-measuring state, the weight of the measured object and the weight of the floating frame are transmitted to the fixed frame through the protection device (5), and the measured object is protected from being damaged when being subjected to abnormal force.
2. The air-floating wind tunnel force measuring device according to claim 1, wherein: the suspension height is in micron order, which means: the height between the bottom of the air floatation supporting device (4) and the supporting platform (8) is in micron grade.
3. The air-floating wind tunnel force measuring device according to claim 1, wherein: the weight of the measured object in the lateral direction of the measured object is perpendicular to the plane where the axial direction and the vertical direction are located together.
4. The air-floating wind tunnel force measuring device according to claim 1, wherein: according to the reading of the high-precision force measuring sensor assembly (3) arranged in the axial direction of the measured object, the resistance F acting on the axial direction of the measured object is obtained, and the method specifically comprises the following steps:
when no incoming flow exists in the wind tunnel, the reading of a high-precision force measuring sensor component (3) arranged in the axial direction of a measured object is U1; during a wind tunnel test, incoming flow exists in a wind tunnel, the reading of a high-precision force measuring sensor assembly (3) arranged in the axial direction of a measured object is U2, and the change delta U = U2-U1 of the reading;
f = k Δ U; k is a set calibration coefficient.
5. The air-floating wind tunnel force measuring device according to claim 4, wherein: the calibration coefficient k is determined as follows:
and (4) carrying out weight loading through a calibration device (6) to obtain loading data, and calculating through the loading data to obtain the value of the calibration coefficient k.
6. The air-floating wind tunnel force measuring device according to claim 4, wherein: k is a set calibration coefficient and is 1.04kg/V.
7. The air-floating wind tunnel force measuring device according to claim 1, wherein: the fixed frame (1) is fixed on the lower wall of the test section in the wind tunnel.
8. The air-floating wind tunnel force measuring device according to claim 1, wherein: and outputting readings through four high-precision force measuring sensor assemblies (3) corresponding to the lateral direction of the measured object, and measuring the lateral force and the yaw moment of the measured object when the measured object has a sideslip angle.
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| JPS57154026A (en) * | 1981-03-19 | 1982-09-22 | Ishikawajima Harima Heavy Ind Co Ltd | Thrust measuring apparatus for jet engine |
| CN101216359A (en) * | 2008-01-09 | 2008-07-09 | 南京航空航天大学 | Frame type decoupling six component sensor and use method |
| CN101832851B (en) * | 2010-05-31 | 2012-05-30 | 中国航空工业空气动力研究院 | Air flotation force measuring device of wind tunnel model |
| DE102011085640A1 (en) * | 2011-11-02 | 2013-05-02 | Maha-Aip Gmbh & Co. Kg | Wind tunnel balance |
| CN105806586B (en) * | 2016-05-11 | 2018-02-23 | 中国空气动力研究与发展中心超高速空气动力研究所 | A kind of small asymmetric reentry body aerodynamics force measurement device of air-bearing support |
| CN108132133A (en) * | 2017-12-04 | 2018-06-08 | 中国航空工业集团公司北京长城计量测试技术研究所 | A kind of combined type multi -components flapping wing aircraft high-lift systems test method |
| CN108106812A (en) * | 2018-01-04 | 2018-06-01 | 中国空气动力研究与发展中心低速空气动力研究所 | A kind of dynamometric system for thrust calibration |
| CN108945538A (en) * | 2018-08-31 | 2018-12-07 | 天津航天机电设备研究所 | A kind of super-large space capsule expansion zero-g simulator |
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