An air inlet balance calibration device and method for simulating test states

Abstract

The present invention belongs to the technical field of wind tunnel test, and discloses an inlet balance calibration device and method for simulating test states. The inlet balance calibration device includes a calibration strut, a connecting piece, a balance, and a loading head that are connected in sequence from the rear to the front. The rear end of the calibration strut is fixed on a two-degree-of-freedom balance calibration frame; a bellows connecting piece is installed on the connecting piece and slides along the connecting piece; the rear end of the bellows is fixed on the front end face of the bellows connecting piece, and the front end of the bellows is connected to the inlet. The inlet is fixed on the lower surface of the front section of the balance through a square boss above. The inlet balance calibration method includes performing optical balance calibration; performing model assembly; adjusting the position of the bellows connecting piece; performing inlet balance calibration; and performing wind tunnel tests. The inlet balance calibration device and method for simulating test states of the present invention achieve precise calibration of the parallel force measurement system of the balance, the inlet, and the bellows, and can efficiently and accurately measure the inlet load.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind tunnel tests, and particularly relates to an air inlet balance calibration device and method for simulating test states. Background Art

[0002] As an important part of the engine, the air inlet plays a crucial role during the operation of the aircraft. Its performance directly affects the working efficiency of the engine, the power characteristics and the overall performance of the aircraft. The core of the research on the force measurement of the aircraft air inlet is to measure the thrust and moment generated inside the air inlet. Wind tunnel tests are one of the most important ways to conduct ground force measurement of the aircraft air inlet. In recent years, with the continuous development of wind tunnel test technologies and sensors, the force measurement methods and means have become more accurate and diversified, mainly including the following three: balance measurement method, surface pressure distribution measurement method, and inertial force measurement method. The surface pressure distribution measurement method and the inertial force measurement method have problems such as highly depending on the performance of sensors, complex systems, and high test costs, and are mainly applied to some specific scenarios with complex flow fields or large changes in dynamic loads. The balance measurement method is still commonly used in the conventional force measurement wind tunnel tests of air inlets.

[0003] The balance measurement method has the advantages of simple installation, convenient operation, intuitive measurement results, and mature design methods. However, since the installation of the balance will cause a certain disturbance to the air inlet flow field, in order to reduce this interference, bellows are used in combination during the test. The stiffness of the bellows is generally much smaller than that of the balance to ensure that most of the loads of the air inlet are transmitted to the balance, thereby improving the measurement sensitivity. However, due to the small stiffness of the bellows, it is extremely easy to deform, and different installation states will affect the stiffness distribution of the entire measurement system, thereby affecting the measurement accuracy. Therefore, how to ensure that the bellows are in the same state during calibration and testing is the key factor affecting the accuracy of test measurement.

[0004] Currently, there is an urgent need to develop an air inlet balance calibration device and method for simulating test states. Summary of the Invention

[0005] One technical problem to be solved by the present invention is to provide an air inlet balance calibration device for simulating test states, and another technical problem to be solved by the present invention is to provide an air inlet balance calibration method for simulating test states to overcome the defects of the prior art.

[0006] The air inlet balance calibration device for simulating test states of the present invention includes a calibration strut, a connector, a balance, and a loading head that are connected in sequence from back to front. The rear end of the calibration strut is fixed on a two-degree-of-freedom balance calibration frame; the bellows connector is clamped on the connector and slides along the connector; the rear end of the bellows is fixed on the front end face of the bellows connector, the front end of the bellows is connected to the air inlet, and the air inlet is fixed on the lower surface of the front section of the balance through a square boss above.

[0007] Further, the balance is a square six-component force measuring balance, which is used to measure three forces including the drag force X, the lift force Y, and the side force Z, and three moments including the rolling moment Mx, the yaw moment My, and the pitch moment Mz.

[0008] The front connection section, the middle measurement section, and the rear connection section of the square six-component force measuring balance are all square bodies, and are installed inside the flat test model; positioning blocks that are symmetrical front and back are provided on the front connection section and the rear connection section for connection and positioning; pin holes and several symmetrically distributed screw holes centered on the upper surface of the front connection section are used to position and fix the connecting piece, and pin holes and several symmetrically distributed screw holes centered on the upper and lower surfaces of the rear connection section are provided. The upper surface is used to position and fix the loading head, and the lower surface is used to position and fix the square boss; the middle measurement section is a square column, and the four planes of up, down, left, and right can all be used as measurement planes.

[0009] Further, the loading head is a frame structure, which is integrally machined from aluminum, and mechanically decomposes the three forces of the drag force X, the lift force Y, and the side force Z; the main body of the loading head is a square frame located in the vertical plane; a bayonet matching the front connection section of the balance extends from the center point of the square frame; 4 horizontally symmetrically distributed loading rods are provided at the midpoints of the upper, lower, left, and right sides of the square frame, and a total of 8 loading points are provided at the front and rear ends of each horizontally loading rod, which are respectively named loading point Ⅰ, loading point Ⅱ, loading point Ⅲ, loading point Ⅳ, loading point Ⅴ, loading point Ⅵ, loading point Ⅶ, and loading point Ⅷ; on the upper midpoint and the lower midpoint of the square frame, an upward upper loading rod and a downward lower loading rod are respectively provided. The upper end of the upper loading rod is provided with loading point Ⅹ, and the lower end of the lower loading rod is provided with loading point Ⅻ; on the left midpoint and the right midpoint of the square frame, a left loading rod and a right loading rod are respectively provided. The left end of the left loading rod is provided with loading point Ⅸ, and the right end of the right loading rod is provided with loading point Ⅺ;

[0010] Each loading point is a through hole, and both ends of the through hole can be used to install a center point. A weight tray is suspended on the center point, and the loading of forces and moments in each direction is achieved by adding standard weights on the weight tray; loading points Ⅰ, Ⅱ, Ⅲ, and Ⅳ are used for positive and negative loading in the lift force Y direction; after the air intake balance calibration device rotates 90° around the axis, loading points Ⅴ, Ⅵ, Ⅶ, and Ⅷ are used for positive and negative loading in the side force Z direction; loading points Ⅸ, Ⅹ, Ⅺ, and Ⅻ are used for loading in the drag force X direction. When calibrating the lift force direction, loads are applied at loading points Ⅹ and Ⅻ to achieve the combined loading of the lift force Y and the drag force X; when calibrating the side force direction, loads are applied at loading points Ⅸ and Ⅺ to achieve the combined loading of the side force Z and the drag force X.

[0011] Further, the front end face of the corrugated pipe is connected to the air inlet duct through a flange, the rear end face of the corrugated pipe is connected to the front end face of the corrugated pipe connector through a flange, and the central axis of the corrugated pipe is parallel to the central axis of the balance.

[0012] Further, the upper section of the corrugated pipe connector is a clamping groove, the clamping groove is installed on the connector, and a locking buckle for locking with the connector is arranged on the clamping groove; the lower section of the corrugated pipe connector is a flat plate, and a plurality of circumferentially distributed screw holes matching the flange of the corrugated pipe are arranged on the front end face of the flat plate.

[0013] Further, the air inlet duct is a twin-engine air inlet duct that is symmetric about the left and right, the corrugated pipe connector is arranged as an independent structure that is symmetric about the left and right, and each independent structure is respectively installed on the connector to adapt to the twin-engine air inlet duct.

[0014] The air inlet duct balance calibration method in the simulated test state of the present invention includes the following steps:

[0015] S10. Perform optical balance calibration;

[0016] Connect the calibration strut, connector, balance, and loading head in sequence from the rear to the front to obtain an optical balance calibration device, then install the calibration strut on the two-degree-of-freedom balance calibration rack, and perform optical balance calibration according to the conventional six-component balance calibration method to obtain the optical balance calibration formula;

[0017] S20. Perform model assembly;

[0018] Install the balance, air inlet duct, and corrugated pipe inside the flat test model, and record the length of the corrugated pipe and the initial reading of the balance after installation;

[0019] S30. Adjust the position of the corrugated pipe connector;

[0020] Install the calibration strut, connector, balance, air inlet duct, corrugated pipe, and corrugated pipe connector, observe the reading of the balance, and adjust the position of the corrugated pipe connector until the balance reading is the same as the initial reading of the balance;

[0021] S40. Perform air inlet duct balance calibration;

[0022] Install the loading head, then install the calibration strut on the two-degree-of-freedom balance calibration rack, and perform calibration with the corrugated pipe according to the conventional six-component balance calibration method to obtain the calibration formula of the parallel force-measuring system composed of the balance, air inlet duct, and corrugated pipe, that is, the air inlet duct balance calibration formula;

[0023] S50. Perform wind tunnel test;

[0024] Remove the balance, inlet duct, and bellows as a whole from the two-degree-of-freedom balance calibration rig, and install them as a whole onto the test model before the test to avoid installation errors caused by repeated disassembly and assembly. During the test, use the inlet duct balance calibration formula to calculate the six-component force measurement data.

[0025] The inlet duct balance calibration device for simulating the test state of the present invention has the following characteristics:

[0026] a. The balance in the present invention adopts a square structure, which is not only convenient for installation in a flat test model, but also the four planes of the square frame can be used as measurement planes, facilitating the measurement of the deformation of the square balance after being loaded.

[0027] b. Traditional slider-type or sleeve-type loading heads can only achieve loading in one direction. After the lift Y calibration is completed, the loading head must be removed, the balance rotated 90°, the loading head reinstalled, and then the lateral Z loading carried out. Each installation requires readjusting the centering position, and the process is cumbersome. The loading head in the present invention adopts an aluminum frame structure, which not only reduces weight significantly but also retains sufficient stiffness. The loading points in the present invention are symmetrically arranged up and down, left and right, front and back. It can not only accurately mechanically decompose the loads in three directions of drag X, lift Y, and side force Z, but also rotate the loading head and the balance together during calibration to complete the loading calibration in four directions in one installation on the two-degree-of-freedom balance calibration rig, avoiding the disassembly and assembly of the loading head and the balance when changing directions and improving the calibration efficiency.

[0028] c. During the wind tunnel test, the front end of the bellows is connected to the inlet duct. Since the stiffness of the balance is much greater than that of the bellows, when the inlet duct is stressed, most of the loads act on the balance, and the bellows plays a role of passing air without transmitting force in the entire force measurement system. However, the telescopic state of the bellows will affect the stiffness distribution of the entire test model. The present invention uses the card slot on the upper section of the bellows connector to slide along the connector to adjust the telescopic state of the bellows, ensuring that the telescopic state of the bellows during calibration is the same as that during the test.

[0029] d. The present invention utilizes the characteristics of the balance as a high-precision force sensor. After obtaining the working formula of the optical balance through optical balance calibration, the reading of the optical balance is precisely controlled during the test and calibration processes to ensure the consistency of the connection state of the balance force measurement system during the test and calibration processes.

[0030] The inlet duct balance calibration device for simulating the test state of the present invention simulates the actual force on the balance and the deformation of the bellows after being installed inside the test model through a parallel force measurement system composed of the balance, inlet duct, and bellows. The inlet duct balance calibration method for simulating the test state of the present invention can ensure that the states of the balance, inlet duct, and bellows during calibration are the same as those during the wind tunnel test, achieve precise calibration of the parallel force measurement system of the balance, inlet duct, and bellows, and measure the inlet duct load efficiently and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the inlet balance calibration device in the simulated test state of the present invention;

[0032] Figure 2 It is a schematic structural diagram of the balance in the inlet balance calibration device in the simulated test state of the present invention;

[0033] Figure 3 It is a schematic structural diagram of the loading head in the inlet balance calibration device in the simulated test state of the present invention;

[0034] Figure 3 In the figure, Ⅰ, Ⅱ, Ⅲ... Ⅻ are the serial numbers of the loading points;

[0035] Figure 4 It is a schematic structural diagram of the bellows connector in the inlet balance calibration device in the simulated test state of the present invention;

[0036] Figure 5 It is a schematic diagram of the optical balance calibration installation of the inlet balance calibration device in the simulated test state of the present invention.

[0037] In the figure, 1. calibration support rod; 2. connector; 3. balance; 4. loading head; 5. inlet; 6. bellows; 7. bellows connector. DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0039] Embodiment: As Figure 1 shown, the inlet balance calibration device in the simulated test state of this embodiment includes a calibration support rod 1, a connector 2, a balance 3, and a loading head 4 connected in sequence from back to front. The rear end of the calibration support rod 1 is fixed on a two-degree-of-freedom balance calibration frame; the bellows connector 7 is clamped on the connector 2 and slides along the connector 2; the rear end of the bellows 6 is fixed on the front end face of the bellows connector 7, and the front end of the bellows 6 is connected to the inlet 5, and the inlet 5 is fixed on the lower surface of the front section of the balance 3 through a square boss above.

[0040] Furthermore, as Figure 2 shown, the balance 3 is a square six-component force-measuring balance, which is used to measure three forces of drag X, lift Y, and side force Z and three moments of roll moment Mx, yaw moment My, and pitch moment Mz;

[0041] The front connection section, middle measurement section, and rear connection section of the square six-component force measuring balance are all square bodies and are installed inside a flat test model. Positioning blocks that are symmetrical front and back are provided on the front connection section and the rear connection section for connection and positioning. Pin holes and several symmetrically distributed screw holes centered on the upper surface of the front connection section are used for positioning and fixing the connecting piece 2. Pin holes and several symmetrically distributed screw holes centered on both the upper and lower surfaces of the rear connection section are provided. The upper surface is used for positioning and fixing the loading head 4, and the lower surface is used for positioning and fixing the square boss. The middle measurement section is a square column, and the four planes of up, down, left, and right can all be used as measurement planes.

[0042] Furthermore, as Figure 3 shown, the loading head 4 is a frame structure and is integrally machined from aluminum. Mechanical decomposition of the three forces of drag X, lift Y, and side force Z is carried out. The main body of the loading head 4 is a square frame located in a vertical plane. At the center point of the square frame, a bayonet matching the front connection section of the balance 3 extends. At the midpoint of the upper, lower, left, and right sides of the square frame, 4 horizontally symmetrically distributed loading rods are provided. A total of 8 loading points are provided at the front and rear ends of each horizontal loading rod, and are respectively named loading point Ⅰ, loading point Ⅱ, loading point Ⅲ, loading point Ⅳ, loading point Ⅴ, loading point Ⅵ, loading point Ⅶ, and loading point Ⅷ. At the upper midpoint and lower midpoint of the square frame, an upward upper loading rod and a downward lower loading rod are respectively provided. At the upper end of the upper loading rod, a loading point Ⅹ is provided, and at the lower end of the lower loading rod, a loading point Ⅻ is provided. At the left midpoint and right midpoint of the square frame, a leftward left loading rod and a rightward right loading rod are respectively provided. At the left end of the left loading rod, a loading point Ⅸ is provided, and at the right end of the right loading rod, a loading point Ⅺ is provided.

[0043] Each loading point is a through hole, and both ends of the through hole can be used to install the center point 8. A weight tray is suspended on the center point 8, and loading of forces and torques in various directions is achieved by adding standard weights on the weight tray. Loading points Ⅰ, Ⅱ, Ⅲ, and Ⅳ are used for positive and negative loading in the lift Y direction. After the intake balance calibration device rotates 90° around the axis, loading points Ⅴ, Ⅵ, Ⅶ, and Ⅷ are used for positive and negative loading in the side force Z direction. Loading points Ⅸ, Ⅹ, Ⅺ, and Ⅻ are used for drag X direction loading. When calibrating the lift direction, loads are applied at loading points Ⅹ and Ⅻ to achieve combined loading of lift Y and drag X. When calibrating the side force direction, loads are applied at loading points Ⅸ and Ⅺ to achieve combined loading of side force Z and drag X.

[0044] Furthermore, the front end face of the bellows 6 is connected to the intake duct 5 through a flange, the rear end face of the bellows 6 is connected to the front end face of the bellows connecting piece 7 through a flange, and the central axis of the bellows 6 is parallel to the central axis of the balance 3.

[0045] Furthermore, as Figure 4As shown, the upper section of the corrugated pipe connector 7 is a clamping groove, which is clamped on the connector 2, and a locking buckle for locking with the connector 2 is arranged on the clamping groove; the lower section of the corrugated pipe connector 7 is a flat plate, and a plurality of circumferentially distributed screw holes matching the flange of the corrugated pipe 6 are arranged on the front end face of the flat plate.

[0046] Furthermore, the intake air duct 5 is a twin-engine intake air duct that is symmetrical left and right, and the corrugated pipe connector 7 is arranged as an independent structure that is symmetrical left and right. Each independent structure is respectively clamped on the connector 2 to adapt to the twin-engine intake air duct.

[0047] The method for calibrating the intake air duct balance in the simulated test state of this embodiment includes the following steps:

[0048] S10. Perform optical balance calibration;

[0049] As Figure 5 shown, connect the calibration support rod 1, the connector 2, the balance 3, and the loading head 4 in sequence from back to front to obtain an optical balance calibration device. Then install the calibration support rod 1 on the two-degree-of-freedom balance calibration frame, and perform optical balance calibration according to the conventional six-component balance calibration method to obtain the optical balance calibration formula;

[0050] S20. Perform model assembly;

[0051] Install the balance 3, the intake air duct 5, and the corrugated pipe 6 inside the flat test model, and record the length of the corrugated pipe 6 and the initial reading of the balance 3 after installation;

[0052] S30. Adjust the position of the corrugated pipe connector 7;

[0053] Install the calibration support rod 1, the connector 2, the balance 3, the intake air duct 5, the corrugated pipe 6, and the corrugated pipe connector 7, observe the reading of the balance 3, and adjust the position of the corrugated pipe connector 7 until the reading of the balance 3 is the same as the initial reading of the balance 3;

[0054] S40. Perform intake air duct balance calibration;

[0055] Install the loading head 4, then install the calibration support rod 1 on the two-degree-of-freedom balance calibration frame, and perform calibration with the corrugated pipe according to the conventional six-component balance calibration method to obtain the calibration formula of the parallel force measuring system composed of the balance 3, the intake air duct 5, and the corrugated pipe 6, that is, the intake air duct balance calibration formula;

[0056] S50. Perform wind tunnel test;

[0057] Remove the balance 3, the intake air duct 5, and the corrugated pipe 6 as a whole from the two-degree-of-freedom balance calibration frame, and install them on the test model as a whole before the test to avoid installation errors caused by repeated disassembly and assembly; during the test, calculate the six-component force measuring data using the intake air duct balance calibration formula.

[0058] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, without departing from the principle of the present invention, all features disclosed in the present invention, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to specific details and the illustrated and described examples here.

Claims

1. An intake balance calibration device for simulating test states, characterized in that, The described inlet balance calibration device includes a calibration strut (1), a connecting piece (2), a balance (3), and a loading head (4) connected in sequence from the rear to the front. The rear end of the calibration strut (1) is fixed on a two-degree-of-freedom balance calibration frame; a bellows connecting piece (7) is clamped on the connecting piece (2) and slides along the connecting piece (2); the rear end of the bellows (6) is fixed on the front end face of the bellows connecting piece (7), and the front end of the bellows (6) is connected to the inlet (5), and the inlet (5) is fixed on the lower surface of the front section of the balance (3) through a square boss above.

2. The inlet balance calibration device for simulating test states according to claim 1, wherein The described balance (3) is a square six-component force-measuring balance, which is used to measure three forces, namely drag X, lift Y, and side force Z, and three moments, namely rolling moment Mx, yaw moment My, and pitch moment Mz. The front connecting section, middle measuring section, and rear connecting section of the square six-component force-measuring balance are all square bodies and are installed inside a flat test model; positioning blocks that are symmetric in the front and rear are provided on the front connecting section and the rear connecting section for connection and positioning; a pin hole and several screw holes symmetrically distributed around the center are provided on the upper surface of the front connecting section for positioning and fixing the connecting piece (2), and pin holes and several screw holes symmetrically distributed around the center are provided on both the upper and lower surfaces of the rear connecting section. The upper surface is used for positioning and fixing the loading head (4), and the lower surface is used for positioning and fixing the square boss; the middle measuring section is a square column, and the four planes of the upper, lower, left, and right can all be used as measuring planes.

3. The inlet balance calibration device for simulating test states according to claim 2, characterized in that, The described loading head (4) is a frame structure, integrally machined from aluminum, and mechanically decomposes the three forces of drag X, lift Y, and side force Z; the main body of the loading head (4) is a square frame located in a vertical plane; a bayonet matching the front connecting section of the balance (3) extends from the center point of the square frame; 4 horizontal loading rods that are symmetric in the front and rear are provided at the midpoints of the upper, lower, left, and right of the square frame, and a total of 8 loading points are provided at the front and rear ends of each horizontal loading rod, which are respectively named loading point Ⅰ, loading point Ⅱ, loading point Ⅲ, loading point Ⅳ, loading point Ⅴ, loading point Ⅵ, loading point Ⅶ, and loading point Ⅷ; an upward upper loading rod and a downward lower loading rod are respectively provided at the upper midpoint and the lower midpoint of the square frame. A loading point Ⅹ is provided at the upper end of the upper loading rod, and a loading point Ⅻ is provided at the lower end of the lower loading rod; a left loading rod and a right loading rod are respectively provided at the left midpoint and the right midpoint of the square frame. A loading point Ⅸ is provided at the left end of the left loading rod, and a loading point Ⅺ is provided at the right end of the right loading rod. Each loading point is a through hole, and both ends of the through hole can be used to install the center point (8). A code disk is suspended on the center point (8), and the loading of forces and torques in all directions is achieved by adding standard weights to the code disk. Loading points I, II, III, and IV are used for positive and negative loading in the lift Y direction. After the intake balance calibration device rotates 90° around the axial direction, loading points V, VI, VII, and VIII are used for positive and negative loading in the side force Z direction. Loading points IX, X, XI, and XII are used for drag X direction loading. When calibrating in the lift direction, loads are applied at loading points X and XII to achieve combined loading of lift Y and drag X. When calibrating in the side force direction, loads are applied at loading points IX and XI to achieve combined loading of side force Z and drag X.

4. The intake balance calibration device for simulating test states according to claim 3, characterized in that, The front end face of the bellows (6) is connected to the intake duct (5) through a flange, and the rear end face of the bellows (6) is connected to the front end face of the bellows connector (7) through a flange. The central axis of the bellows (6) is parallel to the central axis of the balance (3).

5. The inlet balance calibration device for simulating test states according to claim 4, characterized in that, The upper section of the bellows connector (7) is a clamping groove, which is clamped on the connector (2), and a locking buckle for locking with the connector (2) is provided on the clamping groove. The lower section of the bellows connector (7) is a flat plate, and a number of circumferentially distributed screw holes matching the flange of the bellows (6) are provided on the front end face of the flat plate.

6. The inlet balance calibration device for simulating test states according to claim 5, wherein The intake duct (5) is a twin-engine intake duct that is symmetric about the left and right. The bellows connectors (7) are arranged as independent structures that are symmetric about the left and right, and each independent structure is respectively clamped on the connector (2) to adapt to the twin-engine intake duct.

7. An inlet balance calibration method for simulating test states, which is used for the inlet balance calibration device for simulating test states according to claim 5, characterized in that, The intake balance calibration method includes the following steps: S10. Perform optical balance calibration; Connect the calibration support rod (1), connector (2), balance (3), and loading head (4) in sequence from the back to the front to obtain an optical balance calibration device. Then install the calibration support rod (1) on the two-degree-of-freedom balance calibration frame, and perform optical balance calibration in the conventional six-component balance calibration method to obtain the optical balance calibration formula. S20. Perform model assembly; Install the balance (3), intake duct (5), and bellows (6) inside the flat test model, and record the length of the bellows (6) and the initial reading of the balance (3) after installation. S30. Adjust the position of the bellows connector (7); Install the calibration support rod (1), connector (2), balance (3), intake duct (5), bellows (6), and bellows connector (7), observe the reading of the balance (3), and adjust the position of the bellows connector (7) until the reading of the balance (3) is the same as the initial reading of the balance (3). S40. Perform intake balance calibration; Install the loading head (4), then install the calibration support rod (1) on the two-degree-of-freedom balance calibration frame, and perform calibration with the bellows in the conventional six-component balance calibration method to obtain the calibration formula of the parallel force-measuring system composed of the balance (3), intake duct (5), and bellows (6), that is, the intake balance calibration formula. S50. Perform wind tunnel tests; Remove the balance (3), inlet duct (5) and bellows (6) as a whole from the two-degree-of-freedom balance calibration fixture and install them as a whole on the test model before the test to avoid installation errors caused by repeated disassembly and assembly; during the test, use the inlet duct balance calibration formula to calculate the six-component force measurement data.

Images