Aerodynamic characteristic testing equipment and aerodynamic characteristic compensation and correction method for water surface aircraft under pool test environment

Abstract

This invention discloses an aerodynamic characteristic testing device and aerodynamic characteristic compensation and correction method for a surface-to-air vehicle under a water tank test environment. During the aerodynamic characteristic test of the surface-to-air vehicle under the water tank test environment, the towing device drives the side bridge, heave rod, navigation rod, and attitude control rod to move simultaneously. Under the traction of the navigation plate, the surface-to-air vehicle model and the six-component force balance, the single-component force balance, and the angle sensor move together along the heading. The six-component force balance, the angle sensor, and the single-component force balance record the center of gravity position and aerodynamic lift L of the surface-to-air vehicle model during the motion process, respectively. mf Resistance D mf The attitude angle θ in the pitch direction and the aerodynamic lift L at the tail of the surface aircraft model. ma This results in a comprehensive aerodynamic characteristic data map of a physical water tank environment. The operating method proposed in this invention is simple and effective, and can directly support lift compensation analysis for all surface aircraft.

Description

Technical Field

[0001] This invention belongs to the technical field of design and testing of surface aircraft, and particularly relates to an aerodynamic characteristic testing device and aerodynamic characteristic compensation and correction method for surface aircraft in a water tank test environment. Background Technology

[0002] In the design and finalization process of surface-to-air vehicles (SIAs), hydrodynamic tests using a scaled-down full-scale model are typically employed to verify and evaluate the vehicle's gliding motion, stability, water load, and splash characteristics. However, in a water tank environment, the similarity between the scaled-down full-scale model and the actual aircraft in terms of shape and performance parameters primarily relies on the Froude similarity criterion. The aerodynamic similarity between the actual aircraft and the scaled-down model, on the other hand, is mainly based on the Reynolds number similarity criterion. The existence of these two similarity criteria inevitably leads to significant differences in aerodynamic characteristic parameters, such as lift coefficient, drag coefficient, and moment coefficient. When conducting scaled-down full-scale model tests in a physical water tank environment using aerodynamic characteristic parameters obtained through hydrodynamic testing methods, the resulting model's gliding attitude, motion frequency, and overload impact parameters differ significantly from those of the actual SIA, directly impacting the optimization and design finalization of the SIA. Summary of the Invention

[0003] Purpose of the invention

[0004] To improve the accuracy of aerodynamic and hydrodynamic characteristic simulation during hydrodynamic testing of surface aircraft, this invention provides an aerodynamic characteristic testing device and aerodynamic characteristic compensation and correction method for surface aircraft in a water tank testing environment.

[0005] Invention Technology Solutions

[0006] A device for testing the aerodynamic characteristics of a surface-to-water aircraft in a pool test environment includes a surface-to-water aircraft model, a side bridge, a heave bar, a navigation bar, an attitude control bar, a navigation plate, a six-component balance, a two-degree-of-freedom device, an angle sensor, a single-component balance, an attitude control assembly, and a hinge device. A center of gravity plate is horizontally arranged inside the surface-to-water aircraft model. Both ends of the center of gravity plate are connected to a vertically arranged longitudinal frame, which is connected to the surface-to-water aircraft model. The six-component balance is connected to the upper surface of the center of gravity plate. The six-component balance is connected to the angle sensor via the two-degree-of-freedom device. The angle sensor is connected to the vertically arranged heave bar. The attitude control assembly is connected to the tail of the surface-to-water aircraft model. The upper part of the attitude control assembly is connected to a horizontal plate via a hinge device. A single-component balance is fixed on the horizontal plate and connected to the vertically arranged attitude control bar, which is fixed to the attitude control assembly. The lower part of the navigation bar passes through a hole in the navigation plate. The upper parts of the navigation bar, attitude control bar, and heave bar are all fixed to the side bridge.

[0007] During aerodynamic characteristic tests of a surface-to-air vehicle in a pool test environment, the towing device drives the side bridge, heave bar, navigation stick, and attitude control stick to move simultaneously. Under the traction of the navigation plate, the surface-to-air vehicle model, along with a six-component force balance, a single-component force balance, and an angle sensor, move collaboratively along the heading. The six-component force balance, angle sensor, and single-component force balance record the center of gravity position and aerodynamic lift of the surface-to-air vehicle model during the motion. L mf ,resistance D mf The attitude angle of the water surface aircraft model in the pitch direction i Tail-end aerodynamic lift L ma This results in a comprehensive aerodynamic characteristic data map of the physical pool environment.

[0008] Preferably, before conducting aerodynamic characteristic tests in a water tank environment, the longitudinal attitude of the water surface vehicle model is adjusted. Angle sensors provide real-time feedback of the current attitude parameters. When this value matches the target value, the attitude control components are locked. At this point, the pitch angle of the water surface vehicle model is... i Fix; adjust the relative position h between the side bridge and the water surface. At this point, the installation and pre-test preparation work for the water surface aircraft model is complete.

[0009] Preferably, the vertical line of the center of gravity of the water surface aircraft model always passes through the center of the six-component balance, the two-degree-of-freedom device, and the angle sensor.

[0010] Preferably, the two-degree-of-freedom device consists of a mounting base, a transverse rotating shaft, a transverse rotating shaft sleeve, a vertical support rod, and a horizontal top plate. The mounting base is connected to the top of the six-component balance 9. The two ends of the transverse rotating shaft are respectively rotatably set inside the transverse rotating shaft sleeve, and the transverse rotating shaft sleeve is fixed on the mounting base. One end of the vertically set vertical support rod is fixedly connected to the middle position of the transverse rotating shaft, and the other end is fixedly connected to the horizontally set horizontal top plate. An angle sensor is connected to the horizontal top plate.

[0011] Preferably, the center of gravity plate is set at the center of gravity of the water surface aircraft model.

[0012] Preferably, the centerline of the navigation plate passes through the plane of symmetry of the surface aircraft model and is higher than the waterline at the front.

[0013] Preferably, the bottom end of the attitude control component is connected and fixed to the positioning plate reserved on the water surface aircraft model by a screw, and one end of the attitude control component is hinged to the upper part of the hinge device, and the other end of the hinge device is hinged to the bottom surface of the horizontal plate.

[0014] An aerodynamic characteristic compensation and correction method using an aerodynamic characteristic testing device in a water tank test environment for surface aircraft, the method comprising:

[0015] Step 1: Obtain the deflection of the waterplane model 1 under a series of fixed elevators through wind tunnel testing or numerical analysis of aerodynamic characteristics. d a Below, the total lift coefficient of the surface aircraft model 1 relative to its center of gravity. C L drag coefficient C D and torque coefficient C M Follow the posture i A graph showing the changes;

[0016] Step 2: Conduct aerodynamic characteristic tests in a physical water tank environment by adjusting the horizontal towing speed v and the pitch angle of the water surface aircraft model. i and elevator deflection d apy Obtain the aerodynamic lift at the center of gravity position under a series of corresponding states. L mf ,resistance D mf and tail aerodynamic lift L ma Experimental values;

[0017] The experimental values ​​were converted to the relative center of gravity position, and then converted using formulas (1) to (3) based on the relative position of the forces and the principles of flight:

[0018] Aerodynamic lift coefficient at the center of gravity in a water tank environment:

[0019] (1)

[0020] Aerodynamic drag coefficient at the center of gravity in a pool environment:

[0021] (2)

[0022] Moment coefficient relative to the center of gravity in a pool environment:

[0023] (3)

[0024] In the above formula, S is the wing area of ​​the scaled-down model; ρ is the air density; The mean aerodynamic chord length of the model wing; L mf and D mf The aerodynamic lift and aerodynamic drag at the center of gravity position are measured by a six-component balance (9), respectively. L ma The tail aerodynamic lift force measured by a single-component balance (12); g is the gravitational acceleration; i L represents the pitch angle of the model; c The distance between the center of gravity and the measurement center of the single-component balance (12) is the distance between the center of gravity and the measurement center. ;where △X is the longitudinal distance between the measurement center and the center of gravity of the single-component balance (12), and △Z is the longitudinal distance between the measurement center and the center of gravity of the single-component balance (12). f The height difference between the center of a six-component balance and the center of gravity, ΔZ, is measured using a balance with six components (9). a The height difference between the measurement center of the single-component balance (12) and the measurement center of the six-component balance (9);

[0025] Step 3: Using the aerodynamic characteristic coefficients obtained in Step 1 and Step 2 as the ordinate and the attitude angles in the pitch direction of the surface aircraft model as the coordinates. i x-axis, elevator deflection angle d a and d apy Plot the lift coefficient and moment coefficient curves to represent the changes. Compare the moment coefficients of the surface vehicle under wind tunnel and hydrodynamic test environments. C M、 C mhy Attitude angles in the pitch direction of the water surface aircraft model i Find the elevator deflection corresponding to the two sets of curves when the moment coefficients coincide, based on the changing curves. d a目标 , d apy对标 And the corresponding lift coefficient under rudder deflection C L目标 and C Lhy对标 The lift ΔL at the center of gravity position required to compensate for each velocity point of the water surface aircraft model during the hydrodynamic test is calculated using formula (4):

[0026] (4).

[0027] Preferably, the calculated lift ΔL at the center of gravity is actually the difference in lift between the model and the actual aircraft at the center of gravity under the conditions of Froude similarity and Reynolds number similarity, respectively. After obtaining this value, additional lift compensation correction needs to be made to the center of gravity when conducting hydrodynamic towing tests in a pool environment. The test results obtained at this time can truly characterize the gliding motion performance of the aircraft.

[0028] Preferably, when searching for the test state where the moment coefficients coincide under two different environments, the moment coefficient corresponding to the wind tunnel data is used. C M Attitude angles in the pitch direction of the water surface aircraft model i The variation curve is a reference value; the moment coefficient under hydrodynamic test conditions. Cmhy Attitude angles in the pitch direction of the water surface aircraft model i The change curve is used to compare parameters with the benchmark value. At this point, there are two possible scenarios:

[0029] a) A curve exists that matches the benchmark value: Record the corresponding elevator deflection at this time. d a目标 , d apy对标 and their respective lift coefficients under rudder deflection C L目标 and C Lhy对标 The magnitude of the lift compensation at the center of gravity position is calculated according to formula (4);

[0030] b) No curve matches the reference value: Since the elevator deflection has angular intervals within a certain range, there may be reference values ​​that do not perfectly match the reference value. In this case, it is necessary to compare different elevator deflection angles near the reference value. d apy Below C mhy Follow the posture i Interpolation is performed on the changing curve to determine the corresponding benchmark value. d apy对标 Then, the same method was used to... d apy对标 Two nearby groups C Lhy Attitude angles in the pitch direction of the water surface aircraft model i Interpolating the change curve can yield the result. d apy对标 Corresponding C Lhy对标 Then, the magnitude of the lift compensation at the center of gravity position is calculated according to formula (4).

[0031] Advantages of this invention:

[0032] I. The operating method proposed in this invention is simple and effective, and can directly support lift compensation analysis for all surface aircraft. During operation, based on wind tunnel tests / numerical analysis of aerodynamic characteristics and aerodynamic characteristic tests under water tank test environments, the aerodynamic lift coefficient and moment coefficient corresponding to Reynolds number similarity and Froude similarity conditions can be obtained.

[0033] Second, this invention can provide more accurate aerodynamic lift compensation parameters for hydrodynamic tests of scaled-down models of water-based aircraft. Hydrodynamic characteristic tests conducted based on aerodynamic lift compensation correction can more accurately reflect the true motion state of water-based aircraft.

[0034] Third, this invention requires no structural or hardware modifications and is highly feasible. Without altering the commonly used hydrodynamic testing equipment and methods for surface aircraft, the hydrodynamic characteristics of surface aircraft can be tested by adjusting the unloading size of the constant force unloading device by using the lift compensation value of the center of gravity obtained by this invention as input. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the aerodynamic characteristics testing device for a surface aircraft under hydrodynamic testing environment according to the present invention.

[0036] Figure 2 This is a schematic diagram showing the test parameters and relative positions for aerodynamic characteristics testing in a physical water tank environment.

[0037] Figure 3 a) is the curve of aerodynamic lift coefficient at the center of gravity as a function of attitude in a physical water tank environment. Figure 3 b) is the curve of the moment coefficient at the center of gravity position in a physical water tank environment as a function of attitude.

[0038] Figure 4 a) is the curve of aerodynamic lift coefficient as a function of attitude, based on wind tunnel test / numerical evaluation results. Figure 4 b) Based on wind tunnel test / numerical evaluation results, the torque coefficient varies with attitude curve.

[0039] Figure 5 This is a schematic diagram of a two-degree-of-freedom device.

[0040] In the diagram: 1. Water surface aircraft model, 2. Side bridge, 3. Heave rod, 4. Navigation rod, 5. Attitude control rod, 6. Navigation plate, 7. Longitudinal frame, 8. Center of gravity plate, 9. Six-component balance, 10. Two-degree-of-freedom device, 11. Angle sensor, 12. Single-component balance, 13. Attitude control assembly, 14. Hinge device. Detailed Implementation

[0041] The present invention is achieved through the following technical solution.

[0042] like Figure 1 As shown, an aerodynamic characteristic testing device for a surface aircraft in a pool test environment includes a surface aircraft model 1, a side bridge 2, a heave bar 3, a navigation bar 4, an attitude control bar 5, a navigation plate 6, a longitudinal frame 7, a center of gravity plate 8, a six-component force balance 9, a two-degree-of-freedom device 10, an angle sensor 11, a single-component force balance 12, an attitude control assembly 13, and a hinge device 14. The six-component force balance 9, the angle sensor 11, and the single-component force balance 12 are test sensor devices.

[0043] The navigation plate 6 is made of aluminum plate, and its centerline passes through the symmetry plane of the surface aircraft model 1 and is higher than the waterline position at the front. After confirming the position, it is bonded to the front of the surface aircraft model 1 using carbon fiber cloth. The two vertical longitudinal frames 7 and the horizontally placed center plate 8 are the internal structure of the surface aircraft model 1. They are designed and assembled according to the structural design and center of gravity distribution position during the model manufacturing process. The two are fixed by preset threaded holes. The six-component balance 9 is installed and fixed on the upper end face of the center plate 8. The two-degree-of-freedom device 10 and the angle sensor 11 are installed in sequence above the six-component balance 9. The center of the six-component balance 9, the two-degree-of-freedom device 10 and the angle sensor 11 always passes through the vertical line of the center of gravity of the surface aircraft model 1. The attitude control component 13 is a horizontal aluminum part at the bottom. Its bottom end is connected and fixed to the positioning piece reserved on the surface aircraft model 1 by a screw. The top end is a horizontal aluminum plate with a hinge device 14 for the installation of the single-component balance 12. At this point, the surface aircraft model 1, along with the various test sensors, the model itself, and the attitude adjustment device, forms a fixed whole.

[0044] The two-degree-of-freedom device 10 consists of a mounting base 101, a transverse rotating shaft 102, a transverse rotating shaft sleeve 103, a vertical support rod 104, and a horizontal top plate 105. The mounting base is connected to the top of the six-component balance (9). The two ends of the transverse rotating shaft are respectively rotatably installed in the transverse rotating shaft sleeve, which is fixed on the mounting base. One end of the vertically installed vertical support rod is fixedly connected to the middle position of the transverse rotating shaft, and the other end is fixedly connected to the horizontally installed horizontal top plate. An angle sensor (11) is connected to the horizontal top plate.

[0045] The side bridge 2 is arranged below the towing device in the test pool and is used to connect the test device and provide horizontal motion power; the heave rod 3 is placed vertically above the water surface aircraft model 1, with its upper end fixed to the side bridge 2 by a screw and its lower end fixed to the upper end face of the angle sensor 11; the navigation rod 4 is placed vertically at the front end of the water surface aircraft model 1 and passes through the center point of the slot of the navigation plate 6; the attitude control rod 5 is installed vertically at the tail of the water surface aircraft model 1, with its upper end fixed to the side bridge 2 by a screw and its lower end fixed to the upper end face of the single component force balance 12.

[0046] Before conducting aerodynamic characteristic tests in a water tank environment, the longitudinal attitude of the water surface aircraft model 1 is adjusted using the two-degree-of-freedom device 10 above the center of gravity and the hinge device 14 at the tail of the water surface aircraft model 1. The angle sensor 11 provides real-time feedback on the current attitude parameters. When the value matches the target value, the attitude control component 13 is locked (this can be achieved by tightening the screw at the hinge point between the hinge device 14 and the attitude control component 13; similarly, the screw at the hinge point between the hinge device 14 and the horizontal plate can also be tightened). At this point, the longitudinal attitude of the water surface aircraft model 1 is... iFix. Adjust the relative position h between the side bridge 2 and the water surface to achieve positional control of the test altitude of the water surface aircraft model 1. At this point, the installation and pre-test preparation work for the water surface aircraft model 1 is complete.

[0047] During the aerodynamic characteristic test of the water-based aircraft in the pool test environment, the towing device drives the side bridge 2, heave bar 3, navigation stick 4, and attitude control stick 5 to move simultaneously. Under the traction of the navigation plate 6, the water-based aircraft model 1 and all test sensors move together along the heading. The six-component force balance 9, angle sensor 11, and single-component force balance 12 record the center of gravity position and aerodynamic lift of the model during the motion. L mf ,resistance D mf Model in fixed posture i Tail-end aerodynamic lift L ma To generate a comprehensive aerodynamic characteristic data map under a physical water tank environment, the horizontal towing speed v and attitude during the experiment were analyzed. i and elevator deflection d apy All are experimental variables.

[0048] A method for compensating and correcting the aerodynamic characteristics of a surface aircraft under a pool test environment using the above-mentioned testing device includes the following steps:

[0049] Step 1: Obtain the deflection of the waterplane under a series of fixed elevators using wind tunnel testing or numerical aerodynamic analysis. d a Below, the total lift coefficient of the aircraft relative to its center of gravity. C L drag coefficient C D and torque coefficient C M Follow the posture i A graph showing the changes;

[0050] Step 2: In a physical water tank environment, based on Step 1, conduct aerodynamic characteristic tests by adjusting the horizontal towing speed v and attitude. i and elevator deflection d apy Obtain the aerodynamic lift at the center of gravity position under a series of corresponding states. L mf ,resistance D mf and tail aerodynamic lift L ma Experimental values.

[0051] The experimental values ​​were converted to the relative center of gravity position, and then converted using formulas (1) to (3) based on the relative position of the forces and the principles of flight:

[0052] Aerodynamic lift coefficient at the center of gravity in a water tank environment:

[0053] (1)

[0054] Aerodynamic drag coefficient at the center of gravity in a pool environment:

[0055] (2)

[0056] Moment coefficient relative to the center of gravity in a pool environment:

[0057] (3)

[0058] In the above formula, S is the wing area of ​​the scaled-down model; ρ is the air density; The mean aerodynamic chord length of the model wing; L mf and D mf These are the aerodynamic lift and aerodynamic drag at the center of gravity position, as measured by the six-component balance 9. L ma ρ is the tail aerodynamic lift measured by the single-component balance 12; g is the gravitational acceleration. i L represents the pitch angle of the model; c The distance between the center of gravity and the measurement center of the single-component balance 12. Where △X is the longitudinal distance between the measurement center and the center of gravity of the single-component force balance 12, and △Z is... f The height difference between the center of a six-component balance and the center of gravity, ΔZ a This represents the height difference between the measurement centers of the single-component balance 12 and the six-component balance 9.

[0059] Step 3: Using the aerodynamic characteristic coefficients obtained in Step 1 and Step 2 as the ordinate and attitude respectively. i x-axis, elevator deflection angle d a and d apy Plot the lift coefficient and moment coefficient curves to represent the changes. Compare the moment coefficients of the surface vehicle under wind tunnel and hydrodynamic test environments. C M、 C mhy attitude angle i Find the elevator deflection corresponding to the two sets of curves when the moment coefficients coincide, based on the changing curves. d a目标 , d apy对标 And the corresponding lift coefficient under rudder deflection C L目标 and C Lhy对标 At this time, there is a certain difference in the lift coefficient between the wind tunnel conditions and the pool environment. Based on the wind tunnel test / numerical calculation results, the lift ΔL at the center of gravity position that needs to be compensated at each velocity point during the hydrodynamic test of the scaled-down model of the water surface aircraft is calculated using formula (4):

[0060] (4).

[0061] Before conducting aerodynamic characteristic compensation and correction analysis, it is necessary to use the aforementioned testing equipment to test the aerodynamic characteristics of the water-based aircraft in a physical water tank environment during gliding, and to obtain aerodynamic characteristic data results that satisfy the Reynolds number similarity criterion using wind tunnel testing or aerodynamic characteristic numerical analysis methods. That is, steps 1 and 3.

[0062] The calculated lift ΔL at the center of gravity is actually the difference in lift between the model and the actual aircraft at the center of gravity under the conditions of Froude similarity and Reynolds number similarity, respectively. After obtaining this value, additional lift compensation correction needs to be made to the center of gravity position when conducting hydrodynamic towing tests in a pool environment (usually achieved with the help of a dynamic constant force unloading device). The test results obtained at this time can truly characterize the gliding motion performance of the water surface aircraft.

[0063] When searching for the test state where the moment coefficients coincide under two different environments, the moment coefficients corresponding to the wind tunnel data are used. C M Follow the posture i The variation curve is a reference value; the moment coefficient under hydrodynamic test conditions. C mhy Follow the posture i The change curve is used to compare parameters with the benchmark value. At this point, there are two possible scenarios:

[0064] a) A curve exists that matches the benchmark value: Record the corresponding elevator deflection at this time. d a目标 , d apy对标 and their respective lift coefficients under rudder deflection C L目标 and C Lhy对标 The magnitude of the lift compensation at the center of gravity position is calculated according to formula (4);

[0065] b) No curve matches the reference value: Since the elevator deflection has angular intervals within a certain range, there may be reference values ​​that do not perfectly match the reference value. In this case, it is necessary to compare different elevator deflection angles near the reference value. d apy Below C mhy Follow the posture i Interpolation is performed on the changing curve to determine the corresponding benchmark value. d apy对标 Then, the same method was used to... d apy对标 Two nearby groups C Lhy Follow the posture i Interpolating the change curve can yield the result. d apy对标 Corresponding C Lhy对标 Then, the magnitude of the lift compensation at the center of gravity position is calculated according to formula (4).

[0066] In this embodiment, after the testing device is installed, the longitudinal attitude of the water surface aircraft model 1 is adjusted according to the test requirements. i By adjusting the relative position of the side bridge 2 and the water surface, the vertical distance between the lowest point of the water surface vehicle model 1 and the water surface is controlled to be 20mm. In this example, the longitudinal attitude angle of the water surface vehicle model 1 is taken as... i The angles are 0°, 2°, 4°, 6°, and 8° respectively. The elevator deflection angles are -8°, -4°, 0°, and 4°. The horizontal speed of the towing device is set to 7 m / s.

[0067] Then, the aerodynamic characteristics test in the pool test environment was carried out: according to the test conditions, the elevator bias was fixed at a certain angle, and the longitudinal attitude of the water surface aircraft model 1 was adjusted in sequence. The towing device always drove the water surface aircraft model (1) to move horizontally at a speed of 7 m / s. The six-component balance (9), the angle sensor 11, and the single-component balance 12 recorded the aerodynamic lift of the model's center of gravity position during the motion process. L mf / resistance D mf Model in fixed posture i Tail-end aerodynamic lift L ma The aerodynamic characteristic parameters and their relative positions are as follows: Figure 2 As shown.

[0068] Then, the aerodynamic characteristic parameters at the center of gravity are calculated:

[0069] Based on the relative positions of the forces and the principles of flight, formulas (1) to (3) are used to convert the experimental values ​​to the relative center of gravity position. Aerodynamic characteristic coefficients are used as the ordinate, and attitude angles are used as the coordinates. i x-axis, elevator deflection angle d apy Plot the lift coefficient as the change. C Lhy Torque coefficient C mhy curve. Figure 3 This is the aerodynamic characteristic curve graph under the corresponding hydrodynamic test environment in this example.

[0070] For this example, different elevator deflection angles d apy Below, lift coefficient C Lhy Torque coefficient C mhy attitude angle i The curves of change are basically parallel, but the values ​​are somewhat different.

[0071] Then, the aerodynamic characteristic compensation was analyzed under the water tank test environment:

[0072] The moment coefficient corresponding to wind tunnel data C M Follow the posture i The variation curve is a reference value; the moment coefficient under hydrodynamic test conditions. C mhy attitude angle i The change curve is used to compare parameters with the benchmark value and find the test state where the torque coefficient coincides under two different environments (such as...). Figure 4 (As shown). In this example, the elevator deflection angle in the wind tunnel data... d a目标 =-2°, and there exists a corresponding set of lift coefficients. C L目标 Torque coefficient C M目标 Curve. Upon comparison, the aforementioned torque coefficient... C M目标 Curve and hydrodynamic test environment d apy对标 Moment coefficient at -4° C mhy对标 Since they are essentially overlapping, the lift coefficient curve corresponding to this elevator deflection angle is... C Lhy对标The lift coefficients under target rudder deflection, the lift coefficients under benchmark rudder deflection, and the difference between the two are shown in Table 1 below. From the data in the table, it can be seen that the difference in lift coefficients at the center of gravity position under Froude similarity and Reynolds number similarity conditions is between 1.2 and 1.45. In this embodiment, the average value is taken as 1.31. The lift compensation at different speeds during the hydrodynamic towing test in the pool environment can be calculated according to formula (4). The specific values ​​are shown in Table 2 below.

[0073] Table 1 Summary of Aerodynamic Lift Coefficients under Wind Tunnel and Water Tank Test Environments

[0074]

[0075] Table 2 Aerodynamic lift compensation under water tank test environment

[0076]

[0077] Hydrodynamic towing test considering aerodynamic lift compensation:

[0078] When conducting hydrodynamic towing tests in a pool environment (including but not limited to wave resistance tests and wave resistance tests of water surface aircraft), an additional vertical lift compensation is applied to the center of gravity (usually achieved with the help of a dynamic constant force unloading device). The test results obtained at this time can truly characterize the gliding motion performance of the water surface aircraft.

[0079] Using the test apparatus and correction method of this invention, aerodynamic lift and torque parameters relative to the center of gravity can be obtained under a water tank test environment. Based on this, wind tunnel test / numerical evaluation results based on the aerodynamic characteristics of water-based aircraft can be compared to obtain a set of aerodynamic lift compensation values ​​based on different horizontal velocities under a physical water tank test environment. This allows for the aerodynamic lift correction of water-based aircraft for tests such as wave resistance and wave resistance, providing input for the hydrodynamic performance verification and evaluation of water-based aircraft.

[0080] The scope of protection of this invention is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its scope. If such modifications and variations fall within the scope of the claims of this invention and their equivalents, then the intent of this invention also includes these modifications and variations.

Claims

1. An aerodynamic characteristic testing device for a surface aircraft in a water tank test environment, characterized in that, The system includes a surface aircraft model, side bridge, heave bar, navigation stick, attitude control stick, navigation plate, six-component balance, two-degree-of-freedom device, angle sensor, single-component balance, attitude control assembly, and articulation device. A center of gravity plate is horizontally positioned inside the surface aircraft model. Both ends of the center of gravity plate are connected to vertically positioned longitudinal frames, which are connected to the surface aircraft model. The six-component balance is connected to the upper surface of the center of gravity plate. The six-component balance is connected to the angle sensor via the two-degree-of-freedom device. The angle sensor is connected to the vertically positioned heave bar. The attitude control assembly is connected to the tail of the surface aircraft model. The upper part of the attitude control assembly is connected to a horizontal plate via an articulation device. A single-component balance is fixed to the horizontal plate and connected to the vertically positioned attitude control stick, which is fixed to the attitude control assembly. The lower part of the navigation stick passes through a hole in the navigation plate. The upper parts of the navigation stick, attitude control stick, and heave bar are all fixed to the side bridge. During aerodynamic characteristic tests of a surface-to-air vehicle in a pool test environment, the towing device drives the side bridge, heave bar, navigation stick, and attitude control stick to move simultaneously. Under the traction of the navigation plate, the surface-to-air vehicle model, along with a six-component force balance, a single-component force balance, and an angle sensor, move collaboratively along the heading. The six-component force balance, angle sensor, and single-component force balance record the center of gravity position and aerodynamic lift of the surface-to-air vehicle model during the motion. L mf ,resistance D mf The attitude angle of the water surface aircraft model in the pitch direction θ Tail-end aerodynamic lift L ma This forms a comprehensive aerodynamic characteristic data map of a physical water tank environment; the two-degree-of-freedom device consists of a mounting base, a transverse rotating shaft, a transverse rotating shaft sleeve, a vertical support rod, and a horizontal top plate. The mounting base is connected to the top of a six-component balance. The two ends of the transverse rotating shaft are respectively rotatably set inside the transverse rotating shaft sleeve, which is fixed on the mounting base. One end of the vertically set vertical support rod is fixedly connected to the middle position of the transverse rotating shaft, and the other end is fixedly connected to the horizontally set horizontal top plate. An angle sensor is connected to the horizontal top plate.

2. The aerodynamic characteristic testing device for a surface aircraft in a water tank test environment as described in claim 1, characterized in that, Before conducting aerodynamic characteristic tests on the surface vehicle in a pool test environment, the longitudinal attitude of the surface vehicle model is adjusted. The angle sensor provides real-time feedback on the current attitude parameters. When the value matches the target value, the attitude control component is locked. At this point, the pitch angle of the surface vehicle model is... θ Fix; adjust the relative position h between the side bridge and the water surface. At this point, the installation and pre-test preparation work for the water surface aircraft model is complete.

3. The aerodynamic characteristic testing device for a surface aircraft in a water tank test environment as described in claim 1, characterized in that, The vertical line of the center of gravity of the water surface aircraft model always passes through the center of the six-component balance, the two-degree-of-freedom device, and the angle sensor.

4. The aerodynamic characteristic testing device for a water-based aircraft under a pool test environment as described in claim 1, characterized in that, The center of gravity plate is set at the center of gravity of the watercraft model.

5. The aerodynamic characteristic testing device for a surface aircraft in a pool test environment as described in claim 1, characterized in that, The centerline of the navigation chip passes through the plane of symmetry of the surface aircraft model and is above the waterline position at the front.

6. The aerodynamic characteristic testing device for a surface aircraft in a pool test environment as described in claim 1, characterized in that, The bottom of the attitude control component is connected and fixed to the positioning plate reserved on the water surface aircraft model by a screw. The upper part of the attitude control component is hinged to one end of the hinge device, and the other end of the hinge device is hinged to the bottom surface of the horizontal plate.

7. An aerodynamic characteristic compensation and correction method using an aerodynamic characteristic testing device for a surface aircraft in a pool test environment as described in any one of claims 1 to 6, characterized in that, The method includes: Step 1: Obtain the deflection of the surface aircraft model under a series of fixed elevators through wind tunnel testing or aerodynamic numerical analysis. δ a Below, the total lift coefficient of the water surface aircraft model relative to its center of gravity. C L drag coefficient C D and torque coefficient C M Follow the posture θ A graph showing the changes; Step 2: Conduct aerodynamic characteristic tests in a physical water tank environment by adjusting the horizontal towing speed v and the pitch angle of the water surface aircraft model. θ and elevator deflection δ apy Obtain the aerodynamic lift at the center of gravity position under a series of corresponding states. L mf ,resistance D mf and tail aerodynamic lift L ma Experimental values; The experimental values ​​were converted to the relative center of gravity position using formula ~ formula, based on the relative position of the forces and the principles of flight: Aerodynamic lift coefficient at the center of gravity in a water tank environment: (1) Aerodynamic drag coefficient at the center of gravity in a pool environment: (2) Moment coefficient relative to the center of gravity in a pool environment: (3) In the above formula, θ c The initial state is simulated with zero pitch angle, and the angle between the line connecting the center of gravity of the initial state and the center of gravity of the tail sensor and the horizontal plane; S is the wing area of ​​the scaled-down model; ρ is the air density. The mean aerodynamic chord length of the model wing; L mf and D mf These are the aerodynamic lift and aerodynamic drag at the center of gravity position, as measured by a six-component balance. L ma The tail aerodynamic lift is measured by a single-component balance; g is the acceleration due to gravity. θ L represents the pitch angle of the model; c The distance between the center of gravity and the measurement center of the single-component force balance. Where △X is the longitudinal distance between the measurement center of the single-component balance and the center of gravity, and △Z is the longitudinal distance between the measurement center and the center of gravity. f The height difference between the center of the six-component balance and the center of gravity, ΔZ a The height difference between the measurement centers of a single-component force balance and a six-component force balance. Step 3: Using the aerodynamic characteristic coefficients obtained in Step 1 and Step 2 as the ordinate and the attitude angles in the pitch direction of the surface aircraft model as the coordinates. θ x-axis, elevator deflection angle δ a and δ apy For the variables of change, plot the lift coefficient and moment coefficient curves; compare the moment coefficients of the surface vehicle under wind tunnel and hydrodynamic test environments. C M、 C mhy Attitude angles in the pitch direction of the water surface aircraft model θ Find the elevator deflection corresponding to the two sets of curves when the moment coefficients coincide, based on the changing curves. δ a目标 , δ apy对标 And the corresponding lift coefficient under rudder deflection C L目标 and C Lhy对标 The lift ΔL required to compensate for the center of gravity position at each velocity point during the hydrodynamic test of the water-based aircraft model is calculated using the following formula: (4)。 8. The method according to claim 7, characterized in that, The calculated lift ΔL at the center of gravity is actually the difference in lift between the model and the actual aircraft at the center of gravity under the conditions of Froude similarity and Reynolds number similarity, respectively. After obtaining this value, additional lift compensation correction needs to be made to the center of gravity when conducting hydrodynamic towing tests in a pool environment. The test results obtained at this time can truly characterize the gliding motion performance of the water surface aircraft.

9. The aerodynamic characteristic compensation and correction method for a surface aircraft under a pool test environment according to claim 7, characterized in that, When searching for the test state where the moment coefficients coincide under two different environments, the moment coefficients corresponding to the wind tunnel data are used. C M Attitude angles in the pitch direction of the water surface aircraft model θ The variation curve is a reference value; the moment coefficient under hydrodynamic test conditions. C mhy Attitude angles in the pitch direction of the water surface aircraft model θ The change curve is used to compare parameters with the benchmark value. At this point, there are two possible scenarios: a) A curve exists that matches the benchmark value: Record the corresponding elevator deflection at this time. δ a目标 , δ apy对标 and their respective lift coefficients under rudder deflection C L目标 and C Lhy对标 Calculate the magnitude of lift compensation at the center of gravity position according to the formula; b) No curve matches the reference value: Since the elevator deflection has angular intervals within a certain range, there may be reference values ​​that do not perfectly match the reference value. In this case, it is necessary to compare different elevator deflection angles near the reference value. δ apy Below C mhy Follow the posture θ Interpolation is performed on the changing curve to determine the corresponding benchmark value. δ apy对标 Then, the same method was used to... δ apy对标 Two nearby groups C Lhy Attitude angles in the pitch direction of the water surface aircraft model θ Interpolating the change curve can yield the result. δ apy对标 Corresponding C Lhy对标 Then, the magnitude of the lift compensation at the center of gravity position is calculated according to the formula.

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