A wind tunnel test method for evaluating the aerodynamic compatibility of two aircraft

Abstract

The application discloses a wind tunnel test method for evaluating aerodynamic compatibility of two aircrafts, and belongs to the technical field of wind tunnel tests.The method comprises the following steps: step one, determining wind tunnel test simulation parameters; step two, testing a scaled model of a front aircraft; step three, testing a scaled model of a rear aircraft; step four, measuring aerodynamic forces of the scaled model of the front aircraft and the scaled model of the rear aircraft in different position combinations; step five, measuring aerodynamic force characteristics of the scaled model of the rear aircraft alone; and step six, evaluating aerodynamic compatibility of the two aircrafts.The application aims to solve the problems of high cost, high risk and difficulty in full working condition coverage of flight tests for evaluating aerodynamic compatibility of the two aircrafts, difficulty in effectively verifying the precision of numerical simulation, lack of standardized methods for traditional wind tunnel tests, and difficulty in accurately stripping support interference and measuring pure aerodynamic interference of the front aircraft on the rear aircraft, so as to meet actual engineering requirements of safety design and simulation verification of the two aircrafts in cooperative flight.

Description

Technical Field

[0001] This invention relates to a wind tunnel test method for evaluating the aerodynamic compatibility of two engines, belonging to the field of wind tunnel testing technology. Background Technology

[0002] Aerial refueling, formation flying, and drone swarms are core technologies for improving operational efficiency and expanding application boundaries in modern aviation. During close-range collaborative operations, the flow fields of the lead and follower aircraft will overlap and couple, resulting in significant aerodynamic interference effects. The closer the relative distance between the two aircraft, the greater the aerodynamic disturbance, which will directly change the aerodynamic and torque characteristics of the follower aircraft, significantly reducing its flight stability and handling quality, and in severe cases, even causing flight safety accidents.

[0003] Accurately quantifying the aerodynamic interference of two aircraft under different relative positions and attitude combinations, and conducting scientific and effective aerodynamic compatibility assessments, is a core technical prerequisite for defining flight safety envelopes, optimizing flight control strategies, and ensuring the safety of coordinated flight between two aircraft. Currently, aerodynamic compatibility assessments for two aircraft mainly rely on two technical approaches: flight testing and numerical simulation. Flight testing is not only costly and extremely risky, but it also cannot comprehensively cover various test conditions in the early stages of aircraft design, making it difficult to systematically obtain aerodynamic interference data under all positions and attitudes of the two aircraft. Furthermore, the testing cycle is long and its engineering applications are limited. Numerical simulation, on the other hand, is limited by the accuracy of turbulence and wake vortex models, making simulation results difficult to verify with actual data and exhibiting significant uncertainties. Therefore, it cannot be directly used as a reliable basis for flight safety design and control strategy formulation.

[0004] As an authoritative technical means to quantify the aerodynamic characteristics of aircraft and verify simulation results, wind tunnel testing has not yet formed a standardized evaluation method for static aerodynamic interference between two aircraft. There are problems such as inconsistent model scaling rules, insufficient accuracy in simulating the relative position and attitude of the two aircraft, inability to effectively separate interference from the support system, and an imperfect aerodynamic measurement and compatibility evaluation system. It is difficult to accurately isolate the pure aerodynamic interference of the lead aircraft to the follower aircraft, and it cannot meet the actual needs of engineering evaluation of aerodynamic compatibility between two aircraft in scenarios such as aerial refueling, formation flight, and UAV swarms.

[0005] Therefore, there is an urgent need to propose a wind tunnel test method for evaluating the aerodynamic compatibility of two engines in order to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to address the problems of high cost, high risk, and difficulty in covering all operating conditions in existing dual-aircraft aerodynamic compatibility assessments, which rely on flight testing. Numerical simulation accuracy cannot be effectively verified, and traditional wind tunnel testing lacks standardized methods, making it impossible to accurately isolate support interference and measure the pure aerodynamic interference of the preceding aircraft on the following aircraft. This invention provides a wind tunnel testing method for dual-aircraft aerodynamic compatibility assessment that is standardized in simulation, accurate in measurement, and efficient in data processing, meeting the practical engineering needs of dual-aircraft cooperative flight safety design and simulation verification. A brief overview of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0007] The technical solution of this invention:

[0008] A wind tunnel testing method for evaluating the aerodynamic compatibility of two engines includes the following steps:

[0009] Step 1: Determine the simulation parameters for the wind tunnel test;

[0010] Since the two aircraft cannot be directly placed in the wind tunnel for testing, they need to be scaled down, resulting in scaled-down models for the front aircraft test and the rear aircraft test:

[0011] First, determine the experimental geometric scaling factor K as:

[0012] K=b s1 / 0.7B(1)

[0013] In the formula b s1 B represents the wingspan of the actual aircraft, and B represents the width of the wind tunnel.

[0014] Calculate the wingspan b of the scaled-down model of the previous test aircraft. m1 The wingspan b of the scaled-down model of the rear test aircraft m2 :

[0015] b m1 =b s1 / K(2)

[0016] b m2 =b s2 / K(3)

[0017] The experimentally simulated Reynolds number Re is:

[0018] Re=ρvl / μ(4)

[0019] In the formula, ρ is the air density, v is the flow velocity, l is the reference length, and μ is the dynamic viscosity coefficient;

[0020] The speed of the pressure Q is

[0021] Q=ρv 2 / 2(5)

[0022] The simulated relative position parameters of the scaled-down models of the front and rear test machines are equal to the actual relative position parameters of the two machines divided by the scaling factor.

[0023] [L xm L ym L zm ]=[L xs L ys L zs ] / K (6)

[0024] In the formula, L xm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the x-direction. ym L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the y-direction. zm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the z-direction. xs L represents the relative position of the two physical objects in the x-direction. ys L represents the relative position of the two physical objects in the y-direction. zs The relative positions of the two physical objects in the z-direction;

[0025] Step 2: Attitude simulation of the scaled-down model during the initial test;

[0026] The main support system is installed at the center of the small turntable on the upper wall of the wind tunnel. The scaled-down model of the front test is installed on the main support system in the form of a back support. The change of the slip angle on the side of the scaled-down model of the front test is achieved by rotating the small turntable on the upper wall of the wind tunnel, and the change of the angle of attack of the scaled-down model of the front test is achieved by the main support system.

[0027] Step 3: Simulation of the position and attitude of the scaled-down model for the rear test;

[0028] A secondary support system is installed at a certain distance behind the scaled-down model of the front test aircraft on the wind tunnel wall. A measuring balance is arranged inside the fuselage of the scaled-down model of the rear test aircraft. The front end of the measuring balance is connected to the fuselage of the scaled-down model of the rear test aircraft, and the rear end of the measuring balance is connected to the secondary support system. The measuring balance is connected to the VXI acquisition system via a data cable. The angle of attack change of the scaled-down model of the rear test aircraft is realized through the angle of attack mechanism on the secondary support system. The sideslip angle simulation of the scaled-down model of the rear test aircraft is realized through the turntable mechanism on the secondary support system. The height position simulation of the scaled-down model of the rear test aircraft is realized through the lifting mechanism on the secondary support system. The lateral position simulation of the scaled-down model of the rear test aircraft is realized through the left and right traveling mechanism. The distance position simulation of the two aircraft of the scaled-down model of the rear test aircraft is realized through the front and rear traveling mechanism.

[0029] Step 4: Measure the aerodynamic forces under different position combinations of the scaled-down models of the front and rear test engines;

[0030] First, control the main support system to adjust the scaled-down model of the front test, and control the auxiliary support system to adjust the scaled-down model of the rear test, so that the scaled-down models of the front and rear tests are in the model position of the test reference. Adjust the angle of attack and sideslip angle of the scaled-down models of the front and rear tests to 0°, trigger the VXI acquisition system to acquire the data output by the balance at this time, the acquisition time is 1 second, the acquisition frequency is 1000Hz, and the zero point data is recorded as data0.

[0031] Then, the wind tunnel motor was started. After the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting data from the balance at this time. The acquisition time was 5 seconds, and the acquisition frequency was 1000 Hz. The obtained data is data1. The aerodynamic forces of the scaled-down model of the front test and the main support system under the combined interference of the scaled-down model of the front test and the main support system were calculated. :

[0032] F1=mean(data1)-mean(data0)(7)

[0033] Then, the scaled-down model of the front test unit was removed, and the above measurement operations were repeated. The wind tunnel motor was started, and after the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting the balance data at this time. The balance data data at the target wind speed, data2, was obtained, and the aerodynamic forces of the scaled-down model of the rear test unit under the interference of the main support system were calculated. :

[0034] F2=mean(data2)-mean(data0)(8)

[0035] Further calculations can yield the aerodynamic changes of the scaled-down model of the rear aircraft test under the disturbance of the scaled-down model of the front aircraft test alone. :

[0036] ΔF = F1 - F2 (9)

[0037] Dimensionless transformation yields the corresponding changes in aerodynamic coefficients:

[0038] (10)

[0039] In the formula, S is the reference area;

[0040] Step 5: Measure the aerodynamic characteristics of the scaled-down model of the rear engine test unit.

[0041] Remove the main support system, leaving only the scaled-down rear engine test model and the auxiliary support system. Using the same data acquisition operation as in step four, obtain the aerodynamic force F of the scaled-down rear engine test model. 0；

[0042] Dimensionless transformation yields the aerodynamic coefficients:

[0043] (11)

[0044] Step Six: Dual-machine aerodynamic compatibility assessment;

[0045] In step four above, the change in aerodynamic coefficient C1 of the scaled-down model of the rear engine test under the disturbance of the scaled-down model of the front engine test alone was obtained. In step five, the aerodynamic coefficient C2 of the scaled-down model of the rear engine test alone was obtained. Furthermore, the relative value R of the disturbance of the scaled-down model of the front engine test on the aerodynamic coefficient of the scaled-down model of the rear engine test can be obtained:

[0046] R = C1 / C2 (12)

[0047] The aerodynamic compatibility of the two engines can be evaluated using R, as follows:

[0048]

[0049] Where R CL Let R be the relative value of the lift coefficient disturbance, i.e., the component of R in the lift direction, and std1 be the lift safety margin threshold. Cl R represents the relative value of the rolling torque disturbance, i.e., the component of R in the rolling torque. Cm is the relative value of the pitch moment disturbance, i.e., the component of R in the pitch moment, and std2 is the torque safety margin tolerance.

[0050] Preferably, the main support system includes a motor, a connecting seat, a main support rod, a lead screw, a lead screw nut, a sliding sleeve, a sliding rod, a support head, a connecting rod, and a model support plate. The connecting seat is installed at the center of a small turntable on the upper wall of the wind tunnel. A motor is installed on the top of the connecting seat, and the main support rod is installed at the bottom of the connecting seat. The main support rod has a cavity inside, and a lead screw is rotatably installed on the central axis of the cavity. A lead screw is threaded with a lead screw nut. The output end of the motor drives the lead screw to rotate. The sliding rod is slidably installed on the main support rod through a sliding sleeve. The axis of the sliding rod is parallel to the axis of the main support rod. One end of the sliding rod extends into the cavity and connects to the lead screw nut. The other end of the sliding rod extends out of the main support rod and is hinged to the connecting rod. The connecting rod is hinged to the model support plate, and the model support plate is hinged to the support head installed at the bottom of the main support rod.

[0051] Preferably, one side wall of the main support rod is provided with a sliding groove communicating with the internal cavity along the axial direction, and the side wall of the connecting rod slides in cooperation with the sliding groove through a slider.

[0052] Preferably, the auxiliary support system includes an angle-of-attack mechanism, a turntable mechanism, a lifting mechanism, a left-right traveling mechanism, and a front-back traveling mechanism. The left-right traveling mechanism is mounted on the turntable mechanism, the front-back traveling mechanism is mounted on the left-right traveling mechanism, the lifting mechanism is mounted on the front-back traveling mechanism, the angle-of-attack mechanism is mounted on the lifting mechanism, and a scaled-down model of the rear test is mounted on the angle-of-attack mechanism.

[0053] Preferably, the lifting mechanism includes a fixed frame, a lifting frame, a telescopic motor, and a guide column. The fixed frame is installed on the front and rear traveling mechanism, the lifting frame is slidably installed on the fixed frame through the guide column, the bottom of the telescopic motor is fixedly connected to the fixed frame, and the top of the telescopic motor is fixedly connected to the lifting frame.

[0054] Preferably, the angle-of-attack mechanism includes a tail support rod, a connecting seat, and a lifting motor. One end of the bottom of the tail support rod is hinged to the lifting frame via the connecting seat, and the other end of the bottom of the tail support rod is hinged to the lifting motor. The lifting motor is fixedly installed on the lifting frame.

[0055] The present invention has the following beneficial effects:

[0056] 1. This invention can effectively separate interference from the support system, accurately measure the pure aerodynamic interference of the front machine to the rear machine, and the test data is true and reliable with high measurement accuracy;

[0057] 2. The model scaling rules of this invention are unified, the simulation of the relative position and attitude of the two machines is accurate, the test parameter setting is standardized, and it can fully cover multi-position and multi-attitude combination working conditions;

[0058] 3. The data acquisition and processing flow of this invention is simple and efficient, and can quickly complete multi-condition tests, greatly improving the test efficiency of dual-machine aerodynamic compatibility assessment;

[0059] 4. This invention is highly practical and adaptable to various dual-aircraft collaborative scenarios such as aerial refueling, formation flying, and drone swarms, demonstrating good versatility;

[0060] 5. This invention can provide core experimental support for defining flight safety envelopes and optimizing flight control strategies, while effectively verifying CFD simulation results and supporting aircraft design and simulation iteration. Attached Figure Description

[0061] Figure 1 This is a flowchart of a wind tunnel test method for evaluating the aerodynamic compatibility of two engines;

[0062] Figure 2 This is a structural diagram of the main support system;

[0063] Figure 3 This is a structural diagram of the secondary support system.

[0064] In the diagram: 10-Model support plate, 11-Motor, 12-Connecting seat, 13-Main support rod, 131-Slide groove, 14-Lead screw, 15-Lead nut, 16-Sliding sleeve, 17-Sliding rod, 18-Support head, 19-Connecting rod, 191-Slider, 21-Angle of attack mechanism, 211-Tail support rod, 212-Connecting seat, 213-Lifting motor, 22-Turntable mechanism, 23-Lifting mechanism, 231-Fixed frame, 232-Lifting frame, 233-Telescopic motor, 234-Guide column, 24-Left and right walking mechanism, 25-Front and rear walking mechanism. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0066] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as threaded connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can always be found to achieve the function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a hinged connection can be chosen for detachable connections.

[0067] Combination Figures 1-3 This embodiment describes a wind tunnel testing method for evaluating the aerodynamic compatibility of two engines, comprising the following steps:

[0068] Step 1: Determine the simulation parameters for the wind tunnel test;

[0069] Since the two aircraft cannot be directly placed in the wind tunnel for testing, they need to be scaled down, resulting in scaled-down models for the front aircraft test and the rear aircraft test:

[0070] First, determine the experimental geometric scaling factor K as:

[0071] K=b s1 / 0.7B(1)

[0072] In the formula b s1 B represents the wingspan of the actual aircraft, and B represents the width of the wind tunnel.

[0073] Calculate the wingspan b of the scaled-down model of the previous test aircraft. m1 The wingspan b of the scaled-down model of the rear test aircraft m2 :

[0074] b m1 =b s1 / K(2)

[0075] b m2 =b s2 / K(3)

[0076] The experimentally simulated Reynolds number Re is:

[0077] Re=ρvl / μ(4)

[0078] In the formula, ρ is the air density, v is the flow velocity, l is the reference length, and μ is the dynamic viscosity coefficient;

[0079] The speed of pressure Q is:

[0080] Q=ρv 2 / 2(5)

[0081] The simulated relative position parameters of the scaled-down models of the front and rear test machines are equal to the actual relative position parameters of the two machines divided by the scaling factor.

[0082] [L xm L ym L zm ]=[L xs L ys L zs ] / K (6)

[0083] In the formula, L xm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the x-direction. ym L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the y-direction. zm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the z-direction. xs L represents the relative position of the two physical objects in the x-direction. ys L represents the relative position of the two physical objects in the y-direction. zs The relative positions of the two physical objects in the z-direction;

[0084] Step 2: Attitude simulation of the scaled-down model during the initial test;

[0085] The main support system is installed at the center of the small turntable on the upper wall of the wind tunnel. The scaled-down model of the front test is installed on the main support system in the form of a back support. The change of the slip angle on the side of the scaled-down model of the front test is achieved by rotating the small turntable on the upper wall of the wind tunnel, and the change of the angle of attack of the scaled-down model of the front test is achieved by the main support system.

[0086] Step 3: Simulation of the position and attitude of the scaled-down model for the rear test;

[0087] A secondary support system is installed at a certain distance behind the scaled-down model of the front test aircraft on the lower wall of the wind tunnel. A measuring balance is arranged inside the fuselage of the scaled-down model of the rear test aircraft. The front end of the measuring balance is connected to the fuselage of the scaled-down model of the rear test aircraft, and the rear end of the measuring balance is connected to the secondary support system. The measuring balance is connected to the VXI acquisition system via a data cable. The angle of attack change of the scaled-down model of the rear test aircraft is realized by the angle of attack mechanism 21 on the secondary support system. The sideslip angle simulation of the scaled-down model of the rear test aircraft is realized by the turntable mechanism 22 on the secondary support system. The height position simulation of the scaled-down model of the rear test aircraft is realized by the lifting mechanism 23 on the secondary support system. The lateral position simulation of the scaled-down model of the rear test aircraft is realized by the left and right traveling mechanism 24. The distance position simulation of the two aircraft of the scaled-down model of the rear test aircraft is realized by the front and rear traveling mechanism 25.

[0088] Step 4: Measure the aerodynamic forces under different position combinations of the scaled-down models of the front and rear test engines;

[0089] First, control the main support system to adjust the scaled-down model of the front test, and control the auxiliary support system to adjust the scaled-down model of the rear test, so that the scaled-down models of the front and rear tests are in the model position of the test reference. Adjust the angle of attack and sideslip angle of the scaled-down models of the front and rear tests to 0°, trigger the VXI acquisition system to acquire the data output by the balance at this time, the acquisition time is 1 second, the acquisition frequency is 1000Hz, and the zero point data is recorded as data0.

[0090] Then, the wind tunnel motor was started. After the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting data from the balance at this time. The acquisition time was 5 seconds, and the acquisition frequency was 1000 Hz. The obtained data is data1. The aerodynamic forces of the scaled-down model of the front test and the main support system under the combined interference of the scaled-down model of the front test and the main support system were calculated. :

[0091] F1=mean(data1)-mean(data0)(7)

[0092] Then, the scaled-down model of the front test unit was removed, and the above measurement operations were repeated. The wind tunnel motor was started, and after the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting the balance data at this time. The balance data data at the target wind speed, data2, was obtained, and the aerodynamic forces of the scaled-down model of the rear test unit under the interference of the main support system were calculated. :

[0093] F2=mean(data2)-mean(data0)(8)

[0094] Further calculations can yield the aerodynamic changes of the scaled-down model of the rear aircraft test under the disturbance of the scaled-down model of the front aircraft test alone. :

[0095] ΔF = F1 - F2 (9)

[0096] Dimensionless transformation yields the corresponding changes in aerodynamic coefficients:

[0097] (10)

[0098] In the formula, S is the reference area;

[0099] Step 5: Measure the aerodynamic characteristics of the scaled-down model of the rear engine test unit.

[0100] Remove the main support system, leaving only the scaled-down rear engine test model and the auxiliary support system. Using the same data acquisition operation as in step four, obtain the aerodynamic force F of the scaled-down rear engine test model. 0；

[0101] Dimensionless transformation yields the aerodynamic coefficients:

[0102] (11)

[0103] Step Six: Dual-machine aerodynamic compatibility assessment;

[0104] In step four above, the change in aerodynamic coefficient C1 of the scaled-down model of the rear engine test under the disturbance of the scaled-down model of the front engine test alone was obtained. In step five, the aerodynamic coefficient C2 of the scaled-down model of the rear engine test alone was obtained. Furthermore, the relative value R of the disturbance of the scaled-down model of the front engine test on the aerodynamic coefficient of the scaled-down model of the rear engine test can be obtained:

[0105] R = C1 / C2 (12)

[0106] The aerodynamic compatibility of the two engines can be evaluated using R, as follows:

[0107]

[0108] Where R CL Let R be the relative value of the lift coefficient disturbance, i.e., the component of R in the lift direction, and std1 be the lift safety margin threshold. Cl R represents the relative value of the rolling torque disturbance, i.e., the component of R in the rolling torque. Cm is the relative value of the pitch moment disturbance, i.e., the component of R in the pitch moment, and std2 is the torque safety margin tolerance.

[0109] The main support system includes a motor 11, a connecting seat 12, a main support rod 13, a lead screw 14, a lead screw nut 15, a sliding sleeve 16, a sliding rod 17, a support head 18, a connecting rod 19, and a model support plate 10. The connecting seat 12 is installed at the center of a small turntable on the upper wall of the wind tunnel. The motor 11 is installed on the top of the connecting seat 12, and the main support rod 13 is installed on the bottom of the connecting seat 12. The main support rod 13 has a cavity inside, and the lead screw 14 is rotatably installed on the central axis of the cavity. The upper thread is fitted with a threaded nut 15. The output end of the motor 11 drives the lead screw 14 to rotate. The slide rod 17 is slidably installed on the main support rod 13 through the sliding sleeve 16. The axis of the slide rod 17 is parallel to the axis of the main support rod 13. One end of the slide rod 17 extends into the cavity and connects with the threaded nut 15. The other end of the slide rod 17 extends out of the main support rod 13 and is hinged to the connecting rod 19. The connecting rod 19 is hinged to the model tray 10. The model tray 10 is hinged to the support head 18 installed at the bottom of the main support rod 13.

[0110] The main support rod 13 has a groove 131 that communicates with the internal cavity along one side wall along the axial direction, and the side wall of the connecting rod 19 slides in cooperation with the groove 131 through the slider 191.

[0111] The auxiliary support system includes an angle-of-attack mechanism 21, a turntable mechanism 22, a lifting mechanism 23, a left and right traveling mechanism 24, and a front and rear traveling mechanism 25. The left and right traveling mechanism 24 is installed on the turntable mechanism 22, the front and rear traveling mechanism 25 is installed on the left and right traveling mechanism 24, the lifting mechanism 23 is installed on the front and rear traveling mechanism 25, the angle-of-attack mechanism 21 is installed on the lifting mechanism 23, and a scaled-down model of the rear test is installed on the angle-of-attack mechanism 21.

[0112] The left and right walking mechanism 24 and the front and rear walking mechanism 25 are both linear modules driven by a motor and are linear positioning slides. The movement direction of the left and right walking mechanism 24 is perpendicular to the movement direction of the front and rear walking mechanism 25. The turntable mechanism 22 is an electric turntable.

[0113] The lifting mechanism 23 includes a fixed frame 231, a lifting frame 232, a telescopic motor 233, and a guide column 234. The fixed frame 231 is mounted on the front and rear traveling mechanism 25. The lifting frame 232 is slidably mounted on the fixed frame 231 through the guide column 234. The bottom of the telescopic motor 233 is fixedly connected to the fixed frame 231, and the top of the telescopic motor 233 is fixedly connected to the lifting frame 232.

[0114] The angle-of-attack mechanism 21 includes a tail support rod 211, a connecting seat 212, and a lifting motor 213. One end of the bottom of the tail support rod 211 is hinged to the lifting frame 232 through the connecting seat 212, and the other end of the bottom of the tail support rod 211 is hinged to the lifting motor 213. The lifting motor 213 is fixedly installed on the lifting frame 232.

[0115] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0116] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wind tunnel test method for evaluating the aerodynamic compatibility of two engines, characterized in that... This includes the following steps: Step 1: Determine the simulation parameters for the wind tunnel test; Since the two physical prototypes cannot be directly placed into the wind tunnel for testing, they need to be scaled down, and scaled down into a scaled-down model for the front prototype test and a scaled-down model for the rear prototype test. Step 2: Attitude simulation of the scaled-down model during the initial test; The main support system is installed at the center of the small turntable on the upper wall of the wind tunnel. The scaled-down model of the front test is installed on the main support system in the form of a back support. The sideslip angle of the scaled-down model of the front test is changed by rotating the small turntable on the upper wall of the wind tunnel, and the angle of attack of the scaled-down model of the front test is changed by the main support system. Step 3: Simulation of the position and attitude of the scaled-down model for the rear test; A secondary support system is installed at a certain distance behind the front test scale model on the lower wall of the wind tunnel. A measuring balance is arranged inside the fuselage of the rear test scale model. The front end of the measuring balance is connected to the fuselage of the rear test scale model, and the rear end of the measuring balance is connected to the secondary support system. The measuring balance is connected to the VXI acquisition system through a data cable. The angle of attack of the rear test scale model is changed through the angle of attack mechanism (21) on the secondary support system. The sideslip angle of the rear test scale model is simulated through the turntable mechanism (22) on the secondary support system. The height position of the rear test scale model is simulated through the lifting mechanism (23) on the secondary support system. The lateral position of the rear test scale model is simulated through the left and right walking mechanism (24). The distance position between the two machines of the rear test scale model is simulated through the front and rear walking mechanism (25). Step 4: Measure the aerodynamic forces under different position combinations of the scaled-down models of the front and rear test engines; First, control the main support system to adjust the scaled-down model of the front test, and control the auxiliary support system to adjust the scaled-down model of the rear test, so that the scaled-down models of the front and rear tests are in the model position of the test reference. Adjust the angle of attack and sideslip angle of the scaled-down models of the front and rear tests to 0°, trigger the VXI acquisition system to acquire the data output by the balance at this time, the acquisition time is 1 second, the acquisition frequency is 1000Hz, and the zero point data is recorded as data0. Then, the wind tunnel motor was started. After the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting data from the balance at this time. The acquisition time was 5 seconds, and the acquisition frequency was 1000 Hz. The obtained data is data1. The aerodynamic forces of the scaled-down model of the front test and the main support system under the combined interference of the scaled-down model of the front test and the main support system were calculated. : F1 = mean(data1) - mean(data0)(7); Then, the scaled-down model of the front test unit was removed, and the above measurement operations were repeated. The wind tunnel motor was started, and after the wind speed in the wind tunnel test section reached the target wind speed and stabilized for 5 seconds, the VXI acquisition system was triggered to start collecting the balance data at this time. The balance data data at the target wind speed, data2, was obtained, and the aerodynamic forces of the scaled-down model of the rear test unit under the interference of the main support system were calculated. : F2 = mean(data2) - mean(data0)(8); Further calculations can yield the aerodynamic changes of the scaled-down model of the rear aircraft test under the disturbance of the scaled-down model of the front aircraft test alone. : ΔF = F1 - F2 (9); Dimensionless transformation yields the corresponding aerodynamic coefficient change C1: （10）； In the formula, S is the reference area and Q is the rapid pressure; Step 5: Measure the aerodynamic characteristics of the scaled-down model of the rear engine test unit. Remove the main support system, leaving only the scaled-down model of the rear engine test and the auxiliary support system. Use the same data acquisition operation as in step four to obtain the aerodynamic force F0 of the scaled-down model of the rear engine test. Dimensionless transformation yields the aerodynamic coefficient C2: （11）； Step Six: Dual-machine aerodynamic compatibility assessment; In step four above, the change in aerodynamic coefficient C1 of the scaled-down model of the rear engine test under the disturbance of the scaled-down model of the front engine test alone was obtained. In step five, the aerodynamic coefficient C2 of the scaled-down model of the rear engine test alone was obtained. Furthermore, the relative value R of the disturbance of the scaled-down model of the front engine test on the aerodynamic coefficient of the scaled-down model of the rear engine test can be obtained: R = C1 / C2 (12); The aerodynamic compatibility of the two engines can be evaluated using R, as follows: ； Where R CL Let R be the relative value of the lift coefficient disturbance, i.e., the component of R in the lift direction, and std1 be the lift safety margin threshold. Cl R represents the relative value of the rolling torque disturbance, i.e., the component of R in the rolling torque. Cm is the relative value of the pitch moment disturbance, i.e., the component of R in the pitch moment, and std 2 is the torque safety margin tolerance.

2. The wind tunnel test method for evaluating the aerodynamic compatibility of two engines according to claim 1, characterized in that: Step one includes: First, determine the experimental geometric scaling factor K as: K = b s1 / 0.7B(1); In the formula b s1 B represents the wingspan of the actual aircraft, and B represents the width of the wind tunnel. Calculate the wingspan b of the scaled-down model of the previous test aircraft. m1 The wingspan b of the scaled-down model of the rear test aircraft m2 : b m1 = b s1 / K(2); b m2 = b s2 / K(3); The experimentally simulated Reynolds number Re is: Re = ρvl / μ(4; In the formula, ρ is the air density, v is the flow velocity, l is the reference length, and μ is the dynamic viscosity coefficient; The speed of pressure Q is: Q = ρv 2 / 2(5); The simulated relative position parameters of the scaled-down models of the front and rear test machines are equal to the actual relative position parameters of the two machines divided by the scaling factor. [L xm ,L ym ,L zm ] = [L xs ,L ys ,L zs ] / K(6); In the formula, L xm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the x-direction. ym L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the y-direction. zm L represents the relative position of the scaled-down model of the front-end test and the scaled-down model of the rear-end test in the z-direction. xs L represents the relative position of the two physical objects in the x-direction. ys L represents the relative position of the two physical objects in the y-direction. zs The relative positions of the two physical objects in the z-direction.

3. The wind tunnel test method for evaluating the aerodynamic compatibility of two engines according to claim 1, characterized in that: The main support system includes a motor (11), a connecting seat (12), a main support rod (13), a lead screw (14), a lead screw nut (15), a sliding sleeve (16), a sliding rod (17), a support head (18), a connecting rod (19), and a model support plate (10). The connecting seat (12) is installed at the center of the small turntable on the upper wall of the wind tunnel. The motor (11) is installed on the top of the connecting seat (12), and the main support rod (13) is installed at the bottom of the connecting seat (12). The main support rod (13) has a cavity inside, and the lead screw (14) is rotatably installed on the central axis of the cavity. The upper thread is fitted with a threaded nut (15). The output end of the motor (11) drives the lead screw (14) to rotate. The slide rod (17) is slidably installed on the main support rod (13) through the sliding sleeve (16). The axis of the slide rod (17) is parallel to the axis of the main support rod (13). One end of the slide rod (17) is inserted into the cavity and connected to the threaded nut (15). The other end of the slide rod (17) is inserted out of the main support rod (13) and hinged to the connecting rod (19). The connecting rod (19) is hinged to the model tray (10). The model tray (10) is hinged to the support head (18) installed at the bottom of the main support rod (13).

4. The wind tunnel test method for evaluating the aerodynamic compatibility of two engines according to claim 3, characterized in that: The main support rod (13) has a groove (131) that communicates with the internal cavity on one side wall along the axial direction. The side wall of the connecting rod (19) slides in cooperation with the groove (131) through the slider (191).

5. The wind tunnel test method for evaluating the aerodynamic compatibility of a dual-engine system according to claim 4, characterized in that: The auxiliary support system includes an angle-of-attack mechanism (21), a turntable mechanism (22), a lifting mechanism (23), a left and right traveling mechanism (24), and a front and rear traveling mechanism (25). The left and right traveling mechanism (24) is installed on the turntable mechanism (22), the front and rear traveling mechanism (25) is installed on the left and right traveling mechanism (24), the lifting mechanism (23) is installed on the front and rear traveling mechanism (25), the angle-of-attack mechanism (21) is installed on the lifting mechanism (23), and the rear test scale model is installed on the angle-of-attack mechanism (21).

6. The wind tunnel test method for evaluating the aerodynamic compatibility of a dual-engine system according to claim 5, characterized in that: The lifting mechanism (23) includes a fixed frame (231), a lifting frame (232), a telescopic motor (233), and a guide column (234). The fixed frame (231) is installed on the front and rear walking mechanism (25). The lifting frame (232) is slidably installed on the fixed frame (231) through the guide column (234). The bottom of the telescopic motor (233) is fixedly connected to the fixed frame (231), and the top of the telescopic motor (233) is fixedly connected to the lifting frame (232).

7. The wind tunnel test method for evaluating the aerodynamic compatibility of a dual-engine system according to claim 6, characterized in that: The angle-of-attack mechanism (21) includes a tail support rod (211), a connecting seat (212), and a lifting motor (213). One end of the bottom of the tail support rod (211) is hinged to the lifting frame (232) through the connecting seat (212), and the other end of the bottom of the tail support rod (211) is hinged to the lifting motor (213). The lifting motor (213) is fixedly installed on the lifting frame (232).

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