Full-size external store separation trajectory aerodynamic force correction method

Abstract

The present application belongs to the technical field of wind tunnel test, and discloses a full-size external object separation trajectory aerodynamic force correction method. The correction method comprises the following steps: setting full-size external object separation initial conditions; establishing a free flow aerodynamic force coefficient difference database of different scaled external object models; performing small model separation trajectory test and obtaining small model aerodynamic parameters; performing large model aerodynamic parameter correction; performing external object separation trajectory calculation and termination condition judgment, taking the corrected large model aerodynamic force coefficient as the input parameter of the full-size external object, obtaining the position and attitude of the full-size external object at the next moment; if the position and attitude of the full-size external object at the next moment do not trigger the pre-set end condition, the small model separation trajectory test is continuously performed; otherwise, the small model separation trajectory is output, and the small model separation trajectory test is completed. The correction method can correct the influence of the aerodynamic characteristic difference of the geometric size of the external object model on the external object separation trajectory, and has engineering practical value.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, specifically relating to a method for aerodynamic correction of the separation trajectory of a full-size external attachment. Background Technology

[0002] The safe release and separation of airborne external stores is a crucial prerequisite for aircraft to perform aerospace missions. When external stores are released from the carrier platform, the aircraft and its other external stores significantly disrupt the surrounding airflow, creating a complex flow field environment that severely affects the external store's trajectory and could potentially lead to a collision with the aircraft, causing a serious flight accident. To ensure the safety of external store release, the separation process needs to be predicted and assessed. Trajectory capture wind tunnel testing, a key technique for assessing the safety of external store separation, acquires real-time aerodynamic forces and moments acting on an external store model at specific positions and attitudes. Using six-degree-of-freedom motion equations, the motion state of the external store at the next moment is calculated. The six-degree-of-freedom motion mechanism then drives the model to a new position based on the calculation results, continuing the next round of measurement and calculation. Through this cyclical process of "measurement-calculation-movement," the complete trajectory of the external store from separation to stable flight can be simulated. In actual tests, to simulate the spatial relationship between the aircraft and its external stores, small-scale aircraft and external store models are typically fabricated based on the uniform flow field in the wind tunnel, according to aerodynamic similarity theory. However, these small-scale scaled-down models of external stores (generally called small models) cannot fully simulate the geometric characteristics of real full-size or large-scale models (generally called large models), resulting in significant differences in their aerodynamic characteristics compared to actual aircraft.

[0003] Therefore, there is an urgent need to develop a full-size external attachment separation trajectory aerodynamic correction method to ensure the accuracy of wind tunnel test data and the practical application value of test results. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for aerodynamic correction of the separation trajectory of full-size external attachments, so as to solve the problem of shape simulation distortion in large-scale external attachment models and its impact on the separation trajectory of external attachments.

[0005] The aerodynamic correction method for the separation trajectory of full-size external attachments of the present invention includes the following steps: S10. Set initial conditions for the separation of full-size external attachments; The initial conditions for the separation of full-size external stores include the aircraft's state at the moment of separation, the position, attitude angle, velocity, angular velocity, and mass characteristics of the full-size external stores relative to the aircraft; the aircraft state parameters include the flight Mach number Ma, altitude H, and overload Nz, which are obtained in advance from flight experiments; the state parameters of the full-size external stores include the position, attitude angle, and mass characteristics of the full-size external stores relative to the aircraft, which are obtained in advance from ground experiments. S20. Establish a database of free-flow aerodynamic coefficient differences for external attachment models of different scales; Different scaled-down external stores models are defined as large models and small models, respectively. Using large models and small models as test objects, free-flow aerodynamic wind tunnel tests are conducted based on aircraft state parameters and full-size external stores state parameters to obtain free-flow aerodynamic data of large models and small models without aircraft model interference, and to construct a database of free-flow aerodynamic coefficient differences between large models and small models. S30. Conduct small-scale model separation trajectory tests and obtain small-scale model aerodynamic parameters; A small-scale model separation trajectory test was conducted in a wind tunnel. The small model's position (X, Y, Z) and attitude angle (α) were measured using a balance. F,小模型 ,β F,小模型 Aerodynamic forces and aerodynamic torques under α F,小模型 For the pitch angle of the small model, β F,小模型 The yaw angle of the small model is given, and the aerodynamic coefficient C of the small model is calculated. 小模型 and small model aerodynamic moment coefficient; small model aerodynamic coefficient C 小模型 The current position (X, Y, Z) and attitude angle (α) of the small model. F,小模型 ,β F,小模型 The aerodynamic forces under the given conditions are divided by the inflow velocity, pressure, and reference area; the aerodynamic moment coefficients of the small model are the current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic torque under the given conditions is divided by the inflow velocity pressure, reference area, and reference length. S40. Perform aerodynamic parameter correction for the large model; Using the free-flow aerodynamic coefficient difference database of the large and small models of S20, the aerodynamic coefficient C of the small model in S30 is analyzed. 小模型 Make corrections and obtain the corrected large model aerodynamic coefficients C. 修正 ; S50. Perform external attachment separation trajectory calculation and termination condition determination; The corrected aerodynamic coefficient C of the large model 修正As input parameters for the full-size external attachment, the resultant force and resultant moment of the full-size external attachment are calculated by combining the external forces acting on it at the current position and attitude angle, including gravity, ejection force, and thrust. Then, the six-degree-of-freedom rigid body motion equation (6DOF) is solved to obtain the position and attitude of the full-size external attachment at the next moment. If the position and attitude of the full-size external attachment at the next moment do not trigger the pre-set termination condition, the loop continues to S30 to continue the small model separation trajectory test; otherwise, the small model separation trajectory is output to complete the small model separation trajectory test.

[0006] Furthermore, the construction of the free-flow aerodynamic coefficient difference database for the large and small models in S20 includes the following steps: S21. Obtain free-flow aerodynamic data of a large model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the large model of the external attachment as a function of attitude angle (α). F,大模型 ,β F,大模型 ) Large-scale model free-flow aerodynamic coefficient data, α F,大模型 For the pitch angle of the large model, β F,大模型 For the yaw angle of the large model; S22. Obtain free-flow aerodynamic data of a small model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the external attachment small model as a function of attitude angle (α). F,小模型 ,β F,小模型 The data includes the free-flow aerodynamic coefficients of the small model, which vary; and the data structure of the free-flow aerodynamic coefficients of the small model is the same as that of the large model. S23. According to α F,小模型 =α F,大模型 And β F,小模型 =β F,大模型 To meet the requirements, the free-flow aerodynamic coefficient difference database between the large model and the small model is obtained by subtracting the corresponding large model free-flow aerodynamic data.

[0007] Furthermore, the large model aerodynamic parameter correction in S40 includes the following steps: S41. The full-size external stores are large models, and the overall aerodynamic coefficient of the full-size external stores under the aircraft interference flow field is C; S42. Conduct a small model separation trajectory test, using a balance to measure the small model's current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic coefficient C of the small model under ) 小模型 : S43. Interpolate the free-flow aerodynamic coefficient difference database of the large and small models to obtain the difference ΔC between the aerodynamic coefficients of the large and small models at the same attitude angle. s ; S44. The aerodynamic forces of full-size external stores under aircraft interference flow fields are described using the incremental method, C=C 修正 =△C s +C 小模型 We obtained the aerodynamic coefficients of the large model based on the size differences of the external attachments.

[0008] The aerodynamic correction method for the separation trajectory of full-size external attachments of the present invention can correct the problem of shape simulation distortion in large-scale external attachment models and its impact on the separation trajectory of external attachments, and has practical engineering value. Attached Figure Description

[0009] Figure 1 A comparative curve showing the pitching moment differences between different scaled-down models of external attachments; Figure 2 This is a flowchart of an engineering-applicable method for correcting the trajectory of external attachments. Figure 3 A comparison curve of X-axis displacement after correction of the separation trajectory of the external attachment; Figure 4 A comparison curve of Y-axis displacement after correction of the external attachment separation trajectory; Figure 5 A comparison curve of Z-axis displacement after correction of the separation trajectory of the external attachment; Figure 6 A comparison curve of yaw angle displacement after correction of the external attachment separation trajectory; Figure 7 A comparison curve of pitch angle displacement after correction of the external attachment separation trajectory; Figure 8 A comparison curve of roll angle displacement after correction of the separation trajectory of the external attachment. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0011] Comparative example: Figure 1 The diagram shows a comparison of pitch moment curves for different scaled-down models of a certain external attachment. From... Figure 1 It can be seen that if the differences in aerodynamic characteristics between the large and small models of the external attachment are not corrected, the aerodynamic forces and moments measured in the wind tunnel test will directly lead to a large deviation from the actual full-size model, thus significantly reducing the accuracy of the separation trajectory prediction results.

[0012] Example: The wind tunnel used in this example is a 2.4-meter temporary blast wind tunnel. The cross-section of the wind tunnel test section is 2.4m × 2.4m, and the Mach number ranges from 0.3 to 1.4. The subsonic transonic test section is 7m long, with straight bore walls on both sides equipped with optical glass observation windows. The external payload model is a high-load experimental projectile model, and a six-component rod strain gauge with a diameter of 20mm is used to measure the aerodynamic load. The test Mach number is 0.8. Figure 2 As shown, the engineering application external attachment separation trajectory correction method in this embodiment includes the following steps: S10. Set initial conditions for the separation of full-size external attachments; The initial conditions for the separation of full-size external stores include the aircraft's state at the moment of separation, the position, attitude angle, velocity, angular velocity, and mass characteristics of the full-size external stores relative to the aircraft; the aircraft state parameters include the flight Mach number Ma, altitude H, and overload Nz, which are obtained in advance from flight experiments; the state parameters of the full-size external stores include the position, attitude angle, and mass characteristics of the full-size external stores relative to the aircraft, which are obtained in advance from ground experiments. The main parameters involved in the initial separation conditions of this embodiment are shown in Table 1. It should be noted that some parameters are processed in this embodiment. Among them, parameter I in the table below... XX I YY I ZZ These represent the moments of inertia of a full-size external attachment about its body axes Xt, Yt, and Zt, respectively. Table 1 ; S20. Establish a database of free-flow aerodynamic coefficient differences for external attachment models of different scales; Different scaled-down external stores models are defined as large models and small models, respectively. Using large models and small models as test objects, free-flow aerodynamic wind tunnel tests are conducted based on aircraft state parameters and full-size external stores state parameters to obtain free-flow aerodynamic data of large models and small models without aircraft model interference, and to construct a database of free-flow aerodynamic coefficient differences between large models and small models. S30. Conduct small-scale model separation trajectory tests and obtain small-scale model aerodynamic parameters; A small-scale model separation trajectory test was conducted in a wind tunnel. The small model's position (X, Y, Z) and attitude angle (α) were measured using a balance. F,小模型 ,β F,小模型 Aerodynamic forces and aerodynamic torques under α F,小模型 For the pitch angle of the small model, β F,小模型 The yaw angle of the small model is given, and the aerodynamic coefficient C of the small model is calculated. 小模型 and small model aerodynamic moment coefficient; small model aerodynamic coefficient C 小模型 The current position (X, Y, Z) and attitude angle (α) of the small model.F,小模型 ,β F,小模型 The aerodynamic forces under the given conditions are divided by the inflow velocity, pressure, and reference area; the aerodynamic moment coefficients of the small model are the current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic torque under the given conditions is divided by the inflow velocity pressure, reference area, and reference length. S40. Perform aerodynamic parameter correction for the large model; Using the free-flow aerodynamic coefficient difference database of the large and small models of S20, the aerodynamic coefficient C of the small model in S30 is analyzed. 小模型 Make corrections and obtain the corrected large model aerodynamic coefficients C. 修正 ; S50. Perform trajectory calculation and termination condition determination for external attachment separation: The corrected aerodynamic coefficient C of the large model 修正 As input parameters for the full-size external attachment, the resultant force and resultant moment of the full-size external attachment are calculated by combining the external forces acting on it at the current position and attitude angle, including gravity, ejection force, and thrust. Then, the six-degree-of-freedom rigid body motion equations (6DOF) are solved to obtain the position and attitude of the full-size external attachment at the next moment. If the position and attitude of the full-size external attachment at the next moment do not trigger the pre-set termination condition, the loop continues to S30 to continue the small model separation trajectory test; otherwise, the small model separation trajectory is output to complete the small model separation trajectory test.

[0013] Furthermore, the construction of the free-flow aerodynamic coefficient difference database for the large and small models in S20 includes the following steps: S21. Obtain free-flow aerodynamic data of a large model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the large model of the external attachment as a function of attitude angle (α). F,大模型 ,β F,大模型 ) Large-scale model free-flow aerodynamic coefficient data, α F,大模型 For the pitch angle of the large model, β F,大模型 For the yaw angle of the large model; S22. Obtain free-flow aerodynamic data of a small model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the external attachment small model as a function of attitude angle (α). F,小模型 ,β F,小模型 The data includes the free-flow aerodynamic coefficients of the small model, which vary; and the data structure of the free-flow aerodynamic coefficients of the small model is the same as that of the large model. S23. According to α F,小模型 =α F,大模型 And β F,小模型 =β F,大模型To meet the requirements, the free-flow aerodynamic coefficient difference database between the large model and the small model is obtained by subtracting the corresponding large model free-flow aerodynamic data.

[0014] Furthermore, the large model aerodynamic parameter correction in S40 includes the following steps: S41. The full-size external stores are large models, and the overall aerodynamic coefficient of the full-size external stores under the aircraft interference flow field is C; S42. Conduct a small model separation trajectory test, using a balance to measure the small model's current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic coefficient C of the small model under ) 小模型 : S43. Interpolate the free-flow aerodynamic coefficient difference database of the large and small models to obtain the difference ΔC between the aerodynamic coefficients of the large and small models at the same attitude angle. s ; S44. The aerodynamic forces of full-size external stores under aircraft interference flow fields are described using the incremental method, C=C 修正 =△C s +C 小模型 We obtained the aerodynamic coefficients of the large model based on the size differences of the external attachments.

[0015] This embodiment obtains as follows: Figures 3-8 The comparison curves shown indicate that after correcting the external attachment separation trajectory, the changes in the X, Y, and Z displacements along the separation trajectory are not significant; however, the pitch, yaw, and roll attitude angles along the separation trajectory line differ significantly from the uncorrected data. The maximum difference in roll attitude angle is approximately 26°.

[0016] 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, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for aerodynamic correction of the separation trajectory of a full-size external attachment, characterized in that, Includes the following steps: S10. Set initial conditions for the separation of full-size external attachments; The initial conditions for the separation of full-size external stores include the aircraft's state at the moment of separation, the position, attitude angle, velocity, angular velocity, and mass characteristics of the full-size external stores relative to the aircraft; the aircraft state parameters include the flight Mach number Ma, altitude H, and overload Nz, which are obtained in advance from flight experiments; the state parameters of the full-size external stores include the position, attitude angle, and mass characteristics of the full-size external stores relative to the aircraft, which are obtained in advance from ground experiments. S20. Establish a database of free-flow aerodynamic coefficient differences for external attachment models of different scales; Different scaled-down external stores models are defined as large models and small models, respectively. Using large models and small models as test objects, free-flow aerodynamic wind tunnel tests are conducted based on aircraft state parameters and full-size external stores state parameters to obtain free-flow aerodynamic data of large models and small models without aircraft model interference, and to construct a database of free-flow aerodynamic coefficient differences between large models and small models. S30. Conduct small-scale model separation trajectory tests and obtain small-scale model aerodynamic parameters; A small-scale model separation trajectory test was conducted in a wind tunnel. The small model's position (X, Y, Z) and attitude angle (α) were measured using a balance. F,小模型 ,β F,小模型 Aerodynamic forces and aerodynamic torques under α F,小模型 For the pitch angle of the small model, β F,小模型 The yaw angle of the small model is given, and the aerodynamic coefficient C of the small model is calculated. 小模型 and small model aerodynamic moment coefficient; small model aerodynamic coefficient C 小模型 The current position (X, Y, Z) and attitude angle (α) of the small model. F,小模型 ,β F,小模型 The aerodynamic forces under the given conditions are divided by the inflow velocity, pressure, and reference area; the aerodynamic moment coefficients of the small model are the current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic torque under the given conditions is divided by the inflow velocity pressure, reference area, and reference length. S40. Perform aerodynamic parameter correction for the large model; Using the free-flow aerodynamic coefficient difference database of the large and small models of S20, the aerodynamic coefficient C of the small model in S30 is analyzed. 小模型 Make corrections and obtain the corrected large model aerodynamic coefficients C. 修正 ; Specifically, the following steps are included: S41. The full-size external stores are large models, and the overall aerodynamic coefficient of the full-size external stores under the aircraft interference flow field is C; S42. Conduct a small model separation trajectory test, using a balance to measure the small model's current position (X, Y, Z) and attitude angle (α). F,小模型 ,β F,小模型 The aerodynamic coefficient C of the small model under ) 小模型 : S43. Interpolate the free-flow aerodynamic coefficient difference database of the large and small models to obtain the difference ΔC between the aerodynamic coefficients of the large and small models at the same attitude angle. s ; S44. The aerodynamic forces of full-size external stores under aircraft interference flow fields are described using the incremental method, C=C 修正 =△C s +C 小模型 We obtained the aerodynamic coefficients of the large model based on the size differences of the external attachments; S50. Perform external attachment separation trajectory calculation and termination condition determination; The corrected aerodynamic coefficient C of the large model 修正 As input parameters for the full-size external attachment, the resultant force and resultant moment of the full-size external attachment are calculated by combining the external forces acting on it at the current position and attitude angle, including gravity, ejection force, and thrust. Then, the six-degree-of-freedom rigid body motion equation (6DOF) is solved to obtain the position and attitude of the full-size external attachment at the next moment. If the position and attitude of the full-size external attachment at the next moment do not trigger the pre-set termination condition, the loop continues to S30 to continue the small model separation trajectory test; otherwise, the small model separation trajectory is output to complete the small model separation trajectory test.

2. The aerodynamic correction method for the separation trajectory of a full-size external attachment according to claim 1, characterized in that, The construction of the free-flow aerodynamic coefficient difference database for the large and small models of S20 includes the following steps: S21. Obtain free-flow aerodynamic data of a large model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the large model of the external attachment as a function of attitude angle (α). F,大模型 ,β F,大模型 ) Large-scale model free-flow aerodynamic coefficient data, α F,大模型 For the pitch angle of the large model, β F,大模型 For the yaw angle of the large model; S22. Obtain free-flow aerodynamic data of a small model through free-flow aerodynamic wind tunnel tests, and construct the aerodynamic coefficients of the external attachment small model as a function of attitude angle (α). F,小模型 ,β F,小模型 The data includes the free-flow aerodynamic coefficients of the small model, which vary; and the data structure of the free-flow aerodynamic coefficients of the small model is the same as that of the large model. S23. According to α F,小模型 =α F,大模型 And β F,小模型 =β F,大模型 To meet the requirements, the free-flow aerodynamic coefficient difference database between the large model and the small model is obtained by subtracting the corresponding large model free-flow aerodynamic data.

Images