Analytical method for high angle of attack and high angle of attack aerodynamic interpolation
By constructing a coordinate system and transformation matrix to analyze the angle of attack and sideslip angle of the aircraft, and combining aerodynamic parameter tables for interpolation, the problem of calculating aerodynamic forces and aerodynamic torques of aircraft with high angle of attack was solved, and accurate dynamic and aerodynamic interpolation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GENERAL ENG RES INST CHINA ACAD OF ENG PHYSICS
- Filing Date
- 2023-12-28
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies are not applicable to the calculation methods of angle of attack and sideslip angle in axisymmetric aircraft with large angles of attack and statically unstable aircraft, resulting in distortion of aerodynamic force and aerodynamic moment interpolation calculations and making it impossible to directly analyze the direction of sideslip angle.
By acquiring the launch system velocity vector and flight attitude of the aircraft, a missile body and velocity coordinate system are constructed. The angle of attack, sideslip angle and total angle of attack are analyzed using the transformation matrix. Interpolation is performed using the aerodynamic parameter table to decompose the aerodynamic forces and aerodynamic moments into the missile body coordinate system.
It enables accurate aerodynamic force and aerodynamic moment calculations for high angle-of-attack and statically unstable aircraft, simplifies the number of state point spaces, avoids data distortion, and improves computational efficiency.
Smart Images
Figure CN117763734B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of computer technology methods, and in particular to an analysis method for large angle of attack and large angle of attack aerodynamic interpolation. Background Technology
[0002] For axisymmetric aircraft, during the iterative process of solving the flight dynamics equations, aerodynamic parameters are interpolated at each iteration step based on the current flight state parameters to obtain aerodynamic forces and aerodynamic torques. These are then substituted into the dynamics equations to calculate the dynamic center of mass motion and rotation equations about the center of mass.
[0003] In solving the dynamic equations, attitude angles (pitch angles) are usually used first. The equation relating yaw angle ψ and roll angle γ), and velocity angles (ballistic inclination angle θ, ballistic deflection angle σ) is used to calculate the sideslip angle, and then the angle of attack and total angle of attack are calculated. The formulas for calculating the sideslip angle, angle of attack, and total angle of attack are as follows:
[0004]
[0005] This method calculates angles of attack and sideslip angles within the range of -90° to 90°, which is fine for most stable aircraft. However, for aircraft with large angles of attack exceeding 90° or statically unstable aircraft, the range of angle of attack and total angle of attack will exceed 90°. The angle of attack range is defined as -180° to 180°, and the total angle of attack range is defined as 0° to 180°. In these cases, the above method will no longer be applicable. Furthermore, the sideslip angle needs to be determined by the flight status, and the results cannot be directly analyzed using the above calculation method.
[0006] In aerodynamic parameter interpolation, for axisymmetric aircraft, pitch parameters are typically "symmetrically" mapped to yaw parameters. Then, aerodynamic forces and moments for pitch and yaw are calculated using angle of attack and sideslip angle interpolation, respectively, and then substituted into the dynamic equations for calculation. Since the methods for calculating angle of attack and sideslip angle are not applicable, the interpolation calculations for aerodynamic forces and moments are also inapplicable. Furthermore, for axisymmetric aircraft, aerodynamic parameters usually only provide angle of attack information; when using "symmetrical" aerodynamic data interpolation at large angles of attack, data distortion will result. Summary of the Invention
[0007] The purpose of this invention is to design an analysis method for large angle of attack and large angle of attack aerodynamic interpolation in order to solve the above problems.
[0008] The present invention achieves the above objectives through the following technical solutions:
[0009] Analysis methods for high angle of attack and high angle of attack aerodynamic interpolation include:
[0010] S1. Obtain the launch system velocity vector of the aircraft and acquire the flight attitude of the aircraft in real time;
[0011] S2. Construct the projectile coordinate system and velocity coordinate system;
[0012] S3. Analyze the transformation matrix from the launch system to the missile body coordinate system based on the current flight status of the aircraft;
[0013] S4. Analyze the velocity vector of the projectile coordinate system based on the transformation matrix and the velocity vector of the launching system;
[0014] S5. Based on the velocity vector of the projectile coordinate system and the angular relationship between the projectile coordinate system, the vector method is used to analyze the angle of attack α, sideslip angle β and total angle of attack η of the aircraft.
[0015] S6. In the plane of total angle of attack, using the aerodynamic parameter table, interpolate the total normal force coefficient C in the plane of total angle of attack. N Total axial coefficient C A and total pitching moment coefficient m h ;
[0016] S7, the total normal force coefficient C N and total axial force coefficient C A Decompose the aerodynamic coefficients to the projectile coordinate system, and decompose the total pitching moment coefficient m. h Torque coefficients decomposed into the projectile coordinate system.
[0017] The beneficial effects of this invention are as follows: This method can analyze angles of attack exceeding 90° based on velocity vectors, and is applicable to the analysis of angles of attack and sideslip angles in flight with large angles of attack or statically unstable flight. It can also directly analyze the direction of sideslip angles. The aerodynamic force and aerodynamic moment conversion method of the total angle of attack plane in this method can convert the aerodynamic force and aerodynamic moment of the total angle of attack plane to the projectile coordinate system while ensuring interpolation accuracy, which can simplify the number of aerodynamic calculation state points in the space. Attached Figure Description
[0018] Figure 1 This is a diagram showing the Euler angle relationship between the velocity coordinate system and the projectile coordinate system in this invention;
[0019] Figure 2 This is a diagram showing the velocity vector rotation relationship in this invention. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the coordinate system referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0024] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.
[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0026] Analysis methods for high angle of attack and high angle of attack aerodynamic interpolation include:
[0027] S1. Obtain the launch system velocity vector (V) of the aircraft. x V y V z It also acquires the aircraft's flight attitude in real time, including pitch angle. Yaw angle ψ and roll angle γ.
[0028] S2. Construct the projectile coordinate system and the velocity coordinate system; the origin of the projectile coordinate system is located at the projectile's center of mass, the O1X1 axis points towards the nose along the projectile's longitudinal axis, and the O1Y1 axis points upwards along the projectile's principal axis of symmetry. O1-X1Y1Z1 form a right-handed coordinate system; the origin of the velocity coordinate system is located at the projectile's center of mass, O1X... v The axis points forward along the direction of the projectile's flight, O1Y v The axis, along the principal axis of symmetry of the projectile, faces upwards, O1-X v Y v Z v This forms a right-handed coordinate system.
[0029] S3. Analyze the transformation matrix from the launch system to the missile body coordinate system based on the current flight status of the aircraft. The transformation matrix is expressed as:
[0030]
[0031] S4. Based on the transformation matrix and the velocity vector of the launch system, analyze the velocity vector of the projectile coordinate system. The velocity vector of the projectile coordinate system is expressed as:
[0032]
[0033] Among them, V x V y V z Let V be the velocity vector of the launching system. x1 V y1 V z1 The velocity vector is the velocity vector in the projectile's coordinate system.
[0034] S5. Based on the angular relationship between the velocity vector and the projectile coordinate system, and using the vector method, analyze the aircraft's angle of attack α, sideslip angle β, and total angle of attack η; specifically: the angular relationship between the projectile coordinate system and the velocity vector is as follows: Figure 1 As shown, the sideslip angle β is O1X v Around O1Y v The angle between the axis and the plane O1X1Y1, O1X v The axis becomes O1X' v The angle of attack α is O1X' v The angle of rotation about O1Z1 to the O1X1 axis; the total angle of attack η is O1X v The spatial angles between the axis and the O1X1 axis, the total angle of attack η, the angle of attack α, and the sideslip angle β are expressed as follows:
[0035]
[0036]
[0037] α=-arctan2(V y1 V x1 )
[0038] Where V is the magnitude of the resultant velocity, atctan2(V y1 V x1 ) is defined as:
[0039]
[0040] The sideslip angle β ranges from -90° to 90°, the angle of attack α ranges from -180° to 180°, and the total angle of attack η ranges from 0° to 180°.
[0041] S6. In the plane of total angle of attack, using the aerodynamic parameter table, the total normal force coefficient C in the plane of total angle of attack is interpolated using traditional linear or spline interpolation methods. N Total axial coefficient C A and total pitching moment coefficient m h ;
[0042] S7, the total normal force coefficient C N and total axial force coefficient C A Decompose the aerodynamic coefficients to the projectile coordinate system, and decompose the total pitching moment coefficient m. h The moment coefficients decomposed to the projectile coordinate system; specifically:
[0043] Total axial force coefficient C A If the body axis of the projectile coordinate system points towards the head, then the total axial force coefficient C A Direction vector in the projectile coordinate system Represented as:
[0044]
[0045] In the formula: These are the unit vectors in the directions of the O1-X1Y1Z1 coordinate axes of the projectile coordinate system;
[0046] Total normal force coefficient C N Located in the total angle of attack plane O1X1X V Inside, perpendicular to the total axial force coefficient C A Direction vector Along the O1Y1Z1 plane and O1X1X V The total normal force coefficient C along the plane intersection line O1P1. N The rotation sequence from the decomposition to the projectile coordinate system is as follows; see below for the specific rotation directions. Figure 2 As shown:
[0047] a) The unit vector of velocity in the projectile coordinate system: V( In the formula: || operation represents the modulus of a vector (the same applies below) cross product have to Perpendicular to the plane of total angle of attack O1X1X V ,correspond Figure 2 Sino-US relations①;
[0048] b) Then through Cross product get Perpendicular to the plane correspond Figure 2 Sino-US relations ②.
[0049] At this point, we arrive at C. N vector direction
[0050] The direction vector of the total normal force in the system The velocity in the projectile coordinate system is expressed as:
[0051]
[0052] After expanding the cross product of vectors, we have:
[0053]
[0054] As can be seen from the above formula, the total normal force does not contribute to the axial force.
[0055] The aerodynamic coefficients in the projectile coordinate system are then expressed as:
[0056]
[0057] According to the definition of aerodynamic moment, the total pitching moment m h The direction is perpendicular to O1X1X v Plane, direction pointing Then the total pitching moment coefficient m h Direction vector Represented as:
[0058]
[0059] Expanding the above formula, the total pitching moment coefficient m h The velocity vector in the projectile coordinate system is represented as:
[0060]
[0061] The moment coefficient of the projectile coordinate system is expressed as:
[0062]
[0063] From the above formula or The vector expression shows that the rolling moment is 0. Aerodynamic analysis also indicates that the projectile's axis lies in the plane of total angle of attack, and the contribution of the total angle of attack plane moment to the rolling moment is zero. The rolling moment is typically calculated independently through the rolling path.
[0064] Compared to solving for angle of attack and sideslip angle using the relationship equations between attitude angles (pitch, yaw, roll) and velocity angles (ballistic tilt, ballistic deflection), this method can solve for large angles of attack exceeding 90°, and can directly solve for the direction of sideslip angle through formulas; it can be directly used for dynamic calculations and aerodynamic interpolation calculations of high angle of attack flight or statically unstable aircraft; in addition, the calculation method derived in this invention has simpler formulas and higher calculation efficiency.
[0065] The method for converting total angle of attack plane aerodynamic force and aerodynamic torque proposed in this paper can effectively avoid the accuracy loss caused by "symmetrical" aerodynamic data, and can effectively reduce the calculated state quantities of aerodynamic data tables.
[0066] The method described in this paper is also applicable to dynamic calculations and aerodynamic interpolation calculations for small angles of attack.
[0067] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. An analytical method for high angle of attack and high angle of attack aerodynamic interpolation, characterized in that, include: S1. Obtain the launch system velocity vector of the aircraft and acquire the flight attitude of the aircraft in real time; S2. Construct the projectile coordinate system and velocity coordinate system; specifically: the origin of the projectile coordinate system is located at the projectile's center of mass, the O1X1 axis points towards the head along the projectile's longitudinal axis, the O1Y1 axis points upwards along the projectile's principal axis of symmetry, and O1-X1Y1Z1 form a right-handed coordinate system; the origin of the velocity coordinate system is located at the projectile's center of mass, O1X... v The axis points forward along the direction of the projectile's flight, O1Y v The axis, along the principal axis of symmetry of the projectile, faces upwards, O1-X v Y v Z v Construct a right-handed coordinate system; S3. Analyze the transformation matrix from the launch system to the missile body coordinate system based on the current flight status of the aircraft; S4. Analyze the velocity vector of the projectile coordinate system based on the transformation matrix and the velocity vector of the launching system; S5. Based on the velocity vector of the projectile coordinate system and the angular relationship between the projectile coordinate system and the projectile coordinate system, the vector method is used to analyze the aircraft's angle of attack α, sideslip angle β, and total angle of attack η; specifically: The sideslip angle β is O1X v Around O1Y v The angle between the axis and the plane O1X1Y1, O1X v The axis becomes O1X' v The angle of attack α is O1X' v The angle of rotation about O1Z1 to the O1X1 axis; the total angle of attack η is O1X v The spatial angle between the axis and the O1X1 axis; the total angle of attack η, angle of attack α, and sideslip angle β are calculated based on the velocity vector of the projectile coordinate system and the angular relationship between the projectile coordinate system and the projectile coordinate system, and are expressed as: ； Where V is the magnitude of the resultant velocity, ;atctan2(V y1 V x1 ) is defined as: ； The sideslip angle β ranges from -90° to 90°, the angle of attack α ranges from -180° to 180°, and the total angle of attack η ranges from 0° to 180°; where V x1 V y1 V z1 The velocity vector in the projectile coordinate system; S6. In the plane of total angle of attack, using the aerodynamic parameter table, interpolate the total normal force coefficient C in the plane of total angle of attack. N Total axial coefficient C A and total pitching moment coefficient m h ; S7, the total normal force coefficient C N and total axial force coefficient C A Decompose the aerodynamic coefficients to the projectile coordinate system, and decompose the total pitching moment coefficient m. h Torque coefficients decomposed into the projectile coordinate system.
2. The analysis method for high angle of attack and high angle of attack aerodynamic interpolation according to claim 1, characterized in that, Obtain the launch system velocity vector V of the aircraft x V y V z And flight attitude, which includes pitch angle φ, yaw angle ψ, and roll angle γ, V x V y V z Let be the velocity vector of the launching system.
3. The analysis method for high angle of attack and high angle of attack aerodynamic interpolation according to claim 2, characterized in that, In S3, the transformation matrix is represented as: 。 4. The analysis method for high angle of attack and high angle of attack aerodynamic interpolation according to claim 1, characterized in that, In S4, the velocity vector of the projectile coordinate system is expressed as: ； Among them, V x V y V z Let V be the velocity vector of the launching system. x1 V y1 V z1 Let V be the velocity vector in the projectile coordinate system. This is the transformation matrix.
5. The analysis method for high angle of attack and high angle of attack aerodynamic interpolation according to claim 1, characterized in that, Total axial force coefficient C A If the body axis of the projectile coordinate system points towards the head, then the total axial force coefficient C A Direction vector in the projectile coordinate system Represented as: ； In the formula: , , These are the unit vectors in the directions of the O1-X1Y1Z1 coordinate axes of the projectile coordinate system; Total normal force coefficient C N Located in the total angle of attack plane O1X1X V Inside, perpendicular to the total axial force coefficient C A Direction vector Along the O1Y1Z1 plane and O1X1X V If the plane intersection line O1P1 is in the direction, then the total normal force coefficient C N Direction vectors decomposed into projectile coordinates Represented as: ； in, Let velocity be the unit vector in the projectile coordinate system, denoted as: , Operations represent vector modulo operations; The aerodynamic coefficients in the projectile coordinate system are then expressed as: ； According to the definition of aerodynamic moment, the total pitching moment m h The direction is perpendicular to O1X1X v Plane, direction pointing to [ × ], then the total pitching moment m h Direction vector of coefficient Represented as: ； The moment coefficient of the projectile coordinate system is expressed as: 。