1. A method for determining aerodynamic loading of an aircraft in a mobile wind farm environment, comprising:

s1, acquiring each speed component of the aircraft on the body axis system at the current moment;

step S2, carrying out grid division on the aircraft;

s3, interpolating the given mobile wind field data to obtain wind field speeds of the aircraft in all directions corresponding to all axes of the body axis system;

step S4, determining equivalent velocity components of each grid of the aircraft according to each velocity component of the aircraft and the wind field velocity in each direction;

step S5, determining an equivalent pneumatic attack angle and an equivalent sideslip angle of each grid of the aircraft according to the equivalent velocity component;

s6, interpolating pressure distribution data based on the equivalent pneumatic attack angle and the equivalent sideslip angle to obtain pressure coefficients of each grid of the aircraft;

and step S7, determining aerodynamic force and aerodynamic moment of each grid of the aircraft based on the pressure coefficient, returning to step S3, and calculating the wind field speed at the next moment until the simulation is finished.

2. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein in step S2, velocity components of the aircraft are determined based on the initialized aircraft flight speed, aircraft angle of attack, and aircraft sideslip angle.

3. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein step S3 further comprises:

step S11, determining simulation time t;

step S12, surrounding speed V of aircraft based on moving wind field_ΔDetermining equivalent time t of each grid of the aircraft in a mobile wind field_i：t_i＝t-Δx_i/V_ΔWherein, Δ x_iThe horizontal distance between the ith grid centroid and the rear boundary of the aircraft empennage;

step S13, obtaining the horizontal moving wind field speed U received by each grid position according to the moving wind field data interpolation_x(t_i) Lateral moving wind field speed U_y(t_i) Speed U of vertical moving wind field_z(t_i)。

4. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein step S4 further comprises:

step S41, acquiring a transformation matrix L from the geodetic coordinate system to the airplane body axis system_bg；

Step S42, determining equivalent velocity components u at each grid of the aircraft based on the transformation matrix_i(t)、v_i(t)、w_i(t)：

Wherein U (t), v (t), w (t) are each velocity component of the aircraft, U_x(t_i)、U_y(t_i)、U_z(t_i) Wind field speeds in all directions.

5. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 4, wherein the transformation matrix is determined from initialized aircraft roll, pitch and yaw angles.

6. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein in step S6, the pressure distribution data comprises raw base pressure distribution data of the aircraft, the raw base pressure distribution data of the aircraft being obtained by wind tunnel testing or CFD simulation.

7. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 6, further comprising, prior to the interpolation process in step S6:

acquiring the flight Mach number of the aircraft;

and acquiring the centroid dimensionless position of each grid when the surface grid of the aircraft is divided.

8. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein step S7 further comprises:

step S71, determining aerodynamic force of each grid of the aircraft according to the pressure coefficient, the equivalent velocity pressure, the normal vector of the object plane and the grid area of each grid of the aircraft;

step S72, determining aerodynamic moment of each grid of the aircraft according to aerodynamic force and centroid position vector of each grid of the aircraft;

step S73, determining aerodynamic force and aerodynamic moment outside the aircraft according to the aerodynamic force and the aerodynamic moment at each grid of the aircraft;

and the normal vector of the object plane, the grid area and the centroid position vector are determined during grid division.

9. The method for determining aerodynamic loading of an aircraft in a mobile wind farm environment according to claim 1, wherein in step S2, the mesh divided by the aircraft surface is a triangular mesh.

Background

The mobile wind field is a special gust, and compared with a common wind field model, the mobile wind field has the following 3-point difference: (1) the mobile wind field has the characteristic of high-speed propagation, and generally expands at supersonic speed or sonic speed, while the common wind field generally does not consider the propagation speed of the wind field per se; (2) the disturbance energy carried by the mobile wind field is larger, which is reflected in that the speed of the wind field is larger; (3) the speed of the moving wind field is spatial and can be perturbed along both the heading and normal of the aircraft. When the moving wind field surrounds the aircraft from behind at sonic speed (or slightly above sonic speed), the tail wing is affected by the moving wind field first and then the wing is disturbed at a relatively low speed.

The existing method for determining the aerodynamic load of the aircraft in the mobile wind field environment generally adopts a surface element method, the calculation technology and the flow of the aerodynamic load are complex, the calculation precision is low, and especially the deviation in the aerodynamic non-linear area is larger.

Disclosure of Invention

In order to solve the technical problem, the present application provides a method for determining an aerodynamic load of an aircraft in a mobile wind farm environment, so as to simplify a determination process of the aerodynamic load and improve determination accuracy of the aerodynamic load, and the method for determining the aerodynamic load of the aircraft in the mobile wind farm environment includes:

s1, acquiring each speed component of the aircraft on the body axis system at the current moment;

step S2, carrying out grid division on the aircraft;

s3, interpolating the given mobile wind field data to obtain wind field speeds of the aircraft in all directions corresponding to all axes of the body axis system;

step S4, determining equivalent velocity components of each grid of the aircraft according to each velocity component of the aircraft and the wind field velocity in each direction;

step S5, determining an equivalent pneumatic attack angle and an equivalent sideslip angle of each grid of the aircraft according to the equivalent velocity component;

s6, interpolating pressure distribution data based on the equivalent pneumatic attack angle and the equivalent sideslip angle to obtain pressure coefficients of each grid of the aircraft;

and step S7, determining aerodynamic force and aerodynamic moment of each grid of the aircraft based on the pressure coefficient, returning to step S3, and calculating the wind field speed at the next moment until the simulation is finished.

Preferably, in step S2, each velocity component of the aircraft is determined based on the initialized aircraft flight speed, aircraft angle of attack, and aircraft sideslip angle.

Preferably, the step S3 further includes:

step S11, determining simulation time t;

step S12, surrounding speed V of aircraft based on moving wind field_ΔDetermining equivalent time t of each grid of the aircraft in a mobile wind field_i：t_i＝t-Δx_i/V_ΔWherein, Δ x_iThe horizontal distance between the ith grid centroid and the rear boundary of the aircraft empennage;

step S13, obtaining the horizontal moving wind field speed U received by each grid position according to the moving wind field data interpolation_x(t_i) Lateral moving wind field speed U_y(t_i) Speed U of vertical moving wind field_z(t_i)。

Preferably, the step S4 further includes:

step S41, acquiring a transformation matrix L from the geodetic coordinate system to the airplane body axis system_bg；

Step S42, determining equivalent velocity components u at each grid of the aircraft based on the transformation matrix_i(t)、v_i(t)、w_i(t)：

Wherein U (t), v (t), w (t) are each velocity component of the aircraft, U_x(t_i)、U_y(t_i)、U_z(t_i) Wind field speeds in all directions.

Preferably, the transformation matrix is determined from the initialized aircraft roll, pitch and yaw angles.

Preferably, in step S6, the pressure distribution data includes raw base pressure distribution data of the aircraft, and the raw base pressure distribution data of the aircraft is obtained through a wind tunnel test or a CFD simulation.

Preferably, before the interpolation process in step S6, the method further includes:

acquiring the flight Mach number of the aircraft;

and acquiring the centroid dimensionless position of each grid when the surface grid of the aircraft is divided.

Preferably, the step S7 further includes:

step S71, determining aerodynamic force of each grid of the aircraft according to the pressure coefficient, the equivalent velocity pressure, the normal vector of the object plane and the grid area of each grid of the aircraft;

step S72, determining aerodynamic moment of each grid of the aircraft according to aerodynamic force and centroid position vector of each grid of the aircraft;

step S73, determining aerodynamic force and aerodynamic moment outside the aircraft according to the aerodynamic force and the aerodynamic moment at each grid of the aircraft;

and the normal vector of the object plane, the grid area and the centroid position vector are determined during grid division.

Preferably, in step S2, the mesh divided by the aircraft surface is a triangular mesh.

The method and the device consider the influence of the process of surrounding the aircraft by the movable wind field on the pneumatic load, simplify the determining process of the pneumatic load and improve the determining precision of the pneumatic load.

Drawings

FIG. 1 is a flow chart of a preferred embodiment of the present application for a method for determining aerodynamic loading of an aircraft in a mobile wind farm environment.

FIG. 2 is a dynamic response plot of lift coefficients for the aircraft of the embodiment of the present application shown in FIG. 1.

FIG. 3 is a dynamic response plot of the aerodynamic pitching moment coefficient of the aircraft according to the embodiment of the present application shown in FIG. 1.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all embodiments of the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application, and should not be construed as limiting the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Embodiments of the present application will be described in detail below with reference to the drawings.

The application provides a method for determining aerodynamic loads of an aircraft in a mobile wind field environment, which mainly comprises the following steps:

s1, acquiring each speed component of the aircraft on the body axis system at the current moment;

step S2, carrying out grid division on the aircraft;

s3, interpolating the given mobile wind field data to obtain wind field speeds of the aircraft in all directions corresponding to all axes of the body axis system;

step S4, determining equivalent velocity components of each grid of the aircraft according to each velocity component of the aircraft and the wind field velocity in each direction;

step S5, determining an equivalent pneumatic attack angle and an equivalent sideslip angle of each grid of the aircraft according to the equivalent velocity component;

s6, interpolating pressure distribution data based on the equivalent pneumatic attack angle and the equivalent sideslip angle to obtain pressure coefficients of each grid of the aircraft;

and step S7, determining aerodynamic force and aerodynamic moment of each grid of the aircraft based on the pressure coefficient, returning to step S3, and calculating the wind field speed at the next moment until the simulation is finished.

Fig. 1 shows a specific implementation process, and referring to fig. 1, the working principle of the present application is: dividing the whole aircraft according to triangular meshes, and calculating centroid position vectors, object plane normal vectors, areas and centroid dimensionless positions of all the meshes; advancing according to the time axis of the mobile wind field, updating local equivalent time of each grid on the surface of the aircraft, interpolating according to the equivalent time to obtain the speed of the mobile wind field at each grid, and considering the influence of the mobile wind field on the grids at different positions in detail so as to further consider the dynamic effect of the grids entering and exiting the mobile wind field; aiming at different grids, local parameters such as an attack angle, a sideslip angle and a rapid pressure of the grids are respectively calculated, and then a pressure coefficient at the grids is obtained through interpolation, so that the method has a positive effect on improving the calculation precision of the external pneumatic load of the aircraft; the original pressure distribution data of the aircraft are obtained through wind tunnel tests or CFD simulation, the data accuracy is high, the calculation result accuracy is high, and the method has a positive effect on improving the calculation accuracy of the external pneumatic load of the aircraft in the mobile wind field environment.

The following description is given with reference to the examples.

1.1, triangular meshing of the surface of the aircraft: the surface of the whole aircraft is divided into triangular meshes, and the main information of any ith mesh is as follows: centroid position vector r_iNormal vector n of object plane_iArea s_iDimensionless location of centroid

The division of the triangular meshes on the surface of the aircraft can be completed by adopting commercial software such as CATIA (computer-graphics aided three-dimensional interactive application), and the number of the meshes needs to be as large as possible so as to improve the calculation precision of the external aerodynamic load of the aircraft; the surface of the aircraft is divided into triangular meshes by commercial software such as CATIA (computer-graphics aided three-dimensional Interactive application), information such as mesh node coordinates and mesh component node numbers is required to be derived, and the 5 parameters of the meshes are calculated according to a right-hand rule. In one embodiment, the surface of an aircraft is divided into triangular meshes, and 26892 meshes are obtained in total.

1.2. Initializing calculation parameters of the pneumatic load, namely inputting the flying height H and the flying speed V of the aircraft_A(corresponding to the flight Mach number M), an aircraft attack angle alpha, an aircraft sideslip angle beta and three Euler angles (a rolling angle phi, a pitch angle theta and a yaw angle psi) of the aircraft. For example, the flying height H of the aircraft is 1500m, and the flying speed V of the aircraft_AThe average value of the flight parameters is 200.7M/s (the corresponding flight Mach number M is 0.6), 1g of trim is carried out on the aircraft, the trim incidence angle alpha of the aircraft is 1.2 degrees, the sideslip angle beta of the aircraft is 0 degree, and the three Euler angles of the aircraft (the rolling angle phi is 0 degree, the pitch angle theta is 1.2 degrees, and the yaw angle psi is 0 degree) are obtained.

1.3, calculating the speed of the aircraft surrounded by the mobile wind field: calculating the speed of sound V at the current altitude according to the flying altitude H of the aircraft in the step 1.2_SAtmospheric density ρ, velocity V of the moving wind field surrounding the aircraft_ΔThe calculation formula is shown as (1):

V_Δ＝V_S-V_A (1)

obtaining the sound velocity V at the current altitude by adopting a standard atmosphere calculation method according to the flight altitude of the aircraft_SAtmospheric density ρ; when the moving wind field surrounds the aircraft from the rear, the surrounding speed needs to be calculated according to the above formula. For example, the atmospheric density ρ at a flying height H of 1500m is 1.0581kg/m³(ii) a Speed of sound V_SAt 334.5m/s, calculating the speed V of the moving wind field surrounding the aircraft according to a formula_ΔIt was 133.8 m/s.

And 1.4, obtaining the current time point t of the time axis of the mobile wind field. The current time point t of the time axis of the mobile wind field is also the current simulation time, and the position of the aircraft in the mobile wind field can be known according to the time.

1.5, calculating the speed component of the shafting of the aircraft body according to the flying speed V of the aircraft in the step 1.2_AThe aircraft angle of attack alpha and the aircraft sideslip angle beta, and calculating the flight speed V according to the formula (2)_AVelocity component u on the X-axis, velocity component v on the Y-axis, and velocity component w on the Z-axis of the body axis:

calculating to obtain the flying speed V at the moment when t is 0 according to the formula 2_AThe velocity component u on the X-axis of the body axis is 200.66m/s, the velocity component v on the Y-axis is 0m/s, and the velocity component w on the Z-axis is 4.1946 m/s.

1.6, updating of grid 'equivalent time': the "equivalent time" t of any ith grid in a moving wind field_iThe calculation is shown in formula (3);

t_i＝t-Δx_i/V_Δ (3)

wherein, Δ x_iThe horizontal distance between the centroid of the ith grid and the rear boundary of the aircraft empennage.

1.7, interpolation of the speed of the moving wind field at the grid: horizontal moving wind field speed U suffered by any ith grid_x(t_i) Lateral moving wind field speed U_y(t_i) Speed U of vertical moving wind field_z(t_i) And obtaining the data according to the moving wind field data through interpolation. If the grid has not entered the wind farm, or has exited the wind farm, the velocity of the moving wind farm is zero.

1.8, grid local equivalent speed updating: equivalent velocity component u at arbitrary ith grid_i(t)、v_i(t)、w_i(t) the calculation is shown in equation (4):

wherein, U_x(t_i)、U_y(t_i)、U_z(t_i) Respectively representing the horizontal, lateral and vertical components of the moving wind field at time t_iThe wind speed of (d); l is_bgFor the transformation matrix of the geodetic coordinate system to the aircraft body axis, according to the Euler angle, L, of the aircraft in step 1.2_bgThe calculation is shown in equation (5):

1.9, grid local equivalent airspeed determination: according to u in step 1.8_i(t)、v_i(t)、w_i(t), equivalent airspeed V at any ith grid_iThe calculation formula is shown as (6):

1.10 local equivalent aerodynamic angle of attack alpha of grid_iDetermining: according to u in step 1.8_i(t)、v_i(t)、w_i(t) according to V in step 1.9_iEquivalent aerodynamic angle of attack α at any ith grid_iEquivalent sideslip angle beta_iThe calculation formula is shown as (7):

1.11, determining the local equivalent pressure of the grid: according to the atmospheric density rho in step 1.3 and V in step 1.9_iEquivalent voltage Q at any ith grid_iThe calculation formula is shown as (8):

1.12, determining the pressure coefficient at the grid: according to the mesh centroid dimensionless position in step 1.1Flight Mach number M in step 1.2, and equivalent aerodynamic angle of attack α in step 1.10_iEquivalent sideslip angle beta_iPressure coefficient Cp at any ith grid_i(t) is obtained by interpolation of the raw pressure distribution data Cp0 (obtained by wind tunnel test or CFD simulation) of the aircraft, and the determination formula is shown as (9):

in this embodiment, a multidimensional interpolation method is used to obtain a pressure coefficient at the grid according to the pneumatic state parameter and the geometric parameter of the grid.

1.13, determination of grid aerodynamic load: from the centroid position vector r in step 1.1_iNormal vector n of object plane_iArea s_iAccording to the equivalent voltage Q in step 1.11_iPressure coefficient Cp in step 1.12_i(t), aerodynamic force f of any ith grid_iAnd aerodynamic moment m_iThe calculation formula (2) is shown as (10):

1.14, determination of the external aerodynamic load of the aircraft: according to aerodynamic force f in step 1.13_iAnd aerodynamic moment m_iThe aerodynamic force F outside the aircraft is obtained by integrating the entire grid_S(t) aerodynamic moment M_S(t), the concrete calculation formulas are respectively shown as (11) and (12):

wherein N is the number of all the grids of the outer surface of the aircraft; f_xS(t)、F_yS(t)、F_zS(t) are the projection components of the external aerodynamic force of the aircraft on the X axis, the Y axis and the Z axis respectively; m_xS(t)、M_yS(t)、M_zSAnd (t) are projection components of the external aerodynamic moment of the aircraft on an X axis, a Y axis and a Z axis respectively.

By making a pair F_xS(t)、F_yS(t)、F_zS(t)、M_xS(t)、M_yS(t)、M_zS(t) dimensionless processing to obtain dimensionless forms of the variables; f_zSDimensionless of (t)In the form of lift coefficients CL, M of the aircraft_ySThe dimensionless form of (t) is the aircraft aerodynamic pitch moment coefficient Cmy.

1.15, returning to the step 1.4, and updating the calculation time until the calculation is finished.

FIG. 2 is a dynamic response diagram of lift coefficients of an aircraft according to an embodiment of the present invention, where the horizontal axis is time, the vertical axis is the lift coefficients of the aircraft, the curve with the square symbols represents the dynamic response of the lift coefficients in consideration of the process of surrounding the aircraft by a moving wind field, the curve with the triangular symbols represents the dynamic response of the lift coefficients in the process of neglecting the surrounding of the aircraft by a moving wind field, and the curve with the dotted line represents the excitation signal of a step-moving wind field;

FIG. 3 is a dynamic response diagram of the aerodynamic pitch moment coefficient of the aircraft according to an embodiment of the present invention, where the horizontal axis is time, the vertical axis is the aerodynamic pitch moment coefficient of the aircraft, the curve with a square symbol represents the dynamic response of the aerodynamic pitch moment coefficient in consideration of the process of surrounding the aircraft by the moving wind field, the curve with a triangular symbol represents the dynamic response of the aerodynamic pitch moment coefficient in consideration of the process of surrounding the aircraft by the moving wind field, and the curve with a dotted line represents the excitation signal of the stepped moving wind field;

from fig. 2 and 3, it can be seen that for the calculation case of ignoring the process of surrounding the aircraft by the moving wind field, the lift force and the pneumatic pitching moment of the aircraft suddenly change to values corresponding to the stable state; in the calculation process of considering the movable wind field to surround the aircraft, information details such as the position of each grid in the wind field and the like are fully considered, so that the lift force and the aerodynamic pitching moment of the aircraft gradually reach values of a stable state; the aerodynamic forces of the two calculations are the same when the aircraft is fully immersed in a stepped-motion wind field.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.