A gust flow field sensing method based on surface pressure

Abstract

This application discloses a surface pressure-based method for sensing gust flow fields, relating to the field of gust flow field sensing. The method fits the airfoil leading-edge parabola to determine the flow model around the airfoil leading-edge parabola; establishes the relationship between the abscissa of the stagnation point and the effective angle of attack of the incoming flow; constructs a residual function between the measured pressure and the fitted pressure; uses dynamic pressure sensors distributed on the aircraft wing surface to sense the current gust flow field, while simultaneously fitting the current gust flow field using the airfoil leading-edge parabola flow model; based on the measured and fitted pressures, and using the residual function, employs a nonlinear least squares method to obtain the current combined velocity of the incoming flow and the abscissa of the current stagnation point; thereby calculating the current effective angle of attack of the incoming flow, the horizontal and vertical velocities of the current gust flow, and the frequency of the current gust. This application can measure and sense different cross-sections and unsteady flow parameters of an aircraft wing.

Description

Technical Field

[0001] This application relates to the field of gust flow field sensing, and in particular to a method for gust flow field sensing based on surface pressure. Background Technology

[0002] Aircraft sometimes encounter gusts of wind during flight. These irregular and rapidly changing airflows can cause sudden loads on the aircraft, creating safety hazards. Therefore, researchers have conducted extensive studies on the response of aircraft to gusts, a crucial aspect of which is the perception of gust flow. Obtaining the flow parameters on the wing surface is essential for studying the stress characteristics and patterns of the wing under gust flow fields. These flow parameters can be used as a reference for aircraft load feedback or feedforward control.

[0003] Over the past few decades, numerous technologies and methods for sensing flow field parameters have been developed, such as pitot tubes, porous probes, and embedded atmospheric sensing systems on fighter jets. These methods can effectively detect parameters such as atmospheric velocity and flight attitude, but they also have limitations. The most obvious problem is that these methods can only measure and sense localized flow regions, failing to adequately cover different cross-sections of aircraft wings, resulting in incomplete flow information. Furthermore, for unsteady flow phenomena in gust flow fields, the response speed of previous measurement methods may not be able to fully resolve velocity fluctuations in the flow, leading to distortion of flow information. All of these negatively impact the understanding of the characteristics and patterns of such flows. Summary of the Invention

[0004] The purpose of this application is to provide a surface pressure-based method for sensing gust flow fields, which can measure and sense different cross sections and unsteady flow parameters of aircraft wings.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] This application provides a method for sensing gust flow fields based on surface pressure, comprising: fitting the airfoil leading edge shape of an aircraft wing with a parabola to obtain an airfoil leading edge parabola; determining a flow model around the airfoil leading edge parabola based on the airfoil leading edge parabola; establishing the relationship between the abscissa of the stagnation point and the effective angle of attack of the incoming flow; constructing a residual function between the measured pressure and the fitted pressure; using dynamic pressure sensors distributed on the surface of the aircraft wing to sense the current gust flow field, and simultaneously fitting the current gust flow field flow using the airfoil leading edge parabola flow model; and determining the flow model around the airfoil leading edge parabola based on the current airfoil leading edge parabola flow field. The measured pressure from the forward flow sensing and the current fitted pressure from the parabolic flow model around the airfoil's leading edge are used. Based on the residual function, a nonlinear least squares method is employed to obtain the current incoming flow convergence velocity and the current stagnation point position x-coordinate. Using the relationship between the current stagnation point position x-coordinate and the effective angle of attack of the incoming flow, the current effective angle of attack of the incoming flow is obtained. Based on the current effective angle of attack, the current incoming flow convergence velocity is decomposed to obtain the horizontal and vertical velocities of the current gust flow. Spectral analysis is performed on the horizontal and vertical velocities of the current gust flow to obtain the frequency of the current gust.

[0007] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0008] This application provides a surface pressure-based method for sensing gust flow fields. By using dynamic pressure sensors distributed on the surface of an aircraft wing to sense the gust flow field, and by utilizing the measured pressure from the flow sensing and the fitted pressure from the parabolic flow model around the airfoil leading edge, the method effectively senses and estimates the horizontal velocity, vertical velocity, effective angle of attack of the incoming gust flow, and the stagnation point position at the leading edge of the wing. This enables the measurement and sensing of different cross sections and unsteady flow parameters of the aircraft wing. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a flowchart illustrating a surface pressure-based gust flow field sensing method in one embodiment of this application.

[0011] Figure 2 A schematic diagram of the leading edge geometry parameters of an airfoil provided for another embodiment of this application;

[0012] Figure 3 This is a schematic diagram of the fitting result of the leading edge of a symmetrical airfoil provided in another embodiment of this application;

[0013] Figure 4 A schematic diagram of CLARKY airfoil fitting provided for another embodiment of this application;

[0014] Figure 5 This is a schematic diagram of flow transformation provided in another embodiment of this application;

[0015] Figure 6 This is a schematic diagram of a nonlinear fitting process provided for another embodiment of this application. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] In one exemplary embodiment, such as Figure 1 As shown, this embodiment provides a method for sensing gust flow fields based on surface pressure, including the following steps 101 to 109. Wherein:

[0019] Step 101: Fit the airfoil leading edge shape of the aircraft wing with a parabola to obtain the airfoil leading edge parabola;

[0020] Step 102: Determine the flow model around the airfoil leading edge parabola based on the airfoil leading edge parabola;

[0021] Step 103: Establish the relationship between the x-coordinate of the station location and the effective angle of attack of the incoming flow;

[0022] Step 104: Construct the residual function between the measured pressure and the fitted pressure;

[0023] Step 105: Use dynamic pressure sensors distributed on the surface of the aircraft wing to sense the current gust flow field, and at the same time use the parabolic flow model around the leading edge of the airfoil to fit the current gust flow field.

[0024] Step 106: Based on the measured pressure of the current flow sensing and the current fitted pressure of the parabolic flow model around the airfoil leading edge, and using the nonlinear least squares method based on the residual function, obtain the current incoming flow velocity and the current stagnation point position x-coordinate.

[0025] Step 107: Based on the current x-coordinate of the station position, use the relationship between the x-coordinate of the station position and the effective angle of attack of the incoming flow to obtain the current effective angle of attack of the incoming flow;

[0026] Step 108: Decompose the current incoming flow velocity based on the current effective angle of attack of the incoming flow to obtain the current horizontal and vertical velocities of the incoming gust.

[0027] Step 109: Perform spectral analysis on the horizontal and vertical velocities of the current gust to obtain the frequency of the current gust.

[0028] Inspired by the distributed "sensors" in bird feathers, the method of this application implements steps 101 to 109 above. It uses dynamic pressure sensors distributed on the wing surface to sense the frontal airflow field and uses distributed pressure measurement physical parameters to fit a mathematical model. This allows for effective sensing and estimation of the vertical velocity of the frontal airflow, the local angle of attack of each section of the wing, and the location of the stagnation point at the leading edge of the wing, thus overcoming the shortcomings of existing sensing and measurement methods.

[0029] In another exemplary embodiment of this application, when the airfoil of the aircraft wing is a symmetrical airfoil, step 101 above is replaced by steps 201 to 204:

[0030] Step 201: The parabolic equation for fitting the leading edge shape of the aircraft wing is: In the formula, y0 is the coordinate of the parabola in the vertical direction, x0 is the coordinate of the parabola in the horizontal direction, and r is the leading edge radius of the airfoil.

[0031] Step 202: Establish the deviation function between the airfoil leading edge and the parabola in the region where x' / c' < 5% as follows: In the formula, x' is the distance along the airfoil chord direction, c' is the standardized parameter, and δ is the deviation value. Let be the vertical coordinates of the i-th point on the parabola. Let be the vertical coordinate of the i-th point on the leading edge of the airfoil, and N be the number of points in the region where x' / c' < 5% on the leading edge of the airfoil.

[0032] Step 203: Iterate through the airfoil leading edge radius r to obtain the airfoil leading edge radius that minimizes the deviation value in the deviation function, and determine it as the airfoil leading edge shape parameter.

[0033] Step 204: Substitute the airfoil leading edge shape parameters into the parabola equation to obtain the airfoil leading edge parabola.

[0034] In another exemplary embodiment of this application, when the airfoil of the aircraft wing is an asymmetric airfoil, step 101 above is replaced by steps 301 to 304:

[0035] Step 301: Change the equation to The parabola is rotated at zero angle of attack to obtain a parabola that fits the airfoil leading edge shape of the aircraft wing; where y0 is the coordinate of the parabola in the vertical direction, x0 is the coordinate of the parabola in the horizontal direction, and r is the airfoil leading edge radius.

[0036] Step 302: Establish the deviation function between the airfoil leading edge and the parabola in the region where x' / c' < 5% as follows: In the formula, x' is the distance along the airfoil chord direction, c' is the standardized parameter, and δ is the deviation value. Let be the vertical coordinates of the i-th point on the parabola. Let be the vertical coordinate of the i-th point on the leading edge of the airfoil, and N be the number of points in the region where x' / c' < 5% on the leading edge of the airfoil.

[0037] Step 303: Iterate through the airfoil leading edge radius r to obtain the airfoil leading edge radius that minimizes the deviation value in the deviation function, and determine it as the airfoil leading edge shape parameter.

[0038] Step 304: Substitute the airfoil leading edge shape parameters into the fitted parabolic equation to obtain the airfoil leading edge parabola.

[0039] Based on the two exemplary embodiments above, the first step in obtaining the airfoil leading edge parabola is to make a reasonable approximation of the airfoil's geometry, where a parabola is used to fit the leading edge shape. Figure 2 The key parameters required to describe the leading edge shape of an airfoil are given, where r is the leading edge radius of the airfoil and θ is the deflection angle of the central axis of the parabola required to fit the leading edge shape.

[0040] (1) Symmetrical airfoil

[0041] For symmetrical airfoils, the only leading-edge shape parameter is the leading-edge radius *r*, and the vertical camber of the airfoil is zero, therefore there is no need to set the value of *θ*. The process of determining the *r* parameter is as follows:

[0042] The generated parabola is compared with the coordinates of the airfoil leading edge position where x / c < 5%, and a deviation function is established. In the formula, p and a represent the parabola and airfoil, respectively.

[0043] Iterate the value of r within a certain range with a sufficiently small step size, so that the value of the δ function is reduced to a minimum. Figure 3 An approximate fitting result is given. Figure 3 NACA0015 is the designation of the NACA four-position airfoil.

[0044] (2) Asymmetric airfoil

[0045] For asymmetric airfoils, an additional pilot step is required: the parabola is rotated by θ = α0 based on the airfoil's zero-lift angle of attack α0. The calculation method for the r value after rotation is the same as that for symmetric airfoils. Figure 4 A schematic diagram of the fitting of the CLARKY airfoil is given.

[0046] In another exemplary embodiment of this application, the flow around the leading edge of the airfoil can be regarded as the flow around a parabola. Using the parabolic equation to fit the leading edge of the airfoil (x / c < 5%), when the free flow passes over the parabola at a certain angle of attack, there is a stagnation point and a corresponding suction point on the parabolic surface. When the airfoil of the aircraft wing is a symmetrical airfoil, the above step 102 is replaced by the following steps 401 to 406:

[0047] Step 401: Determine the velocity expression of the gust airflow flowing over the parabolic surface of the airfoil's leading edge as follows: In the formula, U is the velocity of the gust flow over the parabolic surface of the airfoil leading edge, x is the coordinate of the parabolic airfoil leading edge in the horizontal direction, β is the coordinate position of the stagnation point on the complex plane ξ, and r is the radius of the airfoil leading edge.

[0048] Step 402: Let The expression for the ratio of the velocity of the incoming gust flowing over the parabolic surface of the airfoil's leading edge to the combined velocity of the incoming flow is: In the formula, a' is an intermediate parameter, U ∞ Let A be the incoming flow velocity, and let A be a first-order multiplier.

[0049] Step 403: According to the ratio expression and the pressure coefficient expression Cp=1-(U / U ∞ ) 2 The coordinates of the point where the pressure coefficient is 1 are obtained and used as the coordinates of the stationary point. In the formula, Cp is the pressure coefficient, and x stag Let y be the x-coordinate of the stationary point. stag y is the vertical coordinate of the stationary point.

[0050] Step 404: Based on the ratio expression and the suction peak pressure expression The coordinates of the suction peak were obtained as follows In the formula, Cp ，peak For suction peak pressure, x peak y is the x-axis of the suction peak. peak The vertical axis represents the suction peak.

[0051] Step 405: Establish the formula for the difference between the surface pressure of the parabola and the incoming flow pressure as follows: In the formula, P is the surface pressure of the parabola, P ∞ ρ is the atmospheric pressure at infinity, and ρ is the air density.

[0052] Step 406: Substitute the difference formula into the ratio expression to obtain the parabolic flow model around the airfoil leading edge:

[0053] The specific implementation process of the velocity expression in step 401 above can be summarized in steps 501 to 506 as follows:

[0054] Step 501: Use conformal transformation to transform the parabolic flow in the z(x,y) plane into a planar stagnation flow in the ζ(ξ,η) plane; where x is the horizontal coordinate of the airfoil leading edge parabola, y is the vertical coordinate of the airfoil leading edge parabola, ξ is the real part of the coordinates in the complex plane ζ, η is the imaginary part of the coordinates in the complex plane ζ, and ζ = ξ + iη.

[0055] Transform the parabolic flow in the z(x,y) plane into a planar stagnation flow in the ζ(ξ,η) plane, such as... Figure 5 As shown. Figure 5 Part (a) shows the planar stationary flow in the ζ(ξ,η) plane. Figure 5 Part (b) shows the parabolic flow in the z(x,y) plane.

[0056] Step 502: Establish the reset potential for planar stagnation flow in the ζ(ξ,η) plane as follows: In the formula, F(ζ) is the reset potential of the flow, φ(ζ) is the potential function in the reset potential of the flow, and ψ(ζ) is the stream function in the reset potential of the flow.

[0057] Step 503: Using the transformation formula Convert the flow's reset potential into In the formula, Let z be the complex plane z-reset potential.

[0058] Step 504: Differentiate the transformed reset potential to obtain In the formula, Let be the derivative of the reset potential, and u and v be the horizontal and vertical velocities in the complex plane z, respectively. In the formulas of steps 501 to 504 above, i is a complex number.

[0059] Step 505: Based on the restoring potential obtained by differentiation, determine the initial velocity expression of the gust flow over the parabolic surface of the airfoil's leading edge as follows:

[0060] Step 506: Substitute the parabolic equation into the initial velocity expression to obtain the final velocity expression of the gust flow over the parabolic surface of the airfoil's leading edge:

[0061] Steps 401-406 and 501-506 above pertain to the parabolic equation with a horizontal centerline. This case corresponds to a symmetrical airfoil. When the airfoil has camber, the parabolic equation should be rewritten as follows: This will produce a rotational effect on the parabola, where λ = tanθ. That is, when the aircraft wing has an asymmetric airfoil, the flow model around the parabola at the airfoil's leading edge is:

[0062]

[0063] In the formula, λ is the tangent of the angle θ of the parabola's central axis deflection, λ=tanθ.

[0064] In another exemplary embodiment of this application, step 103 above can be divided into two cases to establish the relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow, specifically:

[0065] Before the airfoil stalls, the relationship between the x-coordinate of the stagnation point and the effective angle of attack of the incoming flow is: x s =ctan 2 α; where x s Let be the x-coordinate of the stagnation point, α be the effective angle of attack of the incoming flow, and c be the airfoil chord length. After defining the angle of attack interval, the correspondence between the x-coordinate of the stagnation point and the effective angle of attack of the incoming flow within that interval can be obtained.

[0066] When airfoil stalls or nonlinear separation occurs, a lookup table relationship between the stagnation point position x-coordinate and the effective angle of attack of the incoming flow is established through experiments or CFD simulation. Nonlinear interpolation is then used to construct a relationship model between the stagnation point position x-coordinate and the effective angle of attack of the incoming flow.

[0067] In another exemplary embodiment of this application, the residual function between the measured pressure and the fitted pressure established in step 104 above is:

[0068]

[0069] ε j =P j -F j (x j U ∞ ,A,a')

[0070] In the formula, S is the residual value between the measured pressure and the fitted pressure, and ε j To measure pressure at position x j The difference between the measured pressure and the fitted pressure at point P j For dynamic pressure sensors at pressure measurement position x j The pressure measured at F j (x j U ∞,A,a') represents the pressure measurement position x j Fitted pressure at point U ∞ Let A be the incoming confluence velocity, A be the first-order multiplier, and a' be an intermediate parameter. β is the coordinate position of the stationary point on the complex plane ξ, and r is the leading edge radius of the airfoil.

[0071] In another exemplary embodiment of this application, after confirming the internal airfoil leading-edge parabolic flow model, it is necessary to use the airfoil leading-edge parabolic flow model to fit the actual flow. The fitting process will confirm three unknowns U. ∞ ,A,a'. Nonlinear fitting is divided into fitting on the stagnation side and fitting on the suction side. Using different parameters for each side can achieve better estimation accuracy. For example Figure 6 As shown, the specific implementation process of step 106 above is as follows: steps 601 to 604:

[0072] Step 601: Obtain the measured pressure of two points on the leading edge of the airfoil corresponding to the same chord direction coordinate of the dynamic pressure sensor, and determine the side with the larger measured pressure as the stagnation side and the side with the smaller measured pressure as the suction side.

[0073] Step 602: Based on the measured pressure of the current flow sensing at the stagnation point and the current fitted pressure of the parabolic flow model around the airfoil leading edge, the current incoming flow velocity and the current intermediate parameters are obtained by fitting the residual function using the nonlinear least squares method.

[0074] Step 603: Based on the measured pressure of the current flow sensing on the suction side and the current fitted pressure of the parabolic flow model around the airfoil leading edge, the current first multiplier is obtained by using the nonlinear least squares method based on the residual function.

[0075] Step 604: Use the square of the current intermediate parameter as the x-coordinate of the current stationary point position.

[0076] The general process of using the nonlinear least squares method described above is as follows: Initial values ​​U0, A0, a'0 are given during estimation, and x represents the chordal coordinates of the airfoil to be introduced. This yields an estimated value. Using the nonlinear least squares algorithm, gradient-based iterations are performed based on the constructed residual function. The initial values ​​for the iterations are the aforementioned U0, A0, a'0, ultimately resulting in a U value that conforms to the actual physical flow. ∞ If A and a' are found, the solution is complete.

[0077] In another exemplary embodiment of this application, the horizontal velocity of the current gust flow in step 108 above is:

[0078] u x =U′ ∞ cosα′

[0079] In the formula, u x U′ is the horizontal velocity of the current gust flow. ∞ α is the current incoming flow velocity, and α′ is the current effective angle of attack of the incoming flow.

[0080] The current vertical velocity of the incoming gust is:

[0081] v y =U′ ∞ sinα′

[0082] In the formula, v y This represents the vertical velocity of the current gust of wind.

[0083] The current incoming flow velocity and the current stagnation point position x-coordinate parameters were obtained from the regression in step 106, where the stagnation point position x-coordinate is... s =a' 2 Then, based on the relationship between the x-coordinate of the stationary point and the effective angle of attack of the incoming flow, i.e., α = f(x s ), where f(x) s The ) represents the relationship between the stationary point position and the angle of attack, which can be used to determine the incoming confluence velocity U′. ∞ Decompose to obtain u x =U′ ∞ cosα′,v y =U′ ∞ sinα′, thus enabling the perception of the velocity of the convex wind, and further recording u x and v y The time-series data can be used for spectral analysis to obtain the frequency of gusts.

[0084] The beneficial effects of the method described in this application are as follows:

[0085] 1. This method uses distributed pressure measurement on the wing surface to sense information such as the vertical velocity of the incoming gust and the change of the stagnation point at the leading edge of the wing section with the gust, thus overcoming the problems of traditional sensing and measurement methods that cannot perform multi-section measurements or sense unsteady flow parameters.

[0086] 2. This method is easy to implement and requires little physical information; it only needs pressure coefficient information at a few points on the wing cross-section to complete the sensing. Due to its simplicity, this method can be easily applied to real aircraft for real-time flow parameter sensing.

[0087] 3. This method is highly versatile and can be used in various airfoils and most gust flow field conditions.

[0088] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for sensing gust flow fields based on surface pressure, characterized in that, include: The airfoil leading edge shape is fitted with a parabola to obtain the airfoil leading edge parabola; Based on the airfoil leading-edge parabola, determine the flow model around the airfoil leading-edge parabola; Establish the relationship between the x-coordinate of the station location and the effective angle of attack of the incoming flow; Construct a residual function between the measured pressure and the fitted pressure; The flow of the current gust is sensed by dynamic pressure sensors distributed on the surface of the aircraft wing, and the flow of the current gust is fitted by the parabolic flow model around the leading edge of the airfoil. Based on the measured pressure from the current flow sensing and the current fitted pressure from the parabolic flow model around the airfoil leading edge, the current incoming flow velocity and the current stagnation point position x-coordinate are obtained using the nonlinear least squares method based on the residual function. Based on the x-coordinate of the current stagnation point, the effective angle of attack of the incoming flow is obtained by using the relationship between the x-coordinate of the stagnation point and the effective angle of attack of the incoming flow. Based on the current effective angle of attack of the incoming flow, the current incoming flow velocity is decomposed to obtain the current horizontal and vertical velocities of the incoming gust. Spectral analysis is performed on the horizontal and vertical velocities of the current gust wind to obtain the frequency of the current gust wind.

2. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, When an aircraft wing has a symmetrical airfoil, a parabola is used to fit the leading edge shape of the airfoil to obtain the leading edge parabola, which specifically includes: The parabolic equation for fitting the leading edge shape of an aircraft wing is: In the formula, y0 is the coordinate of the parabola in the vertical direction, x0 is the coordinate of the parabola in the horizontal direction, and r is the leading edge radius of the airfoil. The deviation function between the airfoil leading edge and the parabola in the region x' / c'<5% is established as follows: In the formula, x' is the distance along the airfoil chord direction, c' is the standardized parameter, and δ is the deviation value. Let be the vertical coordinates of the i-th point on the parabola. Let x' be the vertical coordinate of the i-th point on the leading edge of the airfoil, and N be the number of points in the region where x' / c' < 5% on the leading edge of the airfoil. Iterate through the leading edge radii r of the airfoil to obtain the leading edge radius of the airfoil that minimizes the deviation value in the deviation function, and determine it as the leading edge shape parameter of the airfoil; Substituting the airfoil leading edge shape parameters into the parabolic equation yields the airfoil leading edge parabola.

3. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, When an aircraft wing has an asymmetric airfoil, a parabola is used to fit the leading edge shape of the airfoil to obtain the leading edge parabola, which specifically includes: The equation is The parabola is rotated at zero angle of attack to obtain a parabola that fits the airfoil leading edge shape of the aircraft wing; where y0 is the coordinate of the parabola in the vertical direction, x0 is the coordinate of the parabola in the horizontal direction, and r is the airfoil leading edge radius. The deviation function between the airfoil leading edge and the parabola in the region x' / c'<5% is established as follows: In the formula, x' is the distance along the airfoil chord direction, c' is the standardized parameter, and δ is the deviation value. Let be the vertical coordinates of the i-th point on the parabola. Let x' be the vertical coordinate of the i-th point on the leading edge of the airfoil, and N be the number of points in the region where x' / c' < 5% on the leading edge of the airfoil. Iterate through the leading edge radii r of the airfoil to obtain the leading edge radius of the airfoil that minimizes the deviation value in the deviation function, and determine it as the leading edge shape parameter of the airfoil; The airfoil leading edge shape parameters are substituted into the fitted parabolic equation to obtain the airfoil leading edge parabola.

4. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, When the airfoil of an aircraft wing is a symmetrical airfoil, the flow model around the airfoil's leading-edge parabola is determined based on the parabola of the airfoil's leading edge, specifically including: The velocity expression for the gust of air flowing over the parabolic surface of the airfoil's leading edge is determined as follows: In the formula, U is the velocity of the gust flow over the parabolic surface of the airfoil leading edge, x is the coordinate of the parabolic airfoil leading edge in the horizontal direction, β is the coordinate position of the stagnation point on the complex plane ξ, and r is the radius of the airfoil leading edge. make The expression for the ratio of the velocity of the incoming gust flowing over the parabolic surface of the airfoil's leading edge to the combined velocity of the incoming flow is: In the formula, a' is an intermediate parameter, U ∞ Let A be the incoming flow velocity, and A be a first-order multiplier. According to the ratio expression and the pressure coefficient expression Cp=1-(U / U ∞ ) 2 The coordinates of the point where the pressure coefficient is 1 are obtained and used as the coordinates of the stationary point. In the formula, Cp is the pressure coefficient, and x stag Let y be the x-coordinate of the stationary point. stag The vertical coordinate of the stationary point; Based on the ratio expression and the peak suction pressure expression The coordinates of the suction peak were obtained as follows In the formula, Cp ，peak For suction peak pressure, x peak y is the x-axis of the suction peak. peak The vertical axis represents the suction peak; The formula for the difference between the surface pressure of the parabola and the incoming flow pressure is as follows: In the formula, P is the surface pressure of the parabola, P ∞ ρ is the atmospheric pressure at infinity, and ρ is the air density. Substituting the difference formula into the ratio expression, the parabolic flow model around the airfoil leading edge is obtained as follows:

5. The method for sensing gust flow field based on surface pressure according to claim 4, characterized in that, The velocity expression for the gust of air flowing over the parabolic surface of the airfoil's leading edge is determined as follows: Specifically, it includes: The conformal transformation method is used to transform the parabolic flow in the z(x,y) plane into a planar stagnation flow in the ζ(ξ,η) plane; where x is the horizontal coordinate of the airfoil leading edge parabola, y is the vertical coordinate of the airfoil leading edge parabola, ξ is the real part of the coordinates in the complex plane ζ, and η is the imaginary part of the coordinates in the complex plane ζ, ζ=ξ+iη; The restoring potential for planar stagnation flow in the ζ(ξ,η) plane is: In the formula, F(ζ) is the reset potential of the flow, φ(ζ) is the potential function in the reset potential of the flow, and ψ(ζ) is the stream function in the reset potential of the flow. Using transformation Convert the flow's reset potential into In the formula, The z-reset potential of the complex plane; Differentiating the transformed reset potential, we get In the formula, Let be the derivative of the reset potential, and u and v be the horizontal and vertical velocities in the complex plane z, respectively. Based on the restoring potential obtained by differentiation, the initial velocity expression of the gust flow over the parabolic surface of the airfoil's leading edge is determined as follows: Substituting the parabolic equation into the initial velocity expression, the final velocity expression of the gust flow over the parabolic surface of the airfoil's leading edge is obtained as follows:

6. The method for sensing gust flow field based on surface pressure according to claim 4, characterized in that, When the airfoil of an aircraft wing is an asymmetric airfoil, the parabolic flow model around the leading edge of the airfoil is as follows: In the formula, λ is the tangent of the angle θ of the parabola's central axis deflection, λ=tanθ.

7. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, Establish the relationship between the x-coordinate of the station location and the effective angle of attack of the incoming flow, specifically including: Before the airfoil stalls, the relationship between the x-coordinate of the stagnation point and the effective angle of attack of the incoming flow is: x s =ctan 2 α; where x s Let x be the x-coordinate of the stagnation point, α be the effective angle of attack of the incoming flow, and c be the airfoil chord length; When airfoil stalls or nonlinear separation occurs, a lookup table relationship between the stagnation point position x-coordinate and the effective angle of attack of the incoming flow is established through experiments or CFD simulation. Nonlinear interpolation is then used to construct a relationship model between the stagnation point position x-coordinate and the effective angle of attack of the incoming flow.

8. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, The residual function between the measured pressure and the fitted pressure is: ε j =P j -F j (x j ,U ∞ ,A,a'); In the formula, S is the residual value between the measured pressure and the fitted pressure, and ε j To measure pressure at position x j The difference between the measured pressure and the fitted pressure at point P j For dynamic pressure sensors at pressure measurement position x j The pressure measured at F j (x j U ∞ ,A,a') represents the pressure measurement position x j Fitted pressure at point U ∞ Let A be the incoming confluence velocity, A be the first-order multiplier, and a' be an intermediate parameter. β is the coordinate position of the stationary point on the complex plane ξ, and r is the leading edge radius of the airfoil.

9. The method for sensing gust flow field based on surface pressure according to claim 8, characterized in that, Based on the measured pressure from the current flow sensing and the currently fitted pressure from the parabolic flow model around the airfoil's leading edge, and using the residual function, a nonlinear least squares method is employed to obtain the current incoming confluence velocity and the current stagnation point position's abscissa, specifically including: The dynamic pressure sensor measures the pressure at two points on the leading edge of the airfoil corresponding to the same chord direction coordinate, and the side with the larger measured pressure is determined as the stagnation side, and the side with the smaller measured pressure is determined as the suction side. Based on the measured pressure of the current flow sensing at the stagnation point and the current fitted pressure of the parabolic flow model around the airfoil leading edge, the current incoming flow velocity and the current intermediate parameters are obtained by fitting the residual function using the nonlinear least squares method. Based on the measured pressure of the current flow sensing on the suction side and the current fitted pressure of the parabolic flow model around the airfoil leading edge, the current first multiplier is obtained by fitting the residual function using the nonlinear least squares method. Use the square of the current intermediate parameter as the x-coordinate of the current stationary point position.

10. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that, The current horizontal velocity of the incoming gust is: u x =U′ ∞ cosα′; In the formula, u x U′ is the horizontal velocity of the current gust flow. ∞ α' is the current incoming flow velocity, and α′ is the current effective angle of attack of the incoming flow; The current vertical velocity of the incoming gust is: v y =U′ ∞ sinα′; In the formula, v y This represents the vertical velocity of the current gust of wind.

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