Gust flow field sensing method based on surface pressure

Abstract

The invention discloses a gust flow field sensing method based on surface pressure, and relates to the field of gust flow field sensing. According to the method, an airfoil front edge parabola is fitted, and an airfoil front edge parabola streaming model is determined; establishing a relationship between a stationary point position abscissa and an incoming flow effective attack angle; constructing a residual function between the measured pressure intensity and the fitting pressure intensity; dynamic pressure sensors distributed on the surface of an aircraft wing are used for conducting flow sensing on the current gust flow field, and meanwhile, a wing section front edge parabola streaming model is adopted for fitting the flow of the current gust flow field; according to the measurement pressure intensity and the fitting pressure intensity, based on a residual function, a nonlinear least square method is adopted, and the current incoming flow resultant velocity and the current stationary point position abscissa are obtained; and calculating the effective attack angle of the current incoming flow, the horizontal speed and the vertical speed of the current gust incoming flow and the frequency of the current gust. According to the invention, different sections and unsteady flow parameters of aircraft wings can be measured and sensed.

Description

Technical Field

[0001] The present application relates to the field of gust flow field perception, and in particular to a gust flow field perception method based on surface pressure. Background Art

[0002] Aircraft may sometimes encounter gusts of wind during flight. These irregular and drastically changing airflows may cause sudden changes in loads on aircraft, thus posing safety risks. Therefore, researchers have conducted extensive research on the response of aircraft to gusts, an important part of which is the perception of gusts. Obtaining the flow parameters on the wing surface plays a vital role in studying the force characteristics and laws of the wing under gust flow fields. These flow parameters can be used as a reference for aircraft load feedback or feedforward control.

[0003] In the past few decades, many technologies and methods for sensing flow field parameters have been developed, such as pitot tubes, multi-hole probes, embedded atmospheric sensing systems on fighter jets, etc. The above 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 local flow areas, but it is difficult to take into account the different cross-sections of the aircraft wing, which leads to incomplete perception of flow information. In addition, for unsteady flow phenomena in gust flow fields, the response speed of previous measurement methods may not be able to fully resolve the velocity fluctuations in the flow, which in turn leads to distortion of flow information, which has an adverse effect on mastering the regular characteristics of such flows. Summary of the invention

[0004] The purpose of this application is to provide a gust flow field sensing method based on surface pressure, 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 solutions:

[0006] The present application provides a gust flow field sensing method based on surface pressure, comprising: fitting the airfoil leading edge shape of an aircraft wing using a parabola to obtain the airfoil leading edge parabola; determining the airfoil leading edge parabola flow around model based on the airfoil leading edge parabola; establishing a relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow; constructing a residual function between the measured pressure and the fitted pressure; using a dynamic pressure sensor distributed on the surface of the aircraft wing to sense the current gust flow field, and using the airfoil leading edge parabola flow around model to fit the flow of the current gust flow field; according to the current The measured pressure sensed by the front flow and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil are used, based on the residual function, and the nonlinear least squares method is used to obtain the current incoming flow combined velocity and the current stagnation point position horizontal coordinate; according to the current stagnation point position horizontal coordinate, the relationship between the stagnation point position horizontal coordinate and the effective angle of attack of the incoming flow is used to obtain the current effective angle of attack of the incoming flow; the current incoming flow combined velocity is decomposed according to the current effective angle of attack of the incoming flow to obtain the horizontal velocity and vertical velocity of the current gust of wind; the horizontal velocity and vertical velocity of the current gust of wind are subjected to spectrum analysis to obtain the frequency of the current gust of wind.

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

[0008] The present application provides a gust flow field perception method based on surface pressure, which performs flow perception of the gust flow field through dynamic pressure sensors distributed on the surface of the aircraft wing, and utilizes the measured pressure of the flow perception and the fitting pressure of the parabolic flow model around the leading edge of the airfoil to effectively perceive and estimate the horizontal velocity, vertical velocity, effective angle of attack of the gust flow and the stagnation point position of the leading edge of the wing, thereby realizing the measurement perception of different cross-sections of the aircraft wing and unsteady flow parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 This is a flow chart of a method for sensing a gust flow field based on surface pressure in one embodiment of the present application;

[0011] Figure 2 A schematic diagram of geometric parameters of an airfoil leading edge provided in another embodiment of the present application;

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

[0013] Figure 4 A schematic diagram of CLARKY airfoil fitting provided in another embodiment of the present application;

[0014] Figure 5 A schematic diagram of flow transformation provided in another embodiment of the present application;

[0015] Figure 6 A schematic diagram of a nonlinear fitting process provided by another embodiment of the present application. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0018] In an exemplary embodiment, Figure 1 As shown, this embodiment provides a gust flow field sensing method based on surface pressure, including the following steps 101 to 109. Among them:

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

[0020] Step 102: determining a parabolic flow model around the leading edge of the airfoil according to the leading edge parabola of the airfoil;

[0021] Step 103: establishing a relationship between the horizontal coordinate of the stationary point position and the effective angle of attack of the incoming flow;

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

[0023] Step 105: using dynamic pressure sensors distributed on the wing surface of the aircraft to sense the current gust flow field, and using the parabolic flow model around the leading edge of the airfoil to fit the flow of the current gust flow field;

[0024] Step 106: according to the measured pressure sensed by the current flow and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil, based on the residual function, a nonlinear least square method is used to obtain the current incoming flow combined velocity and the current stagnation point position abscissa;

[0025] Step 107: according to the current horizontal coordinate of the stationary point position, using the relationship between the horizontal coordinate of the stationary point position and the effective angle of attack of the incoming flow, obtain the current effective angle of attack of the incoming flow;

[0026] Step 108: Decompose the current combined velocity of the incoming flow according to the current effective angle of attack of the incoming flow to obtain the horizontal velocity and vertical velocity of the current gust of wind;

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

[0028] Implementing the above-mentioned steps 101 to 109, inspired by the distributed "receptors" of bird feathers, the method of the present application will perform flow perception on the gust flow field based on dynamic pressure sensors distributed on the wing surface, and use the distributed pressure measurement physical parameters to fit the mathematical model, so as to effectively perceive and estimate the vertical velocity of the gust flow, the local angle of attack of each section of the wing, and the position of the stagnation point of the leading edge of the wing, thereby making up for the shortcomings of existing perception and measurement methods.

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

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

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

[0032] Step 203: traverse the airfoil leading edge radius r, 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 the present application, when the airfoil of the aircraft wing is an asymmetric airfoil, the above step 101 is replaced by the following steps 301 to 304:

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

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

[0037] Step 303: traverse the airfoil leading edge radius r, 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 parabola equation to obtain the airfoil leading edge parabola.

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

[0040] (1) Symmetrical airfoil

[0041] For a symmetrical airfoil, the leading edge shape parameter is only the leading edge radius r, and the upper and lower symmetrical curvature of the airfoil is 0, so there is no need to set the θ value. The process of determining the r parameter is as follows:

[0042] Compare the generated parabola with the coordinates of the airfoil leading edge where x / c<5% to establish a deviation function Where p and a represent parabola and airfoil respectively.

[0043] Iterate the r value within a certain range with a sufficiently small step size to minimize the value of the delta function. Figure 3 The approximate fitting effect is given. Figure 3 NACA0015 is the NACA four-digit airfoil number.

[0044] (2) Asymmetric airfoil

[0045] For an asymmetric airfoil, a pilot step needs to be added, that is, the parabola is rotated by θ=α0 according to the zero lift angle of attack α0 of the airfoil. The calculation method of the r value after rotation is consistent with that of the symmetric airfoil. Figure 4 The fitting diagram of CLARKY airfoil is given.

[0046] In another exemplary embodiment of the present application, the flow around the leading edge of the airfoil can be regarded as the flow around the parabola, and the parabola equation is used to fit the leading edge of the airfoil x / c < 5%. When the free flow flows through the parabola at a certain angle of attack, there is a stagnation point and a corresponding suction point on the surface of the parabola. 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 flow passing through the parabolic surface of the airfoil leading edge: Where U is the velocity of the gust flow passing through the parabolic surface of the leading edge of the airfoil, x is the horizontal coordinate of the parabola of the leading edge of the airfoil, β is the coordinate position of the stagnation point on the complex plane ξ, and r is the radius of the leading edge of the airfoil.

[0048] Step 402: Order Then the ratio of the velocity of the gust flow passing through the parabolic surface of the airfoil leading edge to the combined velocity of the gust flow is expressed as: In the formula, a' is the intermediate parameter, U ∞ is the combined velocity of the incoming flow, and A is the first-order multiplier.

[0049] Step 403: According to the ratio expression and the pressure coefficient expression Cp=1-(U / U ∞ ) 2 , obtain the coordinates of the maximum pressure point when the pressure coefficient is 1, and use it as the stationary point coordinates Where Cp is the pressure coefficient, x stag is the horizontal coordinate of the stationary point, y stag is the vertical coordinate of the stationary point.

[0050] Step 404: Based on the ratio expression and the suction peak pressure expression The suction peak coordinates are obtained as In the formula, Cp ，peak is the peak suction pressure, x peak is the horizontal coordinate of the suction peak, y peak is the vertical coordinate of the suction peak.

[0051] Step 405: Establish the difference formula between the parabola surface pressure and the incoming flow pressure: Where P is the surface pressure of the parabola, P ∞ 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 leading edge of the airfoil:

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

[0054] Step 501: Use the conformal transformation method to transform the parabolic flow in the z (x, y) plane into a planar stagnation point flow in the ζ (ξ, η) plane; wherein x is the coordinate of the airfoil leading edge parabola in the horizontal direction, y is the coordinate of the airfoil leading edge parabola in the vertical direction, ξ is the value of the real part of the coordinate in the complex plane ζ, η is the value of the imaginary part of the coordinate 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, as Figure 5 shown. Figure 5 Part (a) shows the planar stagnation point flow in the ζ(ξ,η) plane. Figure 5 Part (b) in FIG. 5 shows the parabolic flow in the z(x,y) plane.

[0056] Step 502: Establish the reset potential of the planar stagnation point flow in the ζ(ξ,η) plane as: Where 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 reset potential of the flow into In the formula, is the reset potential in the complex plane z.

[0058] Step 504: Derivative the converted reset potential to obtain In the formula, is the derivative of the reset potential, u and v are the horizontal velocity and the vertical velocity in the complex plane z, respectively. i in the formulas of the above steps 501 to 504 is a complex number.

[0059] Step 505: According to the reset potential obtained by derivation, the initial velocity expression of the gust flow passing through the parabolic surface of the airfoil leading edge is determined as:

[0060] Step 506: Substitute the parabola equation into the initial velocity expression to obtain the final velocity expression of the gust flow passing through the parabola surface of the leading edge of the airfoil:

[0061] The above steps 401 to 406 and 501 to 506 are for the parabolic equation of the centerline level. This situation corresponds to a symmetrical airfoil. When the airfoil has curvature, the parabolic equation should be rewritten as This will produce a rotation effect on the parabola, where λ = tanθ. That is, when the airfoil of the aircraft wing is an asymmetric airfoil, the parabolic flow model around the leading edge of the airfoil is:

[0062]

[0063] Where λ is the tangent value of the deflection angle θ of the central axis of the parabola, λ = tanθ.

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

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

[0066] When the airfoil stalls or experiences nonlinear separation, a lookup table relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow is established through experiments or CFD calculation simulation methods, and a relationship model between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow is constructed using nonlinear interpolation.

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

[0068]

[0069] ε j =P j -F j (x j ,U ∞ ,A,a')

[0070] Where S is the residual value between the measured pressure and the fitted pressure, ε j is the pressure measuring position x j The difference between the measured pressure and the fitted pressure at j is the dynamic pressure sensor at the pressure measuring position x j The measured pressure at j (x j ,U ∞,A,a') is the pressure measurement position x j The fitting pressure at ∞ is the combined velocity of the incoming flow, A is the first-order multiplier, a' is the 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 the present application, after confirming the parabolic flow model around the leading edge of the airfoil, it is necessary to use the parabolic flow model around the leading edge of the airfoil to fit the real flow. The fitting process will confirm three unknown quantities U ∞ ,A,a'. Nonlinear fitting is divided into fitting on the stagnation point side and fitting on the suction side. Using different parameters on both sides can obtain better estimation accuracy. Figure 6 As shown, the specific implementation process of the above step 106 is as follows: Steps 601 to 604:

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

[0073] Step 602: According to the measured pressure sensed by the current flow at the stagnation point side and the current fitted pressure of the parabolic flow model around the leading edge of the airfoil, based on the residual function, a nonlinear least squares method is used to fit the current incoming flow velocity and the current intermediate parameters.

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

[0075] Step 604: The square of the current intermediate parameter is used as the horizontal coordinate of the current stationary point position.

[0076] The general process of using the nonlinear least squares method is as follows: when making an estimate, the initial values ​​U0, A0, a'0 are given first, and x is the chord direction coordinate of the airfoil to be entered, thereby obtaining an estimated value. The nonlinear least squares algorithm can be used to perform gradient-based iteration based on the constructed residual function. The initial values ​​of the iteration are the above-mentioned U0, A0, a'0, and finally the U0 that conforms to the real physical flow is obtained. ∞ ,A,a', the solution is completed.

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

[0078] u x =U′ ∞ cosα′

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

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

[0081] v y =U′ ∞ sinα′

[0082] In the formula, v y is the vertical velocity of the current gust flow.

[0083] The current incoming flow combined velocity and the current stagnation point position abscissa parameters are obtained by regression in step 106, where the abscissa of the stagnation point position x s =a' 2 , and then from the relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow, that is, α=f(x s ), where f(x s ) represents the relationship between the stagnation point position and the angle of attack, which can be used to calculate the combined velocity U′ of the incoming flow. ∞ Decompose to get u x =U′ ∞ cosα′,v y =U′ ∞ sinα′, thereby sensing the gust flow speed, and further recording u x and v y The time series data can be subjected to spectrum analysis to obtain the frequency of gusts.

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

[0085] 1. This method senses the vertical velocity of the gust flow, the change of the leading edge stagnation point of the wing section with the gust of wind, and other information through the distributed pressure measurement on the wing surface. This makes up for the problems that traditional sensing and measurement methods cannot measure multiple sections and cannot perceive unsteady flow parameters.

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

[0087] 3. This method has strong universality and can be used in various airfoils and most gust flow conditions.

[0088] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A gust flow field sensing method based on surface pressure, characterized in that: include: Using a parabola to fit the leading edge shape of an aircraft wing, the leading edge parabola of the airfoil is obtained; According to the airfoil leading edge parabola, a parabolic flow model of the airfoil leading edge is determined; Establish the relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow; Constructing a residual function between the measured pressure and the fitted pressure; The current gust flow field is sensed by using dynamic pressure sensors distributed on the wing surface of the aircraft, and the parabolic flow around the leading edge of the airfoil is used to fit the flow of the current gust flow field; According to the measured pressure sensed by the current flow and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil, based on the residual function, a nonlinear least square method is used to obtain the current incoming flow combined velocity and the current stagnation point position abscissa; According to the current horizontal coordinate of the stationary point position, the current effective angle of attack of the incoming flow is obtained by utilizing the relationship between the horizontal coordinate of the stationary point position and the effective angle of attack of the incoming flow; Decompose the current combined velocity of the incoming flow according to the current effective angle of attack of the incoming flow to obtain the horizontal velocity and vertical velocity of the current gust of wind; Perform spectrum analysis on the horizontal and vertical velocities of the current gust flow to obtain the frequency of the current gust.

2. The method for sensing gust flow field based on surface pressure according to claim 1, characterized in that: When the airfoil of the aircraft wing is a symmetrical airfoil, a parabola is used to fit the leading edge shape of the airfoil of the aircraft wing to obtain the leading edge parabola of the airfoil, specifically including: The parabolic equation for fitting the leading edge shape of the aircraft wing is: In the formula, y0 is the vertical coordinate of the parabola, x0 is the horizontal coordinate of the parabola, and r is the leading edge radius of the airfoil; The deviation function between the leading edge of the airfoil and the parabola in the region of x' / c'<5% is established as: In the formula, x' is the distance along the chord length of the airfoil, c' is the standardized parameter, and δ is the deviation value. is the vertical coordinate of the i-th point on the parabola, is the vertical coordinate of the ith point on the leading edge of the airfoil, and N is the number of points in the region of x' / c'<5% on the leading edge of the airfoil; Traversing the airfoil leading edge radius r, obtaining the airfoil leading edge radius that minimizes the deviation value in the deviation function, and determining it as the airfoil leading edge shape parameter; Substitute the airfoil leading edge shape parameters into the parabola equation to obtain 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 the airfoil of the aircraft wing is an asymmetric airfoil, a parabola is used to fit the leading edge shape of the airfoil of the aircraft wing to obtain the leading edge parabola of the airfoil, which specifically includes: The equation is The parabola of is rotated at zero lift angle of attack to obtain a parabola fitting the leading edge shape of the aircraft wing; where y0 is the vertical coordinate of the parabola, x0 is the horizontal coordinate of the parabola, and r is the leading edge radius of the airfoil; The deviation function between the leading edge of the airfoil and the parabola in the region of x' / c'<5% is established as: In the formula, x' is the distance along the chord length of the airfoil, c' is the standardized parameter, and δ is the deviation value. is the vertical coordinate of the i-th point on the parabola, is the vertical coordinate of the ith point on the leading edge of the airfoil, and N is the number of points in the region of x' / c'<5% on the leading edge of the airfoil; Traversing the airfoil leading edge radius r, obtaining the airfoil leading edge radius that minimizes the deviation value in the deviation function, and determining it as the airfoil leading edge shape parameter; Substitute the airfoil leading edge shape parameters into the fitted parabola 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 the aircraft wing is a symmetrical airfoil, the parabola flow around the leading edge of the airfoil is determined according to the leading edge parabola of the airfoil, specifically including: The velocity expression for determining the gust flow passing through the parabolic surface of the leading edge of the airfoil is: Where U is the velocity of the gust flow passing through the parabolic surface of the airfoil leading edge, x is the horizontal coordinate of the parabola of the airfoil leading edge, β is the coordinate position of the stationary point on the complex plane ξ, and r is the radius of the airfoil leading edge; make Then the ratio of the velocity of the gust flow passing through the parabolic surface of the airfoil leading edge to the combined velocity of the gust flow is expressed as: In the formula, a' is the intermediate parameter, U ∞ is the combined velocity of the incoming flow, A is the first-order multiplier; According to the ratio expression and pressure coefficient expression Cp = 1-(U / U ∞ ) 2 , obtain the coordinates of the maximum pressure point when the pressure coefficient is 1, and use it as the stationary point coordinates Where Cp is the pressure coefficient, x stag is the horizontal coordinate of the stationary point, y stag is the ordinate of the stationary point; According to the ratio expression and the suction peak pressure expression The suction peak coordinates are obtained as In the formula, Cp ，peak is the peak suction pressure, x peak is the horizontal coordinate of the suction peak, y peak is the ordinate of the suction peak; The formula for the difference between the parabola surface pressure and the incoming flow pressure is: Where P is the surface pressure of the parabola, P ∞ is the atmospheric pressure at infinity, ρ is the air density; Substituting the difference formula into the ratio expression, the parabolic flow model around the leading edge of the airfoil 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 determining the gust flow passing through the parabolic surface of the leading edge of the airfoil is: Specifically include: The parabola flow in the z(x,y) plane is transformed into a planar stagnation point flow in the ζ(ξ,η) plane using the conformal transformation method; wherein x is the horizontal coordinate of the parabola of the leading edge of the airfoil, y is the vertical coordinate of the parabola of the leading edge of the airfoil, ξ is the value of the real part of the coordinate in the complex plane ζ, η is the value of the imaginary part of the coordinate in the complex plane ζ, ζ=ξ+iη; The reset potential of the planar stagnation point flow in the ζ(ξ,η) plane is established as: Where 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 reset potential of the flow into In the formula, is the complex plane z reset potential; Taking the derivative of the converted reset potential, we get In the formula, is the derivative of the reset potential, u and v are the horizontal and vertical velocities in the complex plane z, respectively; According to the reset potential obtained by derivation, the initial velocity expression of the gust flow passing through the parabolic surface of the leading edge of the airfoil is determined as: Substituting the parabola equation into the initial velocity expression, the final velocity expression of the gust flow flowing over the parabolic surface of the leading edge of the airfoil 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: Where λ is the tangent value of the deflection angle θ of the central axis of the parabola, 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 horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow, including: Before the airfoil stalls, the relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow is: s =ctan 2 α; where x s is the horizontal coordinate of the stagnation point position, α is the effective angle of attack of the incoming flow, and c is the chord length of the airfoil; When the airfoil stalls or experiences nonlinear separation, a lookup table relationship between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow is established through experiments or CFD calculation simulation methods, and a relationship model between the horizontal coordinate of the stagnation point position and the effective angle of attack of the incoming flow is constructed using nonlinear interpolation.

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'); Where S is the residual value between the measured pressure and the fitted pressure, ε j is the pressure measuring position x j The difference between the measured pressure and the fitted pressure at j is the dynamic pressure sensor at the pressure measuring position x j The measured pressure at j (x j ,U ∞ ,A,a') is the pressure measurement position x j The fitting pressure at ∞ is the combined velocity of the incoming flow, A is the first-order multiplier, a' is the 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: According to the measured pressure of the current flow perception and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil, based on the residual function, a nonlinear least squares method is used to obtain the current incoming flow combined velocity and the current stagnation point position abscissa, specifically including: Obtain the measured pressure of two points on the leading edge of the airfoil corresponding to the same chord direction coordinates of the dynamic pressure sensor, and determine the side with a larger measured pressure as the stagnation side, and determine the side with a smaller measured pressure as the suction side; According to the measured pressure of the current flow perception at the stagnation point side and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil, based on the residual function, a nonlinear least squares method is used to fit and obtain the current incoming flow combined velocity and the current intermediate parameters; According to the measured pressure of the current flow perception on the suction side and the current fitting pressure of the parabolic flow model around the leading edge of the airfoil, a current first-order multiplier is obtained by fitting based on the residual function and using a nonlinear least squares method; The square of the current intermediate parameter is used as the horizontal 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 horizontal velocity of the current gust flow is: u x =U′ ∞ cosα′; In the formula, u x is the horizontal velocity of the current gust flow, U′ ∞ is the current combined velocity of the incoming flow, α′ is the current effective angle of attack of the incoming flow; The vertical velocity of the current gust flow is: v y =U′ ∞ sinα′; In the formula, v y is the vertical velocity of the current gust flow.

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