CN117094077A - Airfoil optimization method based on transonic aeroelastic analysis - Google Patents
Airfoil optimization method based on transonic aeroelastic analysis Download PDFInfo
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Abstract
The invention discloses an airfoil optimization method based on transonic aeroelastic analysis, which sequentially carries out engineering flutter rapid prediction of airfoils, flutter boundary speed obtained by a flutter prediction method of transonic aerodynamic force correction, and time domain flutter prediction based on CFD and modal coupling; and each step is respectively subjected to flutter safety evaluation, if the flutter safety evaluation does not pass, the airfoil shape and the structural scheme are re-optimized, and the steps are circulated until the three steps meet the flutter safety evaluation. The invention can fully consider the nonlinearity of the aerodynamics of the airfoil in the transonic section, gradually predict and analyze the flutter boundary speed of the airfoil in the transonic section, and optimize the appearance scheme and the structural scheme of the airfoil by taking the flutter boundary speed as a reference. According to the method, the flutter analysis result of the steady aerodynamic force correction is used as a reference, the time domain flutter prediction based on the coupling of the CFD and the modal method is performed, the calculation range is reduced, the calculation accuracy is ensured, the calculation efficiency is considered, and the engineering practicability is high.
Description
Technical Field
The invention belongs to the technical field of aircraft airfoil design, and particularly relates to an airfoil optimization method based on transonic aeroelastic analysis.
Background
Aeroelastic design is a key aspect of aircraft development and retrofitting. Flutter analysis is a major problem in dynamic aero-elastic analysis. The airfoil often experiences a decrease in flutter velocity in the transonic region, which is the most serious region of aeroelastic stability. Nonlinear factors such as transonic speed, large deformation and the like complicate corresponding calculation analysis and physical mechanism, so that the research of the unfolded nonlinear aeroelastic calculation method is a hot spot of the current research.
However, in the aircraft aeroelastic design process, parameters of the aircraft may face multiple rounds of optimization, so that multiple rounds of flutter analysis are required, and a calculation result of the flutter analysis needs enough precision to ensure reliability of the aircraft, and a high-precision transonic flutter analysis often needs a relatively long calculation period. An airfoil aeroelastic design standard flow capable of efficiently performing transonic aerodynamic analysis is lacking to meet engineering design requirements.
Disclosure of Invention
The invention aims to provide an airfoil optimization method based on transonic aeroelastic analysis, and aims to solve the problems.
The invention is realized mainly by the following technical scheme:
an airfoil optimization method based on transonic aeroelastic analysis comprises the following steps:
step A: according to the profile and the structural scheme of the airfoil and modal information provided by an airfoil ground test, carrying out engineering flutter rapid prediction on the airfoil to obtain flutter boundary speeds under various working conditions; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation passes, entering a step B, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
and (B) step (B): on the basis of rapid prediction of engineering flutter of the airfoil, a flutter prediction method of transonic aerodynamic force correction is adopted to predict the flutter boundary speed of a transonic section; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation is passed, entering a step C, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
step C: on the basis of the flutter boundary speed obtained by the flutter prediction method of the transonic aerodynamic correction, carrying out time domain flutter prediction based on CFD and modal coupling; comparing the flutter safety assessment with the flight envelope determined in the design stage; and (3) outputting a final scheme if the flutter safety evaluation passes, otherwise, re-entering the step A, optimizing the profile and structure scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil.
In order to better implement the present invention, further, the method for predicting the flutter of transonic aerodynamic correction in the step B includes the following steps:
step B1: dispersing the airfoil structure into finite elements, solving a undamped free vibration motion equation, and obtaining the modal information of each order of the airfoil by a generalized coordinate transformation method and intercepting the finite order modes;
step B2: dividing an unsteady aerodynamic grid according to the aerodynamic shape of the airfoil, wherein the unsteady aerodynamic grid is a plurality of trapezoid grids with two side edges parallel to incoming flow;
step B3: determining unsteady aerodynamic force distribution on the aerodynamic block by solving a basic equation;
step B4: performing steady aerodynamic force correction, and solving the unsteady aerodynamic force of the airfoil:
firstly, solving through CFD to obtain the distribution of pressure coefficients of the upper surface and the lower surface of the airfoil under the selected dynamic pressure; interpolating the pressure coefficient distribution of the upper surface and the lower surface of the airfoil to the grid center point of the unsteady aerodynamic grid of the airfoil by an interpolation method; solving a transonic small disturbance equation by an equivalent slice theory, so that the airfoil section generates steady pressure distribution matched with the input steady pressure distribution; the pressure coefficient of the profile is obtained by decomposing the unsteady transonic small disturbance equation, and then the unsteady pressure coefficient is used for correction, so that the linear unsteady pressure which can consider transonic shock wave effect or other nonlinear effects is calculated, and the airfoil unsteady aerodynamic force is obtained;
step B5: and B4, carrying out flutter calculation by the p-k method by taking the airfoil unsteady aerodynamic force in the step into a flutter equation of the p-k method.
In order to better implement the present invention, further, in the step B1, a mode superposition method is adopted to represent the physical displacement of the elastic vibration of the structure as a linear combination of several main modes:
wherein f ij The j-th order natural mode of the i-th node,
q j for the j-th generalized coordinate,
m is the number of modes selected and is,
thus obtaining the modal information of each order of the airfoil.
In order to better implement the present invention, further, in the step B3, as known from the linear unsteady aerodynamic theory, the following integral equation should be satisfied for each lattice at 3/4 chord length point:
wherein V is the vibration speed,
ρ is the density of the fluid,
ω i for the wash down speed at the 3/4 chord point of the ith network,
Δc pj for the pressure coefficient on the j-th grid,
Δx j for the middle section length of the jth grid,
for the sweep angle of the j-th grid,
K ij a kernel function is calculated for the aerodynamic force,
l j for the extension of the jth grid past 1/4 chord point,
n is the number of aerodynamic grid segments of the lifting surface.
In order to better implement the present invention, further, in the step B5, the flutter equation of the p-k method is:
where p=ω (γ+i), ω is a circular frequency, γ is an attenuation rate, and i is an imaginary unit;
m is generalized quality diagonal matrix diag (M) 11 ,…,m mm )；
b is the reference half chord length;
v is the flying speed;
a is a generalized aerodynamic force influence coefficient matrix;
k is the generalized stiffness diagonal matrix diag (K) 11 ,…,k mm )；
k is the reduction frequency, k=ωb/V;
independent of time t, is the magnitude vector of the modal coordinates.
To better implement the present invention, further, the CFD and modal coupling-based time domain chatter prediction in the step C includes the steps of:
step C1: dividing a fluid grid, and inputting all-order modal information of the airfoil surface;
step C2: unifying the physical quantities established in different point systems to the same point system by adopting an interpolation technology, and interpolating the airfoil surface each-order modal information of the structural grid node system into a fluid grid by adopting a Thin Plate Spline (TPS) method;
step C3: and C, determining a solved speed range according to the predicted flutter boundary speed of the transonic section in the step B, and evaluating the flutter speed of the airfoil through fluid-solid coupling solution.
In order to better implement the invention, further, the chatter safety assessment meets design requirements by providing a chatter margin.
The beneficial effects of the invention are as follows:
(1) Aiming at the transonic flutter of the airfoil, the nonlinear of the unsteady aerodynamic force of the airfoil in the transonic section can be fully considered, the flutter boundary speed of the airfoil in the transonic section can be gradually predicted and analyzed, and the profile scheme and the structural scheme of the airfoil are optimized by taking the flutter boundary speed as a reference;
(2) According to the method, the flutter analysis result of the steady aerodynamic force correction is used as a reference, the time domain flutter prediction based on the coupling of the CFD and the modal method is carried out, the calculation range of a high calculation cost method is reduced, the calculation accuracy is ensured, the calculation efficiency is considered, and the engineering practicability is strong;
(3) According to the flight envelope requirement of the aircraft aeroelastic design, the invention constructs an aeroelastic design flow for transonic wing surfaces. By applying the airfoil transonic aeroelastic design flow, nonlinearity of airfoil transonic aerodynamic force can be considered, the calculation range of a high calculation cost method is reduced, the calculation accuracy is ensured, the calculation efficiency is considered, and the engineering practicability is high. The invention can efficiently analyze transonic flutter characteristics of the airfoil, shorten the design period and reduce the cost.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a functional block diagram of a method of flutter prediction for transonic aerodynamic correction;
fig. 3 is a functional block diagram of a method of flutter prediction for transonic aerodynamic correction.
Wherein: 1-unsteady aerodynamic grids, 2-airfoil each-order modal information, 3-unsteady aerodynamic, 4-p-k method flutter calculation, 5-CFD solving, 6-airfoil upper and lower surface pressure coefficient distribution, 7-equivalent slice theory, 8-divided fluid grids, 9-fluid-solid coupling solving and 101-conventional flutter analysis.
Detailed Description
Example 1:
an airfoil optimization method based on transonic aeroelastic analysis, as shown in FIG. 1, comprises the following steps:
step A: according to the profile and the structural scheme of the airfoil and modal information provided by an airfoil ground test, carrying out engineering flutter rapid prediction on the airfoil to obtain flutter boundary speeds under various working conditions; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation passes, entering a step B, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
and (B) step (B): on the basis of rapid prediction of engineering flutter of the airfoil, a flutter prediction method of transonic aerodynamic force correction is adopted to predict the flutter boundary speed of a transonic section; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation is passed, entering a step C, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
step C: on the basis of the flutter boundary speed obtained by the flutter prediction method of the transonic aerodynamic correction, carrying out time domain flutter prediction based on CFD and modal coupling; comparing the flutter safety assessment with the flight envelope determined in the design stage; and (3) outputting a final scheme if the flutter safety evaluation passes, otherwise, re-entering the step A, optimizing the profile and structure scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil.
Preferably, as shown in fig. 2, the method for predicting the tremor of the transonic aerodynamic correction in the step B includes the following steps:
step B1: dispersing the airfoil structure into finite elements, solving a undamped free vibration motion equation, and obtaining airfoil mode information 2 of each step by intercepting a finite-order mode through a generalized coordinate transformation method;
step B2: dividing an unsteady aerodynamic grid 1 according to the aerodynamic shape of the airfoil, wherein the unsteady aerodynamic grid 1 is a plurality of trapezoid grids with two side edges parallel to incoming flow;
step B3: determining the distribution of unsteady aerodynamic forces 3 on the aerodynamic blocks by solving a basic equation;
step B4: performing steady aerodynamic force correction, and solving the airfoil unsteady aerodynamic force 3:
firstly, solving 5 through CFD to obtain the pressure coefficient distribution 6 of the upper and lower surfaces of the airfoil under the selected dynamic pressure; interpolating the pressure coefficient distribution 6 of the upper surface and the lower surface of the airfoil to the grid center point of the unsteady aerodynamic grid 1 of the airfoil by an interpolation method; solving a transonic small disturbance equation through an equivalent slice theory 7, so that the airfoil section generates constant pressure distribution matched with the input constant pressure distribution; the pressure coefficient of the profile is obtained by decomposing the unsteady transonic small disturbance equation, and then the unsteady pressure coefficient is used for correction, so that the linear unsteady pressure which can consider transonic shock wave effect or other nonlinear effects is calculated, and the airfoil unsteady aerodynamic force 3 is obtained;
step B5: and B4, carrying out p-k method flutter calculation 4 by taking the airfoil unsteady aerodynamic force 3 into a p-k method flutter equation.
Preferably, as shown in fig. 3, the CFD and modal coupling-based time domain chatter prediction in the step C includes the steps of:
step C1: dividing a fluid grid 8, and inputting all-order modal information 2 of the airfoil;
step C2: unifying the physical quantities established in different point systems to the same point system by adopting an interpolation technology, and interpolating the airfoil surface each-order modal information 2 of the structural grid node system into a fluid grid by adopting a Thin Plate Spline (TPS) method;
step C3: and C, determining a solved speed range according to the predicted flutter boundary speed of the transonic speed section in the step B, and evaluating the flutter speed of the airfoil through fluid-solid coupling solution 9.
Aiming at the transonic flutter of the airfoil, the nonlinear of the unsteady aerodynamic force 3 of the airfoil in the transonic section can be fully considered, the flutter boundary speed of the airfoil in the transonic section can be predicted and analyzed gradually, and the profile scheme and the structural scheme of the airfoil are optimized by taking the nonlinear into consideration. According to the method, the flutter analysis result of the steady aerodynamic force correction is used as a reference, the time domain flutter prediction based on the coupling of the CFD and the modal method is carried out, the calculation range of a high calculation cost method is reduced, the calculation accuracy is ensured, the calculation efficiency is considered, and the engineering practicability is high.
Example 2:
an airfoil optimization method based on transonic aeroelastic analysis, as shown in FIG. 1, comprises the following steps:
and A, carrying out engineering flutter quick estimation on the airfoil according to the airfoil shape and structure scheme and modal information provided by an airfoil ground test to obtain flutter boundary speeds under various working conditions. And comparing the flutter safety assessment with the flight envelope determined in the design stage. And if the flutter margin meets the design requirement, entering the step B. And (3) if the flutter margin is insufficient, optimizing the profile and the structural scheme of the airfoil, and re-entering the engineering flutter of the airfoil in the step (A) for quick estimation.
And B, on the basis of rapid prediction of engineering flutter of the airfoil, predicting the flutter boundary speed of the transonic section by adopting a flutter prediction method of transonic aerodynamic force correction. And comparing the flutter safety assessment with the flight envelope determined in the design stage. And C, if the flutter margin meets the design requirement, entering a step C. If the flutter margin is insufficient, the profile and the structural scheme of the airfoil are optimized, and the engineering flutter of the reentrant airfoil is estimated rapidly.
Step C: and carrying out time domain chatter prediction based on CFD and modal coupling on the basis of the chatter boundary speed obtained by the chatter prediction method of the transonic aerodynamic correction. And comparing the flutter safety assessment with the flight envelope determined in the design stage. If the flutter margin meets the design requirement, a final scheme of the aeroelastic design is obtained and the next stage of aircraft development is entered. And (3) if the flutter margin is insufficient, optimizing the profile and the structural scheme of the airfoil, and re-entering the engineering flutter of the airfoil in the step (A) for quick estimation.
Preferably, as shown in FIG. 2, the conventional flutter analysis method 101 includes an unsteady aerodynamic grid 1, airfoil each-order modal information 2, unsteady aerodynamic 3, and p-k method flutter calculation 4.
Firstly, the airfoil structure is required to be discretized into finite elements, a undamped free vibration motion equation is solved, and a finite order mode is intercepted by a generalized coordinate transformation method to be a system represented by a plurality of finite degrees of freedom. The physical displacement of the elastic vibration of the structure can be expressed as a linear combination of a plurality of main modes by adopting a mode superposition method:
wherein f ij The j-th order natural mode of the i-th node; q j Is the j-th generalized coordinate; m is the selected number of modes. Thus obtaining the modal information 2 of each stage of the airfoil.
Then dividing an unsteady aerodynamic grid 1 according to the aerodynamic shape of the airfoil, wherein the unsteady aerodynamic grid 1 is a plurality of trapezoid grids with two side edges parallel to incoming flow, the x-axis is along the airflow, and the y-axis is along the span outwards. The unsteady aerodynamic force 3 distribution on the aerodynamic block is determined by solving the basic equation. From the linear unsteady aerodynamic 3 theory, the following integral equation should be satisfied for each grid at the 3/4 chord point (i.e., the washdown control point):
wherein omega is i For the wash down speed, Δc, at the 3/4 chord point of the ith grid pj Is the pressure coefficient on the jth grid, deltax j Is the middle section length of the jth grid; l (L) j For the extension of the jth grid past 1/4 chord point,is the sweepback angle, K, of the jth grid ij The kernel function is calculated for aerodynamic forces, and n is the number of aerodynamic grid blocks of the lifting surface.
Solving to obtain an airfoil generalized unsteady aerodynamic force 3, wherein the airfoil generalized unsteady aerodynamic force 3 has the following form:
wherein A is a generalized aerodynamic force influence coefficient matrix.
And carrying the unsteady aerodynamic force 3 into a flutter equation of a p-k method, and carrying out flutter calculation 4 of the p-k method:
given a series of flight speeds, for each speed, m sets of converged values are iteratively calculated. Thus, V-g and V-f curves can be drawn. From the V-g plot, it can be determined that the critical point of g changing from negative to positive, i.e., when g=0, the corresponding V is the chatter velocity, and the corresponding f is the chatter frequency, thereby obtaining the chatter calculation result 4.
Preferably, as shown in FIG. 2, to better address the issue of airfoil transonic flutter speed degradation, a steady aerodynamic correction is also considered.
The airfoil upper and lower surface pressure coefficient distribution 6 at the selected dynamic pressure is first obtained by CFD solving 5. The pressure coefficient distribution 6 of the upper surface and the lower surface of the airfoil is interpolated to the grid center point of the airfoil unsteady aerodynamic grid 1 by an interpolation method. The small disturbance equation of transonic speed is solved through the equivalent slice theory 7, so that the airfoil section generates constant pressure distribution matched with the input constant pressure distribution, the pressure coefficient of the section is obtained through decomposing the small disturbance equation of unsteady transonic speed, and the pressure coefficient is corrected by the unsteady pressure coefficient, so that the linear unsteady pressure which can consider transonic shock effect or other nonlinear effects is calculated. And obtaining an airfoil unsteady aerodynamic force 3, and further carrying out flutter calculation 4 by a p-k method.
Preferably, as shown in fig. 3, CFD and modal coupling based time domain chatter prediction: first, a fluid grid 8 needs to be divided, and at the same time, airfoil order modal information 2 needs to be input. The mode original data corresponds to the structural grid node system, the control points of displacement are nodes of the fluid grid, and aerodynamic force calculation of fluid is required to be carried out in the fluid grid center point system, so that physical quantities established in different point systems are required to be unified under the same point system by adopting an interpolation technology. The airfoil each-order modal information 2 of the structural grid node system is interpolated into the fluid grid using a Thin Plate Spline (TPS) method. And determining a solved speed range according to the result of the p-k method flutter calculation 4 of transonic aerodynamic force correction, and evaluating the airfoil flutter speed through fluid-solid coupling solution 9.
The invention discloses an engineering flutter rapid prediction method based on an airfoil, a flutter prediction method based on transonic aerodynamic force correction and a time domain flutter prediction method based on CFD and modal coupling, and a aeroelastic design flow facing transonic airfoil is constructed according to the flight envelope requirements of the aeroelastic design of an aircraft. By applying the airfoil transonic aeroelastic design flow, nonlinearity of airfoil transonic aerodynamic force can be considered, the calculation range of a high calculation cost method is reduced, the calculation accuracy is ensured, the calculation efficiency is considered, and the engineering practicability is high.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent variation, etc. of the above embodiment according to the technical matter of the present invention fall within the scope of the present invention.
Claims (7)
1. An airfoil optimization method based on transonic aeroelastic analysis is characterized by comprising the following steps:
step A: according to the profile and the structural scheme of the airfoil and modal information provided by an airfoil ground test, carrying out engineering flutter rapid prediction on the airfoil to obtain flutter boundary speeds under various working conditions; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation passes, entering a step B, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
and (B) step (B): on the basis of rapid prediction of engineering flutter of the airfoil, a flutter prediction method of transonic aerodynamic force correction is adopted to predict the flutter boundary speed of a transonic section; comparing the flutter safety assessment with the flight envelope determined in the design stage; if the flutter safety evaluation is passed, entering a step C, otherwise, reentering the step A, optimizing the profile and structural scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil;
step C: on the basis of the flutter boundary speed obtained by the flutter prediction method of the transonic aerodynamic correction, carrying out time domain flutter prediction based on CFD and modal coupling; comparing the flutter safety assessment with the flight envelope determined in the design stage; and (3) outputting a final scheme if the flutter safety evaluation passes, otherwise, re-entering the step A, optimizing the profile and structure scheme of the airfoil, and carrying out engineering flutter quick estimation of the airfoil.
2. The method for optimizing an airfoil based on transonic aeroelastic analysis according to claim 1, wherein the method for predicting flutter for transonic aerodynamic correction in step B comprises the steps of:
step B1: dispersing the airfoil structure into finite elements, solving a undamped free vibration motion equation, and obtaining the modal information of each order of the airfoil by a generalized coordinate transformation method and intercepting the finite order modes;
step B2: dividing an unsteady aerodynamic grid according to the aerodynamic shape of the airfoil, wherein the unsteady aerodynamic grid is a plurality of trapezoid grids with two side edges parallel to incoming flow;
step B3: determining unsteady aerodynamic force distribution on the aerodynamic block by solving a basic equation;
step B4: performing steady aerodynamic force correction, and solving the unsteady aerodynamic force of the airfoil;
firstly, solving through CFD to obtain the distribution of pressure coefficients of the upper surface and the lower surface of the airfoil under the selected dynamic pressure; interpolating the pressure coefficient distribution of the upper surface and the lower surface of the airfoil to the grid center point of the unsteady aerodynamic grid of the airfoil by an interpolation method; solving a transonic small disturbance equation by an equivalent slice theory, so that the airfoil section generates steady pressure distribution matched with the input steady pressure distribution; the pressure coefficient of the profile is obtained by decomposing the unsteady transonic small disturbance equation, and then the unsteady pressure coefficient is used for correction, so that the linear unsteady pressure which can consider transonic shock wave effect or other nonlinear effects is calculated, and the airfoil unsteady aerodynamic force is obtained;
step B5: and B4, carrying out flutter calculation by the p-k method by taking the airfoil unsteady aerodynamic force in the step into a flutter equation of the p-k method.
3. The method for optimizing an airfoil based on transonic aeroelastic analysis according to claim 2, wherein in the step B1, a mode superposition method is adopted to represent the physical displacement of the elastic vibration of the structure as a linear combination of several main modes:
wherein f ij The j-th order natural mode of the i-th node,
q j for the j-th generalized coordinate,
m is the number of modes selected and is,
thus obtaining the modal information of each order of the airfoil.
4. A method of optimizing an airfoil based on transonic aeroelastic analysis according to claim 3, wherein in step B3, as known from linear unsteady aerodynamic theory, the following integral equation should be satisfied for each 3/4 chord length point in the grid:
wherein V is the vibration speed,
ρ is the density of the fluid,
ω i for the wash down speed at the 3/4 chord point of the ith network,
Δc pj for the pressure coefficient on the j-th grid,
Δx j for the middle section length of the jth grid,
for the sweep angle of the j-th grid,
K ij a kernel function is calculated for the aerodynamic force,
l j for the extension of the jth grid past 1/4 chord point,
n is the number of aerodynamic grid segments of the lifting surface.
5. The method for optimizing an airfoil based on transonic aeroelastic analysis according to claim 4, wherein in the step B5, the flutter equation of the p-k method is:
where p=ω (γ+i), ω is a circular frequency, γ is an attenuation rate, and i is an imaginary unit;
m is generalized quality diagonal matrix diag (M) 11 ,…,m mm )；
b is the reference half chord length;
v is the flying speed;
a is a generalized aerodynamic force influence coefficient matrix;
k is the generalized stiffness diagonal matrix diag (K) 11 ,…,k mm )；
k is the reduction frequency, k=ωb/V;
independent of time t, is the magnitude vector of the modal coordinates.
6. A method of optimizing an airfoil based on transonic aeroelastic analysis according to any of claims 1-5, wherein said CFD and modal coupling based time domain chatter prediction in step C comprises the steps of:
step C1: dividing a fluid grid, and inputting all-order modal information of the airfoil surface;
step C2: unifying the physical quantities established in different point systems to the same point system by adopting an interpolation technology, and interpolating the airfoil surface each-order modal information of the structural grid node system into a fluid grid by adopting a Thin Plate Spline (TPS) method;
step C3: and C, determining a solved speed range according to the predicted flutter boundary speed of the transonic section in the step B, and evaluating the flutter speed of the airfoil through fluid-solid coupling solution.
7. The method of claim 1, wherein the flutter safety assessment meets design requirements by providing a flutter margin.
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