Aeroelastic dynamics analysis method for multi-propeller tilting aircraft with three-dimensional complex shape

Abstract

The invention provides an aeroelastic dynamics analysis method for a multi-propeller tilting aircraft with a three-dimensional complex shape. The aeroelastic dynamics analysis method comprises the steps that a multi-propeller tilting wing coupling system dynamics equation is established; defining a coordinate system of the multi-propeller tilting wing coupling system; based on the multi-propeller tilting wing coupling system coordinate system, establishing a multi-propeller tilting wing coupling motion expression; solving the system strain energy delta U, the system kinetic energy delta T and the aerodynamic force virtual work delta W based on the multi-propeller tilting wing coupling motion expression to obtain a rotor wing nacelle kinetic equation, a three-dimensional propeller blade kinetic equation and a wing kinetic equation; based on the three-dimensional blade kinetic equation, a rotor wing overall equation is established through multi-blade coordinate conversion, and the rotor wing nacelle kinetic equation and the wing kinetic equation are coupled to form a multi-blade tilting wing coupling system kinetic equation; and performing dynamic analysis based on the dynamic equation of the multi-propeller tilt wing coupling system.

Description

Technical Field

[0001] The present application belongs to the technical field of helicopter rotor dynamics, and in particular relates to an aeroelastic dynamics analysis method for a multi-blade tiltrotor aircraft with a complex three-dimensional shape. Background Art

[0002] The multi-propeller tilt-wing high-speed rotorcraft is a new type of rotorcraft that comprehensively utilizes the tilt-wing and distributed electric drive concepts. The entire aircraft adopts a tilt-wing layout, and multiple rotor units driven by motors are distributed on the leading edges of the front and rear wings, which can tilt with the entire wing.

[0003] Multi-blade tilt-wing high-speed rotor aircraft have typical flight modes such as vertical take-off and landing, tilt-rotation transition, and high-speed forward flight. In particular, the rotational flutter problem during tilt-rotation transition and high-speed forward flight is the most serious dynamic problem of this configuration aircraft. Summary of the Invention

[0004] Purpose of the invention: To provide an aeroelastic dynamics analysis method for a multi-rotor tiltrotor aircraft with a three-dimensional complex shape, to study the influence of the complex shape parameters of the wing's extended airfoil and blade tip on the rotational boundary of the distributed multi-rotor flexible tiltrotor wing coupling system, and to assist in the technical development and model development of multi-rotor tiltrotor aircraft.

[0005] The present application provides an aeroelastic dynamics analysis method for a multi-propeller tiltrotor aircraft with a complex three-dimensional shape, the method comprising:

[0006] Establishing a dynamic equation for a multi-blade tilt-wing coupling system; wherein the dynamic equation for the multi-blade tilt-wing coupling system includes system strain energy δU, system kinetic energy δT and system external force virtual work; the system external force virtual work includes aerodynamic virtual work δW;

[0007] Define the coordinate system of the multi-propeller tilt-wing coupling system;

[0008] Based on the multi-blade tilt-wing coupling system coordinate system, a multi-blade tilt-wing coupling motion expression is established;

[0009] Based on the coupled motion expression of the multi-blade tilt-wing, the system strain energy δU, the system kinetic energy δT and the aerodynamic virtual work δW are solved to obtain the rotor nacelle dynamic equation, the three-dimensional blade dynamic equation and the wing dynamic equation;

[0010] Based on the three-dimensional blade dynamic equation, the rotor overall equation is established through multi-blade coordinate transformation, and the rotor nacelle dynamic equation and the wing dynamic equation are coupled to form the multi-blade tilt-wing coupled system dynamic equation;

[0011] Dynamic analysis is performed based on the dynamic equations of the multi-propeller tilt-wing coupling system.

[0012] Preferably, the establishing of the multi-propeller tilt-wing coupling system dynamic equations includes:

[0013] Based on the Lagrangian coordinate system, the configuration of any point on the coupled system in the inertial coordinate system is described relative to the inertial coordinate system, and the Hamilton principle is used to derive the dynamic equation of the multi-propeller tilt-wing coupled system, which is expressed as follows:

[0014]

[0015] In the above formula: δU is the strain energy of the system; δT is the kinetic energy of the system; δW is the virtual work of the external force of the system; t1 and t2 are the start and end times of the system;

[0016] Preferably, the system strain energy δU, the system kinetic energy δT and the aerodynamic virtual work δW are respectively as follows:

[0017]

[0018] In the above formula: the subscripts W, P, and b represent the wing, nacelle, and blade respectively, and N b 、N r represent the number of blades and rotors respectively; the nacelle is regarded as a rigid body, the influence of its support stiffness is ignored, and the aerodynamic virtual work is not considered, only the kinetic energy is counted.

[0019] Preferably, the step of defining a multi-propeller tilt-wing coupling system coordinate system includes:

[0020] Establish the fuselage coordinate system at the wing root, that is, the ground inertial coordinate system X F Y F Z F , the three-dimensional wing undeformed coordinate system X J Y J Z J , three-dimensional wing deformation coordinate system X W Y W Z W , rotor nacelle coordinate system X P Y P Z P , the hub does not rotate the coordinate system X H Y H Z H , hub rotation coordinate system X R Y R Z R , hub plane coordinate system X U Y U Z U , the three-dimensional blade undeformed coordinate system X B Y B Z B and the three-dimensional blade deformation coordinate system ξD η D ζ D , and at the same time obtain the transformation matrix T of each coordinate system JF 、T WJ 、T PW 、T HP 、T RH 、T UR 、T BU 、T DB ; Among them, T BF =T BU T UR T RH T HP T PW T WJ T JF , T PI =T PW T WI , T PF =T PW T WJ T JF ;

[0021] Among them, the undeformed coordinate system transformation matrix T of the jth section of the three-dimensional wing is JF i for:

[0022]

[0023] in: Represent the wing sweep, downward deflection and pre-twist angle of the i-th section respectively

[0024] and Respectively and

[0025] Similarly, the transformation matrix T of the undeformed coordinate system of the i-th segment of the three-dimensional blade is BU i for:

[0026]

[0027] in: represent the i-th blade sweep, downward deflection and pre-twist angle respectively, and θ is the blade total pitch angle

[0028] and Respectively and

[0029] According to the above, the transformation relationship between the undeformed coordinates of the jth segment of the 3D wing and the ith segment of the 3D blade and the fuselage coordinates is as follows:

[0030]

[0031] Preferably, establishing a multi-propeller tilt-wing coupling motion expression based on the multi-propeller tilt-wing coupling system coordinate system includes:

[0032] Calculate the expression of the radius vector of any point on the coupled system in the ground inertial coordinate system; where the radius vector of the blade in the inertial coordinate system is It consists of four parts: The radius vector from any point on the blade section to the center of the rotor hub, Radius vector of hub center in nacelle coordinate system, The radius vector of the nacelle rotation center in the wing deformation coordinate system, Radius vector of the wing nacelle attachment point in the wing's undeformed coordinate system.

[0033] Preferably, the variational expressions of the system strain energy and system kinetic energy are as follows:

[0034]

[0035] In the above formula: σ, ε are the stress and strain of the blade or wing section respectively; η, ζ are the coordinates of any point on the section in the section coordinate system, L represents the blade radius or the half span of the wing, strain σ, ε are calculated by Hooke's law and deformation coordination relationship; u, v, w, φ are the degrees of freedom of the blade, x is the h 、y h 、z h 、φ h , α h , ψ h is the degree of freedom at the connection point P; u w 、v w 、w w 、φ w is the wing degree of freedom;

[0036] The variational expression of the aerodynamic virtual work is as follows:

[0037]

[0038] In the above formula: L u , L v , L w , L φ It is a generalized aerodynamic force.

[0039] Preferably, the dynamic equation of the multi-propeller tilt-wing coupling system is expressed as follows:

[0040]

[0041] In the above formula: ξb is the degree of freedom of the blade in the non-rotating coordinate system; x h is the degree of freedom of the connection point between the wing and the nacelle, x ww is the remaining degrees of freedom on the wing; M bb 、C bb , K bb 、F b are the total mass, damping, stiffness matrix and load vector of the blade respectively; M bxh 、C bxh , K bxh are the total mass, damping and stiffness matrices of the blade-wing coupling respectively; M xhb 、C xhb , K xhb are the total mass, damping and stiffness matrices of the wing and blade coupling respectively; M xhxh 、C xhxh , K xhxh 、F xh are the wing coupled total mass, damping, stiffness matrix and load vector respectively; M ww 、C ww , K ww 、 are the mass, damping, stiffness matrix and load vector of the wing except the connection point between the wing and the nacelle.

[0042] Preferably, the performing of dynamic analysis based on the dynamic equation of the multi-propeller tilt-wing coupling system includes:

[0043] Read three-dimensional blade and wing shape parameters;

[0044] The Newmark time finite element method and Floquet theory are used to numerically solve the dynamic equations of the multi-blade tilt-wing coupling system, and the gyroscopic flutter stability of the multi-blade tilt-wing coupling system is obtained.

[0045] Beneficial technical effects of this application:

[0046] This application establishes an aeroelastic dynamics model of a multi-blade tilt-wing coupling system considering three-dimensional complex shapes, constructs an aeroelastic analysis method for a multi-blade tilt-wing coupling system, and studies the influence of the wing's extended airfoil and rotor blade tip shape parameters on the rotational flutter boundary. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 1 is a schematic diagram of the modal frequency of a UH60 swept blade provided in an embodiment of the present application;

[0048] Figure 2 is the system damping and root locus diagram provided by the embodiment of the present application;

[0049] Figure 3 Schematic diagram of the change of system flutter frequency with forward flight speed provided by an embodiment of the present application;

[0050] Figure 4 This is a schematic diagram of the coordinate system definition of a three-dimensional complex-shaped blade provided in an embodiment of the present application. DETAILED DESCRIPTION

[0051] It should be noted that in order to improve the rotation flutter boundary of distributed multi-rotor / tilt-wing high-speed rotorcraft and suppress the occurrence of rotation flutter, two rotation flutter suppression paths, passive suppression and active control, can be adopted. The passive suppression technology mainly designs the complex shape parameters of the wing's extended airfoil and blade tip, and mainly uses the aerodynamic torque generated by the backlash on the extended airfoil and the swept back of the blade tip to play a stabilizing role, thereby achieving the purpose of increasing the system's rotation flutter critical speed.

[0052] This application provides an aeroelastic dynamics analysis method for multi-propeller / tilt-rotor aircraft with a three-dimensional complex shape. For the rotation flutter suppression technology of multi-propeller / tilt-rotor aircraft, an analysis method is developed for the influence of the passive suppression technology on the rotation boundary of the distributed multi-rotor / flexible tilt-rotor coupling system by considering the complex shape parameter design of the wing extended airfoil and the blade tip, and a feasible passive suppression technology for the rotation flutter of distributed multi-rotor / tilt-rotor high-speed rotor aircraft is established. This technology can also be used for the rotation flutter suppression of tilt-rotor and distributed electric propulsion configuration aircraft in the future.

[0053] In the embodiments of this application, the solutions provided by this application are as follows:

[0054] 1. Dynamic equations of the multi-propeller tilt-wing coupling system. This paper describes the configuration of any point on the coupling system in the inertial coordinate system relative to the inertial coordinate system based on the Lagrangian coordinate system, and uses the Hamilton principle to derive the dynamic equations of the multi-propeller tilt-wing coupling system, which are expressed as follows.

[0055]

[0056] In the above formula: δU is the system strain energy; δT is the system kinetic energy; δW is the system external force virtual work, t1 and t2 are the start and end times of the system; each part is composed as follows:

[0057]

[0058] In the above formula: the subscripts W, P, and b represent the wing, nacelle, and blade respectively, and N b 、N r The nacelle is considered as a rigid body, and the influence of its support stiffness is ignored. The aerodynamic virtual work is not considered, and only the kinetic energy is considered.

[0059] 2. Define the coordinate system of the multi-propeller tilt-wing coupling system and establish the fuselage coordinate system (i.e., ground inertial coordinate system) X at the root of the wing. F Y F Z F , the three-dimensional wing undeformed coordinate system X J Y J Z J , three-dimensional wing deformation coordinate system X W Y W Z W , rotor nacelle coordinate system X P Y P Z P , the hub does not rotate the coordinate system X H Y H Z H , hub rotation coordinate system X R Y R Z R , hub plane coordinate system X U Y U Z U , the three-dimensional blade undeformed coordinate system X B Y B Z B and the three-dimensional blade deformation coordinate system ξ D η D At the same time, the transformation matrix T of each coordinate system is obtained JF 、T WJ 、T PW 、T HP 、T RH 、T UR 、T BU 、T DB (Among them, T BF =T BU T UR T RH T HP T PW T WJ T JF , T PI =T PW T WI , T PF =T PW T WJ T JF ).

[0060] The transformation matrix of the undeformed coordinate system of the jth segment of the three-dimensional wing is T JF i for

[0061]

[0062] in: Represent the wing sweep, downward deflection and pre-twist angle of the i-th section respectively

[0063] and Respectively and

[0064] Similarly, the transformation matrix T of the undeformed coordinate system of the i-th segment of the three-dimensional blade is BU i for

[0065]

[0066] in: represent the i-th blade sweep, downward deflection and pre-twist angle respectively, and θ is the blade total pitch angle

[0067] and Respectively and

[0068] According to the above, the transformation relationship between the undeformed coordinates of the jth segment of the 3D wing and the ith segment of the 3D blade and the fuselage coordinates is as follows:

[0069]

[0070] 3. The motion expression of the multi-propeller tilt-wing coupling system, calculate the expression of the radius vector of any point on the coupling system in the ground inertial coordinate system, where the radius vector of the blade in the inertial coordinate system is It consists of four parts: The radius vector from any point on the blade section to the center of the rotor hub, Radius vector of hub center in nacelle coordinate system,

[0071] The radius vector of the nacelle rotation center in the wing deformation coordinate system, The radius vector of the wing nacelle connection point in the wing undeformed coordinate system is as follows: Figure 4 Taking a three-dimensional blade as an example, the radius vector at any point is as follows:

[0072]

[0073] Among them, for the kth blade segment, U k Indicates its undeformed state, D k Indicates its deformed state, P is U k Q is any point on the elastic axis of the blade, and P1 and Q1 are the points on the section perpendicular to the elastic axis. k Then the displacement radius of Q1 to the center of the rotor hub is The expression is as follows:

[0074]

[0075] Let OA1=l0,A1A2=l1,……,A K-1 A k =l k-1 , i, j, k related to the main blade coordinate system are represented here as i0, j0, k0.

[0076] In summary

[0077]

[0078] In the above formula: subscript p represents the p segment within the k segment, s represents the point P and the intersection point A k distance, Indicates the deformation displacement of the blade.

[0079] Similarly, the radius vector of the three-dimensional wing nacelle connection point in the wing undeformed coordinate system is The expression is as follows:

[0080]

[0081] The speed of the blade in the inertial coordinate system is The blade's own speed and the drag speed caused by the wing It consists of two parts, which can be further divided into blade translation Blade motion caused by hub rotation Blade motion caused by wing rotation Wing motion caused by wing rotation Wing translation in From this, the strain energy and kinetic energy variation of any point on the blade, nacelle and wing are derived. Taking the blade as an example, the strain energy and kinetic energy derivation process is as follows:

[0082]

[0083] In the above formula: They are respectively the inertial coordinate system X F Y F Z F Basis vector; U x 、U y 、U z are the velocity components of the blade in each coordinate direction of the inertial coordinate system.

[0084] 4. Aeroelastic dynamics modeling of the multi-propeller tilt-wing coupling system. The variational expressions of the strain energy and kinetic energy of the multi-propeller system are as follows:

[0085]

[0086] In the above formula: σ, ε are the stress and strain of the blade or wing section respectively; η, ζ are the coordinates of any point on the section in the section coordinate system, L represents the blade radius or the half span of the wing, strain σ, ε are calculated by Hooke's law and deformation coordination relationship; u, v, w, φ are the degrees of freedom of the blade, x is the h 、y h 、z h 、φ h , α h , ψ h is the degree of freedom at the connection point P; u w 、v w 、w w 、φ w is the wing degree of freedom;

[0087] The variational expression of the virtual work of the three-dimensional blade and wing aerodynamic force is as follows:

[0088]

[0089] In the above formula: L u 、L v 、L w 、L φ It is a generalized aerodynamic force.

[0090] 5. Based on Hamilton's principle, the rotor overall equation is established through multi-blade coordinate transformation, and then the rotor nacelle and wing are coupled to form the dynamic equation of the multi-blade tilt-wing coupling system with a three-dimensional complex shape. The expression is as follows

[0091]

[0092] In the above formula: ξ b is the degree of freedom of the blade in the non-rotating coordinate system; x h is the degree of freedom of the connection point between the wing and the nacelle, x ww is the remaining degrees of freedom on the wing; M bb 、C bb , K bb 、F b are the total mass, damping, stiffness matrix and load vector of the blade respectively; M bxh 、C bxh , K bxh are the total mass, damping and stiffness matrices of blade / wing coupling respectively; M xhb 、C xhb , K xhb are the total mass, damping and stiffness matrices of the wing / blade coupling respectively; M xhxh、C xhxh , K xhxh 、F xh are the total mass, damping, stiffness matrix and load vector of the wing / wing coupling, respectively; M ww 、C ww , K ww 、 are the mass, damping, stiffness matrix and load vector of the wing except the connection point between the wing and the nacelle.

[0093] 6. Read the three-dimensional blade and wing shape parameters (including the deformation section sweep, downward inversion and pre-twist parameters), including the wing extended wing surface sweep, downward inversion and pre-twist parameters and the blade tip sweep, downward inversion and pre-twist parameters.

[0094] The Newmark time finite element method and Floquet theory are used to numerically solve the dynamic equations of the multi-propeller tilt-rotating wing coupling system, and the system's rotational flutter stability is obtained. The influence of the wing's extended airfoil and blade tip shape parameters on the system's rotational flutter stability is studied. Through computational analysis, the parameter design that is beneficial to improving the system's rotational flutter speed is obtained, and based on this, an aeroelastic dynamics analysis method for a multi-propeller tilt-rotating aircraft with a complex three-dimensional shape is developed.

[0095] This application develops an aeroelastic analysis method for a multi-blade tilt-rotor aircraft with a three-dimensional complex shape, summarizes and generalizes the characteristics of a multi-blade tilt-wing high-speed rotor aircraft, establishes an aeroelastic dynamics model of a multi-blade tilt-wing coupling system considering a three-dimensional complex shape, constructs an aeroelastic analysis method for a multi-blade tilt-wing coupling system, studies the influence of the wing's extended airfoil and rotor blade tip shape parameters on the rotational flutter boundary, and based on this, conducts research on the passive suppression technology of rotational flutter of a distributed multi-rotor-wing coupling system, and masters the design method for improving the critical speed of rotational flutter of the coupling system.

[0096] The dynamic characteristics analysis of the UH-60 blade with swept tip is carried out. Figure 1 A comparison between the calculated values ​​of blade modal frequencies and the experimental values ​​in the literature is given, and the errors are all within 5%. It can be seen that the calculated values ​​are consistent with the experimental values, which proves the accuracy of the aeroelastic analysis method for multi-blade tilt-rotor aircraft with complex three-dimensional shapes established in this paper.

[0097] The calculation is done for a half-span system with three rotors, a wing attack angle of 3 degrees, and a blade effective attack angle of 6 degrees. The modal damping and frequency of the system at different forward flight speeds are as follows: Figure 2 、 Figure 3As shown. With the increase of speed, the modal frequency and damping of the first-order normal bending q1 and the second-order normal bending q3 increase, while the frequency and damping of the chord bending q2 and the torsion p1 decrease. At 127m / s, the modal frequencies of p1 and q3 gradually approach each other and then resonate, causing the damping of p1 to be less than 0, resulting in torsional instability of the wing and rotational flutter. At 151m / s, q2 begins to enter the unstable region. With the increase of speed, the first-order flapping of the propeller (collective type β1, non-reaction type β0 and retreat type β -1 )'s modal frequencies gradually increase, while their modal damping first increases and then decreases.

[0098] The aeroelastic dynamics analysis method for a multi-blade tiltrotor aircraft with a three-dimensional complex shape developed in this application is used to calculate the dynamic characteristics of the three-dimensional blade structure and the rotational flutter stability of the multi-blade tiltrotor aircraft in forward flight. Figure 1 The calculation results of the dynamic characteristics of the UH60 swept blade structure are: Figure 2 is the calculation result of aeroelastic damping of multi-propeller system, Figure 3 is the calculation result of the system chatter frequency.

Claims

1. A method for aeroelastic dynamics analysis of a multi-propeller tiltrotor aircraft with a complex three-dimensional shape, characterized in that: The method comprises: Establishing a dynamic equation for a multi-blade tilt-wing coupling system; wherein the dynamic equation for the multi-blade tilt-wing coupling system includes system strain energy δU, system kinetic energy δT and system external force virtual work; the system external force virtual work includes aerodynamic virtual work δW; Define the coordinate system of the multi-propeller tilt-wing coupling system; Based on the multi-blade tilt-wing coupling system coordinate system, a multi-blade tilt-wing coupling motion expression is established; Based on the coupled motion expression of the multi-blade tilt-wing, the system strain energy δU, the system kinetic energy δT and the aerodynamic virtual work δW are solved to obtain the rotor nacelle dynamic equation, the three-dimensional blade dynamic equation and the wing dynamic equation; Based on the three-dimensional blade dynamic equation, the rotor overall equation is established through multi-blade coordinate transformation, and the rotor nacelle dynamic equation and the wing dynamic equation are coupled to form the multi-blade tilt-wing coupled system dynamic equation; Dynamic analysis is performed based on the dynamic equations of the multi-propeller tilt-wing coupling system.

2. The method according to claim 1, characterized in that The establishment of the multi-propeller tilt-wing coupling system dynamic equations includes: Based on the Lagrangian coordinate system, the configuration of any point on the coupled system in the inertial coordinate system is described relative to the inertial coordinate system, and the Hamilton principle is used to derive the dynamic equation of the multi-propeller tilt-wing coupled system, which is expressed as follows: In the above formula: δU is the strain energy of the system; δT is the kinetic energy of the system; δW is the virtual work of the external force of the system; t1 and t2 are the start and end times of the system.

3. The method according to claim 2, characterized in that The system strain energy δU, the system kinetic energy δT and the aerodynamic virtual work δW are as follows: In the above formula: the subscripts W, P, and b represent the wing, nacelle, and blade respectively, and N b 、N r represent the number of blades and rotors respectively; the nacelle is regarded as a rigid body, the influence of its support stiffness is ignored, and the aerodynamic virtual work is not considered, only the kinetic energy is counted.

4. The method according to claim 3, characterized in that Defining the multi-propeller tilt-wing coupling system coordinate system includes: Establish the fuselage coordinate system at the wing root, that is, the ground inertial coordinate system X F Y F Z F , the three-dimensional wing undeformed coordinate system X J Y J Z J , three-dimensional wing deformation coordinate system X W Y W Z W , rotor nacelle coordinate system X P Y P Z P , the hub does not rotate the coordinate system X H Y H Z H , hub rotation coordinate system X R Y R Z R , hub plane coordinate system X U Y U Z U , the three-dimensional blade undeformed coordinate system X B Y B Z B and the three-dimensional blade deformation coordinate system At the same time, the transformation matrix T of each coordinate system is obtained JF 、T WJ 、T PW 、T HP 、T RH 、T UR 、T BU 、T DB ; Among them, T BF =T BU T UR T RH T HP T PW T WJ T JF , T PI =T PW T WI , T PF =T PW T WJ T JF ; Among them, the undeformed coordinate system transformation matrix T of the jth section of the three-dimensional wing is JF i for: in: Represent the wing sweep, downward deflection and pre-twist angle of the i-th section respectively and Respectively and i=1,2,3,j=1,2,3 Similarly, the transformation matrix T of the undeformed coordinate system of the i-th segment of the three-dimensional blade is BU i for: in: represent the i-th blade sweep, downward deflection and pre-twist angle respectively, and θ is the blade total pitch angle and Respectively and i=1,2,3,j=1,2,3 According to the above, the transformation relationship between the undeformed coordinates of the jth segment of the 3D wing and the ith segment of the 3D blade and the fuselage coordinates is as follows:

5. The method according to claim 4, characterized in that The method of establishing a multi-propeller tilt-wing coupling motion expression based on the multi-propeller tilt-wing coupling system coordinate system includes: Calculate the expression of the radius vector of any point on the coupled system in the ground inertial coordinate system; where the radius vector of the blade in the inertial coordinate system is It consists of four parts: The radius vector from any point on the blade section to the center of the rotor hub, Radius vector of hub center in nacelle coordinate system, The radius vector of the nacelle rotation center in the wing deformation coordinate system, Radius vector of the wing nacelle attachment point in the wing's undeformed coordinate system.

6. The method according to claim 5, characterized in that The variational expressions of the system strain energy and system kinetic energy are as follows: In the above formula: σ, ε are the stress and strain of the blade or wing section respectively; η, ζ are the coordinates of any point on the section in the section coordinate system, L represents the blade radius or the half span of the wing, strain σ, ε are calculated by Hooke's law and deformation coordination relationship; u, v, w, φ are the degrees of freedom of the blade, x is the h 、y h 、z h 、φ h , α h , ψ h is the degree of freedom at the connection point P; u w 、v w 、w w 、φ w is the wing degree of freedom; The variational expression of the aerodynamic virtual work is as follows: In the above formula: L u 、L v 、L w 、L φ It is a generalized aerodynamic force.

7. The method according to claim 6, characterized in that The dynamic equation of the multi-propeller tilt-wing coupling system is expressed as follows: In the above formula: ξ is the degree of freedom of the blade in the non-rotating coordinate system; x h is the degree of freedom of the connection point between the wing and the nacelle, x ww is the remaining degrees of freedom on the wing; M bb 、C bb , K bb 、F b are the total mass, damping, stiffness matrix and load vector of the blade respectively; M bxh 、C bxh , K bxh are the total mass, damping and stiffness matrices of the blade-wing coupling respectively; M xhb 、C xhb , K xhb are the total mass, damping and stiffness matrices of the wing and blade coupling respectively; M xhxh 、C xhxh , K xhxh 、F xh are the wing coupled total mass, damping, stiffness matrix and load vector respectively; M ww 、C ww , K ww 、 are the mass, damping, stiffness matrix and load vector of the wing except the connection point between the wing and the nacelle.

8. The method according to claim 7, characterized in that The performing of dynamic analysis based on the dynamic equation of the multi-propeller tilt-wing coupling system includes: Read three-dimensional blade and wing shape parameters; The Newmark time finite element method and Floquet theory are used to numerically solve the dynamic equations of the multi-blade tilt-wing coupling system, and the gyroscopic flutter stability of the multi-blade tilt-wing coupling system is obtained.

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