A method and system for rapidly calculating the steady-state periodic response of a rigid body rotor flapping.

Abstract

This invention relates to a method and system for rapidly calculating the steady-state periodic response of a rigid body flapping rotor, belonging to the field of rotor flapping response calculation technology. It utilizes a rotor region mesh to iteratively calculate the rigid body flapping angle, flapping velocity, and flow field velocity, and then calculates the rotor's aerodynamic forces based on blade element theory. The aerodynamic forces are then used to calculate the rotor momentum source term. This term is added to the momentum source term in the Navier-Stokes equations, and the rotor region mesh is updated. Finally, the aerodynamic forces are used to calculate the Faroe Islands momentum source term. n This invention updates the rotor rigid body flapping response in a loosely coupled manner. It calculates the rotor's steady-state periodic flapping response to the collective pitch control input, longitudinal periodic pitch control input, and lateral periodic pitch control input. By loosely coupling the rotor momentum source term and the rotor rigid body flapping response, this invention comprehensively considers the influence of aerodynamic components on the flow field, effectively improving computational efficiency.

Description

Technical Field

[0001] This invention relates to the field of rotor flapping response calculation technology, and in particular to a method and system for rapidly calculating the steady-state periodic response of a rigid rotor flapping. Background Technology

[0002] For rotorcraft such as conventional helicopters, coaxial twin-rotor helicopters, autogyros, and tiltrotor aircraft, their rotors exhibit a periodic flapping response. In forward flight or other states of rotor aerodynamic imbalance, the rotor with greater aerodynamic force is forced to flap upwards, thus reducing the angle of attack and consequently decreasing the aerodynamic force. Conversely, the rotor with less aerodynamic force is forced to flap downwards, increasing the angle of attack and consequently increasing the aerodynamic force. The rotor flapping response can significantly reduce the tilting moment of the rotorcraft, significantly impacting its stability and maneuverability. Furthermore, the rotor flapping response characteristics have a crucial influence on the aerodynamic characteristics and performance, dynamic characteristics, and flight performance of the rotorcraft. Therefore, the ability to quickly and accurately calculate and evaluate the rotor flapping response characteristics during the design and application phases is a prerequisite for conducting aerodynamic, dynamic, and flight mechanics analyses. Rotor flapping response calculation belongs to the field of fluid-structure interaction simulation. The bidirectional coupling between fluid and structure makes the calculation method of rotor flapping response complex, computationally intensive and slow. How to improve computational efficiency and reduce computation time has always been a hot and difficult problem in rotor flapping response calculation. However, existing fast calculation methods cannot fully consider the influence of other aerodynamic components besides the rotor on the flow field. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping. By loosely coupling the rotor momentum source term and the rotor rigid body flapping response, the steady-state rigid body flapping response of the rotor can be calculated quickly, effectively improving the calculation efficiency while fully considering the influence of aerodynamic components on the flow field.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A method for rapidly calculating the steady-state periodic response of a rotor rigid body flapping, the method comprising:

[0006] Obtain an arbitrary space containing the rotor as the computational domain for the rotor CFD flow field;

[0007] The rotor CFD flow field computation domain is meshed to obtain the rotor region mesh;

[0008] In the hub coordinate system, the flapping displacement X of the rigid body tips located at various azimuth angles of the rotor is utilized. n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ;

[0009] Using the tip flapping speed V of the rotor in the hub coordinate system n Calculate the flapping speed V of each blade element segment of the rotor. flap n The leaf element micro-segment is a section of the rotor along its span.

[0010] The flow velocity V in the x-direction at the rotor region grid in the inertial coordinate system Gx n Flow velocity V in the y direction Gy n and the flow velocity V in the z-direction Gz n Obtain the first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n First radial flow field velocity Vr planeofdisk n and the first tangential flow field velocity Vt planeofdisk n The x-direction flow field velocity, y-direction flow field velocity, and z-direction flow field velocity are respectively the flow field velocities in the x-direction, y-direction, and z-direction of the inertial coordinate system; the first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively the flow field velocities in the normal direction, radial direction, and tangential direction of the impeller hub coordinate system.

[0011] The rotor rigid body flapping angle β in the hub coordinate system flap n The first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle. planeofdisk n and the first radial flow field velocity Vr planeofdisk n Calculate the second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle in the blade element segment coordinate system. blade n Second tangential flow field velocity Vt blade n The second normal flow velocity and the second tangential flow velocity are the flow velocity in the normal direction and the flow velocity in the tangential direction of the leaf element micro-segment coordinate system, respectively.

[0012] Using the flapping speed V of each blade element segment of the rotor in the blade element micro-segment coordinate system flap n The second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle. blade n Calculate the normal velocity Vn of the flow field relative to the leaf element microsegment. blade bladen ;

[0013] Obtain the rotor collective pitch control input φ0, the rotor longitudinal cyclic pitch control input A, and the rotor lateral cyclic pitch control input B, and calculate the rotor pitch angle;

[0014] In the blade element micro-segment coordinate system, the second tangential flow field velocity Vt at each azimuth angle of the rotor blade element micro-segment is used. blade n The normal velocity Vn of the flow field relative to the leaf element segment blade blade n Based on the rotor pitch angle, the aerodynamic forces (Fareo) of each blade element segment of the rotor at various azimuth angles are calculated according to blade element theory. n ;

[0015] Utilizing the aforementioned aerodynamic Fareo n Calculate the rotor momentum source term Fsource at each azimuth angle. n ;

[0016] The rotor momentum source term Fsource n Add to the momentum source term of the Navier-Stokes equations, and update the flow field velocities in the x, y, and z directions of the rotor region grid in the inertial coordinate system using computational fluid dynamics based on the Navier-Stokes equations.

[0017] Utilizing the aforementioned aerodynamic Fareo n Update the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement X of the rigid body tip at each azimuth angle of the rotor in the hub coordinate system". n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ”;

[0018] The iteration stops when the difference between the tip waving displacements of two consecutive iterations is less than a preset error value.

[0019] The present invention also provides a system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping, the system comprising:

[0020] The computational domain selection unit is used to obtain an arbitrary space containing the rotor as the computational domain for the rotor CFD flow field.

[0021] Mesh generation unit is used to divide the rotor CFD flow field calculation domain into a mesh to obtain the rotor region mesh;

[0022] The rigid body flapping angle calculation unit is used to calculate the flapping displacement X of the rigid body tip at various azimuth angles of the rotor in the hub coordinate system. n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ;

[0023] The flapping speed calculation unit is used to calculate the tip flapping speed V of the rotor in the hub coordinate system. n Calculate the flapping speed V of each blade element segment of the rotor. flap n The leaf element micro-segment is a section of the rotor along its span.

[0024] The flow field velocity acquisition unit is used to obtain the flow field velocity V in the x-direction at the rotor region grid in the inertial coordinate system. Gx n Flow velocity V in the y direction Gy n and the flow velocity V in the z-direction Gz n Obtain the first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n First radial flow field velocity Vr planeofdisk n and the first tangential flow field velocity Vt planeofdisk n The x-direction flow field velocity, y-direction flow field velocity, and z-direction flow field velocity are respectively the flow field velocities in the x-direction, y-direction, and z-direction of the inertial coordinate system; the first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively the flow field velocities in the normal direction, radial direction, and tangential direction of the impeller hub coordinate system.

[0025] The coordinate transformation unit is used to utilize the rotor rigid body flapping angle β in the hub coordinate system. flap n The first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle. planeofdisk n and the first radial flow field velocity Vr planeofdisk n Calculate the second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle in the blade element segment coordinate system. blade n Second tangential flow field velocity Vt blade n The second normal flow velocity and the second tangential flow velocity are the flow velocity in the normal direction and the flow velocity in the tangential direction of the leaf element micro-segment coordinate system, respectively.

[0026] The relative normal velocity calculation unit is used to calculate the flapping velocity V of each blade element segment of the rotor in the blade element segment coordinate system. flap n The second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle. blade n Calculate the normal velocity Vn of the flow field relative to the leaf element microsegment. blade blade n ;

[0027] The input acquisition unit is used to acquire the rotor collective pitch control input φ0, the rotor longitudinal periodic pitch control input A, and the rotor lateral periodic pitch control input B, and to calculate the rotor pitch angle.

[0028] The aerodynamic calculation unit is used to calculate the second tangential flow field velocity Vt of each blade element micro-segment of the rotor at various azimuth angles in the blade element micro-segment coordinate system. blade n The normal velocity Vn of the flow field relative to the leaf element segment blade blade n Based on the rotor pitch angle, the aerodynamic forces (Fareo) of each blade element segment of the rotor at various azimuth angles are calculated according to blade element theory. n ;

[0029] The rotor momentum source term calculation unit is used to utilize the aerodynamic force Fareo n Calculate the rotor momentum source term Fsource at each azimuth angle. n ;

[0030] The rotor CFD flow field calculation domain update unit is used to update the rotor momentum source term Fsource. n Add to the momentum source term of the Navier-Stokes equations, and update the flow field velocities in the x, y, and z directions of the rotor region grid in the inertial coordinate system using computational fluid dynamics based on the Navier-Stokes equations.

[0031] Rigid body flapping response update unit, used to utilize the aerodynamic Fareo n Update the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement X of the rigid body tip at each azimuth angle of the rotor in the hub coordinate system". n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ”;

[0032] The iterative control unit stops iteration when the difference between the tip flapping displacements of two adjacent iterations is less than a preset error value.

[0033] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0034] This invention proposes a method and system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping. First, an arbitrary space containing the rotor is obtained as the rotor CFD flow field computation domain. The rotor CFD flow field computation domain is then meshed to obtain the rotor region mesh. Finally, the flapping displacement X at the rigid body tip of the rotor at various azimuth angles is used in the hub coordinate system. n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n In the hub coordinate system, the tip flapping speed V of the rotor is used as the reference. n Calculate the flapping speed V of each blade element segment of the rotor. flap n The blade element micro-segment is a section of the rotor along its span; then, the flow field velocity V in the x-direction at the rotor region grid in the inertial coordinate system is used. Gx n Flow velocity V in the y direction Gy n and the flow velocity V in the z-direction Gz n Obtain the first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n First radial flow field velocity Vr planeofdisk n and the first tangential flow field velocity Vt planeofdisk n The rotor rigid body flapping angle β in the hub coordinate system is used. flap n The first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle. planeofdisk n and the first radial flow field velocity Vr planeofdisk n Calculate the second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle in the blade element segment coordinate system. blade n Second tangential flow field velocity Vt blade n ; Using the flapping speed V of each blade element segment of the rotor in the blade element micro-segment coordinate system flap n The second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle. blade nCalculate the normal velocity Vn of the flow field relative to the leaf element microsegment. blade blade n ; Obtain the rotor collective pitch control input φ0, rotor longitudinal periodic pitch control input A, and rotor lateral periodic pitch control input B, and calculate the rotor pitch angle; In the blade element micro-segment coordinate system, utilize the second tangential flow field velocity Vt of each blade element micro-segment at each azimuth angle. blade n The normal velocity Vn of the flow field relative to the leaf element segment blade blade n Based on the rotor pitch angle, the aerodynamic forces (Fareo) of each blade element segment of the rotor at various azimuth angles are calculated according to blade element theory. n ; utilizing the aforementioned aerodynamic Fareo n Calculate the rotor momentum source term Fsource at each azimuth angle. n The rotor momentum source term Fsource n The momentum source term of the Navier-Stokes equations is added, and the normal, radial, and tangential flow velocities of the rotor region grid in the inertial coordinate system are updated using computational fluid dynamics methods based on the Navier-Stokes equations. Finally, the aerodynamic Fareo... n Update the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement X of the rigid body tip at each azimuth angle of the rotor in the hub coordinate system". n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n The iteration stops when the difference between the tip flapping displacements of two adjacent iterations is less than a preset error value. This invention calculates the rotor's steady-state periodic flapping response to the collective pitch control input, the longitudinal periodic pitch control input, and the lateral periodic pitch control input. Because this invention loosely couples the rotor momentum source term and the rotor rigid body flapping response, it can quickly calculate the rotor's steady-state rigid body flapping response. Furthermore, when using the rotor momentum source method in this invention, the object surface mesh can contain all other aerodynamic components, thus comprehensively considering the influence of aerodynamic components on the flow field. Therefore, this invention effectively improves computational efficiency while comprehensively considering the influence of aerodynamic components on the flow field. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 and Figure 2 This is a flowchart of a method for rapidly calculating the steady-state periodic response of a rigid rotor body during flapping, as provided in Embodiment 1 of the present invention.

[0037] Figure 3 This is a schematic diagram showing the relationship between the inertial coordinate system, the hub coordinate system, and the blade element micro-segment coordinate system provided in Embodiment 1 of the present invention.

[0038] Figure 4 This is a schematic diagram of the model provided in Embodiment 1 of the present invention in the wind tunnel test section.

[0039] Figure 5 This is a schematic diagram comparing the fuselage pressure coefficient calculated using the method of this embodiment to the steady-state flapping response of the rotor rigid body with the experimental value, as provided in Embodiment 1 of the present invention.

[0040] Figure 6 This is a schematic diagram illustrating the convergence of the rotor rigid body flapping period response with iteration steps, as provided in Embodiment 1 of the present invention.

[0041] Figure 7 This is a block diagram of a system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping, as provided in Embodiment 2 of the present invention.

[0042] Figure 8 This is a flowchart of a method for rapidly calculating the steady-state periodic response of a rotor rigid body during flapping, as provided in Embodiment 3 of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Rotorcraft control methods: For rotorcraft such as conventional helicopters, coaxial twin-rotor helicopters, and tiltrotor aircraft, under different flight conditions and given rotor collective pitch, lateral cyclic pitch, and longitudinal cyclic pitch, their rotors exhibit different periodic rotor tip flapping displacements β. flap Periodic rotor tip flapping displacement β flapThis is manifested in the rotor disk plane having a fixed forward chamfer 'a'. 1s and back chamfer b 1s (The calculation formula is: β) flap =a0-a 1s *cos(θ)-b 1s *sin(θ) Fourier series expansion), the aerodynamic resultant force of the rotor also follows the forward chamfer α of the rotor disk plane. 1s chamfer b 1s The combined aerodynamic force of the forward-tilting and side-tilting rotors exerts forward and lateral forces and moments on the rotorcraft. These forces and moments cause the rotorcraft to roll laterally and pitch forward, thus achieving attitude motion control. Therefore, the attitude motion control of a rotorcraft comprises two parts: 1. Calculating the rotor tip flapping displacement β under rotor control input. flap 2. Displacement β from the rotor tip flapping flap Calculate the forward and lateral forces and moments of the rotorcraft, and calculate the attitude and motion of the rotorcraft (using expertise in flight mechanics).

[0045] In the analysis of rotorcraft control characteristics: Under specific rotor collective pitch, lateral periodic pitch, and longitudinal periodic pitch control inputs, due to differences in flight state and flow field interference, it is desirable to conveniently, quickly, and accurately calculate the periodic rotor tip flapping displacement β. flap It becomes difficult. But for a given periodic rotor tip flapping displacement β flap The forward and lateral forces and moments acting on a rotorcraft are specific and easily calculated. Therefore, the main challenge in accurately evaluating the motion response of a rotorcraft under control inputs lies in accurately calculating the periodic tip flapping displacement β of the rotor under these inputs. flap .

[0046] Existing calculation methods either use CFD-CSD (fluid-structure interaction) to calculate rotor tip flapping displacement, which suffers from extremely high computational costs and slow convergence; or they use rotor blade element-free wake methods to calculate the rotor tip flapping displacement response, which cannot consider the influence of the fuselage on the rotor tip flapping displacement. Therefore, establishing an efficient, accurate, and steady-state periodic method for calculating rotor rigid body tip flapping displacement that can account for fuselage interference is crucial for the study of rotorcraft handling characteristics.

[0047] The purpose of this invention is to provide a method and system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping. This method loosely couples the rotor momentum source term and the rotor rigid body flapping response to quickly calculate the steady-state rigid body flapping response, effectively improving computational efficiency while fully considering the influence of aerodynamic components on the flow field. This invention proposes a method for rapidly calculating the steady-state rigid body flapping response of a rotor by loosely coupling the rotor momentum source method and the rotor rigid body flapping dynamics. This method conveniently considers the aerodynamic interference effects of rotor / fuselage, rotor / control surfaces, etc.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Example 1:

[0050] like Figure 1 and Figure 2 As shown ( Figure 1 As part of the flowchart, Figure 2 (As another part of the flowchart), this embodiment provides a method for rapidly calculating the steady-state periodic response of a rigid rotor flapping. This embodiment uses blade element theory, which considers the rotor flapping angle and flapping speed, to calculate the rotor aerodynamic forces at different azimuth angles during one revolution. The calculated rotor aerodynamic forces are used to update the rotor momentum source, and the rotor flapping angle and rotor flapping speed are updated in a loosely coupled manner. The specific method flow is as follows:

[0051] S1. Obtain an arbitrary space containing the rotor as the rotor CFD flow field calculation domain.

[0052] Define the tip flapping displacement X, tip flapping velocity V, and tip flapping acceleration a of the rigid body rotor at different azimuth angles, and initialize them to 0 to complete the initialization of the rotor's rigid body flapping response. Take any space containing the rotor as the rotor CFD flow field calculation domain. The rotor rotates like a fan. Here, "different azimuth angles" means that if the "rotor region sector mesh" is divided into 36 parts in the circumference (the number of parts is arbitrary), then different azimuth angles refer to 0°, 10°, 20°....340°, 350° (each part is 10°).

[0053] S2. The rotor CFD flow field calculation domain is divided into grids to obtain the rotor region grid.

[0054] The rotor CFD flow field computational domain is divided into meshes, which include the rotor region mesh and the remaining general meshes. The rotor momentum source method is used to simulate the rotor on the fan-shaped mesh of the rotor region, and the flow field velocity (normal flow field velocity V) is assigned to each mesh in the rotor CFD flow field computational domain. Gx Radial flow velocity V Gy Tangential flow velocity V GzThe flow field is initialized by assigning initial values ​​to pressure, density ρ, and temperature.

[0055] S3. Utilizing the flapping displacement X of the rigid body tips at various azimuth angles of the rotor in the hub coordinate system. n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n .

[0056] The calculation formula is: β flap n =X n / R, where β flap n X represents the rigid body flapping angle of the rotor at various azimuth angles in the hub coordinate system during the nth iteration. n R represents the flapping displacement of the rigid body tip of the rotor at various azimuth angles in the hub coordinate system during the nth iteration, and R represents the rotor radius.

[0057] S4. Utilizing the tip flapping speed V of the rotor in the hub coordinate system n Calculate the flapping speed V of each blade element segment of the rotor. flap n The leaf element micro-segment is a section of the rotor along its span.

[0058] The flapping speed V of each blade element segment of the rotor flap n The calculation formula is: V flap n =V n ×r / R.

[0059] Among them, V flap n V represents the flapping velocity of each blade element segment of the rotor in the hub coordinate system during the nth iteration. n Let r represent the tip flapping velocity in the hub coordinate system during the nth iteration, r represent the radius of the center of the blade element micro-segment coordinate system, and R represent the rotor radius.

[0060] S5. The flow velocity V in the x-direction at the rotor region grid in the inertial coordinate system. Gx n Flow velocity V in the y direction Gy n and the flow velocity V in the z-direction Gz n Obtain the first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n First radial flow field velocity Vr planeofdisk n and the first tangential flow field velocity Vt planeofdisk nThe x-direction flow field velocity, y-direction flow field velocity, and z-direction flow field velocity are respectively the flow field velocities in the x-direction, y-direction, and z-direction of the inertial coordinate system; the first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively the flow field velocities in the normal direction, radial direction, and tangential direction of the impeller hub coordinate system.

[0061] The first normal flow field velocity Vn of each blade element segment of the rotor at various azimuth angles in the hub coordinate system. planeofdisk n The calculation formula is: Vn planeofdisk n =V Gz n .

[0062] The first radial flow field velocity Vr of each blade element segment of the rotor at various azimuth angles in the hub coordinate system planeofdisk n The calculation formula is: Vr planeofdisk n =V Gx n ×sin(θ n )+V Gy n ×cos(θ n ); where θ n The rotor azimuth angle is the angle at the nth iteration step.

[0063] The first tangential flow field velocity Vt of each blade element segment of the rotor at various azimuth angles in the hub coordinate system. planeofdisk n The calculation formula is: Vt planeofdisk n =V Gx n ×cos(θ n )-V Gy n ×sin(θ n ).

[0064] Where the superscript n indicates the nth iteration step. V Gx V Gy n V Gz nThis refers to the flow velocity in the inertial coordinate system, which is fixed to the ground. The x-axis points behind the fuselage / rotor azimuth at 0°, and the y-axis points to the right side of the fuselage / rotor azimuth at 90°. The rotor hub coordinate system is fixed on the rotor hub and rotates with the rotor. The normal direction is positive, the tangential direction is opposite to the direction of rotation, and the radial direction is determined by the right-hand rule. The blade element micro-segment coordinate system is fixed in the middle of the blade element micro-segment. It not only rotates with the rotor like the rotor hub coordinate system but also experiences flapping motion. When the rotor flapping angle is zero, the coordinate axis directions are defined in the same way as the rotor hub coordinate system. The relationship between the inertial coordinate system, the rotor hub coordinate system, and the blade element micro-segment coordinate system is as follows: Figure 3 As shown.

[0065] S6. Using the rigid body flapping angles β of the rotor at various azimuth angles in the hub coordinate system. flap n The first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle. planeofdisk n and the first radial flow field velocity Vr planeofdisk n Calculate the second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle in the blade element segment coordinate system. blade n Second tangential flow field velocity Vt blade n The second normal flow field velocity and the second tangential flow field velocity are the flow field velocities in the normal direction and the tangential direction of the leaf element micro-segment coordinate system, respectively.

[0066] The second normal flow field velocity Vn of each blade element segment of the rotor at various azimuth angles in the blade element segment coordinate system. blade n The calculation formula is: Vn blade n =-Vr planeofdisk n ×sin(β flap n )+Vn planeofdisk n ×cos(β flap n ); where β flap n Let Vn be the rigid body flapping angle of the rotor at various azimuth angles in the hub coordinate system during the nth iteration. planeofdisk n Let Vr be the first normal flow velocity of each blade element segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n Let be the first radial flow field velocity of each blade element segment of the rotor at each azimuth angle in the hub coordinate system.

[0067] The second tangential flow field velocity Vt of each blade element segment of the rotor at various azimuth angles in the blade element segment coordinate system. blade n The calculation formula is: Where w is the rotor speed. Let be the azimuth angle in radians corresponding to the i-th circumferential orientation of the rotor in the nth iteration.

[0068] S7. Using the flapping speed V of each blade element segment of the rotor in the blade element micro-segment coordinate system. flap n The second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle. blade n Calculate the normal velocity Vn of the flow field relative to the leaf element microsegment. blade blade n .

[0069] The calculation formula is: Vn blade blade n =Vn blade n -V flap n , where: Vn blade n V is the normal flow velocity in the leaf element micro-segment coordinate system. flap n Vn is the flapping speed of the rotor blade element microsegments. blade blade n Let be the normal velocity of the flow field relative to the leaf element microsegment in the leaf element microsegment coordinate system.

[0070] S8. Obtain the rotor collective pitch control input φ0, the rotor longitudinal periodic pitch control input A, and the rotor lateral periodic pitch control input B, and calculate the rotor pitch angle. In this embodiment, these three inputs are used to calculate the rotor's rigid body flapping steady-state periodic response, providing a foundation for aerodynamic, dynamic, and flight mechanics characteristic analysis.

[0071] The formula for calculating the rotor blade pitch angle is: φ=φ0+A*cos(θ) n )+B*sin(θ n ); where φ is the rotor pitch angle, θ n φ0 is the rotor azimuth angle for the nth iteration (the rotor pitch angle is calculated once using the above three inputs at each azimuth angle), φ0 is the rotor collective pitch control input, A is the rotor longitudinal periodic pitch control input, and B is the rotor lateral periodic pitch control input.

[0072] S9. In the blade element micro-segment coordinate system, the second tangential flow field velocity Vt of each blade element micro-segment of the rotor at each azimuth angle is used.blade n The normal velocity Vn of the flow field relative to the leaf element segment blade blade n Based on the rotor pitch angle, the aerodynamic forces (Fareo) of each blade element segment of the rotor at various azimuth angles are calculated according to blade element theory. n .

[0073] The formula for calculating the aerodynamic forces of each blade element segment of the rotor at various azimuth angles is: Fareo n =0.5×ρ×Vt blade n ×Vt blade n ×(Vn blade blade n / Vt blade n +φ)×2π×c×dr;where ρ is the flow field density, 2π is the lift line slope, c is the rotor chord length, and dr is the length of the blade element along the rotor span.

[0074] S10, utilizing the aforementioned aerodynamic force Fareo n Calculate the rotor momentum source term Fsource at each azimuth angle. n .

[0075] The calculation formula is: Fsource n =Fareo n ×N / k / h, where N is the number of rotor blades, k is the number of discrete rotor disks in the circumferential direction, and h is the thickness of the rotor region grid, which can be obtained directly.

[0076] S11, the rotor momentum source term Fsource n The momentum source term of the Navier-Stokes equations is added, and the flow field velocities in the x, y, and z directions of the rotor region grid in the inertial coordinate system, as well as the pressure, density ρ, and temperature, are updated using computational fluid dynamics based on the Navier-Stokes equations.

[0077] S12, utilizing the aforementioned aerodynamic force Fareo n Update the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement X of the rigid body tip at each azimuth angle of the rotor in the hub coordinate system". n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ".

[0078] Tip flapping acceleration of rotor rigid body flapping response Tip swing speed and tip waving displacement The update process specifically includes:

[0079] From rotor dynamics, the equation for the rigid body flapping dynamics of a rotor is M*a + K*X = Faero. The loosely coupled method for rotor fluid-structure interaction calculations involves first calculating the aerodynamic forces of the rotor at different azimuth angles in the nth iteration step. Then, updating the rotor flapping response at different azimuth angles in the (n+1)th iteration, the formula for updating the rotor rigid body flapping response, as shown above, becomes... The Newmark-β dynamic response solution method can be used to solve this dynamic equation to obtain the tip flapping accelerations of the rotor at various azimuth angles. Tip swing speed and tip waving displacement Where: M is the equivalent mass of the rotor rigid body flapping dynamics, K is the equivalent stiffness of the rotor rigid body flapping dynamics which can be obtained from relevant knowledge of rotor dynamics. i is the label of the rotor circumferential orientation, representing different azimuth angles, and k is the discrete number of the rotor disk circumferential direction. Let be the rotor tip flapping acceleration at the i-th azimuth angle in the (n+1)-th iteration step. Let be the rotor tip flapping speed at the azimuth angle in the (n+1)th iteration step. Let be the aerodynamic force at the i-th azimuth angle in the n-th iteration step.

[0080] S13. Stop iterating until the difference between the tip waving displacements of two adjacent iterations is less than the preset error value.

[0081] If the error of the rigid body wave response period converges If the error is less than the given error value (e.g., 0.005 meters), the rigid body flapping response has reached steady-state convergence, and the calculation stops. The rotor rigid body flapping response calculated in step S12 is the rotor rigid body flapping steady-state periodic response.

[0082] Compared with existing technical solutions, the advantages of this embodiment are:

[0083] Existing technical solution 1: Calculate rotor aerodynamic forces using an inflow model and blade element theory considering flapping velocity, then calculate the rotor flapping response using a loosely coupled method from rotor dynamics. Existing technical solution 2: Calculate rotor aerodynamic forces using blade element-free wake theory considering flapping velocity, then calculate the rotor flapping response using a loosely coupled method from rotor dynamics. Existing technical solution 3: Calculate rotor aerodynamic forces using a body-fitted mesh-based CFD method, which can consider the aerodynamic interference effects of rotor / fuselage, rotor / controller surfaces, etc., and calculate the rotor flapping response using a loosely coupled method of rotor rigid body dynamics and CFD.

[0084] However, existing methods have drawbacks such as difficulty in considering the interference of rotor and multiple aerodynamic surfaces, a large number of empirical parameters, and huge computation time.

[0085] The main drawback of existing technologies is their slow computation speed. In existing technologies 2 and 3, the aerodynamic calculation for solving the rotor flapping response uses an accurate time-progression method, meaning that calculating the rotor flow field at least hundreds of moments is required for one rotor rotation. Furthermore, it typically takes about 10 rotations to achieve a periodic steady-state rotor flapping response. Therefore, the computation time required for the rotor flapping response to reach a periodic steady-state is 10-100 hours or even longer. This significant computation time results in high costs for calculating the periodic steady-state rigid body flapping response of rotors using existing technologies, limiting their application scenarios.

[0086] Disadvantage 2: Existing technical solution 1 cannot consider the influence of other aerodynamic components besides the rotor on the flow field. In existing technology 1, the inflow model is used to calculate the inflow velocity of the rotor. However, the inflow model only considers the forward velocity and the influence induced by the rotor itself, and cannot consider the influence of other aerodynamic components besides the rotor on the flow field. Therefore, it is only suitable for calculations of single rotor configurations, and its application scenarios are severely limited.

[0087] Disadvantage 3: Existing technical solution 2 struggles to account for the influence of aerodynamic components other than the rotor on the flow field. In existing technology 2, the rotor inflow is calculated using a free wake model, which has many empirical parameters and is highly sensitive to these parameters. Furthermore, the influence of the fuselage on the rotor inflow requires point source simulation, which is derived from potential flow theory. However, because potential flow theory assumes inviscidity and irrotation, it cannot simulate the viscous drag and flow separation on surfaces such as fuselage control surfaces. Moreover, modern helicopter fuselage surfaces are complex, and flow separation is prevalent. Therefore, this limitation restricts the use of existing technical solution 2.

[0088] In contrast to the disadvantage 1 (main) of the existing solutions, the advantages of this embodiment are: The rotor aerodynamic calculation part in this embodiment adopts the time-averaged rotor momentum source method, which does not have the concept of accurate time and rotor calculation number. Therefore, the number of calculation iteration steps required for the rotor flapping response to reach the periodic steady state is on the order of hundreds, and the calculation time is 1-2 hours. Compared with the thousands / tens of thousands of iteration steps and 10-100 calculation time of the existing technologies 2 and 3, the calculation speed of the method in this embodiment is significantly faster.

[0089] In contrast to the shortcomings of the existing solutions 2 and 3, the advantages of this embodiment are: because the flow field solution in this embodiment uses CFD (Computational Fluid Dynamics) technology, the influence of objects such as fuselage and control surfaces on the rotor flow field can be easily considered using body mesh technology.

[0090] This embodiment also verifies the above scheme, and the data and results are as follows:

[0091] The experimental data comes from the rotor / fuselage wind tunnel test model at Georgia Institute of Technology. Figure 4 This is a schematic diagram of the model in the wind tunnel test section. Table 1 below shows the model's geometric data.

[0092] Table 1 Geometric data of the test model

[0093]

[0094]

[0095] The method described in this embodiment calculates the steady-state periodic response of the rotor rigid body flapping, and by changing the rotor momentum source term, the influence of rotor wind flapping on the rotor flow field is taken into account. Figure 5 The surface pressure coefficients at the upper and right sides of the fuselage under the steady-state periodic response of rotor rigid body flapping, calculated using the method of this embodiment, are compared with experimental values ​​and values ​​calculated using conventional methods that do not consider rotor flapping. The results calculated by the method of this embodiment show a consistent trend with the experimental values, and the two agree well. The results calculated by the conventional methods that do not consider rotor flapping differ significantly from the experimental values, which proves the feasibility and correctness of the method for calculating the steady-state periodic response of rotor rigid body flapping in this embodiment.

[0096] The verification example rotor model with fuselage shows that the method in this embodiment can conveniently consider the influence of the fuselage, control surfaces and other objects on the rotor. Figure 6 The convergence of the rotor rigid body flapping periodic response with iteration steps is shown. In the 75th iteration step, the rotor rigid body flapping response has converged periodically. It can be found that the difference between the rotor rigid body flapping periodic response in the 60th and 75th iteration steps is very small, indicating the speed of calculating the rotor steady-state rigid body flapping response using the method of this embodiment.

[0097] This embodiment calculates the rotor's steady-state periodic flapping response to the three inputs: rotor collective pitch control input, rotor longitudinal periodic pitch control input, and rotor lateral periodic pitch control input. Because this embodiment loosely couples the rotor momentum source term and the rotor rigid body flapping response, it can quickly calculate the rotor's steady-state rigid body flapping response. Furthermore, this embodiment includes all aerodynamic components in the rotor momentum source term, thus comprehensively considering the influence of aerodynamic components on the flow field. Therefore, this embodiment effectively improves computational efficiency while fully considering the influence of aerodynamic components on the flow field.

[0098] The rotor generates lift to overcome the helicopter's gravity and also serves as the helicopter's control surface, providing the helicopter's climb, pitch, and roll moments. To enable the rotor to perform these tasks, the rotor blades are hinged to the hub, allowing the blades to flap freely up and down during rotation. Under different flight conditions and with varying rotor collective pitch and cyclic pitch control, the steady-state periodic rotor tip flapping displacement β is calculated using the method described in this patent. flap Periodic rotor tip flapping displacement β flap This is manifested in the rotor disk plane having a fixed forward chamfer 'a'. 1s and back chamfer b 1s (The calculation formula is: β) flap =a0-a 1s *cos(θ)-b 1s *sin(θ) Fourier series expansion), (the rotor's flapping response to control input is nonlinear), the rotor's aerodynamic resultant force also follows the rotor disk plane with a forward chamfer α. 1s chamfer b 1s The combined aerodynamic force of the forward-tilting and side-tilting rotors exerts forward and lateral forces and moments on the rotorcraft. These forces and moments cause the rotorcraft to roll laterally and pitch forward, thus achieving attitude motion control. Therefore, the attitude motion control of a rotorcraft comprises two parts: 1. Calculating the rotor tip flapping displacement β under rotor control input. flap 2. Displacement β from the rotor tip flapping flap Calculate the forward and lateral forces and moments of a rotorcraft, and calculate the attitude and motion of the rotorcraft (using expertise in flight mechanics).

[0099] In the analysis of rotorcraft control characteristics: Under specific rotor collective pitch, lateral periodic pitch, and longitudinal periodic pitch control inputs, due to differences in flight state and flow field interference, it is desirable to conveniently, quickly, and accurately calculate the periodic rotor tip flapping displacement β. flap It becomes difficult. But for a given periodic rotor tip flapping displacement β flap The forward and lateral forces and moments acting on a rotorcraft are specific and easily calculated. Therefore, the main challenge in accurately evaluating the motion response of a rotorcraft under control inputs lies in accurately calculating the periodic tip flapping displacement β of the rotor under these inputs. flap Therefore, establishing an efficient, accurate, and steady-state periodic method for calculating the flapping displacement of the rotor rigid body tip that can account for fuselage interference is crucial for the study of the handling characteristics of rotorcraft.

[0100] Example 2:

[0101] like Figure 7 As shown, this embodiment provides a system for rapidly calculating the steady-state periodic response of a rotor rigid body flapping. The system includes:

[0102] The computational domain selection unit M1 is used to obtain an arbitrary space containing the rotor as the computational domain for the rotor CFD flow field.

[0103] Mesh generation unit M2 is used to divide the rotor CFD flow field calculation domain into a mesh to obtain the rotor region mesh.

[0104] The rigid body flapping angle calculation unit M3 is used to calculate the flapping displacement X of the rigid body tip at various azimuth angles of the rotor in the hub coordinate system. n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ;

[0105] The flapping speed calculation unit M4 is used to calculate the tip flapping speed V of the rotor in the hub coordinate system. n Calculate the flapping speed V of each blade element segment of the rotor. flap n The leaf element micro-segment is a section of the rotor along its span.

[0106] The flow field velocity acquisition unit M5 is used to obtain the flow field velocity V in the x-direction at the rotor region grid in the inertial coordinate system. Gx n Flow velocity V in the y direction Gy n and the flow velocity V in the z-direction Gz n Obtain the first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle in the hub coordinate system. planeofdisk n First radial flow field velocity Vr planeofdisk n and the first tangential flow field velocity Vt planeofdisk n The x-direction flow field velocity, y-direction flow field velocity, and z-direction flow field velocity are respectively the flow field velocities in the x-direction, y-direction, and z-direction of the inertial coordinate system; the first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively the flow field velocities in the normal direction, radial direction, and tangential direction of the impeller hub coordinate system.

[0107] Coordinate transformation unit M6 is used to utilize the rotor rigid body flapping angle β in the hub coordinate system. flap n The first normal flow field velocity Vn of each blade element micro-segment of the rotor at each azimuth angle. planeofdisk n and the first radial flow field velocity Vr planeofdisk nCalculate the second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle in the blade element segment coordinate system. blade n Second tangential flow field velocity Vt blade n The second normal flow velocity and the second tangential flow velocity are the flow velocity in the normal direction and the flow velocity in the tangential direction of the leaf element micro-segment coordinate system, respectively.

[0108] The relative normal velocity calculation unit M7 is used to calculate the flapping velocity V of each blade element segment of the rotor in the blade element segment coordinate system. flap n The second normal flow field velocity Vn of each blade element segment of the rotor at each azimuth angle. blade n Calculate the normal velocity Vn of the flow field relative to the leaf element microsegment. blade blade n ;

[0109] The input acquisition unit M8 is used to acquire the rotor collective pitch control input φ0, the rotor longitudinal periodic pitch control input A, and the rotor lateral periodic pitch control input B, and to calculate the rotor pitch angle.

[0110] The aerodynamic calculation unit M9 is used to calculate the second tangential flow field velocity Vt of each blade element micro-segment of the rotor at various azimuth angles in the blade element micro-segment coordinate system. blade n The normal velocity Vn of the flow field relative to the leaf element segment blade blade n Based on the rotor pitch angle, the aerodynamic forces (Fareo) of each blade element segment of the rotor at various azimuth angles are calculated according to blade element theory. n ;

[0111] The rotor momentum source term calculation unit M10 is used to utilize the aerodynamic force Fareo n Calculate the rotor momentum source term Fsource at each azimuth angle. n ;

[0112] The rotor CFD flow field calculation domain update unit M11 is used to update the rotor momentum source term Fsource. n Add to the momentum source term of the Navier-Stokes equations, and update the flow field velocities in the x, y, and z directions of the rotor region grid in the inertial coordinate system using computational fluid dynamics based on the Navier-Stokes equations.

[0113] Rigid body swing response update unit M12, used to utilize the aerodynamic Fareo nUpdate the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement X of the rigid body tip at each azimuth angle of the rotor in the hub coordinate system". n Calculate the rigid body flapping angle β of the rotor at each azimuth angle. flap n ”;

[0114] The iterative control unit M13 is used to stop the iteration when the difference between the tip waving displacements of two adjacent iterations is less than a preset error value.

[0115] Example 3:

[0116] like Figure 8 As shown in the figure, this embodiment provides a method for rapidly calculating the steady-state periodic response of a rotor rigid body flapping, the method comprising:

[0117] 1. Initialize the rotor rigid body flapping response and rotor CFD flow field calculation domain.

[0118] Define the tip flapping displacement X, tip flapping velocity V, and tip flapping acceleration a of the rigid body rotor at different azimuth angles, and initialize them to 0 to complete the initialization of the rotor's rigid body flapping response. Take any space containing the rotor as the rotor CFD flow field computation domain and mesh it. The rotor CFD flow field computation domain then includes a sector-shaped mesh of the rotor region and other general meshes. Simulate the rotor using the rotor momentum source method on the sector-shaped mesh of the rotor region, and assign a flow field velocity (V) to each mesh in the rotor CFD flow field computation domain. Gx V Gy V Gz The flow field is initialized by assigning initial values ​​to pressure, density ρ, and temperature.

[0119] 2. The tip displacement X of the rotor rigid body flapping response at each azimuth angle in the nth iteration step. n Calculate the rigid body flapping angle β of the rotor in each azimuth direction in the hub coordinate system. flap n The tip-waving speed V in the nth iteration step. n Calculate the flapping velocity V of each blade element segment in the rotor hub coordinate system. flap n The flow field velocity V at each blade element micro-segment in each azimuth angle is read from the rotor region mesh in the rotor CFD flow field computation domain of the nth iteration step. Gx n V Gy n V Gz nBy transforming coordinates, the normal flow velocity Vn at each blade element micro-segment in each azimuth angle of the rotor is calculated in the hub coordinate system. planeofdisk n Radial flow velocity Vr planeofdisk n and tangential flow velocity Vt planeofdisk n .

[0120] The formula is: β flap n =X n / R (R is the rotor radius), V flap n =V n ×r / R (r is the radius of the center of the leaf element segment, 0≤r≤R,)Vn planeofdisk n =V Gz n Vr planeofdisk n =V Gx n ×sin(θ n )+V Gy n ×cos(θ n ), Vt planeofdisk n =V Gx n ×cos(θ n )-V Gy n ×sin(θ n ).

[0121] 3. The rotor rigid body flapping angle β in the hub coordinate system in step 2 flap n Normal flow velocity Vn at each leaf element micro-segment in each azimuth angle planeofdisk n and radial flow velocity Vr planeofdisk n Using coordinate transformation, the normal flow field velocity Vn at each blade element micro-segment in each azimuth angle of the rotor is calculated in the blade element micro-segment coordinate system. blade n Tangential flow velocity Vt blade n The formula is:

[0122] Vn blade n =-Vr planeofdisk n ×sin(β flap n )+Vn planeofdisk n×cos(β flap n (where: β) flap n Let Vn be the rotor rigid body flapping angle in the nth iteration. blade n Vn represents the normal flow velocity in the leaf element micro-segment coordinate system. planeofdisk n Vr represents the normal flow velocity at each blade element segment in the hub coordinate system. planeofdisk n (where is the radial flow velocity at each blade element segment in the hub coordinate system).

[0123] (w is the rotor speed, (The azimuth angle in radians corresponding to the i-th circumferential orientation of the rotor in the nth iteration step)

[0124] 4. Consider the flapping speed V of each blade element segment of the rotor calculated in step 2. flap n Calculate the normal velocity Vn of the flow field relative to the rotor blade element micro-segment in the blade element micro-segment coordinate system. blade blade n The aerodynamic forces of each blade element micro-segment at each azimuth angle of the rotor were calculated using blade element theory. n .

[0125] The formula is: Vn blade blade n =Vn blade n -V flap n (where: Vn) blade n V is the normal flow velocity in the leaf element micro-segment coordinate system. flap n Vn is the flapping speed of the rotor blade element microsegments. blade blade n (The normal velocity of the flow field relative to the leaf element micro-segment in the leaf element micro-segment coordinate system)

[0126] Formula for calculating rotor pitch angle φ: φ=φ0+A*cos(θ) n )+B*sin(θ n ).

[0127] (φ0: Rotor collective pitch control input; A: Rotor longitudinal cyclic pitch control input; B: Rotor lateral cyclic pitch control input, θ) n (The rotor azimuth angle at the nth iteration step)

[0128] Fareo n=0.5×ρ×Vt blade n ×Vt blade n ×(Vn blade blade n / Vt blade n +φ)×2π×c×dr

[0129] (ρ is the flow field density in step 1, 2π is the lift line slope, c is the rotor chord length, dr is the length of the blade element along the rotor span, and φ is the rotor pitch angle).

[0130] 5. The aerodynamic force Fareo of the leaf element microsegment in the nth iteration of step 4. n Calculate the rotor momentum source term Fsource for each azimuth angle. n The calculated momentum source term is added to the momentum source term in the Navier-Stokes equations, and the rotor CFD flow field computational domain is updated using CFD (Computational Fluid Dynamics) methods in the (n+1)th iteration (this part covers the rotor momentum source method and the basic methods of computational fluid dynamics). Specifically: Fsource n =Fareo n ×N / k / h (N is the number of rotor blades, k is the number of discrete rotor disks in the circumferential direction, and h is the thickness of the rotor region mesh, which can be obtained directly)

[0131] The aerodynamic force at the i-th azimuth angle obtained in step 4 at the n-th iteration step Update the tip flapping acceleration of the rotor rigid body flapping response at the i-th azimuth angle in the (n+1)-th iteration step in a loosely coupled manner. and tip waving displacement Specifically, as shown below: From rotor dynamics, the equation for the rigid body flapping dynamics of the rotor is M*a + K*X = Faero. The loosely coupled method for rotor fluid-structure interaction calculation is as follows: First, calculate the aerodynamic forces of the rotor at different azimuth angles in the nth iteration step. Then, updating the rotor flapping response at different azimuth angles in the (n+1)th iteration, the formula for updating the rotor rigid body flapping response, as shown above, becomes... The Newmark-β dynamic response solution method can be used to solve this dynamic equation to obtain the tip flapping acceleration at each azimuth angle. Tip swing speed and tip waving displacement (Where: M is the equivalent mass of the rotor rigid body flapping dynamics, K is the equivalent stiffness of the rotor rigid body flapping dynamics, which can be obtained from relevant knowledge of rotor dynamics. i is the label of the rotor circumferential orientation representing different azimuth angles, and k is the discrete number of the rotor disk circumferential direction.) Let be the rotor tip flapping acceleration at the i-th azimuth angle in the (n+1)-th iteration step. Let be the rotor tip flapping speed at the azimuth angle in the (n+1)th iteration step. The aerodynamic force at the i-th azimuth angle in the nth iteration step is calculated by summing the aerodynamic forces of all blade element segments at the i-th azimuth angle in step 4.

[0132] 6. If the error of the rigid body's wavering response period converges If the error is less than the given error value (e.g., 0.005 meters), the rigid body flapping response has reached steady-state convergence, and the calculation stops. The rotor rigid body flapping response calculated in step 5 is the rotor rigid body flapping steady-state periodic response. If it has not converged, the calculation starts from step 2 until the rotor rigid body flapping response periodically converges.

[0133] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0134] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for fast computation of the rigid body flapping steady state periodic response of a rotor, characterized by, The method comprises: acquiring an arbitrary space containing a rotor as a rotor CFD flow field calculation domain; dividing a grid of the rotor CFD flow field calculation domain to obtain a rotor area grid; Utilizing rigid tip flapping displacement of the rotor at each azimuthal angle in the hub coordinate system Computing rigid flapping angle of the rotor at each azimuthal angle ; utilizing the tip flapping velocity of the rotor in the hub coordinate system calculating the flapping velocity of each blade element micro-section of the rotor ; the blade element micro-section is a section of the rotor along the span direction an x-direction flow field velocity at the rotor region grid in an inertial coordinate system , a y-direction flow field velocity , and a z-direction flow field velocity obtaining a first normal flow field velocity , a first radial flow field velocity , and a first tangential flow field velocity of each blade element micro-section of the rotor at each azimuth angle in a hub coordinate system; the x-direction flow field velocity, the y-direction flow field velocity, and the z-direction flow field velocity are respectively an x-direction flow field velocity, a y-direction flow field velocity, and a z-direction flow field velocity of the inertial coordinate system; the first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively a normal-direction flow field velocity, a radial-direction flow field velocity, and a tangential-direction flow field velocity of the hub coordinate system; a first normal flow field velocity of each blade element micro segment of the rotor at each azimuth angle a first radial flow field velocity of each blade element micro segment of the rotor a second normal flow field velocity of each blade element micro segment of the rotor at each azimuth angle a second tangential flow field velocity of each blade element micro segment of the rotor a second tangential flow field velocity of each blade element micro segment of the rotor the second normal flow field velocity and the second tangential flow field velocity are respectively a flow field velocity in a normal direction and a flow field velocity in a tangential direction of the blade element micro segment coordinate system; utilizing the flapping velocity of each bladelet microsegment of the rotor and the second normal flow field velocity at which each bladelet microsegment of the rotor is located at each azimuth angle calculating the normal velocity of the flow field relative to the bladelet microsegment ; Obtaining rotor collective control input , a rotor longitudinal cyclic control input A, and a rotor lateral cyclic control input B, and calculating a rotor pitch angle; under a blade element micro-segment coordinate system, using the second tangential flow field velocity of each blade element micro-segment of the rotor at each azimuth angle , the normal velocity of the flow field relative to the blade element micro-segment and the pitch angle of the rotor, calculating the aerodynamic force of each blade element micro-segment of the rotor at each azimuth angle according to the blade element theory ; Utilizing the aerodynamic force Computing the rotor momentum source term at each azimuthal angle of the rotor ; adding the rotor momentum source term to a momentum source term of Navier-Stokes equations, and updating the x-direction flow field velocity, the y-direction flow field velocity and the z-direction flow field velocity of the rotor region grid under the inertial coordinate system according to the Navier-Stokes equations by a method of computational fluid dynamics; Utilizing the aforementioned aerodynamic force Update the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner Tip swing speed and tip waving displacement And return to step "using the flapping displacement of the rigid body tips of the rotor at various azimuth angles in the hub coordinate system". Calculate the rigid body flapping angle of the rotor at various azimuth angles. ”; stopping iteration until the difference of the tip flapping displacement of the adjacent two iterations is less than a preset error value.

2. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, After the dividing of the grid of the rotor CFD flow field calculation domain to obtain the rotor area grid, the method further comprises: initializing the x-direction flow field velocity, the y-direction flow field velocity, the z-direction flow field velocity and the flow field density at each grid in the rotor area grid; initializing the rigid tip flapping displacement and the tip flapping velocity of the rotor at each azimuth angle.

3. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, The dividing of the grid of the rotor CFD flow field calculation domain to obtain the rotor area grid specifically comprises: dividing a grid of the rotor CFD flow field calculation domain to obtain a grid calculation domain; simulating the rotor in the grid calculation domain by using a rotor momentum source method to obtain a rotor area grid.

4. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor of claim 1, wherein, the rigid tip flapping displacement of the rotor at each azimuth angle in the hub coordinate system the rigid flapping angle of the rotor at each azimuth angle the calculation formula is: wherein, denotes the rigid flapping angle of the rotor at each azimuthal angle in the hub coordinate system in the n-th iteration, X n denotes the rigid tip flapping displacement of the rotor at each azimuthal angle in the hub coordinate system in the n-th iteration, R denotes the rotor radius.

5. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, The tip flapping velocity of the rotor is calculated in the hub coordinate system The flapping velocity of each blade element micro-section of the rotor is calculated The calculation formula is: wherein, represents the flapping velocity of each blade element micro segment of the rotor in the hub coordinate system in the n-th iteration, V n represents the tip flapping velocity in the hub coordinate system in the n-th iteration, r represents the radius at which the center of the blade element micro segment coordinate system is located, R represents the rotor radius.

6. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor of claim 1, wherein, The first normal flow field velocity of each blade element micro-section of the rotor in the hub coordinate system at each azimuth angle The calculation formula is: ; First radial flow field velocity of each blade element micro segment of the rotor in the hub coordinate system at each azimuth angle The calculation formula is: ; wherein, is the first radial flow field velocity of each blade element micro segment of the rotor in the hub coordinate system at each azimuth angle n Iteration step rotor azimuth angle The first tangential flow field velocity of each blade element micro-section of the rotor in the hub coordinate system at each azimuth angle The calculation formula is: .

7. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, The second normal flow field velocity of each blade element segment of the rotor at various azimuth angles in the blade element segment coordinate system. The calculation formula is: ;in, For the first The rotor rigid body flapping angle in the hub coordinate system of the next iteration Let be the first normal flow field velocity of each blade element micro-segment of the rotor in the hub coordinate system. Let be the first radial flow field velocity of each blade element segment of the rotor in the hub coordinate system; The second tangential flow field velocity of each blade element micro segment of the rotor at each azimuth angle in the blade element micro segment coordinate system The calculation formula is: ; wherein, is the rotor speed, is the rotor at the first iteration corresponding to the arc azimuth angle of the first circumferential direction, r indicates the radius where the center of the blade element micro segment coordinate system is located.

8. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, The formula for calculating the rotor pitch angle is: ; wherein, is the rotor pitch angle, is the rotor azimuth angle at the n-th iteration step; The formula for calculating the aerodynamic force of each blade element micro-section of the rotor at each azimuth angle is: ; wherein, is the flow field density, 2 is the lift line slope, is the rotor chord length, is the length of the blade element micro-element along the span direction of the rotor.

9. The method of rapidly calculating the rigid body flapping steady state periodic response of a rotor according to claim 1, wherein, the aerodynamic force updating the tip flapping acceleration of the rotor rigid body flapping response in a loosely coupled manner , tip flapping velocity , and tip flapping displacement , specifically comprising: The updating equation is solved by using the Newmark-β dynamic response solving method to obtain the tip flapping acceleration , the tip flapping speed and the tip flapping displacement of the rotor rigid body flapping response; the updating equation is: ; wherein, is the equivalent mass of the rotor rigid body flapping dynamics, is the equivalent stiffness of the rotor rigid body flapping dynamics, is a mark representing different azimuth angles in the circumferential direction of the rotor, is a discrete number in the circumferential direction of the rotor disc.

10. A system for fast computation of the rigid body flapping steady state periodic response of a rotor, characterized by, The system comprises: a calculation domain selection unit configured to acquire an arbitrary space containing a rotor as a rotor CFD flow field calculation domain; a grid division unit configured to divide a grid of the rotor CFD flow field calculation domain to obtain a rotor area grid; a rigid body flapping angle calculation unit for calculating rigid body flapping angles of the rotor at each azimuth angle using the rigid body tip flapping displacement of the rotor at each azimuth angle in the hub coordinate system calculating rigid body flapping angles of the rotor at each azimuth angle ; flap speed calculation unit for calculating a tip flap speed of the rotor in the hub coordinate system calculating a flap speed of each blade element micro segment of the rotor ; the blade element micro segment is a section of the rotor along the span direction a flow field velocity acquisition unit configured to acquire an x-direction flow field velocity, a y-direction flow field velocity, and a z-direction flow field velocity at the rotor region grid in an inertial coordinate system a first normal flow field velocity, a first radial flow field velocity, and a first tangential flow field velocity of each blade element micro-section of the rotor at each azimuth angle in a hub coordinate system The x-direction flow field velocity, the y-direction flow field velocity, and the z-direction flow field velocity are respectively an x-direction flow field velocity, a y-direction flow field velocity, and a z-direction flow field velocity in an inertial coordinate system. The first normal flow field velocity, the first radial flow field velocity, and the first tangential flow field velocity are respectively a normal-direction flow field velocity, a radial-direction flow field velocity, and a tangential-direction flow field velocity in a hub coordinate system.​​​​ a coordinate conversion unit configured to calculate a first normal flow field velocity and a first tangential flow field velocity at each azimuth angle of each blade element of the rotor , the first normal flow field velocity and the first tangential flow field velocity being respectively a normal direction flow field velocity and a tangential direction flow field velocity of a blade element coordinate system a coordinate conversion unit configured to calculate a second normal flow field velocity and a second tangential flow field velocity at each azimuth angle of each blade element of the rotor , the second normal flow field velocity and the second tangential flow field velocity being respectively a normal direction flow field velocity and a tangential direction flow field velocity of a blade element coordinate system a coordinate conversion unit configured to calculate a second normal flow field velocity and a second tangential flow field velocity at each azimuth angle of each blade element of the rotor , the second normal flow field velocity and the second tangential flow field velocity being respectively a normal direction flow field velocity and a tangential direction flow field velocity of a blade element coordinate system a relative normal velocity calculation unit configured to calculate a normal velocity of the flow field with respect to the blade element micro segment using a flapping velocity of each blade element micro segment of the rotor and a second normal flow field velocity at which each blade element micro segment of the rotor is located at each azimuth angle calculate the normal velocity of the flow field with respect to the blade element micro segment ; an input acquisition unit configured to acquire a rotor collective pitch control input a rotor longitudinal cyclic pitch control input A and a rotor lateral cyclic pitch control input B, and calculate a rotor pitch angle; aerodynamic force calculation unit for calculating aerodynamic forces of each micro-element of the rotor at each azimuth angle based on the second tangential flow field velocity of each micro-element of the rotor at each azimuth angle , the normal velocity of the flow field relative to the micro-element of the blade , and the pitch angle of the rotor, according to the blade element theory ; a rotor momentum source term calculation unit for calculating a rotor momentum source term for the rotor located at each azimuthal angle using the aerodynamic force a rotor momentum source term calculation unit for calculating a rotor momentum source term for the rotor located at each azimuthal angle using the aerodynamic force ; The rotor CFD flow field calculation domain update unit is used to update the rotor momentum source term. Add to the momentum source term of the Navier-Stokes equations, and update the normal flow velocity, radial flow velocity, and tangential flow velocity of the rotor region grid in the inertial coordinate system using computational fluid dynamics based on the Navier-Stokes equations. a rigid body flapping response updating unit for updating the rigid body flapping response of the rotor using the aerodynamic force in a loosely coupled manner the tip flapping velocity and the tip flapping displacement of the rotor at each azimuth angle in the hub coordinate system ; an iteration control unit configured to stop iteration until the difference of the tip flapping displacement of the adjacent two iterations is less than a preset error value.

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