Optimization design method for multi-fulcrum elastic ring supporting structure of aero-engine rotor system

Abstract

The invention relates to an optimization design method for a multi-fulcrum elastic ring supporting structure of an aero-engine rotor system, and belongs to the technical field of aero-engine vibration control and rotor dynamics simulation. Firstly, a finite element or lumped unit model is adopted to establish a coupling kinetic equation of a rotor and an elastic ring, and fluid-solid coupling factors such as inner and outer oil films of the elastic ring and orifice flow are considered; then, through critical rotating speed and vibration harmonic response analysis, sensitivity evaluation is carried out on rigidity and damping characteristics of different supporting positions, and target vibration reduction modes corresponding to all fulcrums are identified; then, coupling simulation and multi-objective optimization are carried out around the number of bosses of the elastic ring, the height of the bosses, the damping aperture, the thickness of a thin wall and other key structure parameters, and the optimal design meeting the vibration reduction requirement of a rotor system and the strength reliability requirement of the elastic ring is obtained through iteration; and finally, an optimization result is applied to structure manufacturing and assembling. The method can effectively reduce the vibration amplitude of the rotor when the rotor crosses the multi-order critical rotating speed.

Description

Technical Field

[0001] The invention belongs to the technical field of aero-engine vibration control and rotor dynamics simulation, and in particular relates to an optimization design method for a multi-support elastic ring support structure of an aero-engine rotor system. Background Art

[0002] The high-speed flexible rotor-support structure system of advanced aircraft engines is typically characterized by high speeds, heavy loads, multi-point support, and the ability to cross multiple critical speeds. This results in complex vibration response characteristics during operation. Due to differences in the vibration modes and motion characteristics of the rotor under different critical states, it is often difficult to effectively suppress the vibration responses of each order if only a spring-loaded damping structure is used at a single support position. To achieve safe crossing of multiple critical speeds, it is necessary to install corresponding spring-loaded damping devices at different support positions. By optimizing the support stiffness and damping parameters, the system's natural frequency can be adjusted and the vibration energy can be effectively dissipated through the movement of the support points, thereby allowing the rotor resonance to avoid the operating speed or smoothly pass through the critical speed.

[0003] The Elastic Ring Squeeze Film Damper (ERSFD) is a novel elastic support damping structure developed from the traditional squeeze film damper. It primarily consists of a thin-walled elastic ring with internal and external bosses and damping holes, and a flowing oil film within the ring gap. During operation, the rotor's precession motion causes the elastic ring to undergo elastic-plastic deformation, squeezing the oil film within the ring and forcing it to flow. The oil film pressure and ring stiffness combine to provide support and damping. The ERSFD can adjust the rotor's critical speed within a certain range and significantly reduce vibration amplitude. Its compact structure and lightweight weight make it suitable for high-speed rotor systems of various sizes.

[0004] However, the stiffness and damping characteristics of ERSFDs are influenced by the coupling of multiple factors, including the elastic ring's geometry, material properties, assembly, and oil film flow, and these factors interact in complex ways. Changes in the elastic ring's structural parameters not only affect its static mechanical properties but also alter the oil film's flow characteristics, thereby coupling them to the system's dynamic characteristics. Therefore, to fully exploit the vibration control advantages of ERSFDs in high-speed flexible rotor systems of aeroengines, comprehensive optimization of the elastic ring's geometry, materials, assembly method, and oil film parameters must be performed based on the rotor's actual deformation and motion characteristics. Currently, a systematic elastic ring design theory and method is lacking, making it difficult to accurately assess key aspects of ERSFDs, such as fatigue life, stiffness measurement, and assembly accuracy. This poses challenges to their application in aeroengine rotor systems. Therefore, it is necessary to establish a systematic design process based on fluid-structure interaction and dynamic optimization to provide feasible theoretical and technical support for the engineering application of ERSFDs in high-speed flexible rotor-support systems. Summary of the Invention

[0005] This paper addresses the design and optimization of elastic ring squeeze film damper (ERSFD) support systems for multi-pivot flexible rotor systems. It proposes an optimized design method for multi-pivot elastic ring support structures for aircraft engine rotor systems that comprehensively considers critical speeds, vibration response, and damping characteristics. This method fully considers the dynamic response characteristics of the rotor system and integrates dynamic modeling, sensitivity assessment, and structural parameter optimization. This method effectively improves the rotor system's vibration control capabilities across multiple critical speeds and ensures long-term reliable performance.

[0006] In order to achieve the above-mentioned object of the invention, the present invention proposes a method for optimizing the design of a multi-point elastic ring support structure of an aero-engine rotor system, and the technical solution adopted is:

[0007] A method for optimizing the design of a multi-point elastic ring support structure of an aero-engine rotor system, the method comprising:

[0008] Step S1: Establishing a coupled dynamic model of the rotor-support system; performing dynamic modeling on the rotor and finite element modeling on the elastic ring, establishing the oil film fluid domain inside and outside the elastic ring and the oil film coupling equation, and characterizing the oil film pressure distribution and orifice flow; coupling the rotor and the elastic ring to form a coupled dynamic equation of the rotor-support system;

[0009] Step S2: Evaluate the sensitivity of the critical speed to the support stiffness; based on the coupled dynamics model, solve the eigenvalue problem of the rotor to obtain the critical speed; by analyzing the safety margin between the critical speed and the operating speed under different support stiffnesses, determine the reasonable range of support stiffness for the elastic rings at different support points;

[0010] Step S3: Evaluate the sensitivity of the rotor response to the damping coefficient; change the damping coefficient of the elastic ring and evaluate the vibration amplitude of the rotor in each critical speed region under different damping coefficients; determine the target vibration reduction speed range of the elastic ring at different support points based on the sensitivity of the modal response of different support points to each critical speed region;

[0011] Step S4: Analyzing the influence of elastic ring structural parameters: Based on the geometric characteristics and material properties of the elastic ring, extract the elastic ring structural parameters and analyze their influence on the elastic ring support stiffness and damping coefficient; combining the critical speed and vibration response requirements of the rotor, screen the elastic ring structural parameter range that meets the target support stiffness and damping coefficient requirements;

[0012] Step S5: Iteratively optimize the elastic ring structural parameters; use the elastic ring structural parameter range as the optimization variable, and minimize the rotor vibration amplitude and the strength and durability of the elastic ring as the optimization goals; calculate the vibration response of each structural parameter at different speeds until the target vibration reduction effect and structural reliability requirements are met, and obtain the optimal structural parameter combination.

[0013] Compared with the traditional method of solving the Reynolds equation for obtaining the mechanical characteristic parameters of the elastic ring oil film, the present invention has the following beneficial effects:

[0014] (1) The present invention takes into account the rotor motion and deformation characteristics during optimization, and fully considers the rotor working characteristics and response characteristics to carry out the structural design of the elastic ring mechanical characteristics.

[0015] (2) This method determines the target vibration reduction modal characteristics and speed corresponding to the elastic ring supports at different positions through sensitivity evaluation, so that the vibration reduction structure design can be carried out for the rotor working characteristics of aircraft engines with multi-order criticality and a wide operating speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic diagram of the structural features of an aircraft engine rotor-support system in an embodiment;

[0018] Figure 2 This is a schematic diagram of an elastic ring support structure in an embodiment;

[0019] Figure 3This is a flow chart of the optimization design method for the multi-point elastic ring support structure of the aircraft engine rotor system;

[0020] Figure 4 is the relationship between the critical speed of the rotor-support system and the elastic ring support stiffness;

[0021] Figure 5 This is a comparison chart of the effect of different elastic ring support damping on reducing the rotor response amplitude at different critical speed orders;

[0022] Figure 6 is the relationship between the elastic ring support stiffness and the number of bosses;

[0023] Figure 7 This is a diagram showing the influence of oil film clearance or boss height on oil film damping characteristics;

[0024] Figure 8 This is a diagram showing the influence of damping aperture on oil film damping characteristics. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention proposes a method for optimizing the design of a multi-point elastic ring support structure for an aero-engine rotor system, and the technical solution adopted is:

[0028] Step S1, establish a coupled dynamic model of the rotor-support system. The elastic ring squeeze film damper is aimed at the vibration reduction of the high-speed flexible rotor system, so the design of the elastic ring should not be limited to itself, but should revolve around the optimization design process of the dynamic response characteristics of the rotor-support system. Therefore, first of all, it is necessary to establish a rotor-elastic ring support deformation coupled dynamic model based on the high-speed rotor structural characteristics and the elastic ring support structural characteristics. When modeling the rotor, the finite element method, transfer matrix method or lumped unit model method is usually used to model the rotor and its supporting structure. For example, when establishing a lumped unit model, the establishment of the rotor's dynamic equation is based on the Lagrangian equation method, and the generalized coordinate equation of the rotor is obtained based on the second-kind Lagrangian equation, which is recorded as:

[0029] ,

[0030] in, is the rotor model mass matrix, is the mass matrix of the elastic ring model, T is the kinetic energy of the rotor, U is the potential energy of the rotor, D represents the damping dissipation energy of the system, q are generalized coordinates, For high-speed flexible rotors, it is necessary to explicitly consider the flexural deformation of the rotor and its influence on the displacement and angle of the support, and obtain the rotor mass matrix through finite element discretization of solid units or shell units. M r , stiffness matrix K r , gyro matrix G r With internal damping matrix C r .

[0031] For the elastic ring, the thin-walled shell unit theory is used to establish the finite element model. The stiffness and mass matrix of the elastic ring are obtained by integrating the Jacobian matrix, strain-displacement matrix and material property matrix in the polar coordinate system. 、 For the oil film of the elastic ring, the oil film fluid domain and its coupling equations are established. The inner and outer oil films are formed between the inner and outer rings of the elastic ring and between the outer side of the elastic ring and the bearing housing, respectively. Several through holes are arranged on the elastic ring to allow the oil to flow between the chambers. According to the Reynolds equation for the inner oil film:

[0032] ,

[0033] in, is the radial deformation of the elastic ring, is the radial velocity of the wall, is the radius of the elastic ring, are cylindrical angular coordinates, For elastic exchange of axial coordinates, is the time parameter, Indicates the thickness of the inner oil film (taking into account factors such as rotor eccentricity, elastic ring deformation and angular deflection), is the internal oil film pressure, μ is the viscosity coefficient, is the vortex velocity. Reynolds equation for the outer oil film:

[0034] ,

[0035] in, is the external oil film pressure, Indicates the thickness of the outer oil film.

[0036] Its distribution is determined by the deformation of the elastic ring, rotor eccentricity, angular deflection, etc. μ is the oil viscosity. If the elastic ring has multiple bosses, the chamber is also divided into multiple circumferential segments. The orifices arranged on the elastic ring serve as channels between adjacent chambers. The Hagen-Poiseuille equation is used:

[0037] ,

[0038] in, For traffic, is the aperture, is the axial length of the hole, is the pressure difference across the hole, For the hole length, the orifice flow conservation condition and the oil film pressure of the adjacent chamber are iteratively solved together to obtain the pressure field distribution of the inner and outer oil films and the orifice flow distribution. In the coupled calculation, the explicit step solution is mainly used. There is no need to converge through multiple iterations at each time to obtain the rotor-support deformation characteristics, and each round of iteration needs to correct the oil film thickness according to the new deformation of the elastic ring, and then solve the pressure distribution by the oil film equation and the orifice flow equation, and at the same time update the oil film force and map the elastic ring model. If the maximum change of the oil film force coefficient or pressure distribution in two adjacent iterations is lower than the preset threshold, it is considered that convergence is achieved. Since the elastic ring and the rotor are only in a half-circle angle ( π ) The boss area in contact bears the main radial force, so this half-circle area can be divided into a separate contact surface, and the other half-circle can be regarded as a free boundary, which is closer to the actual working situation.

[0039] Combining the coupling effect of the elastic ring deformation and the oil film flow, the dynamic equation of the elastic ring-oil film coupling can be expressed as:

[0040] ,

[0041] in, are generalized coordinates, is the excitation force of the elastic ring. Combining the rotor and the elastic ring, the coupled dynamic equation of the entire rotor-support system is obtained, which is expressed as:

[0042] ,

[0043] in, is the generalized coordinates of the rotor equation, 、 are the damping coefficients of the rotor and elastic ring respectively, 、 are cross-term damping, 、 are the stiffness matrices of the rotor and elastic ring respectively, 、 The excitation terms on the right side of the equation include the oil film force. and unbalanced force If we only focus on the intrinsic effect of the oil film force, we can temporarily ignore the unbalanced excitation to simplify the study of the mechanical properties of the elastic ring oil film.

[0044] Step S2: Evaluate the sensitivity of the critical speed to the support stiffness. In this step, the main focus is on evaluating how the critical speed changes with the elastic ring support stiffness, as well as the impact of the stiffness of each support point on the system's vibration response. In this step, the oil film force and the oil film equation are ignored. By changing the stiffness parameters of the rotor support system, the critical speed curves of the rotor system under different support stiffnesses are obtained. Based on the dynamic model of the rotor-support system established in step S1, modal analysis is used to calculate the critical speed, and the impact of support stiffness on the critical speed is evaluated by calculating the operating speed margin (i.e., safety margin).

[0045] The critical speed can be calculated by solving the eigenvalue problem of the rotor system:

[0046] ,

[0047] Among them, det is used to find the determinant of the square matrix, λ is the characteristic value, which represents the square of the critical speed, and are the rotor's stiffness and mass matrices. A sensitivity analysis of the rotor system's response is also required. By simulating the rotor's response under different support stiffnesses, the vibration amplitude near the critical speed is evaluated. The rotor system's safety margin is then assessed based on the relationship between the operating speed and the critical speed. Finally, with the safety margin as the core, the appropriate elastic ring support stiffness is determined based on the engine rotor's operating speed.

[0048] Step S3, evaluate the sensitivity of the rotor response to the damping coefficient. This step performs a sensitivity evaluation on the damping characteristics of the elastic ring and analyzes the effects of different damping coefficients on the vibration response of the rotor system. Specifically, based on the dynamic model of the rotor-support system established in S1, the harmonic response of the rotor-support system is solved by applying an unbalanced excitation force to the wheel position in the model, and by changing a series of different elastic ring damping coefficients, the change in the rotor system response amplitude under different damping coefficients is evaluated, and the effect of damping on vibration suppression is analyzed in combination with the vibration response in the critical speed area. In terms of method, the change in the vibration amplitude and critical speed of the rotor under different damping coefficients can be calculated by changing the damping coefficient of the elastic ring support (such as the oil film damping coefficient, the material damping of the elastic ring itself, etc.). For different damping coefficients, the change in response can be expressed by the following formula:

[0049] ,

[0050] Where ξ is the damping ratio, ω n is the natural frequency, x is the displacement, F The external excitation force is calculated by analyzing the vibration response of the rotor system under different damping conditions. It is determined that the damping coefficients of elastic rings at different locations are more sensitive to modal response suppression at a certain critical order. This allows the target vibration reduction speed corresponding to elastic rings at different locations to be determined, achieving effective vibration suppression.

[0051] Step S4: Analyze the influence of elastic ring structural parameters. By analyzing the elastic ring structural characteristics, structural features are extracted, including factors such as the number of bosses, boss height, thin wall thickness, damping aperture, axial length, boss fit relationship, and ring diameter. Several sensitive parameters are extracted and set within a range of variation. Numerical analysis of the influence of mechanical properties is conducted to determine the influence of structural parameters on the mechanical properties of the elastic ring support.

[0052] Step S5: Iteratively optimize the elastic ring's structural parameters. During the optimization design process, an iterative optimization method, combined with a multi-objective optimization algorithm (such as a genetic algorithm or particle swarm optimization), is used to optimize the elastic ring's structural parameters. The goal is to minimize the rotor's vibration amplitude while ensuring the elastic ring's strength and durability. The optimization objective function can be defined as a weighted sum of the rotor's vibration amplitude and a damping characteristic function. Parameter optimization is performed using a genetic algorithm or particle swarm optimization algorithm. Each iteration updates the elastic ring's structural parameters (such as the number of bosses and the diameter of the damping holes) until the optimization goal is achieved.

[0053] Based on the above optimized iterative design parameters, the elastic ring structure design and processing were carried out to obtain the elastic squeeze film damper structure for the multi-support flexible rotor system.

[0054] In order to clearly illustrate the technical features of the present invention, the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0055] To further verify and illustrate the optimization design method of the multi-point elastic ring support structure for the aero-engine rotor system of the present invention, a dynamic numerical solution and comparative analysis of the results are carried out using an elastic ring support-rotor system model as a representative example. The structure of the elastic ring support-rotor system is shown in the figure below. Figure 1As shown in FIG, the structure includes a first fulcrum 1, a second fulcrum 2, a third fulcrum 4, a fourth fulcrum 5, a shaft 3 and a turbine assembly 6, wherein the elastic ring is arranged on the third fulcrum 4 and the fourth fulcrum 5, the rotor length is 130 mm, the turbine assembly mass is 63 kg, and the material elastic modulus is 195 GPa; the elastic ring structure is as shown in FIG. Figure 2 As shown, an elastic ring boss 7 and a damping hole 8 are provided on the elastic ring. Under the designed working state, the gap between the elastic ring and the mating surface is filled with lubricating oil, so that the lubricating oil can flow through the damping hole during the deformation of the elastic ring by squeezing the rotor, and generate flow damping, thereby suppressing and dissipating vibration energy. Structurally, the axial length of the elastic ring is 21 mm, the material elastic modulus is 205 GPa, the ring thin wall thickness is 1 mm, the damping hole diameter is 0.8 mm, the ring diameter is 80 mm, the boss height is 0.2 mm, and the number of bosses is 8.

[0056] Step S1, such as Figure 3 As shown, this embodiment first simplifies the three-dimensional geometry of the engine power turbine rotor in CAD software, removing local small chamfers and non-critical bosses, and retaining only the main shaft and drum structure that play a decisive role in the overall bending stiffness and mass distribution. Then, using finite element software (such as ANSYS, ABAQUS, or NASTRAN), the rotor is discretized into solid / beam / shell elements, and the rotor mass matrix is ​​obtained respectively. M r , stiffness matrix K r , gyro matrix G r With internal damping matrix C r , so that the flexible bending and gyroscopic effect under high-speed rotation can be accurately reflected in the subsequent analysis. At the same time, the elastic ring is finite element modeled using thin-walled shell elements. The specific approach is: first, based on the geometric definition of the elastic ring, a four-node or eight-node shell element is selected as the discrete primitive, and the shape function, Jacobian matrix, and strain-displacement matrix of the shell element are respectively established in the polar coordinate system. In the "oil film mechanical characteristics analysis" stage that this embodiment focuses on, F The rotor unbalanced force is not considered for the time being in order to focus on the intrinsic influence of the elastic ring-oil film on the vibration characteristics; if the actual operating conditions need to be evaluated later, the unbalanced force term can also be incorporated into the equation for comprehensive calculation. For the oil film of the elastic ring, an oil film fluid domain and its coupling equation are established. In this embodiment, the gap between the inner wall of the elastic ring and the outer surface of the rotor is defined as the inner oil film area, and the gap between the outer wall of the elastic ring and the casing or bearing housing is defined as the outer oil film area. Several oil film chambers are formed by encapsulating them in the end face seal or boss area. According to the Reynolds equation for the inner oil film:

[0057] ,

[0058] in, is the radial deformation of the elastic ring, is the radial velocity of the wall, is the radius of the elastic ring, are cylindrical angular coordinates, For elastic exchange of axial coordinates, is the time parameter, Indicates the thickness of the inner oil film (taking into account factors such as rotor eccentricity, elastic ring deformation and angular deflection), is the internal oil film pressure, μ is the viscosity coefficient, is the vortex velocity. Reynolds equation for the outer oil film:

[0059] ,

[0060] in, is the external oil film pressure, Indicates the thickness of the outer oil film. Its distribution is determined by the deformation of the elastic ring, rotor eccentricity, angular deflection, etc. μ is the oil viscosity. If the elastic ring has multiple bosses, the chamber is also divided into multiple circumferential segments. The orifices arranged on the elastic ring serve as channels between adjacent chambers. The Hagen-Poiseuille equation is used:

[0061] ,

[0062] in, For traffic, is the aperture, is the axial length of the hole, is the hole length, is the orifice pressure difference, which describes the orifice diameter d and the pressure difference Δ p With traffic Q , and setting flow conservation conditions at each orifice to link the chamber's oil film pressures. This approach allows for the coupling of the inner and outer oil films with the orifice at a discrete level, establishing the fluid domain equations that lay the foundation for subsequent iterative solutions to the oil film forces.

[0063] Step S2: Evaluate the sensitivity of the critical speed to the elastic ring support stiffness. This step primarily evaluates how the critical speed changes with the elastic ring support stiffness, as well as the impact of the support stiffness of each support point on the system's vibration response. This step ignores the oil film force and the oil film equation. By varying the elastic ring support stiffness, the critical speed curve for the rotor at different support stiffnesses is obtained. Based on the rotor-support coupling model established in step S1, modal analysis is used to calculate the critical speed, and the impact of the elastic ring support stiffness on the critical speed is evaluated by calculating the operating speed margin (i.e., safety margin).

[0064] The critical speed can be calculated by solving the eigenvalue problem of the rotor:

[0065] ,

[0066] Among them, det represents the determinant function, λ is the characteristic value, which represents the square of the critical speed, K r and M r is the stiffness matrix and mass matrix of the rotor. It is necessary to evaluate and analyze the sensitivity of the rotor system's critical speed to the elastic ring support stiffness, and take the rotor system's critical speed distribution and its relative operating speed safety margin as the core. According to the critical speed distribution-support stiffness characteristics, combined with the operating speed (operating speed, maximum speed, slow speed, etc.), the sensitivity analysis of the rotor's multi-point support stiffness is performed using the critical speed, and the elastic ring support stiffness range is selected to meet the requirements of the critical speed and strain energy distribution design criteria. This example is based on Figure 1 The elastic ring of the third support point 4 of the middle rotor is used as the object to carry out the critical speed distribution sensitivity evaluation, such as Figure 4 As shown, the fourth support stiffness is set to 0.7×10 7 N / m. According to the sensitivity analysis results, in order to ensure the safety margin of the rotor critical speed, the elastic ring support stiffness range of the third support point 4 is selected to be 0.5~1×10 7 N / m, the stiffness of the 4th and 5th fulcrums is maintained at 0.7×10 7 N / m.

[0067] Step S3, evaluate the sensitivity of the rotor response to the damping coefficient. This step performs a sensitivity evaluation on the damping characteristics of the elastic ring and analyzes the effects of different damping coefficients on the rotor vibration response. Specifically, based on the rotor-support coupling model established in S1, the dynamic harmonic response of the rotor-support system is solved by applying an unbalanced excitation force to the wheel position in the model, and by changing a series of different elastic ring support damping ratios, the change in the rotor system response amplitude under different damping conditions is evaluated, and the effect of damping on vibration suppression is analyzed in combination with the vibration response in the critical speed area. Methodologically, the changes in the vibration amplitude and critical speed of the rotor system under different damping conditions can be calculated by changing the damping coefficient of the elastic ring support (such as the oil film damping coefficient, the material damping of the elastic ring itself, etc.). For different damping coefficients, the change in harmonic response can be expressed by the following formula:

[0068] ,

[0069] Where ξ is the damping ratio, ω n is the natural frequency,x is the system displacement, F is the external excitation force. By calculating the vibration response of the rotor under different damping conditions, it is determined that the elastic ring support damping at different positions is more sensitive to the modal response suppression under a certain critical order, thereby determining the vibration reduction target speed corresponding to the elastic rings at different positions to achieve effective vibration suppression. In this embodiment, based on the rotor-support system model established in step S1, the same support damping coefficient is set for the elastic rings located at the 3rd and 4th fulcrums 4 and 5, respectively, and three groups of rotor-support system dynamic harmonic response analyses are carried out, including no damping, only damping at the 3rd fulcrum 4, and only damping at the 4th fulcrum 5. The response amplitudes of the first-stage turbine disk and the second-stage turbine disk are taken, the amplitudes are normalized, and the effects of the elastic rings at different positions on the rotor response amplitudes are compared, such as Figure 5 As shown in the figure, in this embodiment, the elastic ring damping at the third support point 4 is more effective in reducing the second-order critical speed, while the elastic ring damping at the fourth support point 5 is more effective in reducing the first-order critical speed. Therefore, in this embodiment, the third support point 4 targets the second-order critical speed, while the support point 5 targets the first-order critical speed.

[0070] Step S4, analysis of the influence of elastic ring structural parameters. After the elastic ring stiffness range and target vibration reduction speed are determined, it is necessary to further study the working mechanism of the elastic ring, and extract the structural characteristic parameters by combining the elastic ring structural analysis, force and deformation characteristics analysis, etc. In this part, it is necessary to establish a finite element model that can reflect the elastic ring-oil film characteristics. For example, the number of elastic ring bosses is the main influencing parameter of the elastic ring support stiffness. By studying the influence of the number of elastic ring bosses on the support stiffness, the support stiffness corresponding to the optimal critical speed distribution obtained by the rotor-support system analysis is taken as the target value, and the number of elastic ring bosses is determined, such as Figure 6 As shown. After the overall design of the engine is determined, the axial length and radial size of the elastic ring are basically determined. Therefore, in this embodiment, the parameters such as the axial length and the elastic ring diameter are not modified. Since the damping mainly plays a role in absorbing vibration and consuming energy when the rotor-support system passes through the critical speed, the fluid-solid coupling model in step S1 is established with the goal of designing the best damping performance under the critical speed. By changing the excitation frequency, the mechanical characteristics simulation analysis of the elastic ring-oil film support and the influence of parameters such as the number of bosses, oil film gap (boss height), damping aperture, and boss transition radius are carried out, as shown in FIG. Figure 7 and Figure 8 shown.

[0071] Step S5, iterative optimization of the elastic ring structural parameters. During the optimization design process, an iterative optimization method is used, combined with a multi-objective optimization algorithm (such as a genetic algorithm or a particle swarm optimization algorithm), to optimize the elastic ring structural parameters. The goal is to minimize the vibration amplitude of the rotor system and ensure the strength and durability of the elastic ring. The optimization objective function can be defined as the weighted sum of the vibration amplitude of the rotor system and the damping characteristic function, and the parameters are optimized by a genetic algorithm or a particle swarm algorithm. The structural parameters of the elastic ring (such as the number of bosses, the diameter of the damping hole, etc.) are updated in each iteration until the optimization goal is achieved. The optimization range of the number of bosses is 6~12, the dimensionless oil film gap is 0.1~2.5%, the optimization range of the damping hole diameter is 0~2mm, the boss transition radius is 1~10mm, the target vibration reduction critical speed is 7350r / min, and the elastic ring stiffness is close to the target design stiffness when the number of bosses is 8 ( Figure 6 By designing the boss height to 0.2mm, the dimensionless oil film gap is set to 0.25%, so that the elastic ring can fully deform and achieve a larger oil film damping effect ( Figure 7 ); When the diameter of the damping hole is 0.4mm, the elastic ring support damping reaches its maximum value ( Figure 8 ).

[0072] Based on the above optimized iterative design parameters, the elastic ring structure design and processing were carried out to obtain the elastic squeeze film damper structure for the multi-support flexible rotor system.

[0073] The specific embodiments described above are merely preferred embodiments of the present invention. It should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Without departing from the principles of the present invention, any variation, modification, replacement, or replacement of the simulation object made by a person skilled in the art without any innovative work shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system, characterized in that: include: Step S1: establishing a coupled dynamic model of the rotor-support system; Conduct dynamic modeling of the rotor and finite element modeling of the elastic ring, establish the oil film fluid domain inside and outside the elastic ring and the oil film coupling equation, and characterize the oil film pressure distribution and orifice flow rate; The rotor is coupled with the elastic ring to form the coupled dynamic equation of the rotor-support system; Step S2: evaluating the sensitivity of critical speed to support stiffness; Based on the coupled dynamics model, the rotor's eigenvalue problem is solved to obtain the critical speed. By analyzing the critical speed and operating speed safety margin under different support stiffnesses, the reasonable range of support stiffness for elastic rings at different support points is determined. Step S3: Evaluate the sensitivity of the rotor response to the damping coefficient; change the damping coefficient of the elastic ring and evaluate the vibration amplitude of the rotor in each critical speed region under different damping coefficients; determine the target vibration reduction speed range of the elastic ring at different support points based on the sensitivity of the modal response of different support points to each critical speed region; Step S4: Analyzing the influence of elastic ring structural parameters: Based on the geometric characteristics and material properties of the elastic ring, extract the elastic ring structural parameters and analyze their influence on the elastic ring support stiffness and damping coefficient; combining the critical speed and vibration response requirements of the rotor, screen the elastic ring structural parameter range that meets the target support stiffness and damping coefficient requirements; Step S5: Iteratively optimize the elastic ring structural parameters; use the elastic ring structural parameter range as the optimization variable, and minimize the rotor vibration amplitude and the strength and durability of the elastic ring as the optimization goals; calculate the vibration response of each structural parameter at different speeds until the target vibration reduction effect and structural reliability requirements are met, and obtain the optimal structural parameter combination.

2. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 1, characterized in that: In step 1, the lumped element method is used to perform dynamic modeling of the rotor, including obtaining the generalized coordinate equation of the rotor based on the second-kind Lagrangian equation, which is expressed as: ， in, is the mass matrix of the rotor, is the mass matrix of the elastic ring, T is the kinetic energy of the rotor, U is the potential energy of the rotor, D represents the damping dissipation energy, q are generalized coordinates, is the applied force.

3. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 2, characterized in that: In step 1, the elastic ring is modeled by finite element using thin-walled shell elements, including: obtaining the stiffness matrix of the elastic ring by integrating the Jacobian matrix, strain-displacement matrix and material property matrix in the polar coordinate system With the mass matrix .

4. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 3, characterized in that: In step 1, the fluid domain equations of the inner and outer oil films of the elastic ring are established, including: the Reynolds equation of the inner oil film is: ， in, is the radial deformation of the elastic ring, is the radial velocity of the elastic ring wall, is the radius of the elastic ring, are cylindrical angular coordinates, is the axial coordinate of the elastic ring, is the time parameter, Indicates the inner oil film thickness, is the internal oil film pressure, μ is the viscosity coefficient, is the vortex velocity.

5. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 4, characterized in that: In step 1, the fluid domain equations of the inner and outer oil films of the elastic ring are established, including: the Reynolds equation of the outer oil film is: ， in, is the external oil film pressure, represents the outer oil film thickness, μ is the oil viscosity.

6. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 5, characterized in that: Furthermore, if the elastic ring has multiple bosses, the chamber is correspondingly divided into multiple circumferential segments; the orifices arranged on the elastic ring serve as channels between adjacent chambers, and the Hagen-Poiseuille equation is used: ， in, is the orifice flow rate, is the orifice diameter, is the axial length of the hole, is the orifice pressure difference, is the hole length, and the orifice flow conservation condition and the oil film pressure of the adjacent chamber are iteratively solved together to obtain the pressure field distribution of the inner and outer oil films and the orifice flow distribution; the dynamic equation of the elastic ring-oil film coupling is expressed as: ， in, is the generalized coordinate of the elastic ring, is the excitation force of the elastic ring. Combining the rotor and the elastic ring, the coupled dynamic equation of the rotor-support system is obtained, which is expressed as: ， in, are the generalized coordinates of the rotor, 、 are the damping coefficients of the rotor and elastic ring respectively, 、 are cross-term damping, 、 are the stiffness matrices of the rotor and elastic ring respectively, 、 are cross-term stiffnesses, 、 are the oil film force and the unbalanced force respectively.

7. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 1, characterized in that: In step S2, the critical speed is calculated by solving the eigenvalue problem of the rotor: ， Among them, det is used to find the determinant of the matrix, λ is the eigenvalue, which represents the square of the critical speed, K r and M r are the stiffness matrix and mass matrix of the rotor.

8. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 1, characterized in that: In step S3, the damping coefficient of the elastic ring is changed at different supporting points, the coupling effect of multiple supporting points on different-order critical vibration modes is evaluated, and the vibration reduction target speed and damping coefficient range of each supporting point are determined.

9. The method for optimizing the design of a multi-point elastic ring support structure for an aircraft engine rotor system according to claim 8, characterized in that: By changing the damping coefficient, the changes in the vibration amplitude and critical speed of the rotor under different damping coefficients are calculated. For different damping coefficients, the change in response is expressed by the following formula: ， in, ξ is the damping ratio, ω n is the natural frequency, x is the displacement, F The vibration response of the rotor under different support damping coefficients is calculated by using the external excitation force. It is determined that the damping coefficient of the elastic ring at different supports is more sensitive to the modal response suppression under a certain critical order, thereby determining the vibration reduction target speed corresponding to the elastic ring at different supports.

10. The method for optimizing the design of a multi-support elastic ring support structure for an aircraft engine rotor system according to claim 1, characterized in that: The structural parameters in step S4 include: the number of bosses, boss height, thin wall thickness, damping aperture, axial length and ring diameter.

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