Rotor and supporting system supporting rigidity optimization and vibration reduction design method

Abstract

According to the bearing rigidity optimization and vibration reduction design method for the rotor and the bearing system, under the condition that the structural form of the rotor and the bearing system is not subversively adjusted, the elastic bearing and the extrusion oil film damper are arranged and designed, and the bearing rigidity of the rotor and the bearing system is optimized. The fulcrum rigidity is reduced to change the strain energy distribution of the rotor and adjust the critical rotating speed, and the vibration level of the rotor, especially vibration caused by sudden unbalance and transcritical of the multi-fulcrum rotor, is suppressed.

Description

Technical Field

[0001] This application belongs to the field of gas turbine technology, and specifically relates to a method for optimizing the support stiffness and reducing vibration of the rotor and support system. Background Technology

[0002] Gas turbines—especially dual-rotor, triple-rotor, or simultaneous front-to-back and front-to-back gas turbines—have their power turbine rotor shaft passing through the high- and low-pressure rotors. Constrained by the space between the high- and low-pressure rotor discs and the bearing DN values, the rotor shaft is relatively slender, the rotor support span is large, the rotor shaft-to-disc weight ratio is small, and the bending stiffness is weak. A multi-support layout is typically used to improve the rotor's resistance to deformation. However, multi-support, long-span rotors often need to operate across critical speeds, which greatly increases the difficulty of rotor dynamics design. On the one hand, operating across critical speeds makes it difficult to meet the requirements for the rotor's critical speed margin (≥20%) and the distribution of bending strain energy at critical speeds (≤25% of the total strain energy of the rotor-support system). On the other hand, gas turbine speeds exceeding critical speeds or sudden rotor imbalances can easily lead to large vibrations, seriously affecting the safety of the gas turbine.

[0003] During the overall design phase, the critical speed is typically avoided by modifying the rotor structure and appropriately adjusting the rotor mass and support stiffness (such as adjusting the strut span and rotor shaft diameter). However, with the overall gas turbine design and the aerodynamic design of its components already determined, the adjustment range is narrow and there are many influencing factors, making critical speed optimization difficult. Redesigning the rotor and support system would inevitably prolong the design cycle and increase the design difficulty. Summary of the Invention

[0004] The purpose of this application is to provide a method for optimizing the support stiffness and reducing vibration of a rotor and support system, so as to solve or alleviate at least one of the problems in the prior art.

[0005] The technical solution of this application is: a method for optimizing the support stiffness and reducing vibration of a rotor and support system, comprising:

[0006] S100: Determine the structural form of the elastic support; select materials based on the structural form; determine initial structural parameters based on the structural form and selected materials; calculate the stiffness of the elastic support based on the initial structural parameters; if the stiffness requirements are met, perform critical speed analysis and rotor strain energy analysis; if the stiffness or critical speed analysis and rotor strain energy analysis do not meet the requirements, adjust the initial structural parameters; if the critical speed analysis and rotor strain energy analysis meet the requirements, determine the detailed structural parameters of the elastic support; perform strength analysis and fatigue life calculation based on the detailed structural parameters; if the requirements are met, the elastic support is obtained; if not, adjust the material of the elastic support and repeat the above process to obtain the elastic support structure.

[0007] S200, under the condition of obtaining the elastic support structure, determine the design objectives of the extrusion film damper, determine the rigid support modes of the rotor based on the rotor's structural parameters, calculate the rotor's undamped critical speed and mode shape, and the rotor's response under undamped conditions, and determine the i-th modal mass and modal stiffness based on the rotor's modal calculation results to obtain the rotor's equivalent simplified model. Based on the simplified model and design objectives, determine the design point modal damping, calculate the damping value of the extrusion film damper according to the definition formula of modal damping, and determine the extrusion film damping based on the extrusion film damper's damping value. Based on the structure and oil film parameters of the extrusion oil film damper, the vibration reduction performance of the extrusion oil film damper is simulated and verified. The oil film stiffness is calculated, and the support stiffness of the rotor model is corrected according to the oil film stiffness. The rotor response under unbalance is calculated, and the nonlinear factors of the extrusion oil film damper are taken into account in the calculation process. Based on the calculation results, the critical peak value of the rotor over-critical and the degree of attenuation of the vibration amplitude within the rotor's operating speed range are obtained. The vibration reduction performance of the extrusion oil film damper is evaluated accordingly. If the vibration reduction performance does not meet the requirements, the oil film parameters are adjusted.

[0008] In at least one embodiment of this application, the structure of the elastic support includes a squirrel cage elastic support, a steel ring elastic support, and a tie rod elastic support. The squirrel cage elastic support further includes a traditional squirrel cage elastic support, a folding squirrel cage elastic support, and an integrated squirrel cage elastic support.

[0009] For elastic supports integrated with the outer ring of the bearing, bearing steel that balances hardness, toughness, and fatigue performance is selected. For elastic supports not integrated with the outer ring of the bearing, high-strength materials with good fatigue resistance are selected.

[0010] In at least one embodiment of this application, the initial structural parameters of the elastic support include the number of cage bars, their length, and cross-sectional dimensions, and are determined by the following formula:

[0011]

[0012]

[0013] In the formula, k is the elastic support stiffness of the squirrel cage, n is the number of cage bars, E is the elastic modulus of the squirrel cage material, b is the width of the cage bar cross-section, h is the height of the cage bar cross-section, l is the length of the cage bar, and σ max The maximum stress is Y, and the radial displacement of the free end of the elastic support of the squirrel cage is Y.

[0014] In at least one embodiment of this application, the stiffness and / or strength of the elastic support are calculated using the finite element analysis method.

[0015] In at least one embodiment of this application, the process of performing critical speed analysis and rotor strain energy analysis includes:

[0016] A vibration characteristic analysis model of the rotor and support system is established. The rotor shaft and drum are simplified as beam elements based on their cross-sectional dimensions. The rotor blades and disks at each stage are simplified as lumped mass elements based on their mass and moment of inertia, with coordinates located at the center of mass. The support system (bearings and elastic supports) is equivalent to spring elements, replaced by equivalent stiffness. The calculation method for the equivalent stiffness is as follows: Where K is the equivalent stiffness, For the radial stiffness of the bearing, For elastic support stiffness;

[0017] The critical speed calculation and analysis were performed using finite element analysis software to obtain the critical speed of synchronous positive precession of the rotor and the corresponding vibration modes. At least 1.5 times the maximum operating speed was obtained as the calculation results of all critical speeds. The percentage of strain energy distribution of the rotor and support under each vibration mode was calculated.

[0018] In at least one embodiment of this application, the design point modal damping is: ,in, For rotor modal mass, For rotor modal stiffness, This is modal damping.

[0019] In at least one embodiment of this application, the modal damping is defined by the following formula:

[0020] (5)

[0021] In the formula, c sfd ψ is the damping value of the squeeze film damper. i C1 and C2 are the rotor vibration modes, and C1 and C2 are the bearing damping modes.

[0022] In at least one embodiment of this application, the structure of the extrusion oil film damper is divided into open type and closed type according to whether a sealing structure is installed at both ends. When the required damping is large and the open structure cannot meet the requirements, the closed type damper is selected.

[0023] In at least one embodiment of this application, the oil film parameters include the journal eccentricity ζ of the extrusion oil film damper, the oil film radius R, the oil film radius gap c, and the oil film length L;

[0024] The journal eccentricity ζ of the squeeze oil film damper is ≤0.4;

[0025] oil film radius d0 is the bearing diameter, and s is the thickness of the bearing outer ring retaining ring;

[0026] The oil film radius gap ;

[0027] The width of the oil film In the formula, μ is the viscosity of the lubricating oil. Dimensionless oil film damping coefficient .

[0028] In at least one embodiment of this application, the oil film stiffness Calculation formula: In the formula, Ω is the rotor speed. It is a dimensionless stiffness coefficient. .

[0029] The rotor and support system support stiffness optimization and vibration reduction design method provided in this application reduces the support stiffness by setting elastic supports and squeezing oil film dampers, thereby changing the rotor strain energy distribution and adjusting the critical speed, suppressing the rotor vibration level, especially the vibration caused by sudden imbalance and transcriticality of multi-support rotors. This avoids making radical adjustments to the rotor and support system when the overall gas turbine scheme and component aerodynamic schemes are clear, and the rotor structure, mass distribution, support stiffness and other parameters are basically determined. Attached Figure Description

[0030] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0031] Figure 1 This is a schematic diagram of the rotor and support system support stiffness optimization and vibration reduction design method of this application.

[0032] Figure 2 This is a schematic diagram of the elastic support design process in this application.

[0033] Figure 3 This is a schematic diagram of a typical rat cage.

[0034] Figure 4 This is a schematic diagram of a reversible rat cage.

[0035] Figure 5 This is a schematic diagram of an integrated mouse cage.

[0036] Figure 6 This is a schematic diagram of the oil film parameters in this application.

[0037] Figure 7 This is a schematic diagram showing the journal eccentricity and oil film damping coefficient. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0039] This application provides a method for optimizing the support stiffness and reducing vibration of a rotor and support system with multiple supports and long spans. Without making radical changes to the structure of the rotor and support system, the method reduces the stiffness of the supports by setting elastic supports and squeezing oil film dampers, thereby changing the distribution of rotor strain energy and adjusting the critical speed, and suppressing the vibration level of the rotor, especially the vibration caused by sudden imbalance and transcriticality of multi-support rotors.

[0040] like Figure 1 As shown, the rotor and support system support stiffness optimization and vibration reduction design method provided in this application includes the following steps:

[0041] S100: Determine the structural form of the elastic support; select materials based on the structural form; determine initial structural parameters based on the structural form and selected materials; calculate the stiffness of the elastic support based on the initial structural parameters; if the stiffness requirements are met, perform critical speed analysis and rotor strain energy analysis; if the stiffness or critical speed analysis and rotor strain energy analysis do not meet the requirements, adjust the initial structural parameters; if the critical speed analysis and rotor strain energy analysis meet the requirements, determine the detailed structural parameters of the elastic support; perform strength analysis and fatigue life calculation based on the detailed structural parameters; if the requirements are met, the elastic support is obtained; if not, adjust the material of the elastic support and repeat the above process to obtain the optimal structural parameters of the elastic support.

[0042] like Figure 2 The diagram shown in this application illustrates the design process of the elastic support. The process specifically includes:

[0043] S101, determine the structural form of the elastic support (abbreviated as elastic support).

[0044] When designing a flexible support structure, structural constraints of the support space and bearing load requirements should be comprehensively considered. The structural forms of flexible supports include squirrel cage type flexible supports, steel ring type flexible supports, and tie rod type flexible supports. Among them, squirrel cage type flexible supports are more common in the design of rotor support structures. The flexible supports referred to in the following embodiments of this application are all squirrel cage type flexible supports.

[0045] To adapt to structural constraints in terms of fulcrum space, squirrel-cage elastic supports can be designed in various forms—including traditional squirrel-cage elastic supports, folded-back squirrel-cage elastic supports, and integrated squirrel-cage elastic supports. Traditional squirrel-cage elastic supports can save some space in the radial dimension; folded-back elastic supports can save some space in the axial dimension; integrated squirrel-cage supports are integrated with the bearing outer ring, resulting in a high degree of integration, reducing the number of parts, and contributing to weight reduction. Figures 3 to 5 The diagrams show traditional mouse cages, reversible mouse cages, and integrated mouse cages.

[0046] S102, Determine the material of the elastic support.

[0047] For integrated elastic supports that are integrated with the outer ring of the bearing, the material should be a bearing steel that balances hardness, toughness, and fatigue performance, such as 8Cr4Mo4V or M50Nil. For elastic supports that are not integrated with the outer ring of the bearing, such as traditional squirrel cages or folding squirrel cages, there is no need to use bearing steel. Instead, high-strength materials with good fatigue resistance can be used, such as 1Cr12Ni3MoVN, 40CrNiMoA, or 0Cr17Ni4Cu4Nb.

[0048] S103, Selection and calculation of initial structural parameters.

[0049] The design of elastic supports requires achieving a certain stiffness within a given space constraint of the support point. For elastic supports, the main parameters for determining stiffness and strength are the number, length, and cross-sectional dimensions of the cage bars.

[0050] The initial parameters can be calculated and determined using formulas (1) and (2):

[0051] (1)

[0052] (2)

[0053] In the formula, k is the elastic support stiffness of the squirrel cage, and the unit is Newtons per meter (N / m).

[0054] n is the number of bars in the rat cage;

[0055] E represents the elastic modulus of the rat cage material, expressed in Newtons per square meter (N / m²). 2 );

[0056] b is the cross-sectional width of the cage bars, in meters (m).

[0057] h is the height of the cage bar section, in meters (m);

[0058] l represents the length of the cage bars, in meters (m).

[0059] σ maxThe maximum stress is expressed in Pascals (Pa).

[0060] Y represents the radial displacement of the free end of the elastic support of the squirrel cage, in meters (m).

[0061] S104, Stiffness calculation.

[0062] After determining the initial structural parameters of the elastic support, a finite element model is performed. The stiffness of the elastic support is calculated using the finite element analysis method. Based on the calculation results, the initial structural parameters are adjusted iteratively to finally obtain structural parameters that meet the stiffness requirements. During the finite element modeling process, attention must be paid to the mesh quality. The constraints and loads applied during the finite element calculation should simulate the actual state of the engine as much as possible. The loads should be applied to the bearing outer ring mounting surface, and their magnitude should not exceed the elastic limit of the material.

[0063] S105, Critical Speed ​​and Rotor Strain Energy Analysis.

[0064] Establish a vibration characteristic analysis model (one-dimensional beam model or two-dimensional Fourier axisymmetric model) for the rotor and support system. The rotor shaft and drum are simplified into beam elements according to their cross-sectional dimensions (variable cross-section beam elements are used when the cross-sectional characteristics change). The rotor blades and disks at each stage are simplified into lumped mass elements according to their mass and moment of inertia, with the coordinates located at the center of mass. The support system (bearings, elastic supports) is equivalent to spring elements and replaced by equivalent stiffness. The calculation formula is shown in formula (3).

[0065] Calculation of equivalent stiffness of the support system: (3)

[0066] Where K is the equivalent stiffness. For the radial stiffness of the bearing, This refers to the stiffness of the elastic support.

[0067] Critical speed calculations were performed using finite element analysis software Samcef / Rotor or Dynamics R4 to obtain the rotor's synchronous positive precession critical speed and corresponding vibration modes. Calculation results for all critical speeds below 1.5 times the maximum operating speed were provided, and the percentage of strain energy distribution in the rotor and supports under each vibration mode was calculated. After the critical speed and strain energy calculations were completed, they were compared with design criteria to evaluate whether each critical speed met the design specifications. If not, the vibration characteristics of the rotor-support system were optimized by changing the stiffness of each support point.

[0068] S106, Detailed structural design of elastic support.

[0069] Based on the stiffness and critical speed of the elastic support and the iterative calculation results of the rotor strain energy, the detailed structural parameters of the elastic support cage bars are determined, including the number of cage bars, cross-sectional dimensions and length.

[0070] The detailed structural commitment based on the elastic support determines the structural form of the elastic support installation interface (centering with the bearing housing stop, bolt connection) and the corresponding mating dimensions and tolerances with the bearing and bearing housing, according to the interface form of the pivot bearing and bearing housing; based on the calculation results of the settlement under the rotor's self-weight, it is determined whether the installation stop of the elastic support and the positioning surface of the bearing outer ring need to be eccentric.

[0071] S107, Strength and life analysis of elastic bearings.

[0072] The static strength of the elastic support is checked using the finite element method. The static stress of the elastic support under axial load and radial limiting clearance is calculated, and the results are superimposed to ensure that the maximum stress does not exceed the yield strength of the material. The critical points obtained from the static strength calculation are used as input for fatigue life verification. Their mean stress and alternating stress are calculated, and points are plotted on the fatigue limit diagram to determine whether it has an infinite life. If the elastic support fails the strength and life analysis, the material of the elastic support is adjusted.

[0073] S200, under the condition of obtaining the elastic support structure, determines the design objectives of the extrusion oil film damper, determines the rigid support modes of the rotor based on the rotor's structural parameters, calculates the rotor's undamped critical speed and mode shape, and the rotor's response under undamped conditions, and determines the i-th modal mass and modal stiffness based on the rotor's modal calculation results to obtain the rotor's equivalent simplified model. Based on the simplified model and design objectives, determines the design point modal damping, calculates the damping value of the extrusion oil film damper according to the definition formula of modal damping, determines the structural form and oil film parameters of the extrusion oil film damper based on the damping value, and conducts vibration reduction performance simulation verification of the extrusion oil film damper based on the structural form and oil film parameters, calculates the oil film stiffness, corrects the support stiffness of the rotor model based on the oil film stiffness, and calculates the unbalanced... The response of the lower rotor is calculated by taking into account the nonlinear factors of the extrusion oil film damper. Based on the calculation results, the critical peak value of the rotor when it is over-critical and the degree of attenuation of the vibration amplitude within the rotor's operating speed range are obtained. The vibration reduction performance of the extrusion oil film damper is evaluated accordingly. If the vibration reduction performance does not meet the requirements, the oil film parameters are adjusted.

[0074] After the rotor dynamics design is completed, and the rotor's structure, mass distribution, support stiffness and other parameters are basically determined, the vibration level of multi-support, long-span rotors, especially the vibration caused by sudden unbalance and transcriticality, is suppressed by setting up a squeeze oil film damper.

[0075] In this application, the design method for the extrusion oil film damper is as follows:

[0076] S201, Determine the design objective: For example, in this embodiment of the application, by using a squeezed oil film damper, assuming unbalanced excitation... Below this, the vibration amplitude of the rotor within the operating speed range is reduced to over 90%, and the damping ratio of the first-order mode is 7%–10%.

[0077] S202, Based on the rotor's structural parameters, determine the rotor's rigid support mode, calculate the rotor's undamped critical speed and mode shape, and the rotor's response under undamped conditions (select the design speed of the squeeze film damper, i-th order critical speed).

[0078] S203. Based on the modal calculation results of the rotor, determine the i-th modal mass and modal stiffness to obtain the equivalent simplified model of the rotor;

[0079] S204, Determine the modal damping at the design point based on the modal damping ratio of the simplified model and the design target;

[0080] For example, in one embodiment of this application, the modal damping ratio of the simplified model is... We can take 8.5% and calculate the modal damping at the design point according to formula (4): (4)

[0081] in, For rotor modal mass, For rotor modal stiffness, This is modal damping.

[0082] S205, Calculate the damping value c of the extrusion film damper according to the definition formula of modal damping. sfd ;

[0083] (5)

[0084] Where, ψ i Rotor mode shape, bearing damping c1, c2, ..., c n All of these are known quantities. Assume that an extrusion oil film damper (SFD) is added at bearing 1.

[0085] S206, Determine the structural form and oil film parameters of the extrusion oil film damper;

[0086] a) Determine the structural form of the squeeze film damper

[0087] Extrusion film dampers are classified into open and closed types based on whether sealing structures are added to both ends. Open types have a simple structure, without sealing grooves or seals; with proper design, open extrusion film dampers can meet the requirements. When the required damping is very high and the open structure is insufficient, a closed damper should be selected. Closed extrusion film dampers, based on the open structure, have sealing grooves machined at both ends. Oil sealing rings are installed in these grooves to reduce lubricating oil leakage at both ends, thereby increasing damping.

[0088] b) Determine the oil film parameters, including the journal eccentricity ζ of the extrusion oil film damper, the oil film radius R, the oil film radius clearance c, and the oil film length L, such as Figure 6 As shown.

[0089] like Figure 7 As shown, when the journal eccentricity ζ > 0.4, the oil film damping coefficient increases rapidly with the increase of the journal eccentricity, exhibiting strong nonlinearity. Therefore, the journal eccentricity ζ of the extrusion oil film damper is usually ≤ 0.4.

[0090] If the bearing diameter is d0 and the thickness of the bearing outer ring retaining ring is s, then the oil film radius R is:

[0091] The oil film radius gap c is:

[0092] Oil film width (6)

[0093] In the formula, μ is the viscosity of the lubricating oil. The dimensionless oil film damping coefficient is calculated using the following formula:

[0094] (7)

[0095] S207, Simulation Verification of Vibration Reduction Performance of Extruded Oil Film Damper

[0096] Considering the influence of the oil film stiffness of the extrusion oil film damper, the rotor's support stiffness changes, and the rotor's dynamic characteristics may deviate. Therefore, after the parameters of the extrusion oil film damper are determined, the damper's vibration reduction performance must be simulated and verified.

[0097] Oil film stiffness Calculation formula: (8)

[0098] In the formula, Ω is the rotor speed. It is a dimensionless stiffness coefficient. (9)

[0099] Based on the oil film stiffness, the support stiffness of the rotor model is corrected, and the unbalance is calculated. The response of the lower rotor is calculated, taking into account the nonlinearity of the extrusion oil film damper. Based on the calculation results, the critical peak value of the rotor when it passes the critical point and the degree of attenuation of the vibration amplitude within the rotor's operating speed range are obtained, and the vibration reduction performance of the extrusion oil film damper is evaluated accordingly. If the simulation results of the vibration reduction performance of the extrusion oil film damper are not ideal, the above oil film parameters can be appropriately adjusted, such as appropriately reducing the journal eccentricity ζ and the oil film radius clearance c.

[0100] The rotor and support system support stiffness optimization and vibration reduction design method provided in this application reduces the support stiffness by setting elastic supports and squeezing oil film dampers, thereby changing the rotor strain energy distribution and adjusting the critical speed, suppressing the rotor vibration level, especially the vibration caused by sudden imbalance and transcriticality of multi-support rotors. This avoids making radical adjustments to the rotor and support system when the overall gas turbine scheme and component aerodynamic schemes are clear, and the rotor structure, mass distribution, support stiffness and other parameters are basically determined.

[0101] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for optimizing the support stiffness and reducing vibration of a rotor and support system, characterized in that, include: S100: Determine the structural form of the elastic support; select materials based on the structural form; determine initial structural parameters based on the structural form and selected materials; calculate the stiffness of the elastic support based on the initial structural parameters; if the stiffness requirements are met, perform critical speed analysis and rotor strain energy analysis; if the stiffness or critical speed analysis and rotor strain energy analysis do not meet the requirements, adjust the initial structural parameters; if the critical speed analysis and rotor strain energy analysis meet the requirements, determine the detailed structural parameters of the elastic support; perform strength analysis and fatigue life calculation based on the detailed structural parameters; if the requirements are met, the elastic support is obtained; if not, adjust the material of the elastic support and repeat the above process to obtain the elastic support structure. S200, under the condition of obtaining the elastic support structure, determine the design objectives of the extrusion film damper, determine the rigid support modes of the rotor based on the rotor's structural parameters, calculate the rotor's undamped critical speed and mode shape, and the rotor's response under undamped conditions, and determine the i-th modal mass and modal stiffness based on the rotor's modal calculation results to obtain the rotor's equivalent simplified model. Based on the simplified model and design objectives, determine the design point modal damping, calculate the damping value of the extrusion film damper according to the definition formula of modal damping, and determine the extrusion film damping based on the extrusion film damper's damping value. Based on the structure and oil film parameters of the extrusion oil film damper, the vibration reduction performance of the extrusion oil film damper is simulated and verified. The oil film stiffness is calculated, and the support stiffness of the rotor model is corrected according to the oil film stiffness. The rotor response under unbalance is calculated, and the nonlinear factors of the extrusion oil film damper are taken into account in the calculation process. Based on the calculation results, the critical peak value of the rotor over-critical and the degree of attenuation of the vibration amplitude within the rotor's operating speed range are obtained. The vibration reduction performance of the extrusion oil film damper is evaluated accordingly. If the vibration reduction performance does not meet the requirements, the oil film parameters are adjusted.

2. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 2, characterized in that, The structural forms of the elastic support include squirrel cage elastic support, steel ring elastic support, and tie rod elastic support. The squirrel cage elastic support further includes traditional squirrel cage elastic support, folding squirrel cage elastic support, and integrated squirrel cage elastic support. For elastic supports integrated with the outer ring of the bearing, bearing steel that balances hardness, toughness, and fatigue performance is selected. For elastic supports not integrated with the outer ring of the bearing, high-strength materials with good fatigue resistance are selected.

3. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 1, characterized in that, The initial structural parameters of the elastic support include the number, length, and cross-sectional dimensions of the cage bars, which are determined by the following formula: In the formula, k is the elastic support stiffness of the squirrel cage, n is the number of cage bars, E is the elastic modulus of the squirrel cage material, b is the width of the cage bar cross-section, h is the height of the cage bar cross-section, l is the length of the cage bar, and σ max The maximum stress is Y, and the radial displacement of the free end of the elastic support of the squirrel cage is Y.

4. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 3, characterized in that, The stiffness and / or strength of the elastic support are calculated using the finite element method.

5. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 4, characterized in that, The process of performing critical speed analysis and rotor strain energy analysis includes: A vibration characteristic analysis model of the rotor and support system is established. The rotor shaft and drum are simplified as beam elements based on their cross-sectional dimensions. The rotor blades and disks at each stage are simplified as lumped mass elements based on their mass and moment of inertia, with coordinates located at the center of mass. The support system (bearings and elastic supports) is equivalent to spring elements, replaced by equivalent stiffness. The calculation method for the equivalent stiffness is as follows: Where K is the equivalent stiffness, For the radial stiffness of the bearing, For elastic support stiffness; The critical speed calculation and analysis were performed using finite element analysis software to obtain the critical speed of synchronous positive precession of the rotor and the corresponding vibration modes. At least 1.5 times the maximum operating speed was obtained as the calculation results of all critical speeds. The percentage of strain energy distribution of the rotor and support under each vibration mode was calculated.

6. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 1, characterized in that, The design point modal damping: ,in, For rotor modal mass, For rotor modal stiffness, This is modal damping.

7. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 6, characterized in that, The definition formula for modal damping is as follows: （5） In the formula, c sfd ψ is the damping value of the squeeze film damper. i C1 and C2 are the rotor vibration modes, and C1 and C2 are the bearing damping modes.

8. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 6, characterized in that, The extrusion oil film damper can be classified into open and closed types based on whether a sealing structure is installed at both ends. When the required damping is large and the open structure cannot meet the requirements, a closed damper is selected.

9. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 7, characterized in that, The oil film parameters include the journal eccentricity ζ of the extrusion oil film damper, the oil film radius R, the oil film radius clearance c, and the oil film length L; The journal eccentricity ζ of the squeeze oil film damper is ≤0.4; oil film radius d0 is the bearing diameter, and s is the thickness of the bearing outer ring retaining ring; The oil film radius gap ; The width of the oil film In the formula, μ is the viscosity of the lubricating oil. Dimensionless oil film damping coefficient .

10. The rotor and support system support stiffness optimization and vibration reduction design method as described in claim 9, characterized in that, oil film stiffness Calculation formula: In the formula, Ω is the rotor speed. It is a dimensionless stiffness coefficient. .

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