A low-pressure cylinder blade vibration mode optimization and flutter suppression device and assembly method

Abstract

The application discloses a low-pressure cylinder blade vibration mode optimization and flutter suppression device and an assembling method, which comprises the following steps: arranging a plurality of blades in a ring array along the circumference of a low-pressure cylinder rotor; arranging a plurality of damping bosses corresponding to the plurality of blades and arranging the damping bosses on the side surfaces of the blades; arranging a through-shaft reinforcing rib in a straight line and penetrating at least two adjacent damping bosses; arranging a damping sleeve outside the through-shaft reinforcing rib and between the adjacent damping bosses, and arranging the end surface of the damping sleeve to be connected with the damping boss; and arranging a pre-tightening force adjusting mechanism at the end of the through-shaft reinforcing rib, and applying an axial pre-tightening force to the through-shaft reinforcing rib. In the normal working condition, micro-tribological friction energy is generated on the surface of the static friction coefficient of the damping sleeve and the damping boss. In the deep peak regulation working condition, the physical phase change locking is realized by using the thermal expansion difference between the damping sleeve and the through-shaft reinforcing rib, the system equivalent stiffness is adaptively stepped, and the aerodynamic elastic instability under the small volume flow is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of peak shaving technology for thermal power units, and in particular to a device and assembly method for optimizing the vibration mode of low-pressure cylinder blades and suppressing flutter. Background Technology

[0002] With the comprehensive implementation of the new power system construction, thermal power plants have routinely undertaken deep peak-shaving tasks. Under extremely low load conditions or low-pressure cylinder cut-off operation conditions during deep peak shaving, the long blades of the last and second-last stages of the turbine's low-pressure cylinder are in a state of extremely low volumetric flow or even no steam flow. At this time, the high-speed rotating blades generate strong frictional shearing action with the steam trapped in the cylinder, which can easily lead to severe blow-air heating and cause a sharp rise in blade surface temperature. At the same time, under low load conditions, the steam flow is severely separated, the flow field is extremely unstable, and the thermal stress caused by aerodynamic excitation and rapid temperature changes can easily lead to the deterioration and shift of the blade's own vibration modes. When the shifted blade pitch frequency falls into the resonance range, it will cause aeroelastic instability and blade flutter, which, over a long period of time, will lead to high-cycle fatigue cracks or even fracture of the blade.

[0003] For the numerous 300MW subcritical units in service in China, the original design of the blades in the last stage (L-0) and second-to-last stage (L-1) of the low-pressure cylinder did not fully consider long-term operating conditions under extremely low loads of 30% or even 20%. Under the extreme boundary conditions of deep peak shaving, due to the significant deviation from the design reference exhaust temperature, the blade assembly experiences severe uneven thermal expansion and induces huge local additional thermal stress. Under the multi-field coupling effect of the low volumetric flow excitation environment, it is very easy to cause the high-cycle fatigue life of the blade material to deteriorate and shift. At the same time, due to the steam recirculation and eddy current excitation under low volumetric flow, stress concentration is very likely to occur at the blade root and near the tie rod holes.

[0004] To address the high temperature problem on the blade surface, existing technologies often employ water spraying for cooling. This not only results in significant heat energy loss but also causes severe water erosion damage to the high-speed rotating blade's exhaust edge. Regarding peak-shaving flutter, current solutions are largely limited to software algorithm-level state monitoring, lacking physical intervention devices. Furthermore, blade connection structures often employ traditional, single rigid tie rods or loosely mounted damping wire structures. Under frequent load variations during peak-shaving operations, traditional rigid tie rods are prone to thermal stress concentration due to large fluctuations in ambient temperature, leading to tearing at the tie rod holes. While loosely mounted damping wires provide frictional damping, they lack adaptive locking capabilities and cannot provide sufficient stiffness support based on the degree of blade modal deterioration.

[0005] Furthermore, the existing blade connection structure lacks modular adaptation design for different blade specifications during maintenance and replacement. The application of preload during on-site installation often relies on experience without extensive dynamic simulation optimization, resulting in a highly arbitrary vibration suppression effect.

[0006] In view of this, how to provide a device for optimizing the vibration mode of low-pressure cylinder blades and suppressing flutter for peak shaving of power units is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a device and assembly method for optimizing the vibration mode and suppressing flutter of low-pressure cylinder blades, which solves the problems existing in the prior art through a composite damping structure and preload configuration.

[0008] To achieve the above objectives, the present invention provides a device for optimizing the vibration modes and suppressing flutter of a low-pressure cylinder blade, comprising: Multiple blades are arranged in a ring array along the circumference of the low-pressure cylinder rotor; Multiple damping bosses, each corresponding to one of the blades, are disposed on the side of the blades; Through-axis tie rods, passing sequentially through at least two adjacent damping bosses along a straight line; A damping sleeve is fitted on the outside of the through-shaft tie rod and located between adjacent damping bosses, with the end face of the damping sleeve connected to the damping bosses. A preload adjustment mechanism is provided at the end of the through-shaft tie rod, and is used to apply axial preload to the through-shaft tie rod.

[0009] Furthermore, the through-shaft tie rod is a hollow or solid composite rod with an outer diameter of 20mm to 24mm; an initial assembly gap of 0.005mm to 0.012mm is provided between the inner wall of the damping sleeve and the outer surface of the through-shaft tie rod.

[0010] Furthermore, the damping sleeve is made of TC11 titanium alloy, the through-shaft tie is made of austenitic stainless steel, and the thermal expansion difference between the damping sleeve and the through-shaft tie is greater than 6.0 × 10⁻⁶. -6 / ℃, when the temperature of the low-pressure cylinder rises to 80℃~120℃, the damping sleeve and the through-shaft tie rod will produce different radial thermal deformations, eliminating the initial assembly gap.

[0011] Furthermore, the end face of the damping sleeve is prepared by supersonic flame spraying to form an outer surface layer and an inner transition layer with decreasing hardness and increasing toughness from the outside to the inside. The hardness of the outer surface layer is not less than HV1100, and the static friction coefficient between the outer surface layer and the damping boss is 0.20~0.25.

[0012] Furthermore, the preload adjustment mechanism includes: an adjusting shim group, a disc spring group, and a locking nut sequentially sleeved on the end of the through-shaft tie rod. One end of the disc spring group is connected to the locking nut, and the other end is connected to the adjusting shim group. The end of the through-shaft tie rod is provided with an external thread, and the locking nut is connected to the external thread. The adjusting shim group includes multiple annular flat washers, the thickness of which decreases in the direction away from the through-shaft tie rod, and the thickness of the annular flat washers is 0.1mm to 1mm. By rotating the locking nut, the disc spring group can be compressed and an axial preload can be applied to the through-shaft tie rod.

[0013] Furthermore, the target preload applied to the through-shaft tie is 10kN~15kN, the axial preload is 10%~15% of the centrifugal force of the blade, and the contact pressure between the damping sleeve and the damping boss is 50MPa~120MPa.

[0014] Furthermore, there are four annular flat gaskets, and the thicknesses of the four annular flat gaskets are 0.1mm, 0.2mm, 0.5mm and 1.0mm, respectively.

[0015] This invention also provides an assembly method for a low-pressure cylinder blade vibration mode optimization and flutter suppression device. The method includes the following steps: S1: Extract the three-dimensional geometric features of the last stage and / or second-to-last stage blades of the low-pressure cylinder and establish a solid contact assembly model; S2: Construct multi-field coupled boundary conditions, import the centrifugal force field and thermodynamic temperature field under deep peak-shaving conditions, and perform temperature compensation and aerodynamic load conversion correction on the blade vibration frequency. The mathematical model used for correction is as follows: ; In the formula, This is the corrected blade vibration frequency; The nominal natural frequency; and These are the real-time elastic modulus and room temperature elastic modulus of the blade material at the deep peak-shaving temperature, respectively. and These are the real-time volumetric flow load and the rated volumetric flow load in the low-pressure cylinder, respectively. This is the aerodynamic stiffness conversion factor for the low-pressure cylinder flow field, with a value ranging from 0.05 to 0.12. S3: In the stage of solving for the target preload: the integral formula of the frictional dissipation energy of the contact surface is used as the objective function: ; In the formula, The effective contact area between the end face of the damping sleeve and the damping boss; The coefficient of static friction between the contact surfaces of the damping sleeve and the damping boss; This refers to the local contact normal force on the contact surface; The relative slippage of the damping sleeve relative to the damping boss during blade vibration; The target preload force applied to the through-axis tie rod; Simultaneously, apply thermal closure adaptive locking physical constraints: ; In the formula, and These are the coefficients of thermal expansion of the through-shaft tie rod and the damping sleeve, respectively. and These are the outer surface radius of the through-shaft tie rod and the inner surface radius of the damping sleeve, respectively. This refers to the ambient temperature rise when switching from normal operating conditions to deep peak-shaving operating conditions. This is the initial radial assembly gap between the two. Under the premise of satisfying the aforementioned thermal closure adaptive locking physical constraints, the target preload force is obtained by simultaneously solving the above friction dissipation energy integral formula using finite element analysis. ; S4: In the assembly parameter compensation stage: Based on Arrhenius creep theory, a stress relaxation function incorporating activation energy and long-term temperature load is introduced: ; In the formula, , The creep constant of the material of the through-axis tie rod; This refers to the creep activation energy of the material. It is the ideal gas constant; The absolute temperature of the environment in which the through-shaft tie rod is located under deep peak shaving conditions; The expected service life of the through-axis tie rod is given; therefore, the final field installation torque to be applied to the preload adjustment mechanism after adding a 5%~15% creep compensation margin is calculated. .

[0016] The present invention discloses the following technical effects: (1) It overcomes the limitations of traditional rigid tie rods or loose damping in vibration reduction. Under normal operating conditions, it generates micro-friction energy dissipation through the static friction coefficient of the damping sleeve and the damping boss surface; under deep peak adjustment (80℃~120℃) operating conditions, it utilizes the thermal expansion difference between the damping sleeve and the through-shaft tie rod to achieve physical phase change locking, and the system's equivalent stiffness adaptively steps, effectively avoiding aeroelastic instability under small volume flow.

[0017] (2) The target preload applied to the through-shaft tie rod by the present invention is 10kN~15kN, and the contact pressure between the damping sleeve and the damping boss is 50MPa~120MPa, which is within the safe range. This effectively solves the industry pain point that traditional on-site assembly relies on experience and is prone to causing local stress to exceed the limit.

[0018] (3) The end face of the damping sleeve of the present invention is prepared by supersonic flame spraying process to form an outer surface layer with decreasing hardness and increasing toughness from the outside to the inside and an inner transition layer. The hardness of the outer surface layer is not lower than HV1100, and the static friction coefficient between the outer surface layer and the damping boss is 0.20~0.25. Through the gradient combination of the high hardness and wear resistance of the outer surface layer and the high toughness and buffering of the inner transition layer, transient impact loads can be absorbed significantly, extending the effective maintenance-free period of the device to more than 4 major overhaul periods.

[0019] (4) An adjusting shim set was designed for the 300MW unit. The adjusting shim set includes multiple annular flat shims, the thickness of which decreases in the direction away from the through-shaft tie rod. It can accurately compensate for the creep tolerance of the existing rotor disk, adapt to various L-0 / L-1 blades with a height of 800~1050mm, and realize non-destructive rapid modular installation of a single rotor within 24 hours. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the preload adjustment mechanism; Figure 3 This is a simulation diagram; Among them, 100 is the blade; 110 is the damping boss; 200 is the through-shaft tie rod; 300 is the damping sleeve; 400 is the preload adjustment mechanism; 410 is the adjusting shim group; 420 is the disc spring group; and 430 is the lock nut. Detailed Implementation

[0022] 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.

[0023] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0024] 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.

[0025] like Figures 1 to 3 As shown, this embodiment of the invention provides a device for optimizing the vibration modes of a low-pressure cylinder blade and suppressing flutter, comprising: Multiple blades, each 100, are arranged in a ring array along the circumference of the low-pressure cylinder rotor. Multiple damping bosses 110 correspond one-to-one with multiple blades 100 and are disposed on the side of the blades 100. A through-axis tie rod 200 passes through at least two adjacent damping bosses 110 in a straight line. The damping sleeve 300 is sleeved on the outside of the through-shaft tie 200 and located between adjacent damping bosses 110. The end face of the damping sleeve 300 is connected to the damping bosses 110. The preload adjustment mechanism 400 is located at the end of the through-shaft tie 200 and is used to apply axial preload to the through-shaft tie 200.

[0026] In this embodiment, the through-shaft tie rod 200 is a hollow or solid composite rod with an outer diameter of 20mm to 24mm; an initial assembly gap of 0.005mm to 0.012mm is provided between the inner wall of the damping sleeve 300 and the outer surface of the through-shaft tie rod 200.

[0027] In this embodiment, the damping sleeve 300 is made of TC11 titanium alloy, and the through-shaft tie 200 is made of austenitic stainless steel. The thermal expansion difference between the damping sleeve 300 and the through-shaft tie 200 is greater than 6.0 × 10⁻⁶. -6 / ℃, when the temperature of the low-pressure cylinder rises to 80℃~120℃, the damping sleeve 300 and the through-shaft tie rod 200 produce different radial thermal deformations, eliminating the initial assembly gap.

[0028] In this embodiment, the end face of the damping sleeve 300 is prepared by supersonic flame spraying to form an outer surface layer and an inner transition layer with decreasing hardness and increasing toughness from the outside to the inside. The hardness of the outer surface layer is not lower than HV1100, and the static friction coefficient between the outer surface layer and the damping boss 110 is 0.20~0.25.

[0029] In this embodiment, the preload adjustment mechanism 400 includes: an adjustment shim group 410, a disc spring group 420, and a locking nut 430 sequentially sleeved on the end of the through-shaft tie rod 200. One end of the disc spring group 420 is connected to the locking nut 430, and the other end is connected to the adjustment shim group 410. The end of the through-shaft tie rod 200 is provided with an external thread, and the locking nut 430 is connected to the external thread. The adjustment shim group 410 includes multiple annular flat shims. The thickness of the multiple annular flat shims decreases in the direction away from the through-shaft tie rod 200. The thickness of the annular flat shims is 0.1mm to 1mm. Shims of corresponding thickness specifications are selected and superimposed according to the assembly deviation to adapt to the assembly spacing of blades 100 with different chord length specifications of the last stage (L-0) and the second last stage (L-1) of the low-pressure cylinder of the 300MW unit with a height of 800mm to 1050mm and a chord length of 120mm to 260mm, so as to realize modular assembly. Rotating the locking nut 430 compresses the disc spring assembly 420 and applies axial preload to the through-shaft tie rod 200. The spring constant of the disc spring assembly 420 is selected and configured according to the target preload to compensate for the tension attenuation caused by material creep during the unit's operating cycle.

[0030] In this embodiment, the target preload applied to the through-shaft tie 200 is 10kN~15kN, the axial preload is 10%~15% of the centrifugal force of the blade 100, and the contact pressure between the damping sleeve 300 and the damping boss 110 is 50MPa~120MPa.

[0031] In this embodiment, there are four annular flat gaskets, and the thicknesses of the four annular flat gaskets are 0.1mm, 0.2mm, 0.5mm and 1.0mm, respectively.

[0032] This invention also provides an assembly method for a low-pressure cylinder blade vibration mode optimization and flutter suppression device. The method includes the following steps: S1: Extract the three-dimensional geometric features of the last stage and / or second-to-last stage blades 100 of the low-pressure cylinder and establish a solid contact assembly model. S2: In the modal frequency evaluation stage: construct multi-field coupled boundary conditions, import the centrifugal force field and thermodynamic temperature field under deep peak-shaving conditions, and perform temperature compensation and aerodynamic load conversion correction on the 100 vibration frequency of the blade. The mathematical model used for correction is: ; In the formula, This is the corrected blade vibration frequency; The nominal natural frequency; and These are the real-time elastic modulus and room temperature elastic modulus of the blade material at the deep peak-shaving temperature, respectively. and These are the real-time volumetric flow load and the rated volumetric flow load in the low-pressure cylinder, respectively. This is the aerodynamic stiffness conversion factor for the low-pressure cylinder flow field, with a value ranging from 0.05 to 0.12. S3: In the stage of solving for the target preload: the integral formula of the frictional dissipation energy of the contact surface is used as the objective function: ; In the formula, The effective contact area between the end face of the damping sleeve and the damping boss; The coefficient of static friction between the contact surfaces of the damping sleeve and the damping boss; This refers to the local contact normal force on the contact surface; The relative slippage of the damping sleeve relative to the damping boss during blade vibration; The target preload force applied to the through-axis tie rod; Simultaneously, apply thermal closure adaptive locking physical constraints: ; In the formula, and These are the coefficients of thermal expansion of the through-shaft tie rod and the damping sleeve, respectively. and These are the outer surface radius of the through-shaft tie rod and the inner surface radius of the damping sleeve, respectively. This refers to the ambient temperature rise when switching from normal operating conditions to deep peak-shaving operating conditions. This is the initial radial assembly gap between the two. Under the premise of satisfying the aforementioned thermal closure adaptive locking physical constraints, the target preload force is obtained by simultaneously solving the above friction dissipation energy integral formula using finite element analysis. ; S4: In the assembly parameter compensation stage: Based on Arrhenius creep theory, a stress relaxation function incorporating activation energy and long-term temperature load is introduced: ; In the formula, , The creep constant of the material of the through-axis tie rod; This refers to the creep activation energy of the material. It is the ideal gas constant; The absolute temperature of the environment in which the through-shaft tie rod is located under deep peak shaving conditions; The expected service life of the through-axis tie rod is given; therefore, the final field installation torque to be applied to the preload adjustment mechanism after adding a 5%~15% creep compensation margin is calculated. .

[0033] The above assembly method effectively avoids the excitation frequency of the first three pitch diameters of the blade 100 within the fluctuation range of 2550rpm to 3450rpm of the unit, and the synergistic contact pressure generated by the contact surface between the damping sleeve 300 and the damping boss 110 is between 50MPa and 120MPa.

[0034] Simulation data shows that after installing this embodiment, the dynamic stress of the blade 100° decreases by more than 35% under 30% depth peak shaving conditions, effectively widening the safety window for extremely low loads.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for optimizing vibration modes and suppressing flutter in low-pressure cylinder blades, characterized in that, include: Multiple blades (100) are arranged in a ring array along the circumference of the low-pressure cylinder rotor; Multiple damping bosses (110) correspond one-to-one with multiple blades (100) and are disposed on the side of the blades (100); A through-axis tie rod (200) passes through at least two adjacent damping bosses (110) in a straight line. A damping sleeve (300) is sleeved on the outside of the through-shaft tie rod (200) and located between adjacent damping bosses (110). The end face of the damping sleeve (300) is connected to the damping bosses (110). A preload adjustment mechanism (400) is provided at the end of the through-shaft tie (200) for applying axial preload to the through-shaft tie (200).

2. The low-pressure cylinder blade vibration mode optimization and chatter suppression device according to claim 1, characterized in that, The through-shaft tie rod (200) is a hollow or solid composite rod with an outer diameter of 20mm to 24mm; an initial assembly gap is provided between the inner wall of the damping sleeve (300) and the outer surface of the through-shaft tie rod (200), and the initial assembly gap is 0.005mm to 0.012mm.

3. The low-pressure cylinder blade vibration mode optimization and chatter suppression device according to claim 2, characterized in that, The damping sleeve (300) is made of TC11 titanium alloy, and the through-shaft tie rod (200) is made of austenitic stainless steel. The thermal expansion difference between the damping sleeve (300) and the through-shaft tie rod (200) is greater than 6.0 × 10⁻⁶. -6 / ℃, when the temperature of the low-pressure cylinder rises to 80℃~120℃, the damping sleeve (300) and the through-shaft tie rod (200) produce different radial thermal deformations, eliminating the initial assembly gap.

4. The low-pressure cylinder blade vibration mode optimization and chatter suppression device according to claim 3, characterized in that, The end face of the damping sleeve (300) is prepared by supersonic flame spraying process to form an outer surface layer and an inner transition layer with decreasing hardness and increasing toughness from the outside to the inside. The hardness of the outer surface layer is not less than HV1100, and the static friction coefficient between the outer surface layer and the damping boss (110) is 0.20~0.

25.

5. The low-pressure cylinder blade vibration mode optimization and chatter suppression device according to claim 4, characterized in that, The preload adjustment mechanism (400) includes: an adjusting shim group (410), a disc spring group (420), and a locking nut (430) sequentially sleeved on the end of the through-shaft tie rod (200). One end of the disc spring group (420) is connected to the locking nut (430), and the other end is connected to the adjusting shim group (410). The end of the through-shaft tie rod (200) is provided with an external thread, and the locking nut (430) is connected to the external thread. The adjusting shim group (410) includes multiple annular flat washers. The thickness of the multiple annular flat washers decreases in the direction away from the through-shaft tie rod (200). The thickness of the annular flat washers is 0.1mm to 1mm. By rotating the locking nut (430), the disc spring group (420) can be compressed and an axial preload can be applied to the through-shaft tie rod (200).

6. The low-pressure cylinder blade vibration mode optimization and chatter suppression device according to claim 5, characterized in that, The target preload applied to the through-shaft tie rod (200) is 10kN~15kN, the axial preload is 10%~15% of the centrifugal force of the blade (100), and the contact pressure between the damping sleeve (300) and the damping boss (110) is 50MPa~120MPa.

7. The device for optimizing the vibration mode and suppressing flutter of a low-pressure cylinder blade according to claim 5, characterized in that, There are four annular flat gaskets in total, and the thicknesses of the four annular flat gaskets are 0.1mm, 0.2mm, 0.5mm and 1.0mm respectively.

8. An assembly method for a low-pressure cylinder blade vibration mode optimization and flutter suppression device, characterized in that, The application of the low-pressure cylinder blade vibration mode optimization and chatter suppression device according to any one of claims 5-7 includes the following steps: S1: Extract the three-dimensional geometric features of the last stage and / or second-to-last stage blades (100) of the low-pressure cylinder and establish a solid contact assembly model; S2: Construct multi-field coupled boundary conditions, import the centrifugal force field and thermodynamic temperature field under deep peak shaving conditions, and perform temperature compensation and aerodynamic load conversion correction on the vibration frequency of the blade (100). The mathematical model used for correction is: ； In the formula, The corrected vibration frequency of the blade (100); The nominal natural frequency; and These are the real-time elastic modulus and room temperature elastic modulus of the blade (100) material at the deep peak-shaving temperature, respectively; and These are the real-time volumetric flow load and the rated volumetric flow load in the low-pressure cylinder, respectively. This is the aerodynamic stiffness conversion factor for the low-pressure cylinder flow field, with a value ranging from 0.05 to 0.

12. S3: In the stage of solving for the target preload: the integral formula of the frictional dissipation energy of the contact surface is used as the objective function: ； In the formula, The effective contact area between the end face of the damping sleeve (300) and the damping boss (110); The boundary static friction coefficient between the contact surfaces of the damping sleeve (300) and the damping boss (110); This refers to the local contact normal force on the contact surface; The relative slip of the damping sleeve (300) relative to the damping boss (110) when the blade (100) vibrates; The target preload force applied to the through-axis tie rod (200); Simultaneously, apply thermal closure adaptive locking physical constraints: ； In the formula, and The coefficients of thermal expansion of the through-shaft tie rod (200) and the damping sleeve (300) are respectively; and These are the outer surface radius of the through-shaft tie rod (200) and the inner surface radius of the damping sleeve (300), respectively. This refers to the ambient temperature rise when switching from normal operating conditions to deep peak-shaving operating conditions. This is the initial radial assembly gap between the two. Under the premise of satisfying the physical constraints of thermal closure adaptive locking, the target preload force is obtained by simultaneously solving the integral equation of frictional dissipation energy. ; S4: In the assembly parameter compensation stage: Based on Arrhenius creep theory, a stress relaxation function incorporating activation energy and long-term temperature load is introduced: ； In the formula, , The creep constant of the material of the through-axis tie rod (200); This refers to the creep activation energy of the material. It is the ideal gas constant; The absolute temperature of the environment in which the through-shaft tie rod (200) is located under deep peak shaving conditions; The expected service life of the through-shaft tie rod (200) is given; based on this, the final field installation torque to be applied to the preload adjustment mechanism (400) after adding a 5%~15% creep compensation margin is calculated. .

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