A method and device for predicting creep bending of a steam turbine rotor

Abstract

The present application relates to the field of steam turbine technology, and specifically to a method and device for predicting creep bending of a steam turbine rotor. The temperature field and stress field of the rotor are calculated to obtain a first creep strain rate function and a first axial stress deviator function; a one-dimensional shafting model of the steam turbine unit is established, and the axial stress deviator correction function is calculated based on the dynamic load of each node of the one-dimensional shafting model; the first creep strain rate function and the first axial stress deviator function are corrected based on the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a corrected second creep strain rate function; the second creep strain rate function is used as the initial strain, and the bending distribution of the rotor in each time step under a preset time step is calculated in sequence to obtain the creep bending prediction result of the steam turbine rotor in the preset time step. The present application adds dynamic load to obtain the corrected creep strain rate function, thereby making the creep bending prediction result more accurate.

Description

Technical Field

[0001] The present application relates to the technical field of steam turbines, and in particular to a method and device for predicting creep bending of a steam turbine rotor. Background Art

[0002] Steam turbines are important power generation equipment, with their rotors being one of their core components. However, over long-term use, steam turbine rotors are prone to creep bending, which not only affects turbine power generation efficiency but can even lead to serious safety accidents. Therefore, predicting creep bending in steam turbine rotors is of great practical significance.

[0003] Currently, the main method used to predict creep bending of steam turbine rotors is based on material mechanical properties and creep theory. However, practitioners have found that during the actual prediction calculation process, as the steam turbine rotor operates, the predicted results differ significantly from the actual bending distribution. Improving the accuracy of creep bending prediction for steam turbine rotors has become a difficult problem that practitioners urgently need to solve. Summary of the Invention

[0004] In view of the problem that the prediction accuracy of creep bending of steam turbine rotors in related technologies is low and difficult to meet the prediction requirements.

[0005] In a first aspect, an embodiment of the present application provides a method for predicting creep bending of a steam turbine rotor, the method comprising:

[0006] calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function;

[0007] Establish a one-dimensional shafting model of the steam turbine unit and calculate the axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model;

[0008] Correcting the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a corrected second creep strain rate function;

[0009] The second creep strain rate function is used as the initial strain, and the bending distribution of the rotor in each time step under the preset time step is calculated in sequence to obtain the creep bending prediction result of the turbine rotor in the preset time step.

[0010] In combination with the first aspect, in one embodiment, calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function includes:

[0011] According to the geometric parameters and material parameters of the steam turbine rotor, a two-dimensional axisymmetric finite element model of the steam turbine rotor is established;

[0012] The temperature stress field of the steam turbine rotor is calculated according to the operating parameters of the steam turbine, and a first creep strain rate function and a first axial stress deviator function are obtained.

[0013] In conjunction with the first aspect, in one embodiment, the step of calculating the axial stress deviator correction function based on the dynamic loads of each node of the one-dimensional shafting model includes:

[0014] Obtain the dynamic load on each node of the shaft system based on the one-dimensional shaft system model, and calculate the amplitude and phase of the bending moment at each node of the shaft system;

[0015] According to the amplitude and phase of the bending moment at each node of the shaft system, the bending stress generated by the rotor during vortex motion is calculated and analyzed;

[0016] The first axial stress deviator function is corrected according to the bending stress generated by the rotor during vortex motion to obtain an axial stress deviator correction function.

[0017] In conjunction with the first aspect, in one embodiment, calculating the dynamic load on each node of the shaft system according to the one-dimensional shaft system model includes:

[0018] The exciting force vector is calculated based on the initial unbalanced exciting force, the unbalanced exciting force caused by bending and the exciting force caused by the dynamic balance mass in the one-dimensional shafting model;

[0019] The displacement of each node of the rotor is calculated according to the exciting force vector and the dynamic equation of the shaft system under harmonic response, and then the shear force and torque acting on each node of the shaft system are obtained.

[0020] In combination with the first aspect, in one embodiment, calculating the amplitude and phase of the bending moment at each node of the shaft system includes:

[0021] According to the shear force and moment calculation of each node, the bending moment of the i-th node in the y direction is T y,i and the z-direction component T z,i ;

[0022]

[0023] Where, F Sy,i is the shear force in the y direction on the i-th node, F sz,i is the shear force in the z direction on the i-th node, F my,i is the moment about the y-axis on the i-th node, F mz,i is the moment about the z-axis on the i-th node;

[0024] The bending moment at the i-th node is in the y direction component T y,i and the z-direction component T z,iWrite them as time functions that change with time, and get the amplitude expression of the bending moment at the i-th node T b,i (t) and the expression of phase H M,i (t):

[0025]

[0026] Where, T y,i (t) is the time function of the y-direction component of the bending moment at the i-th node, T z,i (T) is the time function of the component of the bending moment in the z direction at the i-th node.

[0027] In combination with the first aspect, in one embodiment, calculating and analyzing the bending stress generated by the rotor during vortex motion based on the amplitude and phase of the bending moment applied to each node of the shaft system includes:

[0028] Calculate the axial stress G generated by the rotor vortex x,w :

[0029]

[0030] Where, T b is the bending moment generated by the rotor vortex, H M is the bending moment phase generated by the rotor vortex, I is the section moment of inertia;

[0031] The axial stress generated by the rotor vortex is taken as the bending stress generated by the rotor vortex.

[0032] In combination with the first aspect, in one embodiment, the step of correcting the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain the second creep strain rate function includes:

[0033] Obtain the material unevenness function of the turbine rotor;

[0034] The corrected second creep strain rate function ε is obtained based on the material inhomogeneity function and the axial stress deviator correction function. x (r,θ,x):

[0035] ε x (r,θ,x)=[R(r,x)·ξ(r,θ,x)]·[S x (r,x)+S w (r,θ,x)]·t

[0036] Where t is the running time, ξ(r,θ,x) is the material inhomogeneity function, R(r,x) is the first creep strain rate function, S x (r,x) is the first axial stress deviator function, S w(r,θ,x) is the axial stress deviator correction function.

[0037] In combination with the first aspect, in one embodiment, the step of sequentially calculating the bending distribution of the rotor in each time step at a preset time step using the second creep strain rate function as the initial strain includes:

[0038] The bending distribution of the rotor at the initial time step is calculated according to the second creep strain rate function;

[0039] The second creep strain rate function at the next time step is updated according to the bending distribution of the rotor at the initial time step;

[0040] The bending amount distribution and the second creep strain rate function are iteratively updated until the bending amount distribution at the last time step in the preset time step is calculated.

[0041] In combination with the first aspect, in one embodiment, calculating the bending distribution of the rotor at the initial time step according to the axial stress deviator correction function includes:

[0042] A three-dimensional finite element model of the steam turbine rotor is established, and the second axial creep strain rate at the initial time step is used as the initial strain calculation unit node load;

[0043] The displacement of each node is calculated according to the unit node load to obtain the bending distribution of the rotor.

[0044] In a second aspect, an embodiment of the present application provides a device for predicting creep bending of a steam turbine rotor, comprising:

[0045] a temperature stress analysis module for calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function;

[0046] Dynamic response analysis module, which is used to establish a one-dimensional shafting model of the steam turbine unit and calculate the axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model;

[0047] a correction module, configured to correct the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function, to obtain a corrected second creep strain rate function;

[0048] The prediction module is used to calculate the bending distribution of the rotor in each time step under the preset time step using the second creep strain rate function as the initial strain, so as to obtain the creep bending prediction result of the turbine rotor in the preset time step.

[0049] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0050] The applicant discovered that as the turbine rotor operated, its predicted results gradually deviated from the actual results. This was primarily due to the failure to consider the impact of dynamic loads on the predicted results. This application incorporates dynamic loads to correct the rotor's stress deviator, thereby deriving a modified creep strain rate function. This modified function is then used to calculate the rotor's bending distribution, thereby achieving more accurate creep bending prediction results. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the process of creep bending prediction method in an embodiment of the present application;

[0052] Figure 2 This is a schematic diagram of the hardware structure of the creep bending prediction device involved in the embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the present invention, 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 creative work are within the scope of protection of this application.

[0054] In view of the problem that the prediction accuracy of creep bending of steam turbine rotors in related technologies is low and difficult to meet the prediction requirements.

[0055] First, as Figure 1 As shown, the present application provides a method for predicting creep bending of a steam turbine rotor, the rotor creep bending prediction method comprising:

[0056] Step S1: Calculate the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function.

[0057] The above step S1 specifically includes:

[0058] Step S1a: establishing a two-dimensional axisymmetric finite element model of the steam turbine rotor according to the geometric parameters and material parameters of the steam turbine rotor.

[0059] Step S1b: Calculate the temperature stress field of the steam turbine rotor according to the operating parameters of the steam turbine, and obtain a first creep strain rate function and a first axial stress deviator function.

[0060] In some preferred implementations, in order to reduce the calculation scale, a two-dimensional axisymmetric model is used to calculate the temperature field and stress field of the high and medium pressure rotors.

[0061] Specifically, the temperature stress field of the turbine rotor can be calculated using general finite element software according to the steam inlet parameters, speed and other operating parameters of the turbine, and the first creep strain rate function R(r,x) and the first axial stress deviator function S can be obtained. x (r,x), the above function is only a function of the radial coordinate r and the axial coordinate x.

[0062] The first creep strain rate function R(r,x) satisfies:

[0063]

[0064] The widely used Norton three-parameter model is selected.

[0065]

[0066] Where T is the Kelvin temperature, and C1, C2, and C3 are material parameters related to material properties.

[0067] Step S2: establishing a one-dimensional shafting model of the steam turbine unit, and calculating an axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model.

[0068] In a specific implementation of the present application, the above step S2 includes:

[0069] Step S2a: Obtain the dynamic load on each node of the shaft system according to the one-dimensional shaft system model, and calculate the amplitude and phase of the bending moment on each node of the shaft system.

[0070] Specifically, a one-dimensional symmetrical finite element model of the turbine rotor shaft system is established, and the dynamic equation of the shaft system under harmonic response satisfies:

[0071] [-ω 2 M+jω(C+ωG)+K]u=F ext

[0072] Where, M, C, G and K are the mass matrix, damping matrix, rotation matrix and stiffness matrix of the shaft system; ω is the angular velocity; u is the displacement complex vector; F ext is the exciting force vector.

[0073] Furthermore, the unbalanced exciting force is composed of the initial unbalanced exciting force F0, the unbalanced exciting force F generated by bending u and the exciting force F generated by the dynamic balance mass b It consists of three parts, which form the exciting force complex vector F according to their respective amplitude and phase. ext :

[0074] F ext =F0+F u +F b

[0075] According to the complex vector F of the exciting force ext Continuing to solve the above dynamic equations, we can get the displacement u of each node, and then we can get the dynamic load F on each node of the shaft system. d :

[0076] F d =Ku+F r

[0077] Where, F r The support reaction force can be obtained by solving the full equilibrium equation including the support degrees of freedom. Furthermore, the dynamic load of each node is composed of shear force and moment, which can be written as:

[0078] F s ={F sy,i ,F sz,i}

[0079] F m ={F my,i ,F mz,i}

[0080] Where i represents the i-th node, F sy,i 、F sz,i 、F my,i 、F mz,i are the shear force in the y direction at the i-th node, the shear force in the z direction at the i-th node, the moment about the y axis at the i-th node, and the moment about the z axis at the i-th node, all of which are complex numbers. Based on the shear force and moment of the dynamic load on each node of the shaft system, the bending moment at the i-th node can be calculated as follows:

[0081]

[0082] Among them, T y,i and T z,i is a complex number, constituting the y- and z-components of the bending moment at the i-th node. It can be written as a function of time as:

[0083]

[0084] Then, we can get the expressions of the amplitude and phase of the bending moment at the i-th node:

[0085]

[0086] It should be noted that within a rotation cycle, the amplitude and phase of the bending moment at the i-th node are an elliptical curve, and the change of the amplitude with the phase is an elliptical curve. The center of the ellipse can be used to obtain the average bending moment amplitude T generated by the rotor vortex at each node. b,i and phase H M,i .

[0087] Step S2b: Calculate and analyze the bending stress generated by the rotor during vortex motion based on the amplitude and phase of the bending moment applied to each node of the shaft system.

[0088] Specifically, since the rotor vortex will generate a bending dynamic load in the middle, the generated bending stress is an axial stress. Calculate the axial stress G generated by the rotor vortex x,w :

[0089]

[0090] Where, T b is the bending moment generated by the rotor vortex, H M is the bending moment phase generated by the rotor vortex, and I is the section inertia moment. The axial stress generated by the rotor vortex is taken as the bending stress generated by the rotor vortex.

[0091] Step S2c: correcting the first axial stress offset function according to the bending stress generated by the rotor during vortex motion to obtain an axial stress offset correction function.

[0092] It should be noted that the axial stress generated by the rotor vortex is greater than the equivalent stress. Very small, the bending stress equivalent stress can be ignored However, according to the distribution characteristics of bending stress, its influence on the axial stress deflection needs to be considered.

[0093] Therefore, according to the stress deviator tensor, the calculation formula of the second axial stress deviator correction function considering the eddy effect dynamic load can be obtained as follows:

[0094]

[0095] Substituting the amplitude and phase of the bending moment in step S2a into the above formula, the second axial stress deviator correction function S can be obtained. w (r,θ,x), which is a function of the radial coordinate r, the circumferential coordinate θ, and the axial coordinate x.

[0096] Step S3: Correct the first creep strain rate function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a second creep strain rate function.

[0097] In some specific implementations, the above step S3 includes:

[0098] Step S3a: Obtain the material unevenness function of the steam turbine rotor.

[0099] Specifically, based on the creep test data of the turbine rotor material, the material unevenness function is fitted and obtained. The function is a function of the radial coordinate r, the circumferential coordinate θ and the axial coordinate x. According to relevant literature, the expression of the material unevenness function is:

[0100]

[0101] Where A ξ Indicates the size of the uneven material. It represents the phase of uneven material, and r0(x) is the cross-sectional radius of the axis segment.

[0102] Step S3b: Correct the first creep strain rate function and the first axial stress deviator function according to the material inhomogeneity function and the axial stress deviator correction function to obtain a corrected second creep strain rate function ε x (r,θ,x):

[0103] ε x (r,θ,x)=[R(r,x)·ξ(r,θ,x)]·[S x (r,x)+S w (r,θ,x)]·t

[0104] Where t is the running time, ξ(r,θ,x) is the material inhomogeneity function, R(r,x) is the first creep strain rate function, S x (r,x) is the first axial stress deviator function, S w (r,θ,x) is the axial stress deviator correction function.

[0105] Furthermore, due to the consideration of the bending moment generated by the rotor vortex, the progressive bending of the high and medium pressure rotors of the steam turbine is affected by the dynamic response of the rotor. As the bending amount increases, the unbalanced exciting force F generated by the bending in step S2a u will change, thus changing the magnitude and phase of the bending moment in the axial stress offset correction function. Similarly, when the dynamic balance quality of the turbine rotor is increased or decreased during the overhaul process, the dynamic response state of the rotor will also change. Therefore, the bending moment T in the axial stress offset correction function b and its phase H M It should be updated every time interval or when the dynamic balance state of the rotor changes. The second axial creep strain rate function is updated to incremental form.

[0106] The specific updating process of the second axial creep strain rate function in incremental form includes:

[0107]

[0108] Among them, Δε x(r,θ,x) is the correction value. is the updated second axial creep strain rate function.

[0109] Step S4: Using the second creep strain rate function as the initial strain, sequentially calculate the bending distribution of the rotor in each time step under the preset time step to obtain the creep bending prediction result of the steam turbine rotor in the preset time step.

[0110] In some specific implementations, the above step S4 includes:

[0111] Step S4a: Calculate the bending distribution of the rotor at the initial time step according to the second creep strain rate function.

[0112] In some implementations, the process of obtaining the curvature distribution includes:

[0113] A three-dimensional finite element model of the steam turbine rotor is established, and the second axial creep strain rate at the initial time step is used as the initial strain calculation unit node load.

[0114] Specifically, based on the finite element principle, the second axial creep strain rate ε x (r,θ,x) as the initial strain will generate nodal loads. The unit node load is expressed as:

[0115]

[0116] Where B is the element shape function matrix and D is the elasticity matrix.

[0117] According to the balanced equation:

[0118]

[0119] Where, {δ} e is the node displacement within the element, [k] e is the element stiffness matrix, which is expressed as:

[0120]

[0121] Furthermore, since each node should satisfy the static equilibrium condition, the overall equilibrium equation can be obtained:

[0122]

[0123] After combining like terms, we get the formula:

[0124]

[0125] Where [K] is the overall stiffness matrix. Solving the above equilibrium equations yields the displacements of each node and, consequently, the bending distribution along the rotor axis.

[0126] Step S4b: updating the second creep strain rate function in the next time step according to the bending distribution of the rotor in the initial time step.

[0127] It should be noted that the bending distribution is calculated for each time step, and the unbalanced force generated by the bending is brought into the calculation formula in the above step S2a. Through the same shafting dynamic response analysis, the axial stress deviator correction function S for the next time step is updated. w (r, θ, x). Then, using the updated axial stress deviator correction function, continue with steps S3 and S4a to obtain the bending distribution of the next time step.

[0128] Step S4c: iteratively update the bending amount distribution and the second creep strain rate function until the bending amount distribution at the last time step in the preset time step is calculated.

[0129] Specifically, the above bending distribution calculation and the update of the axial stress deviator correction function at the next time step are repeated until the bending distribution at the last time step in the preset time step is calculated. The set of bending distributions at each time step within the preset time step is used as the rotor creep bending prediction result.

[0130] It should be noted that the execution order of the above steps S1-S4 can be changed according to actual working conditions.

[0131] Furthermore, the present application provides a specific embodiment based on a 660MW steam turbine generator rotor. The specific implementation of this embodiment includes:

[0132] Step 1: Obtain the geometric and material parameters of the turbine rotor. These parameters include, but are not limited to, the rotor's length, diameter, material elastic modulus, Poisson's ratio, creep coefficient, etc. These parameters can be obtained by measurement or by consulting relevant literature.

[0133] Step 2: Use a two-dimensional axisymmetric model to calculate the temperature and stress fields of the high and medium pressure rotors.

[0134] Specifically, the structure between the centerlines of bearings 1# and 2# was intercepted, retaining features such as fillets, and the mesh at these fillets was refined. The rotor blades within the high- and medium-pressure cylinders were loaded as equivalent masses on the corresponding shaft segments. This resulted in a two-dimensional axisymmetric model of the high- and medium-pressure rotors of a 660MW steam turbine.

[0135] It should be noted that the inlet of the high-temperature steam of the turbine is in the middle of the high and medium pressure cylinders, so only the influence of the temperature field and stress field of the high and medium pressure rotors on creep bending needs to be considered.

[0136] Furthermore, by determining the heat flow boundary and adiabatic boundary, the steady-state temperature field of the high- and medium-pressure rotors of a 660MW steam turbine generator set was calculated. Simultaneously, centrifugal force and temperature loads were applied to obtain the stress distribution under the influence of centrifugal force and thermal stress.

[0137] Substitute the two-dimensional temperature and stress calculation results into the formula:

[0138]

[0139] The creep strain rate function R(r,x) can be obtained. At the same time, the stress calculation results can be extracted to obtain S x (r,x) axial stress deviator function,

[0140] Step 3: Refer to the creep test data in existing literature and use the formula:

[0141]

[0142] Take different material unevenness function calculation parameters A ξ and Calculate the creep bending process under the corresponding calculation conditions.

[0143] Step 4: Use the finite element method to build a one-dimensional shafting model of the unit using the Timoshenko beam model, and load additional structures such as blades into the corresponding shaft segments as equivalent mass and moment of inertia. Obtain the one-dimensional shafting model of the unit.

[0144] [-ω 2 M+jω(C+ωG)+K]u=F ext

[0145] In the equation, the mass matrix M, damping matrix C, rotation matrix G and stiffness matrix K of the shaft system are given. Furthermore, the initial unbalance is set to 0.02 mm (standard requirement) and substituted into the formula:

[0146] F ext =F0+F u +F b

[0147] Acquired exciting force vector F ext . Then according to the formula:

[0148] F d =Ku+F r

[0149] The dynamic load of each node is calculated. Thus, the axial stress deflection correction function distribution S considering the vortex effect dynamic load is calculated. w (r,θ,x).

[0150] Step 5: Through steps 2, 3, and 4, according to the formula:

[0151] ε x (r,θ,x)=[R(r,x)·ξ(r,θ,x)]·[S x (r,x)+S w (r,θ,x)]·t

[0152] The axial creep strain rate function ε is constructed considering the circumferential non-uniformity of the creep characteristics of the rotor material and the influence of the rotor vortex dynamic load. x (r,θ,x)

[0153] Step 6: The uneven circumferential distribution of the axial creep strain rate requires a three-dimensional structural model of the turbine's high- and medium-pressure rotors to calculate the rotor bending distribution. Using three-dimensional solid elements, the two-dimensional axisymmetric model from Step 2 is stretched around the axis to obtain a three-dimensional structural model of the high- and medium-pressure rotors of a 660MW unit.

[0154] Furthermore, the axial creep strain rate function ε x By taking (r,θ,x) as the initial strain, the three-dimensional deformation of the high- and medium-pressure rotor of a 660MW steam turbine unit at the current time step can be calculated, and the bending amount of the rotor can be extracted.

[0155] Step 7: Select a time step of 1000h, calculate the bending distribution at each time step, and substitute the unbalanced force generated by the bending into the formula in step 4. Through the dynamic response analysis of the shafting, update the axial stress deviator correction function ε for the next time step. x (r, θ, x); repeating steps 4 through 6 yields the rotor creep bending prediction results taking into account rotor dynamic loads. It can be seen that both the degree and phase of material inhomogeneity affect the progression of bending. Furthermore, the change in bending rate is affected by rotor vortex. Under the influence of the bending moment in the effective creep zone, a progressively bending rotor exhibits self-stabilizing properties.

[0156] In a second aspect, the present application provides a creep bending prediction device for a steam turbine rotor, which includes: a temperature stress analysis module, a dynamic response analysis module, a correction module and a prediction module; wherein,

[0157] A temperature stress analysis module is used to calculate the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function; a dynamic response analysis module is used to establish a one-dimensional shafting model of the steam turbine unit and calculate the axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model; a correction module is used to correct the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a corrected second creep strain rate function; a prediction module is used to use the second creep strain rate function as the initial strain and sequentially calculate the bending distribution of the rotor in each time step under a preset time step to obtain the creep bending prediction result of the steam turbine rotor in the preset time step.

[0158] The functions of the modules in the creep bending prediction device described above correspond to the steps in the method embodiment of the creep bending prediction device described above, and their functions and implementation processes are not described in detail here.

[0159] In a third aspect, an embodiment of the present application provides a creep bending prediction device, which may be a device with data processing capabilities, such as a personal computer (PC), a laptop computer, or a server.

[0160] Reference Figure 2 , Figure 2 FIG. 1 is a schematic diagram of the hardware structure of a creep bending prediction device involved in an embodiment of the present application. In the embodiment of the present application, the creep bending prediction device may include a processor, a memory, a communication interface, and a communication bus.

[0161] The communication bus may be of any type and is used to interconnect the processor, memory, and communication interface.

[0162] Communication interfaces include input / output (I / O) interfaces, physical interfaces, and logical interfaces, which are used to interconnect components within the creep bend prediction device, as well as interfaces used to interconnect the creep bend prediction device with other devices (such as other computing devices or user devices). Physical interfaces can be Ethernet, fiber, or ATM interfaces; user devices can be displays or keyboards.

[0163] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0164] The processor may be a general-purpose processor that can invoke a creep bend prediction program stored in a memory and execute the creep bend prediction method provided in the embodiments of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the creep bend prediction program is invoked can be referenced to the various embodiments of the creep bend prediction method of the present application and will not be further described here.

[0165] Those skilled in the art will understand that Figure 2 The hardware structure shown in the figure does not constitute a limitation to the present application and may include more or fewer components than shown in the figure, or a combination of certain components, or a different arrangement of components.

[0166] In a fourth aspect, an embodiment of the present application also provides a readable storage medium.

[0167] The readable storage medium of the present application stores a creep bending prediction program, wherein when the creep bending prediction program is executed by a processor, the steps of the creep bending prediction method described above are implemented.

[0168] The method implemented when the creep bending prediction program is executed can refer to the various embodiments of the creep bending prediction method of the present application, and will not be described in detail here.

[0169] In summary, the present application corrects the rotor stress deviator by adding dynamic load, thereby obtaining a corrected creep strain rate function, and then calculates the rotor bending distribution based on the corrected function, thereby making the creep bending prediction result more accurate.

[0170] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0171] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0172] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0173] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0174] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0175] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0176] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for predicting creep bending of a steam turbine rotor, characterized in that: The rotor creep bending prediction method comprises: calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function; Establish a one-dimensional shafting model of the steam turbine unit and calculate the axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model; Correcting the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a corrected second creep strain rate function; Using the second creep strain rate function as the initial strain, the bending distribution of the rotor in each time step under the preset time step is calculated in sequence to obtain the creep bending prediction result of the turbine rotor in the preset time step; The method for calculating the axial stress deviator correction function based on the dynamic load of each node of the one-dimensional shafting model includes: obtaining the dynamic load on each node of the shafting system according to the one-dimensional shafting model, and calculating the amplitude and phase of the bending moment at each node of the shafting system; calculating and analyzing the bending stress generated by the rotor during vortex motion according to the amplitude and phase of the bending moment at each node of the shafting system; and correcting the first axial stress deviator function according to the bending stress generated by the rotor during vortex motion to obtain the axial stress deviator correction function.

2. The method for predicting creep bending of a steam turbine rotor according to claim 1, wherein: Calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function includes: According to the geometric parameters and material parameters of the steam turbine rotor, a two-dimensional axisymmetric finite element model of the steam turbine rotor is established; The temperature field and stress field of the steam turbine rotor are calculated according to the operating parameters of the steam turbine, and a first creep strain rate function and a first axial stress deviator function are obtained.

3. The method for predicting creep bending of a steam turbine rotor according to claim 1, wherein: The calculation of the dynamic loads on each node of the shaft system according to the one-dimensional shaft system model includes: The exciting force vector is calculated based on the initial unbalanced exciting force, the unbalanced exciting force caused by bending and the exciting force caused by the dynamic balance mass in the one-dimensional shafting model; The displacement of each node of the rotor is calculated according to the exciting force vector and the dynamic equation of the shaft system under harmonic response, and then the shear force and torque acting on each node of the shaft system are obtained.

4. The method for predicting creep bending of a steam turbine rotor according to claim 3, wherein: The calculation of the amplitude and phase of the bending moment at each node of the shaft system includes: According to the shear force and moment calculation of each node, the bending moment of the i-th node in the y direction is and the z-direction component ; Where, For the On the node Shear force, For the On the node Shear force, For the Node bypass The torque of the shaft, For the Node bypass The moment of the shaft, is the axial coordinate of the i-th node, is the axial coordinate of the kth node; The y-direction component of the bending moment at the i-th node and the z-direction component Write them as time functions that change with time, and get The amplitude expression of the bending moment at the node and the phase expression : Where, is the time function of the y-direction component of the bending moment at the i-th node, is the time function of the component of the bending moment in the z direction at the i-th node, and ω is the angular velocity of rotation.

5. The method for predicting creep bending of a steam turbine rotor according to claim 4, wherein: The bending stress generated by the rotor vortex is obtained by calculating and analyzing the amplitude and phase of the bending moment applied to each node of the shaft system, including: Calculate the axial stress generated by rotor vortex : Where, is the bending moment generated by the rotor vortex, is the bending moment phase generated by the rotor vortex, is the moment of inertia of the section, is the circumferential coordinate, r is the radial coordinate; The axial stress generated by the rotor vortex is taken as the bending stress generated by the rotor vortex.

6. The method for predicting creep bending of a steam turbine rotor according to claim 1, wherein: The step of correcting the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain the second creep strain rate function includes: Obtain the material unevenness function of the turbine rotor; The corrected second creep strain rate function is obtained based on the material inhomogeneity function and the axial stress deviator correction function. : Where t is the running time, is the material unevenness function, is the first creep strain rate function, is the first axial stress deviator function, is the axial stress deviator correction function, is the radial coordinate, is the circumferential coordinate, is the axial coordinate.

7. The method for predicting creep bending of a steam turbine rotor according to claim 1, wherein: The method of sequentially calculating the bending distribution of the rotor in each time step under a preset time step by using the second creep strain rate function as the initial strain includes: The bending distribution of the rotor at the initial time step is calculated according to the second creep strain rate function; The second creep strain rate function at the next time step is updated according to the bending distribution of the rotor at the initial time step; The bending amount distribution and the second creep strain rate function are iteratively updated until the bending amount distribution at the last time step in the preset time step is calculated.

8. The method for predicting creep bending of a steam turbine rotor according to claim 1, wherein: Calculating the rotor bending distribution at the initial time step according to the axial stress deviator correction function includes: A three-dimensional finite element model of the steam turbine rotor is established, and the second axial creep strain rate at the initial time step is used as the initial strain calculation unit node load; The displacement of each node is calculated according to the unit node load to obtain the bending distribution of the rotor.

9. A creep bending prediction device for a steam turbine rotor, characterized in that: include: a temperature stress analysis module for calculating the temperature field and stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function; A dynamic response analysis module is used to establish a one-dimensional shafting model of the steam turbine unit and calculate an axial stress deviator correction function based on the dynamic loads of each node of the one-dimensional shafting model. The calculation of the axial stress deviator correction function based on the dynamic loads of each node of the one-dimensional shafting model includes: obtaining the dynamic loads on each node of the shafting system according to the one-dimensional shafting model, and calculating the amplitude and phase of the bending moment at each node of the shafting system; calculating and analyzing the bending stress generated by the rotor during vortex motion based on the amplitude and phase of the bending moment at each node of the shafting system; and correcting the first axial stress deviator function based on the bending stress generated by the rotor during vortex motion to obtain the axial stress deviator correction function. A correction module is used to correct the first creep strain rate function and the first axial stress deviator function according to the creep characteristics of the rotor material and the axial stress deviator correction function to obtain a corrected second creep strain rate function; a prediction module is used to use the second creep strain rate function as the initial strain to sequentially calculate the bending distribution of the rotor in each time step under a preset time step to obtain a creep bending prediction result of the turbine rotor in the preset time step.

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