Creep bending prediction method and creep bending prediction device for steam turbine rotor

Abstract

The invention relates to the technical field of steam turbines, in particular to a creep bending prediction method and a creep bending prediction device for a steam turbine rotor. Calculating a temperature field and a stress field of the rotor to obtain a first creep strain rate function and a first axial stress deviator function; establishing a one-dimensional shafting model of the turboset, and calculating an axial stress deviator correction function according to 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; and by taking the second creep strain rate function as initial strain, sequentially calculating the bending amount distribution of the rotor in each time step under the preset time step so as to obtain a creep bending prediction result of the steam turbine rotor in the preset time step. According to the method, the corrected creep strain rate function is obtained by adding the dynamic load, so that the creep bending prediction result is more accurate.

Description

Technical Field

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

[0002] Steam turbine is an important power generation equipment, in which the rotor is one of its core components. However, during long-term use, the turbine rotor is prone to creep bending, which not only affects the power generation efficiency of the turbine, but may even lead to serious safety accidents. Therefore, predicting the creep bending of the turbine rotor is of great practical significance.

[0003] At present, the prediction method for creep bending of steam turbine rotors is mainly based on the mechanical properties of materials and creep theory. However, practitioners have found that during the actual prediction and calculation process, as the steam turbine rotor runs, the prediction results differ greatly from the actual bending distribution. How to improve the prediction accuracy of creep bending of steam turbine rotors has become a difficult problem that practitioners need to solve urgently. Summary of the invention

[0004] In view of the problem that the prediction accuracy of creep bending of steam turbine rotor 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] A one-dimensional shafting model of the steam turbine unit is established, and the axial stress deviator correction function is calculated according to 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 implementation, 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 the first creep strain rate function and the first axial stress deviator function are obtained.

[0013] In combination with the first aspect, in one implementation, the step of calculating the axial stress deviator correction function according to the dynamic loads of each node of the one-dimensional shafting model includes:

[0014] The dynamic load on each node of the shaft system is obtained according to the one-dimensional shaft system model, and the amplitude and phase of the bending moment at each node of the shaft system are calculated;

[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 offset function is corrected according to the bending stress generated by the rotor during vortex motion to obtain an axial stress offset correction function.

[0017] In combination with the first aspect, in one implementation, the 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 balancing mass in the one-dimensional shaft system 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 implementation, the 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 calculations at each node, the bending moment at the i-th node is T in the y direction. y,i and the z-direction component T z,i ;

[0022]

[0023] In the formula, 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 ith node;

[0024] The bending moment at the i-th node is T in the y direction. 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 implementation, the step of calculating and analyzing the bending stress generated by the rotor during vortex motion according to 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 caused by the rotor vortex, H M is the bending moment phase generated by the rotor vortex, and I is the section inertia moment;

[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 implementation, 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 implementation, the step 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:

[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 implementation, the step of 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 creep bending prediction device for a steam turbine rotor, comprising:

[0045] A temperature stress analysis module, which 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;

[0046] A dynamic response analysis module is used to establish a one-dimensional shaft system model of the steam turbine unit and calculate the axial stress deviator correction function according to the dynamic load of each node of the one-dimensional shaft system model;

[0047] A correction module, which 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;

[0048] The 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 the preset time step to obtain the creep bending prediction result of the turbine rotor in the preset time step.

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

[0050] The applicant found that as the turbine rotor runs, its prediction results gradually deviate from the actual results. The main reason is that the influence of dynamic load prediction results is not considered in the prediction process. The present application adds dynamic load to correct the stress deviator of the rotor, thereby obtaining a corrected creep strain rate function, and then calculates the bending distribution of the rotor according to the corrected function, thereby making the creep bending prediction result more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the process of the creep bending prediction method in the 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 solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, 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 rotor 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, and the rotor creep bending prediction method comprises:

[0056] Step S1, 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.

[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 scale of calculation, 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 steam turbine rotor can be calculated using general finite element software according to the steam inlet parameters, speed and other operating parameters of the steam 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] Among them, T is the Kelvin temperature, C1, C2 and C3 are material parameters, which are related to the material properties.

[0067] Step S2: establishing a one-dimensional shaft system model of the steam turbine unit, and calculating the axial stress deviator correction function according to the dynamic load of each node of the one-dimensional shaft system model.

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

[0069] Step S2a, obtaining the dynamic load on each node of the shaft system according to the one-dimensional shaft system model, and calculating 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 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 balancing 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, the displacement u of each node can be obtained, and then the dynamic load F on each node of the shaft system can be obtained. d :

[0076] F d =Ku+F r

[0077] In the formula, F r The reaction force of the support 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, written as:

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

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

[0080] In the formula, i represents the i-th node, F sy,i 、F sz,i 、F my,i 、F mz,i They are the shear force in the y direction on the i-th node, the shear force in the z direction on the i-th node, the moment around the y axis on the i-th node, and the moment around the z axis on the i-th node, all of which are complex numbers. The shear force and moment of each node on the axis system subjected to dynamic loads can be used to calculate the bending moment on the i-th node based on the material mechanics theory:

[0081]

[0082] Among them, T y,i and T z,i is a complex number, which constitutes the y-component and z-component of the bending moment on 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 on 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 according to 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 caused 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 deviator 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 vortex effect dynamic load can be obtained:

[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: correcting 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 implementation manners, the above step S3 includes:

[0098] Step S3a, obtaining the material unevenness function of the steam turbine rotor.

[0099] Specifically, according to the creep test data of the turbine rotor material, the material unevenness function is fitted and obtained, which 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] In the formula, A ξ Indicates the size of uneven material. It represents the phase of uneven material, and r0(x) is the cross-sectional radius of the axis segment.

[0102] Step S3b, correcting 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 caused 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, which will in turn change the magnitude and phase of the bending moment in the axial stress offset correction function. Similarly, when the dynamic balance mass 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 Its phase H M It should be updated every certain period of time or when the dynamic balance state of the rotor changes. The second axial creep strain rate function is updated to an 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, taking the second creep strain rate function as the initial strain, sequentially calculating the bending distribution of the rotor in each time step under the preset time step, so as to obtain the creep bending prediction result of the steam turbine rotor in the preset time step.

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

[0111] Step S4a, calculating 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 bending amount 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 node 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] In the formula, {δ} e is the node displacement within the element, [k] e is the unit stiffness matrix, which is expressed as:

[0120]

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

[0122]

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

[0124]

[0125] Where [K] is the overall stiffness matrix. Solving the above equilibrium equations can obtain the displacement of each node and then obtain the bending distribution on the rotor axis.

[0126] Step S4b: updating the second creep strain rate function at the next time step according to the bending distribution of the rotor at 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 shaft system dynamic response analysis, the axial stress deviator correction function S for the next time step is updated. w (r,θ,x). Then, the updated axial stress deviator correction function is used to continue with step S3 and step S4a. The bending amount distribution of the next time step can be obtained.

[0128] Step S4c, iteratively updating 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 amount distribution calculation and the axial stress deviator correction function at the next time step are repeatedly performed until the bending amount distribution at the last time step in the preset time step is calculated. The bending amount distribution set at each time step in 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 with a rotor of a 660MW steam turbine generator set as the object. The specific implementation of this embodiment includes:

[0132] Step 1: Obtain the geometric parameters and material parameters of the turbine rotor. These parameters include but are not limited to the length, diameter, elastic modulus, Poisson's ratio, creep coefficient, etc. of the rotor. These parameters can be obtained by measurement or by referring to 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 center lines of bearings 1# and 2# is intercepted, structures such as fillets are retained, and the mesh at the fillets is refined. The moving blades in the high and medium pressure cylinders are loaded on the corresponding shaft segments as equivalent masses. Thus, a two-dimensional axisymmetric model of the high and medium pressure rotor of a 660MW unit steam turbine can be obtained.

[0135] It should be noted that the inlet of 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 rotor of a 660MW steam turbine generator set is calculated. Centrifugal force and temperature loads are applied at the same time to obtain the stress distribution under the action 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 shaft system 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 shaft system model of the unit. Get the formula

[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 as follows. 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 loads of each node are calculated. Thus, the axial stress deviator 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 non-uniform characteristics of the rotor material creep characteristics in the circumferential direction and the influence of the rotor vortex dynamic load. x (r,θ,x)

[0153] Step 6: The uneven distribution of the axial creep strain rate in the circumferential direction requires the use of a three-dimensional structural model of the high- and medium-pressure rotors of the steam turbine to calculate the distribution of the rotor bending. Using a three-dimensional solid unit, the two-dimensional axisymmetric model in 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 steam turbine.

[0154] Furthermore, the axial creep strain rate function ε x (r,θ,x) is used as the initial strain, and the three-dimensional deformation of the high- and medium-pressure rotor of a 660MW unit steam turbine at the current time step can be calculated, and then 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 of step 4. Through the dynamic response analysis of the shaft system, update the axial stress deviator correction function ε for the next time step x (r,θ,x); repeat steps 4 to 6 to obtain the prediction results of rotor creep bending considering rotor dynamic load. It can be seen that the degree of material unevenness and the phase of material unevenness will affect the progress of bending. At the same time, the change of bending rate is affected by the rotor vortex. Under the action of the bending moment in the effective creep zone, the progressive bending rotor has the characteristics of self-stabilization.

[0156] In a second aspect, the present application provides a creep bending prediction device for a steam turbine rotor, which comprises: 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 shaft system model of the steam turbine unit, and calculate the axial stress deviator correction function according to the dynamic load of each node of the one-dimensional shaft system 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] Among them, the functional implementation of each module in the above-mentioned creep bending prediction device corresponds to each step in the above-mentioned creep bending prediction device method embodiment, and its functions and implementation processes are no longer repeated 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 function such as a personal computer (PC), a laptop computer, or a server.

[0160] Reference Figure 2 , Figure 2 Schematic diagram of the hardware structure of the creep bending prediction device involved in the 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, the memory, and the communication interface.

[0162] The communication interface includes input / output (I / O) interface, physical interface and logical interface, etc., which are used to realize the interconnection of devices inside the creep bending prediction device, and the interface used to realize the interconnection of the creep bending prediction device with other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, an optical fiber interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[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, and the general-purpose processor may call the creep bending prediction program stored in the memory and execute the creep bending prediction method provided in the embodiment of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the creep bending prediction program is called may refer to the various embodiments of the creep bending prediction method of the present application, and will not be described in detail here.

[0165] Those skilled in the art will understand that Figure 2 The hardware structure shown in the figure does not constitute a limitation on the present application, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[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] Among them, 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 repeated here.

[0169] In summary, the present application corrects the stress deviator of the rotor by adding dynamic load, thereby obtaining a corrected creep strain rate function, and then calculates the bending distribution of the rotor 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 only for description 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 a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially 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, disk, CD) as described above, and includes a number of instructions for 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 the present 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 "first", "second" and "third" to different types.

[0173] In the description of the embodiments of the present application, "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 the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[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; the “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 that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed 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 are not intended to 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; A one-dimensional shafting model of the steam turbine unit is established, and the axial stress deviator correction function is calculated according to 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; 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.

2. The method for predicting creep bending of a steam turbine rotor according to claim 1, characterized in that: The step of 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 comprises: 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 stress field of the steam turbine rotor is calculated according to the operating parameters of the steam turbine, and the first creep strain rate function and the first axial stress deviator function are obtained.

3. The method for predicting creep bending of a steam turbine rotor according to claim 1, characterized in that: The method of calculating the axial stress deviator correction function according to the dynamic load of each node of the one-dimensional shafting model includes: The dynamic load on each node of the shaft system is obtained according to the one-dimensional shaft system model, and the amplitude and phase of the bending moment at each node of the shaft system are calculated; 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; The first axial stress offset function is corrected according to the bending stress generated by the rotor during vortex motion to obtain an axial stress offset correction function.

4. The method for predicting creep bending of a steam turbine rotor according to claim 3, characterized in that: 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 balancing mass in the one-dimensional shaft system 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.

5. The method for predicting creep bending of a steam turbine rotor according to claim 4, characterized in that: 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 calculations at each node, the bending moment at the i-th node is T in the y direction. y,i and the z-direction component T z,i ; In the formula, 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 ith node; The bending moment at the i-th node is T in the y direction. y,i and the z-direction component T z,i Write 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): 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.

6. The method for predicting creep bending of a steam turbine rotor according to claim 5, characterized in that: The bending stress generated by the rotor during vortex motion 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 G generated by the rotor vortex x,w : Where, T b is the bending moment caused 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.

7. The method for predicting creep bending of a steam turbine rotor according to claim 1, characterized in that: The method 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 ε is obtained based on the material inhomogeneity function and the axial stress deviator correction function. x (r,θ,x): εx(r,0,x)=[R(r,x)·(r,0,x)][Sx(r,x)+Sw(r,0,x)]·t Where t is the running time, ′(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.

8. The method for predicting creep bending of a steam turbine rotor according to claim 1, characterized in that: 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.

9. The method for predicting creep bending of a steam turbine rotor according to claim 1, characterized in that: The step of calculating the bending distribution of the rotor 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.

10. A creep bending prediction device for a steam turbine rotor, characterized in that: include: A temperature stress analysis module, which 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 shaft system model of the steam turbine unit and calculate the axial stress deviator correction function according to the dynamic load of each node of the one-dimensional shaft system model; A correction module, which 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; The 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 the creep bending prediction result of the turbine rotor in the preset time step.

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