CN115408909A - Fan blade deformation analysis method and device based on fluid-solid coupling and fatigue damage - Google Patents
Fan blade deformation analysis method and device based on fluid-solid coupling and fatigue damage Download PDFInfo
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Abstract
The invention discloses a method and a device for analyzing the deformation of a fan blade based on fluid-solid coupling and fatigue damage, wherein the method comprises the following steps: acquiring or setting initial parameters of the fan blade, and constructing a fan blade finite element model according to the initial parameters; establishing a fan blade deformation calculation problem according to the fan blade finite element model, and dividing the solution of the fan blade deformation calculation problem into an airflow field distribution area and a structural deformation damage area; and solving an air flow field distribution area according to the boundary conditions of the flow field to obtain pneumatic loads, and solving a node dynamic equation by taking the pneumatic loads as constraint conditions to obtain the deformation information of the fan blade. According to the embodiment of the invention, the mutual influence of the fatigue damage of the fan blade and the fluid-solid coupling behavior is considered, and the deformation of the fan blade in the whole working period can be accurately described; and different solving areas are divided, so that the solving freedom degree of the dynamic equation can be reduced, the dynamic equation is easier to converge, and the accuracy of an analysis result is higher.
Description
Technical Field
The invention relates to the technical field of wind power generation, in particular to a method and a device for analyzing the deformation of a fan blade based on fluid-solid coupling and fatigue damage.
Background
At present, the influence of the fluid-solid coupling effect on the fatigue life or progressive fatigue damage of the fan blade is generally only considered in the analysis of the deformation and the fatigue damage of the fan blade, and the influence of the progressive fatigue damage in the whole working period of the blade on the fluid-solid coupling effect cannot be considered, so that the calculation precision is low; in addition, the numerical method considering the fluid-solid-fatigue coupling effect adopts an integral coupling algorithm to solve the fluid-solid coupling problem, and solves the flow field distribution and the structural deformation under the same calculation frame, so that the degree of freedom of a solution equation is large, and an analysis result is difficult to converge.
Disclosure of Invention
The invention provides a fan blade deformation analysis method and device based on fluid-solid coupling and fatigue damage, and aims to solve the technical problems that in the prior art, when fan blade deformation damage is analyzed, the degree of freedom is high and the analysis result is difficult to converge due to the fact that flow field distribution and structural deformation are solved under the same calculation frame.
In order to solve the technical problem, an embodiment of the present invention provides a method for analyzing a deformation of a fan blade based on fluid-solid coupling and fatigue damage, including:
acquiring or setting initial parameters of the fan blade, and constructing a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients;
establishing a fan blade deformation calculation problem according to the fan blade finite element model, and dividing the solution of the fan blade deformation problem into an airflow field distribution area and a structural deformation damage area; wherein the structural deformation damage region comprises a blade deformation damage profile;
solving the distribution area of the airflow field according to the boundary conditions of the flow field to obtain a pneumatic load, and solving a node power equation by taking the pneumatic load as a constraint condition to obtain deformation information of the fan blade; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
According to the method, a finite element model of the fan blade is established according to the acquired or preset geometric parameters and material coefficients of the fan blade, and then the deformation problem of the fan blade is established according to the finite element model of the fan blade, so that the observation or measurement problem of the actual fan blade is converted into the simulation problem; the method comprises the steps that the deformation problem solution of the fan blade is divided into an air flow field distribution area considering fluid-solid coupling behaviors and a structural deformation damage area considering fatigue damage, so that the degree of freedom of a node dynamic equation is further reduced under constraint conditions, and the node dynamic equation is easier to converge; the fan blade deformation information is used for solving the air flow field distribution area of the next time step, and the mutual influence of fluid-solid coupling and fatigue damage is considered, so that the calculation accuracy is high.
Further, solving the distribution area of the airflow field according to the boundary conditions of the flow field to obtain a pneumatic load, and solving a node dynamic equation by taking the pneumatic load as a constraint condition to obtain the deformation information of the fan blade; the fan blade deformation information is used for solving the air flow field distribution area of the next time step, and specifically comprises the following steps:
solving the structural deformation damage area to obtain node force information;
solving an air flow field distribution area according to the flow field boundary condition to obtain a pneumatic load;
and applying the pneumatic load to the fan blade finite element model, and solving a node dynamic equation to obtain fan blade deformation information.
According to the invention, the solving area is divided into the structural deformation damage area and the air flow field distribution area, when the two areas are respectively solved, the result of the structural deformation damage area participates in the solving process of the air flow field distribution area, the information exchange between the solving areas is realized, the pneumatic load is obtained, the degree of freedom of the node dynamic equation is reduced, and the solving of the node dynamic equation is easier to converge.
Further, the solving of the structural deformation damage area to obtain node force information specifically includes:
the fan blade finite element model is a thick-shell unit model;
performing finite element calculation according to the thick shell unit model to obtain node parameters;
and representing the fatigue damage of the fan blade according to the thick shell unit model and the node parameters to obtain node force information.
Further, the characterizing the fatigue damage of the fan blade according to the thick-shell unit model and the node parameters to obtain node force information, including:
establishing a damaged part in the thick shell unit model according to the node parameters; the lesion part includes: an intralayer damage portion and an interlayer damage portion;
calculating to obtain a first node force according to the in-layer damage part and continuous damage mechanics; calculating to obtain a second node force according to the interlayer damage part and the material coefficient; wherein the node force information comprises: a first node force and a second node force.
In the invention, the inner layer damage and the interlayer damage in the fan blade are simulated by the fan blade finite element model established by the thick shell unit, the factors causing the deformation of the fan blade are more comprehensively covered, and the cohesive strength of the inner unit of the fan blade finite element model is calculated according to the inner layer damage and the interlayer damage to obtain more accurate intermediate quantity, so that the subsequent calculation has higher precision.
Further, solving an air flow field distribution area according to the flow field boundary condition to obtain a pneumatic load, specifically:
the boundary condition of the flow field is the deformation information of the fan blade at the previous time step;
carrying out discrete processing on the air flow field distribution area by using a finite element grid to obtain a discrete air flow field model;
according to the dispersed air flow field model and the deformation information of the fan blade in the previous time step, flow field calculation is carried out according to the aerodynamic force model, and the flow field pressure at the coupling interface is obtained; wherein the flow field pressure is the aerodynamic load.
Further, the applying the pneumatic load to the fan blade finite element model and solving a nodal dynamic equation to obtain fan blade deformation information specifically include:
applying the aerodynamic load, the external load, the inflow boundary condition, and the nodal force information to the fan blade finite element model; wherein the external load comprises: gravity, centripetal force; the inflow boundary conditions include: inflow wind speed, turbulence coefficient and fan arrangement;
solving a node power equation of the fan blade finite element model to obtain fan blade deformation information; wherein the fan blade deformation information includes: nodal displacement, nodal velocity, and nodal acceleration.
According to the method, the flow field boundary condition obtained by solving the structural deformation area of the fan blade and the air flow field distribution established by adopting an aerodynamic model are calculated to obtain the flow field pressure at the coupling interface; the flow field pressure serves as a pneumatic load and becomes a constraint condition for solving a node dynamic equation, so that information exchange of each region of the deformation damage problem is realized, and an analysis result is easier to converge; meanwhile, when the deformation degree is solved by combining the nodal dynamic equation, the method is further based on the external load, the inflow boundary condition and the nodal force information, so that the finally solved deformation information of the fan blade is more accurate.
On the other hand, an embodiment of the present invention provides a fan blade deformation analysis apparatus based on fluid-solid coupling and fatigue damage, including: the system comprises a parameter acquisition module, a problem establishment module and a deformation solving module;
the parameter acquisition module is used for acquiring or setting initial parameters of the fan blade and constructing a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients;
the problem establishing module is used for establishing a fan blade deformation calculation problem according to the fan blade finite element model and dividing the solution of the fan blade deformation problem into an air flow field distribution area and a structural deformation damage area; wherein the structural deformation damage region comprises a blade deformation damage profile;
the deformation solving module is used for solving the distribution area of the airflow field according to the boundary condition of the flow field to obtain pneumatic load, and solving a node dynamic equation by taking the pneumatic load as a constraint condition to obtain the deformation information of the fan blade; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
Further, the deformation solving module comprises: the system comprises a fan blade fatigue damage solving unit, a flow field solving unit and an equation solving unit;
the fan blade fatigue damage solving unit is used for solving a structural deformation damage area to obtain node force information;
the flow field solving unit is used for solving an air flow field distribution area according to the flow field boundary conditions to obtain a pneumatic load;
and the equation solving unit is used for applying the pneumatic load to the fan blade finite element model and solving a node dynamic equation to obtain fan blade deformation information.
Further, the fan blade fatigue damage solving unit includes: a finite element calculating subunit and a stress calculating subunit;
the finite element calculation subunit is used for carrying out finite element calculation according to the thick shell unit model to obtain node parameters;
and the stress calculation subunit is used for representing the fatigue damage of the fan blade according to the thick-shell unit model and the node parameters to obtain node force information.
Further, the flow field solving unit includes: a discrete processing subunit and a flow field calculation subunit;
the discrete processing subunit is used for performing discrete processing on the air flow field distribution area by using a finite element grid to obtain a discrete air flow field model;
the flow field calculation subunit is used for performing flow field calculation according to the dispersed air flow field model and the deformation information of the fan blade in the previous time step and the aerodynamic model to obtain the flow field pressure at the coupling interface; wherein the flow field pressure is the aerodynamic load.
According to the method, a finite element model of the fan blade is established according to the collected initial parameters or the set initial parameters, and then the deformation problem of the fan blade is established according to the finite element model of the fan blade, so that the observation or measurement problem of the actual fan blade is converted into an analog simulation problem; the problem of deformation of the fan blade is solved and divided into a plurality of solving areas, the constraint conditions are obtained according to the solving of the solving areas, the degree of freedom of the node dynamic equation is reduced through the constraint conditions, the node dynamic equation is easier to converge, and the accuracy of an analysis result is higher.
Drawings
FIG. 1 is a schematic flow chart diagram illustrating an exemplary method for analyzing a deformation damage of a fan blade according to the present disclosure;
FIG. 2 is a schematic flow chart diagram illustrating one embodiment of step 103 provided by the present invention;
FIG. 3 is a schematic flow chart diagram illustrating one embodiment of step 201 provided by the present invention;
FIG. 4 is a flow chart illustrating one embodiment of step 202 provided by the present invention;
FIG. 5 is a schematic flow chart diagram illustrating one embodiment of step 203 provided by the present invention;
FIG. 6 is a schematic structural diagram of an embodiment of an apparatus for analyzing a deformation damage of a fan blade according to the present invention;
FIG. 7 is a schematic structural diagram of a deformation solving module 603 provided by the present invention;
fig. 8 is a schematic structural diagram of a fan blade fatigue damage solving unit 701 provided by the present invention;
fig. 9 is a schematic structural diagram of a flow field solving unit 702 provided in the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
Referring to fig. 1, a schematic flow chart of an embodiment of a method for analyzing a deformation damage of a fan blade according to the present invention mainly includes steps 101 to 103, which are as follows:
step 101: acquiring or setting initial parameters of the fan blade, and constructing a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients.
In the embodiment, the structural deformation of the fan blade is simulated and calculated by establishing the fan blade as a finite element model; the initial parameters used for establishing the finite element model can be the material coefficient of the fan blade obtained through collection or the material coefficient set manually.
Step 102: establishing a fan blade deformation calculation problem according to the fan blade finite element model, and dividing the solution of the fan blade deformation calculation problem into an air flow field distribution area and a structural deformation damage area; wherein the structural deformation damage region comprises a blade deformation damage profile.
In the embodiment, the problems of damage and structural deformation of the fan blade are solved by solving a node dynamic equation, and meanwhile, a solving area is constructed into a plurality of solving areas; the method comprises the steps of constructing an air flow field distribution region and a structural deformation damage region; and the structural deformation damage area comprises a blade deformation damage shape to decompose a solving area, the two solving areas are respectively solved, and the information of the two solving areas is exchanged.
Step 103: solving the distribution area of the airflow field according to the boundary conditions of the flow field to obtain a pneumatic load, and solving a node power equation by taking the pneumatic load as a constraint condition to obtain deformation information of the fan blade; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
According to the method, a finite element model of the fan blade is established according to the acquired or preset geometric parameters and material coefficients of the fan blade, and then the deformation problem of the fan blade is established according to the finite element model of the fan blade, so that the observation or measurement problem of the actual fan blade is converted into the simulation problem; solving and dividing the deformation problem of the fan blade into an air flow field distribution area considering fluid-solid coupling behavior and a structural deformation damage area considering fatigue damage; the constraint condition is obtained by solving the air flow field distribution region through the structural deformation damage region, and the mutual influence of the fatigue damage of the fan blade and the fluid-solid coupling behavior is considered, so that the constraint condition further reduces the degree of freedom of the node dynamic equation, the node dynamic equation is easier to converge, and the accuracy of an analysis result is higher.
Fig. 2 is a schematic flow chart of an embodiment of step 103 provided by the present invention. The main difference between fig. 2 and fig. 1 is that it comprises steps 201 to 203.
In this embodiment, step 103 is specifically steps 201 to 203.
Step 201: and solving the structural deformation damage area to obtain node force information.
In the embodiment, a flow field boundary condition required for solving an air flow field distribution region is obtained by solving a structural deformation damage region; wherein, the flow field boundary condition is the node information of fan blade, includes: nodal force information of the fan blade.
Step 202: and solving an air flow field distribution area according to the flow field boundary condition to obtain the pneumatic load.
In this embodiment, the aerodynamic load is obtained by solving the airflow field distribution region, and the aerodynamic load is the constraint condition and is used for solving the node dynamic equation.
Step 203: and applying the pneumatic load to the finite element model of the fan blade, and solving a node dynamic equation to obtain the deformation information of the fan blade.
According to the invention, the solving area is divided into the structural deformation damage area and the air flow field distribution area, when the two areas are respectively solved, the result of the structural deformation damage area participates in the solving process of the air flow field distribution area, the information exchange between the solving areas is realized, the pneumatic load is obtained, the degree of freedom of the node dynamic equation is reduced, and the solving of the node dynamic equation is easier to converge.
Fig. 3 is a schematic flow chart of an embodiment of step 201 provided in the present invention, which mainly includes step 301 and step 302, specifically as follows:
in this embodiment, step 201 is specifically step 301 and step 302.
Step 301: and carrying out finite element calculation according to the thick shell unit model to obtain node parameters.
In this embodiment, the fan blade finite element model is a thick-shell element model; and carrying out finite element calculation after a thick shell unit model is established, wherein the obtained blade parameters provide input parameters for simulating and calculating the damage in the layer and the damage between layers of the fan blade.
Step 302: and representing the fatigue damage of the fan blade according to the thick shell unit model and the node parameters to obtain node force information.
In this embodiment, the characterizing fatigue damage of the fan blade according to the thick-shell unit model and the node parameter to obtain node force information includes: establishing a damaged part in the thick shell unit model according to the node parameters; the lesion part includes: an intralayer damage portion and an interlayer damage portion; calculating to obtain a first node force according to the in-layer damage part and continuous damage mechanics; calculating to obtain a second node force according to the interlayer damage part and the material coefficient; wherein the node force information includes: a first node force and a second node force.
In this embodiment, the second node force is obtained by calculation according to the interlayer damage part and the material coefficient, and specifically includes: calculating to obtain a damage coefficient according to the material coefficient; obtaining the cohesive strength of the interlayer damage part according to the damage coefficient and the preset initial cohesive strength; and calculating to obtain a second node force according to the cohesive strength.
In this embodiment, the analysis of the in-layer damage is based on a continuous damage mechanics method to solve the influence of fatigue damage on constitutive parameters on the gaussian integral point of the thick-shell unit, and further describe the in-layer damage of the fan blade through the degradation effect of the structural rigidity, and an constitutive equation for solving the node force required for describing the degradation of the structural rigidity is as follows:
wherein σ 11 、σ 12 、σ 13 、σ 22 、σ 23 And σ 33 Is the nodal stress; c 11 、C 12 、C 13 、C 22 、C 23 、C 33 、C 44 、C 55 And C 66 Is the initial orthotropic modulus of the composite material; d 11 、D 22 And D 33 Is the amount of damage; epsilon 11 、ε 12 、ε 13 、ε 22 、ε 23 And epsilon 33 Is a strain value; and solving to obtain a first node force according to the constitutive parameters.
In this embodiment, the interlayer damage can also be simulated by the cohesive strength of the cohesive force model of the thick-shell unit, and the material coefficient used for calculating the strength in the year is the initial parameter obtained by collection or artificial setting. In addition, the damage degree can be extrapolated by a cycle jump method; and calculating the current damage coefficient not passed through the extrapolation according to the preset cycle number to obtain the damage coefficient after the extrapolation.
In the invention, the in-layer damage and the interlayer damage in the fan blade are simulated by the fan blade finite element model established by the thick-shell unit, the factors causing the deformation of the fan blade are more comprehensively covered, and meanwhile, the cohesive strength of the unit in the fan blade finite element model is calculated according to the in-layer damage and the interlayer damage to obtain more accurate intermediate quantity, so that the subsequent calculation has higher precision.
Fig. 4 is a schematic flow chart of an embodiment of step 202 provided in the present invention, which mainly includes steps 401 to 402, specifically as follows:
in this embodiment, step 202 is specifically steps 401 to 402.
In this embodiment, the boundary condition of the flow field is the deformation information of the fan blade at the previous time step;
step 401: and carrying out discrete processing on the air flow field distribution area by using a finite element grid to obtain a discrete air flow field model.
In this embodiment, an aerodynamic model may be established based on a large vortex simulation fluid mechanics method, discretization processing is performed on the air flow field distribution through a galois finite element grid, the problem of the air flow field distribution boundary involved in the rotation of the fan blade is processed through a grid overlapping method, and a condition for solving the air flow field distribution region is created.
Step 402: according to the dispersed air flow field model and the deformation information of the fan blade in the previous time step, flow field calculation is carried out according to the aerodynamic force model, and the flow field pressure at the coupling interface is obtained; wherein the flow field pressure is the aerodynamic load.
Fig. 5 is a schematic flow chart of an embodiment of step 203 provided in the present invention, which mainly includes step 501 and step 502, and specifically includes the following steps:
in this embodiment, step 203 is specifically step 501 and step 502.
Step 501: applying the aerodynamic load, the external load, the inflow boundary condition, and the nodal force information to the fan blade finite element model; wherein the external load comprises: gravity, centripetal force; the inflow boundary conditions include: inflow wind speed, turbulence factor and fan arrangement.
In this embodiment, the flow field pressure as the constraint condition is introduced into the process of solving the nodal dynamic equation, so that the degree of freedom of the nodal dynamic equation can be reduced.
Step 502: solving a node power equation of the fan blade finite element model to obtain fan blade deformation information; wherein the fan blade deformation information includes: nodal displacement, nodal velocity, and nodal acceleration.
In the present embodiment, deformation and damage of the fan blade can be represented by node displacement, node velocity and node acceleration; in addition, the deflection of the fan blade can be obtained according to the node displacement, and whether the calculation is stopped can be judged by comparing the deflection of the fan blade with a preset deflection threshold value; if the deflection of the fan blade does not reach the preset deflection threshold value, the circular calculation can be continuously carried out, the deformation information of the fan blade at the time step is used as the boundary condition of the air flow field for solving the distribution area of the air flow field in the next time step until the preset deflection threshold value is met, and the whole process numerical analysis and simulation of the deformation damage of the fan blade are realized.
In this embodiment, the node force information obtained by solving the structural deformation damage region is used as the boundary condition for solving the airflow field distribution region.
According to the method, the flow field boundary condition obtained by solving the structural deformation area of the fan blade and the air flow field distribution established by adopting an aerodynamic model are calculated to obtain the flow field pressure at the coupling interface; the flow field pressure serves as a pneumatic load and becomes a constraint condition for solving a node dynamic equation, so that information exchange of each region of the deformation damage problem is realized, and an analysis result is easier to converge; meanwhile, when the deformation degree is solved by combining the nodal dynamic equation, the method is further based on the external load, the inflow boundary condition and the nodal force information, so that the finally solved deformation information of the fan blade is more accurate.
Fig. 6 is a schematic structural diagram of an embodiment of an apparatus for analyzing a deformation damage of a fan blade according to the present invention, which mainly includes: a parameter acquisition module 601, a problem establishment module 602 and a deformation solving module 603.
In this embodiment, the parameter acquisition module 601 is configured to acquire or set initial parameters of a fan blade, and construct a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients.
The problem establishing module 602 is configured to establish a fan blade deformation calculation problem according to the fan blade finite element model after the parameter acquiring module 601 establishes the fan blade finite element model, and divide a solution of the fan blade deformation calculation problem into an airflow field distribution region and a structural deformation damage region; wherein the structural deformation damage area comprises a blade deformation damage profile.
The deformation solving module 603 is configured to, after the problem establishing module 602 divides the solution of the fan blade deformation problem into a plurality of solving areas, solve the airflow field distribution area according to a flow field boundary condition to obtain a pneumatic load, and solve a node dynamic equation by using the pneumatic load as a constraint condition to obtain fan blade deformation information; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
Fig. 7 is a schematic structural diagram of the deformation solving module 603 provided in the present invention. The main difference between fig. 7 and fig. 6 is that the deformation solving module 603 in fig. 7 further includes: the system comprises a fan blade fatigue damage solving unit 701, a flow field solving unit 702 and an equation solving unit 703.
In this embodiment, the fan blade fatigue damage solving unit 701 is configured to solve the structural deformation damage region to obtain node force information.
The flow field solving unit 702 is configured to, after the fan blade fatigue damage solving unit 701 obtains the flow field boundary conditions, solve the air flow field distribution area according to the flow field boundary conditions, and obtain the aerodynamic load.
The equation solving unit 703 is configured to apply the pneumatic load to the finite element model of the fan blade after the pneumatic load is obtained by the flow field solving unit 702, and solve a node dynamic equation to obtain fan blade deformation information.
In this embodiment, the equation solving unit 703 further includes: a parameter adding subunit and an equation solving subunit. The parameter adding subunit is used for applying the aerodynamic load, the external load, the inflow boundary condition and the node force information to the fan blade finite element model; wherein the external load comprises: gravity, centripetal force; the inflow boundary conditions include: inflow wind speed, turbulence factor and fan arrangement. The equation solving subunit is used for solving a node power equation of the fan blade finite element model after the parameter adding subunit applies the pneumatic load, the external load, the inflow boundary condition and the node force information to the fan blade finite element model, so as to obtain fan blade deformation information; wherein the fan blade deformation information includes: nodal displacement, nodal velocity, and nodal acceleration.
Fig. 8 is a schematic structural diagram of a fan blade fatigue damage solving unit 701 according to the present invention, which mainly includes: a finite element calculation subunit 801 and a force calculation subunit 802.
In this embodiment, the finite element calculation subunit 801 is configured to perform finite element calculation according to the thick shell unit model to obtain node parameters.
The stress calculation subunit 802 is configured to, after the finite element calculation subunit 801 obtains the blade parameters, characterize the fatigue damage of the fan blade according to the thick-shell unit model and the node parameters, and obtain node force information.
Fig. 9 is a schematic structural diagram of a flow field solving unit 702 provided in the present invention, which mainly includes: a discrete processing sub-unit 901 and a flow field calculation sub-unit 902.
The discrete processing subunit 901 is configured to perform discrete processing on the air flow field distribution region by using a finite element grid, so as to obtain a discrete air flow field model.
The flow field calculation subunit 902 is configured to, after the discrete processing subunit 901 obtains the discrete air flow field model, perform flow field calculation according to the discrete air flow field model and the fan blade deformation information of the previous time step and the aerodynamic model, and obtain a flow field pressure at the coupling interface; wherein the flow field pressure is the aerodynamic load.
According to the method, a fan blade finite element model is established through a thick shell unit, in-layer damage and interlayer damage are simulated on the fan blade finite element model, and the strong coupling effect among damage modes is considered more comprehensively; in addition, solving a node dynamic equation on the basis of the finite element model of the fan blade to obtain deformation information of the fan blade; dividing the solving area into a structural deformation damage area and an air flow field distribution area, and converting the original integral fluid-solid coupling analysis method under the same computing frame into an information exchange method with multiple solving areas; when the structural deformation damage area is solved, simulating the in-layer damage and the interlayer damage, solving to obtain node force information, and enabling the node force information to be used for solving a node dynamic equation, so that the overall analysis precision is improved; the pneumatic load is obtained through solving in the plurality of solving areas, the mutual influence of fatigue damage of the fan blade and fluid-solid coupling behaviors is considered, the pneumatic load is used as a constraint condition, the degree of freedom of solving the node dynamic equation is reduced, and the node dynamic equation is easier to converge.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (10)
1. A fan blade deformation analysis method based on fluid-solid coupling and fatigue damage is characterized by comprising the following steps:
acquiring or setting initial parameters of the fan blade, and constructing a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients;
establishing a fan blade deformation calculation problem according to the fan blade finite element model, and dividing the solution of the fan blade deformation calculation problem into an air flow field distribution area and a structural deformation damage area; wherein the structural deformation damage region comprises a blade deformation damage profile;
solving the distribution area of the airflow field according to the boundary condition of the flow field to obtain a pneumatic load, and solving a node power equation by taking the pneumatic load as a constraint condition to obtain the deformation information of the fan blade; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
2. The method for analyzing the deformation of the fan blade based on the fluid-solid coupling and the fatigue damage as claimed in claim 1, wherein the distribution region of the airflow field is solved according to the boundary conditions of the flow field to obtain the aerodynamic load, and the node dynamic equation is solved by taking the aerodynamic load as the constraint condition to obtain the deformation information of the fan blade; the fan blade deformation information is used for solving the air flow field distribution area of the next time step, and specifically comprises the following steps:
solving the structural deformation damage area to obtain node force information;
solving an air flow field distribution area according to the flow field boundary condition to obtain a pneumatic load;
and applying the pneumatic load to the fan blade finite element model, and solving a node dynamic equation to obtain fan blade deformation information.
3. The method for analyzing the deformation of the fan blade based on the fluid-solid coupling and the fatigue damage as claimed in claim 2, wherein the structural deformation damage area is solved to obtain node force information, specifically:
the fan blade finite element model is a thick-shell unit model;
performing finite element calculation according to the thick shell unit model to obtain node parameters;
and representing the fatigue damage of the fan blade according to the thick shell unit model and the node parameters to obtain node force information.
4. The method for analyzing the deformation of the fan blade based on the fluid-solid coupling and the fatigue damage as claimed in claim 3, wherein the characterizing the fatigue damage of the fan blade according to the thick-shell unit model and the node parameters to obtain node force information comprises:
establishing a damaged part in the thick-shell unit model according to the node parameters; the lesion part includes: an intralayer damage portion and an interlayer damage portion;
calculating to obtain a first node force according to the in-layer damage part and continuous damage mechanics; calculating to obtain a second node force according to the interlayer damage part and the material coefficient; wherein the node force information comprises: a first node force and a second node force.
5. The method for analyzing the deformation of the fan blade based on the fluid-solid coupling and the fatigue damage as claimed in claim 2, wherein the air flow field distribution region is solved according to the flow field boundary conditions to obtain the aerodynamic load, specifically:
the boundary condition of the flow field is the deformation information of the fan blade in the previous time step;
carrying out discrete processing on the air flow field distribution area by using a finite element grid to obtain a discrete air flow field model;
according to the dispersed air flow field model and the deformation information of the fan blade in the previous time step, flow field calculation is carried out according to the aerodynamic force model, and the flow field pressure at the coupling interface is obtained; wherein the flow field pressure is the aerodynamic load.
6. The method for analyzing the deformation of the fan blade based on the fluid-solid coupling and the fatigue damage as claimed in claim 2, wherein the applying the aerodynamic load to the finite element model of the fan blade and solving a nodal dynamic equation to obtain the deformation information of the fan blade specifically comprise:
applying the aerodynamic load, the external load, the inflow boundary condition, and the nodal force information to the fan blade finite element model; wherein the external load comprises: gravity, centripetal force; the inflow boundary conditions include: inflow wind speed, turbulence coefficient and fan arrangement;
solving a node power equation of the fan blade finite element model to obtain fan blade deformation information; wherein the fan blade deformation information includes: nodal displacement, nodal velocity, and nodal acceleration.
7. A fan blade deformation analysis device based on fluid-solid coupling and fatigue damage is characterized by comprising: the system comprises a parameter acquisition module, a problem establishment module and a deformation solving module;
the parameter acquisition module is used for acquiring or setting initial parameters of the fan blade and constructing a fan blade finite element model according to the initial parameters; the initial parameters include: geometric parameters and material coefficients;
the problem establishing module is used for establishing a fan blade deformation calculation problem according to the fan blade finite element model and dividing the solution of the fan blade deformation problem into an air flow field distribution area and a structural deformation damage area; wherein the structural deformation damage region comprises a blade deformation damage profile;
the deformation solving module is used for solving the distribution area of the airflow field according to the boundary conditions of the flow field to obtain pneumatic loads, and solving a node dynamic equation by taking the pneumatic loads as constraint conditions to obtain fan blade deformation information; and the fan blade deformation information is used for solving the air flow field distribution area of the next time step.
8. The wind turbine blade deformation analysis device based on fluid-solid coupling and fatigue damage of claim 7, wherein the deformation solving module comprises: the system comprises a fan blade fatigue damage solving unit, a flow field solving unit and an equation solving unit;
the fan blade fatigue damage solving unit is used for solving a structural deformation damage area to obtain node force information;
the flow field solving unit is used for solving an air flow field distribution area according to the flow field boundary conditions to obtain a pneumatic load;
and the equation solving unit is used for applying the pneumatic load to the fan blade finite element model and solving a node dynamic equation to obtain fan blade deformation information.
9. The wind turbine blade deformation analysis device based on fluid-solid coupling and fatigue damage of claim 8, wherein the wind turbine blade fatigue damage solving unit comprises: a finite element calculating subunit and a stress calculating subunit;
the fan blade finite element model is a thick-shell unit model;
the finite element calculation subunit is used for carrying out finite element calculation according to the thick shell unit model to obtain node parameters;
and the stress calculation subunit is used for representing the fatigue damage of the fan blade according to the thick-shell unit model and the node parameters to obtain node force information.
10. The wind turbine blade deformation analysis device based on fluid-solid coupling and fatigue damage of claim 8, wherein the flow field solving unit comprises: a discrete processing subunit and a flow field calculation subunit;
the discrete processing subunit is used for performing discrete processing on the air flow field distribution area by using a finite element grid to obtain a discrete air flow field model;
the flow field calculation subunit is used for performing flow field calculation according to the dispersed air flow field model and the deformation information of the fan blade in the previous time step and the aerodynamic model to obtain the flow field pressure at the coupling interface; wherein the flow field pressure is the aerodynamic load.
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