A method for quantitatively predicting the progressive wear of components of a hydraulic machinery system based on a dynamic mesh technology

Abstract

The application discloses a kind of based on dynamic mesh technology's hydraulic machinery system component progressive wear quantity quantification prediction method, comprising: constructing fluid machinery three-dimensional geometric model;CFD numerical calculation is carried out under specified boundary condition based on fluid machinery three-dimensional geometric model, obtains fluid machinery internal steady-state initial field;Based on fluid machinery internal steady-state initial field, inject silt particles, introduce wear model, obtain transient sand steady flow field;Based on transient sand steady flow field, according to wall surface damage rate, calculate wear depth;The difference of wear depth of current time and last time is calculated, and the grid deformation of current time is obtained;According to the grid deformation of current time, it is decomposed in particle impact velocity direction, reach the effect of wall surface topography change, obtain wear depth under total time, wall surface topography change, transient flow field change.The application improves the prediction precision of fluid machinery wear depth.

Description

Technical Field

[0001] This invention belongs to the field of numerical simulation technology of hydraulic machinery wear characteristics, and particularly relates to a quantitative prediction method for progressive wear of hydraulic machinery system components based on dynamic mesh technology. Background Technology

[0002] Sediment abrasion refers to the phenomenon or process in which sediment particles carried by fluid impact the surface of materials at a certain velocity or angle, causing material loss. In hydraulic machinery systems, the long-term transport of sediment-laden fluids by hydroelectric generators and pipeline systems inevitably leads to deformation of the flow walls of hydraulic system components and material peeling, thus affecting the operating efficiency of the hydraulic machinery system. The cumulative effect of sediment abrasion results in material loss on the flow surfaces. The location of abrasion will experience increased surface roughness due to material loss, causing drastic changes in the local flow pattern, further increasing the intensity of abrasion damage, and in severe cases, causing failure and damage to the transport equipment. Therefore, accurately predicting the erosion damage pattern is a crucial issue that needs to be addressed in hydraulic machinery systems transporting sediment-laden fluids. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a quantitative prediction method for progressive wear of hydraulic machinery system components based on dynamic mesh technology, thereby improving the accuracy and practicality of predicting wear depth in fluid machinery.

[0004] To achieve the above objectives, this invention provides a method for quantitative prediction of progressive wear of components in a hydraulic machinery system based on dynamic mesh technology, comprising:

[0005] S1. Obtain two-dimensional planar three-view drawings of the hydraulic machinery system components and construct a three-dimensional geometric model of the fluid machinery system components;

[0006] S2. Based on the three-dimensional geometric model of the fluid machinery, CFD numerical calculations are performed under specified boundary conditions to obtain the steady-state initial field inside the fluid machinery.

[0007] S3. Based on the steady-state initial field inside the fluid machinery, sediment particles are injected, and a wear model is introduced to obtain the transient stable flow field with sediment.

[0008] S4. Determine whether the flow field is filled with sediment particles. If the flow field is not filled, return to S3. If the flow field is filled, proceed to S5.

[0009] S5. Based on the transient sand-laden steady-state flow field, calculate the wear depth according to the wall damage rate;

[0010] S6. Calculate the difference between the wear depth at the current time and the previous time to obtain the mesh deformation at the current time;

[0011] S7. Determine whether the wear time has reached the set time. If the set time has not been reached, return to S5. If the set time has been reached, proceed to S8.

[0012] S8. Based on the mesh deformation at the current time, decompose the mesh with the direction of particle impact velocity as the reference, and move the distance obtained by decomposing several vertices of each unit surface to achieve the effect of wall morphology change, and obtain the wear depth, wall morphology change and transient flow field change over the total time.

[0013] Optionally, the specified boundary conditions include velocity inlet, total pressure outlet, and no-slip wall.

[0014] Optionally, the transient stable flow field containing sand is characterized by a constant inlet and outlet pressure difference, a regular internal flow field distribution, and a balance between particle injection and particle output.

[0015] Optionally, the Oka wear model can be used.

[0016] Optionally, the calculation of wear depth includes:

[0017]

[0018] Where h is the wear depth; E(α) is the wear rate obtained from the Oka wear model; M d denoted as ρ, where ρ is the particle mass of a single impacting mesh cell in each time step; c is the ratio of the single-step wear duration to the transient calculation time step; and A is the area of ​​a single mesh cell surface.

[0019] Optionally, the decomposition based on the mesh deformation at the current time, with the particle impact velocity direction as the reference, includes:

[0020] Obtain the particle impact velocity vector of the unit mesh surface;

[0021] Normalize the velocity vector and project it onto the three coordinate axes to obtain the components in the three directions;

[0022] The wear depth is multiplied by the components in the three directions, and the resulting offsets are assigned to the three components of the four nodes of the cell mesh surface.

[0023] Optionally, whether the wear time has reached the set time refers to whether the cumulative number of steps per unit wear time step has reached the total number of calculation steps.

[0024] Optionally, the CFD numerical calculations use a scale-adaptive simulation model.

[0025] Technical Effects of this Invention: This invention discloses a quantitative prediction method for progressive wear of components in hydraulic machinery systems based on dynamic mesh technology. It constructs a three-dimensional geometric model of the fluid domain of the fluid machinery; based on the three-dimensional geometric model, it uses a wear model to obtain the wear rate of the flow wall; based on dynamic mesh technology, it calculates the wear deformation under transient conditions at different wear durations; and finally, it obtains the wear depth at different wear times. This invention can significantly improve the prediction accuracy of wear depth in fluid machinery and has strong practicality and scalability. This invention not only focuses on the qualitative description of bend erosion phenomena, but also emphasizes the progressive erosion characteristics of bends through quantitative analysis, providing technical support for the accurate understanding of the degree of bend erosion. This research helps to formulate effective maintenance strategies and thus extend the service life of pipeline systems. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a flowchart illustrating a method for quantitative prediction of progressive wear of components in a hydraulic machinery system based on dynamic mesh technology, according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the geometric model of an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram illustrating the computational domain grid partitioning in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram comparing the predicted wear depth of an embodiment of the present invention with experimental values;

[0031] Figure 5 This is a schematic diagram showing the change in the morphology of the flow-through wall surface in an embodiment of the present invention, predicted every 10 hours from 10 to 50 hours. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0034] like Figure 1As shown, this embodiment provides a method for quantitative prediction of progressive wear of components in a hydraulic machinery system based on dynamic mesh technology, including:

[0035] Step 1: Model the flow channel based on existing data. In this embodiment, the geometric model is a 90° bend, such as... Figure 2 As shown in the figure, the geometric dimensions are indicated.

[0036] Step 2 involves generating a hexahedral core mesh for the 3D fluid domain model established in Step 1. This ensures the accuracy of the main flow simulation while allowing for deformation and reconstruction of the mesh near the flow walls. Simultaneously, the mesh at the bends is refined. The mesh is as follows: Figure 3 As shown.

[0037] Step 3: Apply the three-dimensional fluid domain model established in Step 1 to specified boundary conditions (velocity inlet, V). in = 45.72 m / s; Total pressure outlet, P out CFD numerical simulations were performed at 0 Pa to obtain a good steady-state initial flow field.

[0038] Step 4: Using the flow field obtained in Step 3 as the initial condition, perform transient CFD numerical simulation calculations to obtain a stable transient flow field (the pressure difference between the inlet and outlet is basically stable).

[0039] Step 5: Based on the stable transient flow field obtained in Step 3, add sediment particles (sediment particle information is as follows: particle size dp = 150 μm, inlet velocity remains consistent with the boundary conditions in Step 2, V...). in = 45.72 m / s, sediment particle flow rate Q s =2.0810 -4 (kg / s) Considering the erosion and deposition effect, the added mass force, and the pressure gradient force, the stable transient flow field containing sand is finally obtained.

[0040] Step 6: After obtaining the wear rate of the flow wall, calculate the wear depth using the following formula:

[0041]

[0042] Where h is the wear depth in meters (m); E(α) is the wall wear rate, taking the Oka model as an example, E(α) is in m³ / kg, representing the volume of wall loss per unit particle mass; M d Under transient conditions, the unit is kg, representing the mass of particles impacting the wall surface in each time interval; A is the area of ​​the grid cell; c is the time coefficient, defined as the ratio of the single-step wear time to the transient time step, the purpose of which is to balance the scale difference between the wear time and the transient time step.

[0043] Step 7: Calculate the difference in wear depth between the current time step and the previous time step using the formula below.

[0044] Δh=h t -h t-1 ;

[0045] Where Δh is the wear depth at the current moment, in meters (m). t h represents the total wear depth up to this moment. t-1 This represents the total wear depth up to the previous moment. Δh is used as the mesh deformation at the current moment.

[0046] Step 8: Decompose the obtained mesh deformation at the current moment based on the particle impact velocity vector on the wall, and move the four vertices of each unit face by the distance obtained from the decomposition to achieve the effect of changing the wall morphology. Save the results step by step to obtain the progressive wear characteristics. Figure 4 The comparison between the predicted values ​​and experimental values ​​of this method is shown, and the high degree of agreement with the experimental results demonstrates the feasibility of this method.

[0047] Step 9: Repeat steps 5 to 8. In step 7, determine whether the wear time has reached the total wear time. If it has, exit the calculation and obtain the progressive wear characteristics of the flow wall under the total wear time. If it has not, repeat steps 5 to 8. Figure 5 The image shows a comparison of the wall morphology of the bend after 50 hours of wear with that before wear. The blue arrows indicate the flow direction. The left image shows the geometric changes after 10 hours of wear, and the right image shows a magnified view of the changes in the middle of the outer morphology of the bend after every 10 hours of wear.

[0048] This invention discloses a quantitative prediction method for progressive wear of components in hydraulic machinery systems based on dynamic mesh technology. It constructs a three-dimensional geometric model of the fluid domain of the hydraulic system; based on the three-dimensional geometric model, it uses a wear model to obtain the wear rate of the flow wall; and uses dynamic mesh technology to calculate wear deformation under transient conditions at different wear durations; finally, it obtains the wear depth at different wear times. This invention can significantly improve the prediction accuracy of wear depth in hydraulic machinery and has strong practicality and scalability. This invention not only focuses on the qualitative description of bend erosion phenomena, but also emphasizes the progressive erosion characteristics of bends through quantitative analysis, providing technical support for the accurate understanding of the degree of bend erosion. This research helps to formulate effective maintenance strategies and thus extend the service life of pipeline systems.

[0049] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for quantitative prediction of progressive wear of components in a hydraulic machinery system based on dynamic mesh technology, characterized in that, include: S1. Construct a three-dimensional geometric model of the fluid machinery; S2. Based on the three-dimensional geometric model of the fluid machinery, CFD numerical calculations are performed under specified boundary conditions to obtain the steady-state initial field inside the fluid machinery. The three-dimensional geometric model of fluid machinery established in S1 is divided into hexahedral core meshes to ensure that the mesh near the flow wall is deformed and reconstructed, while the mesh at the bend is densified. S3. Based on the steady-state initial field inside the fluid machinery, sediment particles are injected, and a wear model is introduced to obtain the transient stable flow field with sediment. Based on the stable transient flow field obtained in S3, sediment particles are added, wherein the particle size of the sediment particles is... dp =150μm, the inlet velocity is consistent with the boundary conditions in step 2. V in =45.72 m / s, sediment particle flow rate Q s =2.0810 -4 kg / s, taking into account erosion and deposition effects, additional mass forces, and pressure gradient forces, the stable transient flow field containing sand is finally obtained; S4. Determine whether the flow field is filled with sediment particles. If the flow field is not filled, return to S3. If the flow field is filled, proceed to S5. S5. Based on the transient sand-laden steady-state flow field, calculate the wear depth according to the wall damage rate; S6. Calculate the difference between the wear depth at the current time and the previous time to obtain the mesh deformation at the current time; ； in, The wear depth at the current moment, in meters. This represents the total wear depth up to this point. This represents the total wear depth up to the previous moment; S7. Determine whether the wear time has reached the set time. If the set time has not been reached, return to S5. If the set time has been reached, proceed to S8. S8. Based on the mesh deformation at the current time, decompose the mesh with the direction of particle impact velocity as the reference, and move the distance obtained by decomposing several vertices of each unit surface to achieve the effect of wall morphology change, and obtain the wear depth, wall morphology change and transient flow field change over the total time. The specified boundary conditions include velocity inlet, total pressure outlet, and no-slip wall. The characteristics of a transient, stable flow field containing sand are that the inlet and outlet pressure difference remains constant, the internal flow field distribution follows a regular pattern, and particle injection and particle output remain in balance. The wear model adopted is the Oka wear model; The calculation of wear depth includes: ； in, The wear depth; The wear rate is obtained from the Oka wear model; The particle mass of a single impacting grid cell within each time step; This is the ratio of the single-step wear duration to the transient calculation time step. The area of ​​a single grid cell face; Based on the mesh deformation at the current time, the decomposition, with the particle impact velocity direction as the reference, includes: Obtain the particle impact velocity vector of the unit mesh surface; Normalize the velocity vector and project it onto the three coordinate axes to obtain the components in the three directions; The wear depth is multiplied by the components in the three directions respectively, and the offset is assigned to the three components of the four nodes of the unit mesh surface. Whether the wear time has reached the set time refers to whether the cumulative number of steps per unit wear time step has reached the total number of calculated steps.

2. The method for quantitative prediction of progressive wear of hydraulic machinery system components based on dynamic mesh technology as described in claim 1, characterized in that, The CFD numerical calculation uses a scale-adaptive simulation model.

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