CN108804803A - A kind of method for numerical simulation of the discrete element solid-liquid two-phase abrasive Flow Machining calibre-changeable pipe based on coupling of multiple physics field - Google Patents
A kind of method for numerical simulation of the discrete element solid-liquid two-phase abrasive Flow Machining calibre-changeable pipe based on coupling of multiple physics field Download PDFInfo
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Abstract
The present invention relates to a kind of method for numerical simulation of the discrete element abrasive Flow Machining based on coupling of multiple physics field, and the specific method is as follows：(1) calibre-changeable pipe (research object of the present invention is quadravalence calibre-changeable pipe and five rank calibre-changeable pipes) geometrical model is established；(2) mesh generation of calibre-changeable pipe runner model；(3) CFD-DEM coupling physicals parameter setting；(4) in CFD software and DEM softwares boundary condition setting；(5) working process parameter is chosen；(6) CFD-DEM coupling results are post-processed；Distinct element method of the method for the present invention to calibre-changeable pipe abrasive Flow Machining in coupling of multiple physics field carries out numerical simulation analysis, continuous phase and discrete phase are calculated by CFD-DEM couplings, explore the influence of calibre-changeable pipe abrasive Flow Material Removal Mechanism and machined parameters to calibre-changeable pipe abrasive Flow Machining technology.
Description
Technical field
The numerical simulation side for the discrete element solid-liquid two-phase abrasive Flow Machining based on coupling of multiple physics field that the present invention relates to a kind of
Method belongs to solid-liquid two-phase abrasive Flow precision processing technology field.
Background technology
For solid-liquid two-phase abrasive Flow Machining technology, domestic scholars current research works primarily directed to certain specified conditions
Under theoretical research, the important parameter during the discrete element solid-liquid two-phase abrasive Flow Machining of coupling of multiple physics field is ground
Study carefully it is less, achievement be to the universal directive significance of abrasive Flow Machining it is limited, for study calibre-changeable pipe abrasive Flow Machining technique,
The present invention is using quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpieces as object, to solid-liquid two-phase abrasive Flow Machining in CFD-DEM couplings
Numerical simulation analysis is carried out under the conditions of conjunction, and important technological guidance can be provided for actual production.
Invention content
The discrete element solid-liquid two-phase abrasive Flow Machining based on coupling of multiple physics field that the purpose of the present invention is to provide a kind of
Method for numerical simulation, to provide important technological guidance for actual production.
To achieve the goals above, technical scheme is as follows：
A kind of method for numerical simulation of the discrete element abrasive Flow Machining based on coupling of multiple physics field, the specific method is as follows：
(1) calibre-changeable pipe physical model is established：Using calibre-changeable pipe as research object, chooses quadravalence calibre-changeable pipe and five ranks become
Bore pipe, wherein quadravalence calibre-changeable pipe are step type, and each rank internal diameter size of quadravalence calibre-changeable pipe is followed successively by Φ 1.2mm, Φ
1.0mm, Φ 0.8mm, Φ 0.6mm, five rank calibre-changeable pipes are symmetric form, and five each rank internal diameter sizes of rank calibre-changeable pipe are followed successively by Φ
1.0mm, Φ 0.8mm, Φ 0.6mm, Φ 0.8mm, Φ 1.0mm, using SolidWorks softwares to quadravalence calibre-changeable pipe and five ranks
Calibre-changeable pipe runner carry out geometrical model foundation, using different models to solid-liquid two-phase flow flow behavior in calibre-changeable tube passage into
Row discrete element calculates；
(2) mesh generation of physical model：Using ICEM softwares respectively to quadravalence calibre-changeable pipe and five rank calibre-changeable pipe streams
Road model carries out mesh generation, chooses hexahedral mesh and carries out grid stroke to quadravalence calibre-changeable pipe and five rank calibre-changeable pipes respectively
Point, according to the geometry shape of model, piecemeal processing is carried out to runner model, quadravalence calibre-changeable pipe is formed after mesh generation
441106 nodes, five rank calibre-changeable pipes form 490113 nodes, are carried out to unstrctured grid quality after the completion of mesh generation
Detection, cannot have negative volume, and mesh quality is more than 0.3；
(3) setting of physical model statistic property：When the CFD-DEM Coupled Numerical Simulations of coupling of multiple physics field, need in CFD software
With parameter is respectively set in DEM softwares, therefore set continuous phase in CFD software, set discrete phase in DEM softwares, used
Abrasive machining medium be to be configured by aviation kerosine, activating agent and boron carbide abrasive grain, continuous phase use aviation kerosine and activity
Agent, discrete phase use boron carbide abrasive grain；
(4) setting of boundary condition：Needed in CFD software logarithm simulation calculate carry out inlet and outlet condition, use
The setting of model, computational methods, physical parameter, wall condition is needed in DEM softwares to discrete phase abrasive grain parameter, abrasive grain shape
Shape, Abrasive Particle Size, workpiece material are configured, quadravalence calibre-changeable pipe and five rank calibre-changeable pipe solid-liquid two-phase abrasive Flow Machining numerical value
Analog parameter setting is as follows：
(a) model is used：According to Reynolds number equationIt calculates, ρ-fluid density mill, v- fluid velocities, D- workpiece
Entrance hole diameter, η-viscosity；Abrasive flow can form turbulence state, using k- ε turbulence models；In CFD software, k-
RNG models are selected in epsilon Model, and (RNG k- ε two-equation models, RNG=Re-normalization group are stream
A turbulence model in mechanics), Standard Wall Functions (marks are selected in Near-Wall Treatment
Quasi- wall surface equation), Transient (transient state calculating) is selected in Time；
(b) entrance boundary is arranged：
Continuous phase is set in CFD software：What continuous phase was chosen is aviation kerosine and oiliness improver, and condition for import enters pig's tongue using speed
Part, hydraulic radius are 3mm by actual setting, and entrance velocity is perpendicular to inlet side interface, and simulation, which calculates, chooses different speed, weight
Force direction is identical as entrance velocity；
Discrete phase is set in DEM softwares：Discrete phase is boron carbide abrasive grain, and condition for import equally uses speed entry condition,
Abrasive grain is reduced to spherical shape, simulation, which calculates, chooses difference by setting initial velocity identical with continuous phase in order to simplify Abrasive model
Abrasive Particle Size, abrasive grain gravity direction is consistent with abrasive grain speed direction；
(c) outlet border is arranged：Mainly there is pressure export (Pressure in solid-liquid two-phase middle outlet boundary condition
Outlet) and quality outlet (Outlet), liquid are mutually incompressible fluid, and quadravalence calibre-changeable pipe and five is polished by abrasive Flow
It is found that it is difficult to measure that abrasive Flow, which goes out the speed of workpiece and pressure, outlet end communicates rank calibre-changeable pipe physical condition with the external world, therefore even
Continuous phase export boundary condition is set as free export；
(d) wall surface boundary is arranged：Wall condition is using enhancing wall-function method and without sliding wall condition；
(e) DEM softwares workpiece material is arranged：According to practical abrasive Flow Machining reality, quadravalence calibre-changeable pipe and five ranks are set
Calibre-changeable pipe is stainless steel 304 material；
(f) DEM softwares abrasive grain factory is arranged：According to Lagrangian method, discrete phase abrasive concentration is not more than 10%,
Dynamic (dynamic model) is selected in Fartory Type, and Linear (linear velocity), abrasive grain speed side are selected in Velocity
To identical as continuous phase aviation kerosine and activating agent direction, according to quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece structure features
With the size of abrasive grain, it is 2e-7s that time step is arranged in DEM softwares, and opening Track Collisions, (abrasive grain tracks
Collision), numerical simulation total time is 1s；
(g) CFD-DEM couplings setting：In CFD-DEM coupling process, in the time step and CFD software in DEM softwares
Time step ratio should be 1:1 to 100:Between 1, the time step in DEM softwares cannot be more than the time in CFD software
Step-length；Selection Eulerian-Lagrangian Method is coupled, and setting Sample Points are 10, and an abrasive grain can be in 10 nets
It is moved in lattice, increases the size of Sample Points, the stability of simulation can be increased；Momentum Under- are set
Relaxation is 0.7, reduces relaxation factor and is easier to restrain, and increase the stability of simulation, but calculating speed becomes
Slowly, therefore in the case where simulating stability, relaxation factor appropriate is chosen；
(5) abrasive Flow Machining parameter is chosen：When carrying out quadravalence calibre-changeable Guan Wujie calibre-changeables pipe and numerical simulation, selection
Abrasive Flow Machining is because being known as：Entrance velocity, abrasive concentration, Abrasive Particle Size；Four groups of selected supplemental characteristics are that entrance velocity is
30m/s, 35m/s, 40m/s, 45m/s, abrasive concentration 4%, 6%, 8%, 10%, Abrasive Particle Size have chosen 300 mesh, 400 mesh,
500 mesh, 800 mesh.
(6) numerical simulation result and analysis：Numerical value is carried out to calibre-changeable pipe abrasive Flow Machining technology using Discrete-parcel method
Analogue simulation explores calibre-changeable pipe abrasive Flow Material Removal Mechanism and machined parameters to calibre-changeable pipe abrasive Flow Machining technology
Influence；
(7) CFD-DEM coupling results are post-processed；(a) continuous phase and discrete phase are shown using Ensight softwares
Show；(b) discrete phase abrasive grain is distributed in different time and shows；(c) numerical simulation analysis quadravalence calibre-changeable pipe and five rank calibre-changeable pipes
When, continuous phase dynamic pressure and Turbulent Kinetic, discrete phase abrasive grain gross energy and kinetic energy are shown under the conditions of different entrance velocities；?
Continuous phase velocity and turbulence intensity, discrete phase abrasive grain speed and kinetic energy are shown under the conditions of different abrasive concentrations；In different abrasive grain grains
Continuous phase turbulence dissipation rate and turbulent viscosity, discrete phase abrasive grain kinetic energy and speed are shown under the conditions of diameter, in incidence angles degree item
Continuous phase velocity and dynamic pressure, abrasive grain speed and gross energy are shown under part.
CFD-DEM coupling process in calculating solution procedure, according to physical model dimensional parameters, the abrasive grain of calibre-changeable pipe
Stream processing operating mode carries out numerical simulation setting, and the convergence residual error curve of calibre-changeable pipe CFD-DEM couplings is calculated by solution；
With the increase of iterations, model calculates the 1500 residual error curves of parameters iteration solved and reaches steady, illustrates solid-liquid
Two-phase abrasive Flow Machining reaches stable turbulence state, and calibre-changeable pipe after a period of time under CFD-DEM coupling conditions
The setting of solid-liquid two-phase abrasive Flow Machining CFD-DEM couple solutions parameter and modelling is reasonable；In order to obtain calibre-changeable
Kinetic characteristic of the pipe solid-liquid two-phase abrasive Flow Machining in CFD-DEM coupling Fluid fields, carries out quadravalence calibre-changeable pipe and five ranks becomes
When bore pipe numerical simulation, to computational fluid dynamics pressure of the different entrance velocities under CFD-DEM coupled fields and Turbulent Kinetic, abrasive grain
Gross energy and kinetic energy, fluid velocity of the different abrasive concentrations under CFD-DEM coupled fields and turbulence intensity, abrasive grain speed with it is dynamic
Can, fluid turbulent dissipative shock wave of the different Abrasive Particle Sizes under CFD-DEM coupled fields and turbulent viscosity, abrasive grain kinetic energy and speed, no
With fluid velocity and dynamic pressure, abrasive grain speed and gross energy of the incident angle under CFD-DEM coupled fields, each ginseng is researched and analysed
The influence of its ground effect of number factor pair；
(1) influence that entrance velocity removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Computational fluid dynamics pressure, Turbulent Kinetic and the abrasive grain of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of different entrance velocities
Gross energy, kinetic energy distribution character it is found that increase abrasive Flow polishing workpiece entrance velocity, dynamic pressure and Turbulent Kinetic are therewith
Increase, so as to effectively improve the quality of finish to quadravalence calibre-changeable pipe internal surface.Meanwhile abrasive grain gross energy and kinetic energy also increase
Greatly, gross energy and kinetic energy are bigger, fiercer to workpiece collision with wall, and workpiece surface material removal amount is bigger, is conducive to abrasive Flow
To the skin processing of wall surface；
(2) influence that abrasive concentration removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid velocity, turbulence intensity and the abrasive grain speed of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of different abrasive concentrations
It spends, the distribution character of kinetic energy is it is found that increase abrasive concentration, abrasive grain increases the collision frequency of wall surface, to be conducive to wall surface
Skin processing effect, but the quadravalence calibre-changeable pipe studied herein and five rank calibre-changeable tube workpieces are small bore pipe, and concentration is excessive,
Aperture may be blocked, abrasive grain mobility is unfavorable for.According to Lagrangian computational methods, abrasive concentration should be less than 10%, herein
In range, concentration is bigger, is conducive to the abrasive grain quantity for increasing near wall, improves material removal amount, be conducive to abrasive Flow to wall surface
Precision Machining effect；
(3) influence that Abrasive Particle Size removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid turbulent dissipative shock wave under the conditions of different Abrasive Particle Size degree of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces, turbulent viscosity and
Abrasive grain kinetic energy, speed distribution character need to rely on different-grain diameter it is found that workpiece surface material removing rate and surface quality improve
Abrasive grain；Abrasive Particle Size is smaller, and liquid flows the randomness that followability is preferable, is moved using liquid turbulence, is carried out to workpiece random
Cutting, polishing randomness are conducive to the precision machined uniformity of abrasive Flow；Abrasive Particle Size is bigger, and abrasive grain is got over can be with wall surface for a long time
Scraping, the number of collision is also more than the small abrasive grain of grain size, material removing rate can be improved；
(4) influence that incident angle removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid velocity, dynamic pressure and the abrasive grain speed of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of incidence angles degree
It spends, the distribution character of gross energy makes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece flow fields point it is found that changing incident angle
Cloth changes.
Description of the drawings
Fig. 1 quadravalence calibre-changeable pipe two dimensional models；
Five rank calibre-changeable pipe two dimensional model figures of Fig. 2；
Fig. 3 quadravalence calibre-changeable pipe two dimensional model runner sections divide area schematic；
Five rank calibre-changeable pipe two dimensional model runner sections of Fig. 4 divide area schematic.
Specific implementation mode
(1) calibre-changeable pipe physical model is established：Using calibre-changeable pipe as research object, chooses quadravalence calibre-changeable pipe and five ranks become
Bore pipe, wherein quadravalence calibre-changeable pipe are step type, and each rank internal diameter size of quadravalence calibre-changeable pipe is followed successively by Φ 1.2mm, Φ
1.0mm, Φ 0.8mm, Φ 0.6mm, five rank calibre-changeable pipes are symmetric form, and five each rank internal diameter sizes of rank calibre-changeable pipe are followed successively by Φ
1.0mm, Φ 0.8mm, Φ 0.6mm, Φ 0.8mm, Φ 1.0mm, using SolidWorks softwares to quadravalence calibre-changeable pipe and five ranks
Calibre-changeable pipe runner carry out geometrical model foundation, using different models to solid-liquid two-phase flow flow behavior in calibre-changeable tube passage into
Row discrete element calculates；
(2) mesh generation of physical model：Using ICEM softwares respectively to quadravalence calibre-changeable pipe and five rank calibre-changeable pipe streams
Road model carries out mesh generation, chooses hexahedral mesh and carries out grid stroke to quadravalence calibre-changeable pipe and five rank calibre-changeable pipes respectively
Point, according to the geometry shape of model, piecemeal processing is carried out to runner model, quadravalence calibre-changeable pipe is formed after mesh generation
441106 nodes, five rank calibre-changeable pipes form 490113 nodes, are carried out to unstrctured grid quality after the completion of mesh generation
Detection, cannot have negative volume, and mesh quality is more than 0.3；
(3) setting of physical model statistic property：When the CFD-DEM Coupled Numerical Simulations of coupling of multiple physics field, need in CFD software
With parameter is respectively set in DEM softwares, therefore set continuous phase in CFD software, set discrete phase in DEM softwares, used
Abrasive machining medium be to be configured by aviation kerosine, activating agent and boron carbide abrasive grain, continuous phase use aviation kerosine and activity
Agent, discrete phase use boron carbide abrasive grain；
(4) setting of boundary condition：Needed in CFD software logarithm simulation calculate carry out inlet and outlet condition, use
The setting of model, computational methods, physical parameter, wall condition is needed in DEM softwares to discrete phase abrasive grain parameter, abrasive grain shape
Shape, Abrasive Particle Size, workpiece material are configured, quadravalence calibre-changeable pipe and five rank calibre-changeable pipe solid-liquid two-phase abrasive Flow Machining numerical value
Analog parameter setting is as follows：
(a) model is used：According to Reynolds number equationIt calculates, ρ-fluid density mill, v- fluid velocities, D- workpiece
Entrance hole diameter, η-viscosity；Abrasive flow can form turbulence state, using k- ε turbulence models；In CFD software, k-
RNG models are selected in epsilon Model, and (RNG k- ε two-equation models, RNG=Re-normalization group are stream
A turbulence model in mechanics), Standard Wall Functions (marks are selected in Near-Wall Treatment
Quasi- wall surface equation), Transient (transient state calculating) is selected in Time；
(b) entrance boundary is arranged：Continuous phase is set in CFD software：What continuous phase was chosen is aviation kerosine and oiliness improver, into
It is 3mm by actual setting that pig's tongue part, which uses speed entry condition, hydraulic radius, and entrance velocity is perpendicular to inlet side interface, simulation
It calculates and chooses different speed, gravity direction is identical as entrance velocity；
Discrete phase is set in DEM softwares：Discrete phase is boron carbide abrasive grain, and condition for import equally uses speed entry condition,
Abrasive grain is reduced to spherical shape, simulation, which calculates, chooses difference by setting initial velocity identical with continuous phase in order to simplify Abrasive model
Abrasive Particle Size, abrasive grain gravity direction is consistent with abrasive grain speed direction；
(c) outlet border is arranged：Mainly there is pressure export (Pressure in solid-liquid two-phase middle outlet boundary condition
Outlet) and quality outlet (Outlet), liquid are mutually incompressible fluid, and quadravalence calibre-changeable pipe and five is polished by abrasive Flow
It is found that it is difficult to measure that abrasive Flow, which goes out the speed of workpiece and pressure, outlet end communicates rank calibre-changeable pipe physical condition with the external world, therefore even
Continuous phase export boundary condition is set as free export；
(d) wall surface boundary is arranged：Wall condition is using enhancing wall-function method and without sliding wall condition；
(e) DEM softwares workpiece material is arranged：According to practical abrasive Flow Machining reality, quadravalence calibre-changeable pipe and five ranks are set
Calibre-changeable pipe is stainless steel 304 material；
(f) DEM softwares abrasive grain factory is arranged：According to Lagrangian method, discrete phase abrasive concentration is not more than 10%,
Dynamic (dynamic model) is selected in Fartory Type, and Linear (linear velocity), abrasive grain speed side are selected in Velocity
To identical as continuous phase aviation kerosine and activating agent direction, according to quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece structure features
With the size of abrasive grain, it is 2e-7s that time step is arranged in DEM softwares, and opening Track Collisions, (abrasive grain tracks
Collision), numerical simulation total time is 1s；
(g) CFD-DEM couplings setting：In CFD-DEM coupling process, in the time step and CFD software in DEM softwares
Time step ratio should be 1:1 to 100:Between 1, the time step in DEM softwares cannot be more than the time in CFD software
Step-length；Selection Eulerian-Lagrangian Method is coupled, and setting Sample Points are 10, and an abrasive grain can be in 10 nets
It is moved in lattice, increases the size of Sample Points, the stability of simulation can be increased；Momentum Under- are set
Relaxation is 0.7, reduces relaxation factor and is easier to restrain, and increase the stability of simulation, but calculating speed becomes
Slowly, therefore in the case where simulating stability, relaxation factor appropriate is chosen；
(5) abrasive Flow Machining parameter is chosen：When carrying out quadravalence calibre-changeable Guan Wujie calibre-changeables pipe and numerical simulation, selection
Abrasive Flow Machining is because being known as：Entrance velocity, abrasive concentration, Abrasive Particle Size；Four groups of selected supplemental characteristics are that entrance velocity is
30m/s, 35m/s, 40m/s, 45m/s, abrasive concentration 4%, 6%, 8%, 10%, Abrasive Particle Size have chosen 300 mesh, 400 mesh,
500 mesh, 800 mesh；
(6) CFD-DEM coupling results are post-processed；(a) continuous phase and discrete phase are shown using Ensight softwares
Show；(b) discrete phase abrasive grain is distributed in different time and shows；(c) numerical simulation analysis quadravalence calibre-changeable pipe and five rank calibre-changeable pipes
When, continuous phase dynamic pressure and Turbulent Kinetic, discrete phase abrasive grain gross energy and kinetic energy are shown under the conditions of different entrance velocities；?
Continuous phase velocity and turbulence intensity, discrete phase abrasive grain speed and kinetic energy are shown under the conditions of different abrasive concentrations；In different abrasive grain grains
Continuous phase turbulence dissipation rate and turbulent viscosity, discrete phase abrasive grain kinetic energy and speed are shown under the conditions of diameter, in incidence angles degree item
Continuous phase velocity and dynamic pressure, abrasive grain speed and gross energy are shown under part.
CFD-DEM coupling process in calculating solution procedure, according to physical model dimensional parameters, the abrasive grain of calibre-changeable pipe
Stream processing operating mode carries out numerical simulation setting, and the convergence residual error curve of calibre-changeable pipe CFD-DEM couplings is calculated by solution；
With the increase of iterations, model calculates the 1500 residual error curves of parameters iteration solved and reaches steady, illustrates solid-liquid
Two-phase abrasive Flow Machining reaches stable turbulence state, and calibre-changeable pipe after a period of time under CFD-DEM coupling conditions
The setting of solid-liquid two-phase abrasive Flow Machining CFD-DEM couple solutions parameter and modelling is reasonable；In order to obtain calibre-changeable
Kinetic characteristic of the pipe solid-liquid two-phase abrasive Flow Machining in CFD-DEM coupling Fluid fields, carries out quadravalence calibre-changeable pipe and five ranks becomes
When bore pipe numerical simulation, to computational fluid dynamics pressure of the different entrance velocities under CFD-DEM coupled fields and Turbulent Kinetic, abrasive grain
Gross energy and kinetic energy, fluid velocity of the different abrasive concentrations under CFD-DEM coupled fields and turbulence intensity, abrasive grain speed with it is dynamic
Can, fluid turbulent dissipative shock wave of the different Abrasive Particle Sizes under CFD-DEM coupled fields and turbulent viscosity, abrasive grain kinetic energy and speed, no
With fluid velocity and dynamic pressure, abrasive grain speed and gross energy of the incident angle under CFD-DEM coupled fields, each ginseng is researched and analysed
The influence of its ground effect of number factor pair；
(1) influence that entrance velocity removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Computational fluid dynamics pressure, Turbulent Kinetic and the abrasive grain of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of different entrance velocities
Gross energy, kinetic energy distribution character it is found that increase abrasive Flow polishing workpiece entrance velocity, dynamic pressure and Turbulent Kinetic are therewith
Increase, so as to effectively improve the quality of finish to quadravalence calibre-changeable pipe internal surface.Meanwhile abrasive grain gross energy and kinetic energy also increase
Greatly, gross energy and kinetic energy are bigger, fiercer to workpiece collision with wall, and workpiece surface material removal amount is bigger, is conducive to abrasive Flow
To the skin processing of wall surface；
(2) influence that abrasive concentration removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid velocity, turbulence intensity and the abrasive grain speed of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of different abrasive concentrations
It spends, the distribution character of kinetic energy is it is found that increase abrasive concentration, abrasive grain increases the collision frequency of wall surface, to be conducive to wall surface
Skin processing effect, but the quadravalence calibre-changeable pipe studied herein and five rank calibre-changeable tube workpieces are small bore pipe, and concentration is excessive,
Aperture may be blocked, abrasive grain mobility is unfavorable for.According to Lagrangian computational methods, abrasive concentration should be less than 10%, herein
In range, concentration is bigger, is conducive to the abrasive grain quantity for increasing near wall, improves material removal amount, be conducive to abrasive Flow to wall surface
Precision Machining effect；
(2) influence that abrasive concentration removes quadravalence calibre-changeable tube material：By analyzing quadravalence calibre-changeable pipe in different mills
The distribution character of fluid velocity, turbulence intensity and abrasive grain speed, kinetic energy under material concentration conditions is it is found that increase abrasive concentration, mill
Grain increases the collision frequency of wall surface, to be conducive to the skin processing effect to wall surface, but the quadravalence calibre-changeable studied herein
Pipe is small bore pipe, and concentration is excessive, may block aperture, is unfavorable for abrasive grain mobility.According to Lagrangian computational methods, mill
Material concentration should be less than 10%, and within this range, concentration is bigger, be conducive to the abrasive grain quantity for increasing near wall, improve material removal
Amount, is conducive to the polishing action to wall surface.
(3) influence that Abrasive Particle Size removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid turbulent dissipative shock wave under the conditions of different Abrasive Particle Size degree of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces, turbulent viscosity and
Abrasive grain kinetic energy, speed distribution character need to rely on different-grain diameter it is found that workpiece surface material removing rate and surface quality improve
Abrasive grain；Abrasive Particle Size is smaller, and liquid flows the randomness that followability is preferable, is moved using liquid turbulence, is carried out to workpiece random
Cutting, polishing randomness are conducive to the precision machined uniformity of abrasive Flow；Abrasive Particle Size is bigger, and abrasive grain is got over can be with wall surface for a long time
Scraping, the number of collision is also more than the small abrasive grain of grain size, material removing rate can be improved；
(4) influence that incident angle removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：Pass through analysis four
Fluid velocity, dynamic pressure and the abrasive grain speed of rank calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of incidence angles degree
It spends, the distribution character of gross energy makes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece flow fields point it is found that changing incident angle
Cloth changes.
Claims (2)
1. a kind of method for numerical simulation of the discrete element abrasive Flow Machining based on coupling of multiple physics field, it is characterised in that：Specific step
It is rapid as follows：
(1) calibre-changeable pipe physical model is established：Using calibre-changeable pipe as research object, quadravalence calibre-changeable pipe and five rank calibre-changeables are chosen
Pipe, wherein quadravalence calibre-changeable pipe are step type, and each rank internal diameter size of quadravalence calibre-changeable pipe is followed successively by Φ 1.2mm, Φ 1.0mm, Φ
0.8mm, Φ 0.6mm, five rank calibre-changeable pipes are symmetric form, and five each rank internal diameter sizes of rank calibre-changeable pipe are followed successively by Φ 1.0mm, Φ
0.8mm, Φ 0.6mm, Φ 0.8mm, Φ 1.0mm, using SolidWorks softwares to quadravalence calibre-changeable pipe and five rank calibre-changeable pipes
Runner carries out geometrical model foundation, and discrete element is carried out to solid-liquid two-phase flow flow behavior in calibre-changeable tube passage using different models
It calculates；
(2) mesh generation of calibre-changeable pipe runner physical model：Quadravalence calibre-changeable pipe and five ranks are become respectively using ICEM softwares
Bore pipe runner model carries out mesh generation, chooses hexahedral mesh and is carried out respectively to quadravalence calibre-changeable pipe and five rank calibre-changeable pipes
Mesh generation carries out piecemeal processing, quadravalence calibre-changeable is tubular after mesh generation according to the geometry shape of model to runner model
At 441106 nodes, five rank calibre-changeable pipes form 490113 nodes, after the completion of mesh generation to unstrctured grid quality into
Row detection, cannot have negative volume, and mesh quality is more than 0.3；
(3) setting of CFD-DEM coupling physicals model parameter：When the CFD-DEM Coupled Numerical Simulations of coupling of multiple physics field, need
Parameter is respectively set in CFD software and DEM softwares, therefore sets continuous phase in CFD software, discrete phase is set in DEM softwares,
Used abrasive machining medium is configured by aviation kerosine, activating agent and boron carbide abrasive grain, and continuous phase uses aviation kerosine
And activating agent, discrete phase use boron carbide abrasive grain；
(4) in CFD software and DEM softwares boundary condition setting：Logarithm simulation is needed to calculate into traveling out in CFD software
The setting of pig's tongue part, the model of use, computational methods, physical parameter, wall condition needs to grind discrete phase in DEM softwares
Grain parameter, abrasive grain shape, Abrasive Particle Size, workpiece material are configured, quadravalence calibre-changeable pipe and five rank calibre-changeable pipe solid-liquid two-phases
The setting of abrasive Flow Machining parameters for numerical simulation is as follows：
(a) model is used：
According to Reynolds number equationIt calculates, ρ-fluid density mill, v- fluid velocities, D- workpiece entrance hole diameter, η-viscosity
Coefficient；Abrasive flow can form turbulence state, using k- ε turbulence models；In CFD software, selected in k-epsilon Model
Selecting RNG models, (RNG k- ε two-equation models, RNG=Re-normalization group are a rapidss in hydrodynamics
Flow model), Standard Wall Functions (standard law of wall equation) are selected in Near-Wall Treatment,
Transient (transient state calculating) is selected in Time；
(b) entrance boundary is arranged：
Continuous phase is set in CFD software：What continuous phase was chosen is aviation kerosine and oiliness improver, and condition for import enters pig's tongue using speed
Part, hydraulic radius are 3mm by actual setting, and entrance velocity is perpendicular to inlet side interface, and simulation, which calculates, chooses different speed, weight
Force direction is identical as entrance velocity；
Discrete phase is set in DEM softwares：Discrete phase is boron carbide abrasive grain, and condition for import equally uses speed entry condition, setting
Abrasive grain is reduced to spherical shape, simulation, which calculates, chooses different mills by initial velocity identical with continuous phase in order to simplify Abrasive model
Grain grain size, abrasive grain gravity direction are consistent with abrasive grain speed direction；
(c) outlet border is arranged：
Mainly there are pressure export (Pressure Outlet) and quality outlet in solid-liquid two-phase middle outlet boundary condition
(Outlet), liquid is mutually incompressible fluid, and quadravalence calibre-changeable pipe and the five practical items of rank calibre-changeable pipe are polished by abrasive Flow
Part is it is found that it is difficult to measure that abrasive Flow, which goes out the speed of workpiece and pressure, and outlet end is communicated with the external world, therefore continuous phase export boundary condition
It is set as free export；
(d) wall surface boundary is arranged：
Wall condition is using enhancing wall-function method and without sliding wall condition；
(e) DEM softwares workpiece material is arranged：
According to practical abrasive Flow Machining reality, it is stainless steel 304 material that quadravalence calibre-changeable pipe and five rank calibre-changeable pipes, which is arranged,；
(f) DEM softwares abrasive grain factory is arranged：
According to Lagrangian method, discrete phase abrasive concentration is not more than 10%, selects Dynamic (dynamic in Fartory Type
States model), Linear (linear velocity), abrasive grain speed direction and continuous phase aviation kerosine and activating agent side are selected in Velocity
To identical, according to the size of quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece structure features and abrasive grain, in DEM softwares
Setting time step is 2e-7s, opens Track Collisions (abrasive grain tracking collision), numerical simulation total time is 1s；
(g) CFD-DEM couplings setting：
In CFD-DEM coupling process, the time step ratio in the time step and CFD software in DEM softwares should be 1:1
To 100:Between 1, the time step in DEM softwares cannot be more than the time step in CFD software；Select Euler-Lagrange
Method is coupled, and setting Sample Points are 10, and an abrasive grain can move in 10 grids, increase Sample
The size of Points can increase the stability of simulation；It is 0.7 that Momentum Under-relaxation, which are arranged, reduces relaxation
The factor is easier to restrain, and increases the stability of simulation, but calculating speed is slack-off, therefore the case where simulating stability
Under, choose relaxation factor appropriate；
(5) abrasive Flow Machining technological parameter is chosen：When carrying out quadravalence calibre-changeable Guan Wujie calibre-changeables pipe and numerical simulation, selection
Abrasive Flow Machining is because being known as：Entrance velocity, abrasive concentration, Abrasive Particle Size；Four groups of selected supplemental characteristics are that entrance velocity is
30m/s, 35m/s, 40m/s, 45m/s, abrasive concentration 4%, 6%, 8%, 10%, Abrasive Particle Size have chosen 300 mesh, 400 mesh,
500 mesh, 800 mesh；
(6) CFD-DEM coupling results are post-processed；
(a) continuous phase and discrete phase are shown using Ensight softwares；
(b) discrete phase abrasive grain is distributed in different time and shows；
(c) numerical simulation analysis quadravalence calibre-changeable pipe and when five rank calibre-changeable pipes, shows continuous under the conditions of different entrance velocities
Phase dynamic pressure and Turbulent Kinetic, discrete phase abrasive grain gross energy and kinetic energy；Continuous phase velocity is shown under the conditions of different abrasive concentrations
Degree and turbulence intensity, discrete phase abrasive grain speed and kinetic energy；Shown under the conditions of different Abrasive Particle Sizes continuous phase turbulence dissipation rate with
Turbulent viscosity, discrete phase abrasive grain kinetic energy and speed show continuous phase velocity and dynamic pressure, mill under the conditions of incidence angles degree
Grain speed and gross energy.
2. a kind of numerical value of discrete element solid-liquid two-phase abrasive Flow Machining based on coupling of multiple physics field according to claim 1
Analogy method, it is characterised in that：CFD-DEM coupling process in calculating solution procedure, according to the physical model of calibre-changeable pipe
Dimensional parameters, abrasive Flow Machining operating mode carry out numerical simulation setting, and the CFD-DEM couplings of calibre-changeable pipe are calculated by solution
Restrain residual error curve；With the increase of iterations, model calculates the 1500 residual error curves of parameters iteration solved and reaches
Steadily, illustrate that solid-liquid two-phase abrasive Flow Machining under CFD-DEM coupling conditions, reaches stable turbulence-like after a period of time
State, and the setting of calibre-changeable pipe solid-liquid two-phase abrasive Flow Machining CFD-DEM couple solutions parameter and modelling is reasonable；For
The kinetic characteristic of calibre-changeable pipe solid-liquid two-phase abrasive Flow Machining in CFD-DEM coupling Fluid fields is obtained, quadravalence dialectal switching is carried out
When diameter pipe and five rank calibre-changeable pipe numerical simulations, to computational fluid dynamics pressure of the different entrance velocities under CFD-DEM coupled fields with
Turbulent Kinetic, abrasive grain gross energy and kinetic energy, fluid velocity of the different abrasive concentrations under CFD-DEM coupled fields and turbulence intensity,
Abrasive grain speed and kinetic energy, fluid turbulent dissipative shock wave of the different Abrasive Particle Sizes under CFD-DEM coupled fields and turbulent viscosity, abrasive grain are dynamic
Can and speed, fluid velocity and dynamic pressure of the incidence angles degree under CFD-DEM coupled fields, abrasive grain speed and gross energy,
Research and analyse influence of each parameter factors to its ground effect；
(1) influence that entrance velocity removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：
By analyze computational fluid dynamics pressure under the conditions of different entrance velocities of quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpieces,
Turbulent Kinetic and abrasive grain gross energy, kinetic energy distribution character it is found that increasing the entrance velocity of abrasive Flow polishing workpiece, dynamic pressure
Increase therewith with Turbulent Kinetic, so as to effectively improve the quality of finish to quadravalence calibre-changeable pipe internal surface.Meanwhile abrasive grain is total
Energy and kinetic energy also increase, and gross energy and kinetic energy are bigger, fiercer to workpiece collision with wall, and workpiece surface material removal amount is got over
Greatly, be conducive to skin processing of the abrasive Flow to wall surface；
(2) influence that abrasive concentration removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：
By analyzing fluid velocity under the conditions of different abrasive concentrations of quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpieces, turbulent flow
Intensity and abrasive grain speed, kinetic energy distribution character it is found that increasing abrasive concentration, abrasive grain increases the collision frequency of wall surface, to
Be conducive to the skin processing effect to wall surface, but the quadravalence calibre-changeable pipe studied herein and five rank calibre-changeable tube workpieces are small-bore
Pipe, concentration is excessive, may block aperture, is unfavorable for abrasive grain mobility.According to Lagrangian computational methods, abrasive concentration is answered small
In 10%, within this range, concentration is bigger, is conducive to the abrasive grain quantity for increasing near wall, improves material removal amount, be conducive to grind
Grain stream acts on the Precision Machining of wall surface；
(3) influence that Abrasive Particle Size removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：
By analyzing the fluid turbulent consumption of quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpieces under the conditions of different Abrasive Particle Size degree
The rate of dissipating, turbulent viscosity and abrasive grain kinetic energy, speed distribution character it is found that workpiece surface material removing rate and surface quality improve needs
By the abrasive grain of different-grain diameter；Abrasive Particle Size is smaller, and liquid flows the randomness that followability is preferable, is moved using liquid turbulence,
Workpiece is cut at random, polishing randomness is conducive to the precision machined uniformity of abrasive Flow；Abrasive Particle Size is bigger, and abrasive grain is got over
It can for a long time be scraped with wall surface, the number of collision is also more than the small abrasive grain of grain size, and material removing rate can be improved；
(4) influence that incident angle removes quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpiece materials：
By analyzing fluid velocity under the conditions of incidence angles degree of quadravalence calibre-changeable pipe and five rank calibre-changeable tube workpieces, dynamic
The distribution character of pressure and abrasive grain speed, gross energy makes quadravalence calibre-changeable pipe and five rank calibre-changeable pipes it is found that changing incident angle
The distribution of workpiece flow field changes.
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