Although a series of hypotheses have been proposed,the mechanism underlying coal and gas outburst remains unclear.Given the low-index outbursts encountered in mining practice,we attempt to explore this mechanism using...Although a series of hypotheses have been proposed,the mechanism underlying coal and gas outburst remains unclear.Given the low-index outbursts encountered in mining practice,we attempt to explore this mechanism using a multiphysics coupling model considering the effects of coal strength and gas mass transfer on failure.Based on force analysis of coal ahead of the heading face,a risk identification index C_(m)and a critical criterion(C_(m)≥1)of coal instability are proposed.According to this criterion,the driving force of an outburst consists of stress and gas pressure gradients along the heading direction of the roadway,whereas resistance depends on the shear and tensile strengths of the coal.The results show that outburst risk decreases slightly,followed by a rapid increase,with increasing vertical stress,whereas it decreases with increasing coal strength and increases with gas pressure monotonically.Using the response surface method,a coupled multi-factor model for the risk identification index is developed.The results indicate strong interactions among the controlling factors.Moreover,the critical values of the factors corresponding to outburst change depending on the environment of the coal seams,rather than being constants.As the buried depth of a coal seam increases,the critical values of gas pressure and coal strength decrease slightly,followed by a rapid increase.According to its controlling factors,outburst can be divided into stress-dominated,coal-strength-dominated,gas-pressure-dominated,and multi-factor compound types.Based on this classification,a classified control method is proposed to enable more targeted outburst prevention.展开更多
Aiming at solving problems of low efficiency,low cable capacity in current 300m open-pit mine cable winding truck,a 900 m cable winding plan was proposed.In this paper,the mechanism of the thermal effect of the cable ...Aiming at solving problems of low efficiency,low cable capacity in current 300m open-pit mine cable winding truck,a 900 m cable winding plan was proposed.In this paper,the mechanism of the thermal effect of the cable was described,and a two-dimensional axisymmetric electromagnetic-fluid-temperature multiphysics coupling model of the cable reel was established regarding the 900m cable reel as independent system.Considering the structure of the drum,the number of cable winding layers,the factors of heat conduction,heat radiation and convective heat transfer in the actual working process,the steady state analysis of the multi-physical field coupling was carried out.The sum of the losses of each part of the cable was obtained through the calculation of electromagnetic field,which was used as a heat source to calculate and analyze the temperature distribution of different layers of cable winding,as well as the temperature distribution and heat dissipation characteristics of different structures of the drum.The results show that three layers of cable winding is the best design.The lowest temperature of closed cylindrical drum is 70℃after heat dissipation,which has obvious advantages compared with the lowest temperature of 85℃after heat dissipation of squirrel-cage cylindrical drum.The results provide a reliable theoretical basis for the research and development of a new type of mine cable winding truck with 900 m cable capacity.展开更多
We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numeri...We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numerical simulation and experimental validation. The distribution characteristics and interaction mechanism of the flow field and electromagnetic field of the ICP wind tunnel are investigated using the multi-field coupling method of flow, electromagnetic, chemical, and thermodynamic field. The accuracy of the numerical simulation is validated by comparing the experimental results with the simulation results. Thereafter, the wind tunnel pressure, air velocity, electron density, Joule heating rate, Lorentz force, and electric field intensity obtained using the simulation are analyzed and discussed. The results indicate that for the 1.2-MW ICP wind tunnel, the maximum values of temperature, pressure, electron number density, and other parameters are observed during coil heating. The influence of the radial Lorentz force on the momentum transfer is stronger than that of the axial Lorentz force. The electron number density at the central axis and the amplitude and position of the Joule heating rate are affected by the radial Lorentz force. Moreover, the plasma in the wind tunnel is constantly in the subsonic flow state, and a strong eddy flow is easily generated at the inlet of the wind tunnel.展开更多
The complex interaction between material properties in an induction heating circuit was studied by multi physics simulation and by experimental verification in a full-scale laboratory heater. The work aims to illustra...The complex interaction between material properties in an induction heating circuit was studied by multi physics simulation and by experimental verification in a full-scale laboratory heater. The work aims to illustrate the complexity of the system of interacting materials, but also to propose a method to verify properties of soft magnetic composite materials in an integrated system and to identify which properties are the most critical under different circumstances and load cases. Heat losses at different loads were primarily studied, from DC currents to AC currents at 15, 20 and 25 kHz, respectively. A FE model for magnetic simulation was correlated with a corresponding model for heat simulation. The numerical model, as well as the established input material data, could be verified through the experimental measurements. In this particular study, the current loss in the litz wire was the dominant heat source, thus making the thermal conductivity of the SMC the most important property in this material.展开更多
Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill,an evolutive porous medium used in underground m...Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill,an evolutive porous medium used in underground mine cavities,very few efforts have been made to improve the knowledge on its response under sudden dynamic loading during the curing process.In fact,there is a great need for such information given that cemented backfill structures are often subjected to blast loadings due to mine exploitations.In this study,a coupled thermo-hydro-mechanical-chemical(THMC)-viscoplastic cap model is developed to describe the behavior of cementing mine backfill material under blast loading.A THMC model for cemented backfill is adopted to evaluate its behavior and evolution of its properties in curing processes with coupled thermal,hydraulic,mechanical and chemical factors.Then,the model is coupled to a Perzyna type of viscoplastic model with a modified smooth surface cap envelope and a variable bulk modulus,in order to reasonably capture the nonlinear and rate-dependent behaviors of the cemented tailings backfill under blast loading.All of the parameters required for the variable-modulus viscoplastic cap model were obtained by applying the THMC model to reproducing evolution of cemented paste backfill(CPB)properties in the curing process.Thus,the behavior of hydrating cemented backfill under high-rate impacts can be evaluated under any curing time of concern.The validation results of the proposed model indicate a good agreement between the experimental and the simulated results.The authors believe that the proposed model will contribute to a better understanding of the performance of hydrating cemented backfill under blasting,and also to practical risk management of backfill structures associated with such a dynamic condition.展开更多
The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiph...The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.展开更多
Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage cave...Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage caverns under stress-low temperature coupling effect is the key factor determining the feasibility of LNG storage.First,a mathematical model used for controlling the stress-low temperature coupling and the processes of rock damage evolution is given,followed by a 2-D numerical execution process of the mathematical model mentioned above described based on Comsol Multiphysics and Matlab code.Finally,a series of 2-D simulations are performed to study the influence of LNG storage cavern layout,burial depth,temperature and internal pressure on the stability of surrounding rocks of these underground storage caverns.The results indicate that all the factors mentioned above affect the evolution of deformation and plastic zone of surrounding rocks.The research results contribute to the engineering design of underground LNG storage caverns.展开更多
A numerical model coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in the induction heating process has been developed. The mathematical model and the numerical methods ar...A numerical model coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in the induction heating process has been developed. The mathematical model and the numerical methods are presented here, along with some results ( electric, thermal and mechanical fields in the workpiece)展开更多
In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct pi...In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectriccoupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulationsare used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely(1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weaklycoupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially stronglycoupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation forthe two types of coupling, respectively.Numerical examples using a piezoelectric energy harvester,which is a typicalstructure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most costeffectivealgorithm.展开更多
All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation ...All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation within solid-state electrolytes(SSEs)remain inadequately understood.To address this knowledge gap,we propose an electrochemical-mechanical coupled phase-field model designed to simulate the complex processes of lithium deposition and crack propagation in SSEs.This framework systematically examines the influence of initial defect characteristics—including morphology,dimensions,and fracture toughness—on dendrite penetration dynamics.Furthermore,it identifies potential initiation pathways for detrimental lithium deposition within the electrolyte bulk.The model also quantifies the critical role of electrolyte elastic modulus and grain boundary orientation in modulating deposition behavior.Notably,simulation results demonstrate concordance with existing experimental observations,thereby establishing a fundamental theoretical framework for understanding failure mechanisms.This work provides crucial mechanistic insights and predictive capabilities to guide the rational design of failure-resistant SSEs for all-solid-state lithium metal batteries.展开更多
Differing from traditional pressurized water reactors(PWRs),heat pipe cooled reactors have the unique characteristics of fuel thermal expansion,expansion reactivity feedback,and thermal contact conductance.These react...Differing from traditional pressurized water reactors(PWRs),heat pipe cooled reactors have the unique characteristics of fuel thermal expansion,expansion reactivity feedback,and thermal contact conductance.These reactors require a new multiphysics coupling method.In this paper,a transient coupling method based on OpenFOAM is proposed.The method considers power variation,thermal expansion,heat pipe operation,thermal contact conductance,and gap conductance.In particular,the reactivity feedback caused by working medium redistribution in a heat pipe is also preliminarily considered.A typical heat pipe cooled reactor KRUSTY(Kilowatt Reactor Using Stirling TechnologY)is chosen as the research object.Compared with experimental results of load following,the calculated results are in good agreement and show the validity of the proposed method.To discuss the self-adjusting capability of this type of reactor system,a hypothetical accident is simulated.It is assumed that at the beginning of this accident,loss of the heat sink occurs.After 1500 s of the transient process,the reactor system recovers immediately.During this hypothetical accident,the control rod is always out of the reactor core,and the reactor only relies on the reactivity feedback to regulate the fission power.According to the simulation,the peak temperature is only about 1112 K,which is far below the safety limit.As for system recovery,the reactor needs approximately 2500 s to return to a steady state and can realize effective power regulation by reactivity feedback.This study confirms the availability of this coupling method and that it can be an effective tool for the simulation of heat pipe cooled reactors.展开更多
General reductions in lubricant viscosities and increasing loads in machine components highlight the role of tribofilms in providing surface protection against scuffing.However,the relationship between the scuffing pr...General reductions in lubricant viscosities and increasing loads in machine components highlight the role of tribofilms in providing surface protection against scuffing.However,the relationship between the scuffing process and the growth and removal of tribofilm is not well understood.In this study,a multiphysics coupling model,which includes hydrodynamic lubrication,asperity contact,thermal effect,tribochemistry reaction,friction,and surface wear,was developed to capture the initiation of surface scuffing.Simulations and experiments for a piston ring and cylinder liner contact were conducted following a step-load sequence under different temperature conditions.The results show that high temperature and extreme load could induce the lubricant film collapse,which in turn triggers the breakdown of the tribofilm due to the significantly increased removal process.The failures of both lubricant film and tribofilm progress instantaneously in a coupling way,which finally leads to severe scuffing.展开更多
Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest pos...Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.展开更多
An explicitly coupled two-dimensional (2D) multiphysics finite element method (FEM) framework comprised of thermal, phase field, mechanical and electromagnetic (TPME) equations was developed to simulate the conversion...An explicitly coupled two-dimensional (2D) multiphysics finite element method (FEM) framework comprised of thermal, phase field, mechanical and electromagnetic (TPME) equations was developed to simulate the conversion of solid kerogen in oil shale to liquid oil through </span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"> pyrolysis by radio frequency heating. Radio frequency heating as a method of <i></span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"></i> pyrolysis represents a tenable enhanced oil recovery method, whereby an applied electrical potential difference across a target oil shale formation is converted to thermal energy, heating the oil shale and causing it to liquify to become liquid oil. A number of <i></span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"></i> pyrolysis methods are reviewed but the focus of this work is on the verification of the TPME numerical framework to model radio frequency heating as a potential dielectric heating process for enhanced oil recovery.</span></span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">Very few studies exist which describe production from oil shale;furthermore, there are none that specifically address the verification of numerical models describing radio frequency heating. As a result, the Method of Manufactured Solutions (MMS) was used as an analytical verification method of the developed numerical code. Results show that the multiphysics finite element framework was adequately modeled enabling the simulation of kerogen conversion to oil as a part of the analysis of a TPME numerical model.展开更多
基金This work was supported by the National Natural Science Foundation of China(52004276)National Postdoctoral Program for Innovative Talents(BX20190369)+1 种基金Natural Science Foundation of Jiangsu Province(BK20200636)China Postdoctoral Science Foundation(2019M661996).
文摘Although a series of hypotheses have been proposed,the mechanism underlying coal and gas outburst remains unclear.Given the low-index outbursts encountered in mining practice,we attempt to explore this mechanism using a multiphysics coupling model considering the effects of coal strength and gas mass transfer on failure.Based on force analysis of coal ahead of the heading face,a risk identification index C_(m)and a critical criterion(C_(m)≥1)of coal instability are proposed.According to this criterion,the driving force of an outburst consists of stress and gas pressure gradients along the heading direction of the roadway,whereas resistance depends on the shear and tensile strengths of the coal.The results show that outburst risk decreases slightly,followed by a rapid increase,with increasing vertical stress,whereas it decreases with increasing coal strength and increases with gas pressure monotonically.Using the response surface method,a coupled multi-factor model for the risk identification index is developed.The results indicate strong interactions among the controlling factors.Moreover,the critical values of the factors corresponding to outburst change depending on the environment of the coal seams,rather than being constants.As the buried depth of a coal seam increases,the critical values of gas pressure and coal strength decrease slightly,followed by a rapid increase.According to its controlling factors,outburst can be divided into stress-dominated,coal-strength-dominated,gas-pressure-dominated,and multi-factor compound types.Based on this classification,a classified control method is proposed to enable more targeted outburst prevention.
基金This work was supported in part by 2019 Local Project of Science and Tech nology Research Service of Liaoning Provincial Department of Education(LJ2019FL003)by 2019 Science and Technology Research and Innovation Te am Project of Liaoning Provincial Department of Education(LT2019007)by 2020 Youth Science and Technology Talents"Nursery"Projects of Scient ific Research of Liaoning Province Education Department(LJ2020QNL019).
文摘Aiming at solving problems of low efficiency,low cable capacity in current 300m open-pit mine cable winding truck,a 900 m cable winding plan was proposed.In this paper,the mechanism of the thermal effect of the cable was described,and a two-dimensional axisymmetric electromagnetic-fluid-temperature multiphysics coupling model of the cable reel was established regarding the 900m cable reel as independent system.Considering the structure of the drum,the number of cable winding layers,the factors of heat conduction,heat radiation and convective heat transfer in the actual working process,the steady state analysis of the multi-physical field coupling was carried out.The sum of the losses of each part of the cable was obtained through the calculation of electromagnetic field,which was used as a heat source to calculate and analyze the temperature distribution of different layers of cable winding,as well as the temperature distribution and heat dissipation characteristics of different structures of the drum.The results show that three layers of cable winding is the best design.The lowest temperature of closed cylindrical drum is 70℃after heat dissipation,which has obvious advantages compared with the lowest temperature of 85℃after heat dissipation of squirrel-cage cylindrical drum.The results provide a reliable theoretical basis for the research and development of a new type of mine cable winding truck with 900 m cable capacity.
基金supported by the National Natural Science Foundation of China (Grant No. 11705143)the Open Foundation for Key Laboratories of National Defense Science and Technology of China (Grant No. 6142202031901)the Foundation for Research and Development of Applied Technology in Beilin District of Xi’an,China (Grant No. GX2047)。
文摘We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numerical simulation and experimental validation. The distribution characteristics and interaction mechanism of the flow field and electromagnetic field of the ICP wind tunnel are investigated using the multi-field coupling method of flow, electromagnetic, chemical, and thermodynamic field. The accuracy of the numerical simulation is validated by comparing the experimental results with the simulation results. Thereafter, the wind tunnel pressure, air velocity, electron density, Joule heating rate, Lorentz force, and electric field intensity obtained using the simulation are analyzed and discussed. The results indicate that for the 1.2-MW ICP wind tunnel, the maximum values of temperature, pressure, electron number density, and other parameters are observed during coil heating. The influence of the radial Lorentz force on the momentum transfer is stronger than that of the axial Lorentz force. The electron number density at the central axis and the amplitude and position of the Joule heating rate are affected by the radial Lorentz force. Moreover, the plasma in the wind tunnel is constantly in the subsonic flow state, and a strong eddy flow is easily generated at the inlet of the wind tunnel.
文摘The complex interaction between material properties in an induction heating circuit was studied by multi physics simulation and by experimental verification in a full-scale laboratory heater. The work aims to illustrate the complexity of the system of interacting materials, but also to propose a method to verify properties of soft magnetic composite materials in an integrated system and to identify which properties are the most critical under different circumstances and load cases. Heat losses at different loads were primarily studied, from DC currents to AC currents at 15, 20 and 25 kHz, respectively. A FE model for magnetic simulation was correlated with a corresponding model for heat simulation. The numerical model, as well as the established input material data, could be verified through the experimental measurements. In this particular study, the current loss in the litz wire was the dominant heat source, thus making the thermal conductivity of the SMC the most important property in this material.
文摘Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill,an evolutive porous medium used in underground mine cavities,very few efforts have been made to improve the knowledge on its response under sudden dynamic loading during the curing process.In fact,there is a great need for such information given that cemented backfill structures are often subjected to blast loadings due to mine exploitations.In this study,a coupled thermo-hydro-mechanical-chemical(THMC)-viscoplastic cap model is developed to describe the behavior of cementing mine backfill material under blast loading.A THMC model for cemented backfill is adopted to evaluate its behavior and evolution of its properties in curing processes with coupled thermal,hydraulic,mechanical and chemical factors.Then,the model is coupled to a Perzyna type of viscoplastic model with a modified smooth surface cap envelope and a variable bulk modulus,in order to reasonably capture the nonlinear and rate-dependent behaviors of the cemented tailings backfill under blast loading.All of the parameters required for the variable-modulus viscoplastic cap model were obtained by applying the THMC model to reproducing evolution of cemented paste backfill(CPB)properties in the curing process.Thus,the behavior of hydrating cemented backfill under high-rate impacts can be evaluated under any curing time of concern.The validation results of the proposed model indicate a good agreement between the experimental and the simulated results.The authors believe that the proposed model will contribute to a better understanding of the performance of hydrating cemented backfill under blasting,and also to practical risk management of backfill structures associated with such a dynamic condition.
基金support from the OpenGeoSys communitypartially funded by the Prime Minister Research Fellowship,Ministry of Education,Government of India with the project number SB21221901CEPMRF008347.
文摘The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.
基金funded by the Major science and technology project of CNOOC(KJZX-2022-12-XNY-0803).
文摘Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage caverns under stress-low temperature coupling effect is the key factor determining the feasibility of LNG storage.First,a mathematical model used for controlling the stress-low temperature coupling and the processes of rock damage evolution is given,followed by a 2-D numerical execution process of the mathematical model mentioned above described based on Comsol Multiphysics and Matlab code.Finally,a series of 2-D simulations are performed to study the influence of LNG storage cavern layout,burial depth,temperature and internal pressure on the stability of surrounding rocks of these underground storage caverns.The results indicate that all the factors mentioned above affect the evolution of deformation and plastic zone of surrounding rocks.The research results contribute to the engineering design of underground LNG storage caverns.
文摘A numerical model coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in the induction heating process has been developed. The mathematical model and the numerical methods are presented here, along with some results ( electric, thermal and mechanical fields in the workpiece)
基金the Japan Society for the Promotion of Science,KAKENHI Grant Nos.20H04199 and 23H00475.
文摘In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectriccoupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulationsare used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely(1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weaklycoupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially stronglycoupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation forthe two types of coupling, respectively.Numerical examples using a piezoelectric energy harvester,which is a typicalstructure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most costeffectivealgorithm.
基金supported by the National Natural Science Foundation of China(No.52476053,No.22409209)Beijing Natural Science Foundation(No.3242017)。
文摘All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation within solid-state electrolytes(SSEs)remain inadequately understood.To address this knowledge gap,we propose an electrochemical-mechanical coupled phase-field model designed to simulate the complex processes of lithium deposition and crack propagation in SSEs.This framework systematically examines the influence of initial defect characteristics—including morphology,dimensions,and fracture toughness—on dendrite penetration dynamics.Furthermore,it identifies potential initiation pathways for detrimental lithium deposition within the electrolyte bulk.The model also quantifies the critical role of electrolyte elastic modulus and grain boundary orientation in modulating deposition behavior.Notably,simulation results demonstrate concordance with existing experimental observations,thereby establishing a fundamental theoretical framework for understanding failure mechanisms.This work provides crucial mechanistic insights and predictive capabilities to guide the rational design of failure-resistant SSEs for all-solid-state lithium metal batteries.
基金supported by the National Key Research and Development Project of China(Grant No.2020YFB1901700)Science Challenge Project(Grant No.TZ2018001)+1 种基金the National Natural Science Foundation of China(Grant Nos.11775126 and 11775127)the Tsinghua University Initiative Scientific Research Program。
文摘Differing from traditional pressurized water reactors(PWRs),heat pipe cooled reactors have the unique characteristics of fuel thermal expansion,expansion reactivity feedback,and thermal contact conductance.These reactors require a new multiphysics coupling method.In this paper,a transient coupling method based on OpenFOAM is proposed.The method considers power variation,thermal expansion,heat pipe operation,thermal contact conductance,and gap conductance.In particular,the reactivity feedback caused by working medium redistribution in a heat pipe is also preliminarily considered.A typical heat pipe cooled reactor KRUSTY(Kilowatt Reactor Using Stirling TechnologY)is chosen as the research object.Compared with experimental results of load following,the calculated results are in good agreement and show the validity of the proposed method.To discuss the self-adjusting capability of this type of reactor system,a hypothetical accident is simulated.It is assumed that at the beginning of this accident,loss of the heat sink occurs.After 1500 s of the transient process,the reactor system recovers immediately.During this hypothetical accident,the control rod is always out of the reactor core,and the reactor only relies on the reactivity feedback to regulate the fission power.According to the simulation,the peak temperature is only about 1112 K,which is far below the safety limit.As for system recovery,the reactor needs approximately 2500 s to return to a steady state and can realize effective power regulation by reactivity feedback.This study confirms the availability of this coupling method and that it can be an effective tool for the simulation of heat pipe cooled reactors.
基金the National Natural Science Foundation of China(52130502,52171315)the National Key R&D Program of China(2022YFB4201102).
文摘General reductions in lubricant viscosities and increasing loads in machine components highlight the role of tribofilms in providing surface protection against scuffing.However,the relationship between the scuffing process and the growth and removal of tribofilm is not well understood.In this study,a multiphysics coupling model,which includes hydrodynamic lubrication,asperity contact,thermal effect,tribochemistry reaction,friction,and surface wear,was developed to capture the initiation of surface scuffing.Simulations and experiments for a piston ring and cylinder liner contact were conducted following a step-load sequence under different temperature conditions.The results show that high temperature and extreme load could induce the lubricant film collapse,which in turn triggers the breakdown of the tribofilm due to the significantly increased removal process.The failures of both lubricant film and tribofilm progress instantaneously in a coupling way,which finally leads to severe scuffing.
基金financially supported by the National Natural Science Foundation of China(52176202)。
文摘Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.
文摘An explicitly coupled two-dimensional (2D) multiphysics finite element method (FEM) framework comprised of thermal, phase field, mechanical and electromagnetic (TPME) equations was developed to simulate the conversion of solid kerogen in oil shale to liquid oil through </span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"> pyrolysis by radio frequency heating. Radio frequency heating as a method of <i></span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"></i> pyrolysis represents a tenable enhanced oil recovery method, whereby an applied electrical potential difference across a target oil shale formation is converted to thermal energy, heating the oil shale and causing it to liquify to become liquid oil. A number of <i></span><i><span style="font-family:Verdana;font-size:12px;">in-situ</span></i><span style="font-family:Verdana;font-size:12px;"></i> pyrolysis methods are reviewed but the focus of this work is on the verification of the TPME numerical framework to model radio frequency heating as a potential dielectric heating process for enhanced oil recovery.</span></span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">Very few studies exist which describe production from oil shale;furthermore, there are none that specifically address the verification of numerical models describing radio frequency heating. As a result, the Method of Manufactured Solutions (MMS) was used as an analytical verification method of the developed numerical code. Results show that the multiphysics finite element framework was adequately modeled enabling the simulation of kerogen conversion to oil as a part of the analysis of a TPME numerical model.
