With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electr...With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electromagnetic braking technology to recoil mechanism.In this paper,prototype tests of a certain artillery were carried out to verify the feasibility of the electromagnetic brake(EMB)and obtain the electromagnetic braking force.Due to the brittleness of Nd Fe B,in order to eliminate the worry about the safety of EMB,SHPB experiments of Nd Fe B were carried out.Then,based on the assumption of uniform crack distribution,the law of crack propagation and damage accumulation was described theoretically,and the damage constitutive model suitable for brittle materials was proposed by combining the Zhu-Wang-Tang(ZWT)equation.Finally,the numerical simulation model of the artillery prototype was established and through calculation,the dynamic mechanical characteristics of Nd Fe B in the prototype were analyzed.The calculation results show that the strength of Nd Fe B can meet the requirements of the use in the working process.From the perspective of damage factor,the damage value of the permanent magnet on the far right is larger,and the damage value of the inner ring gradually decreases to the outer ring.展开更多
Three-dimensional mathematical models were developed for studying the molten steel flow and the trajectories of inclusions and bubbles in continuous casting mold with electromagnetic brake.The results show that the ef...Three-dimensional mathematical models were developed for studying the molten steel flow and the trajectories of inclusions and bubbles in continuous casting mold with electromagnetic brake.The results show that the effect of the electromagnetic brake on the molten steel flow and the movement of inclusions and bubbles depends on the position of electromagnetic brake.While EMBR Ruler is installed at the exit of the submerged entry nozzle,the velocity of the main jet of molten steel from the nozzle can be decreased effectively,the velocity of the molten steel streams near the free surface and the narrow face is reduced obviously;Meantime more inclusions and bubbles could float up to the slag layer.展开更多
The present work numerically investigates two-dimensional (2-D) solidification transport phenomena (EM-STP) during continuous casting (CC) process in the absence and the presence of static magnetic fields (SMFs...The present work numerically investigates two-dimensional (2-D) solidification transport phenomena (EM-STP) during continuous casting (CC) process in the absence and the presence of static magnetic fields (SMFs), based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake (EMBR) effects of various SMFs under the given depth of submerged entry nozzle (SEN) and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.展开更多
Multiphase flow control w ith electromagnetic braking( EMBr) is w idely used in the continuous casting of steel slabs. The basic aim of the flow control system of the process is to deliver molten steel from the ladl...Multiphase flow control w ith electromagnetic braking( EMBr) is w idely used in the continuous casting of steel slabs. The basic aim of the flow control system of the process is to deliver molten steel from the ladle through the tundish,upper tundish nozzle,slide gate,and submerged entry nozzle into the mold region w ith minimal defects. This requires the optimization of turbulence levels at a meniscus to avoid both an excessively fast flow( which creates high fluctuations of the meniscus level in addition to slag entrapment,surface nonuniformities,and surface defects) and insufficient slow flow( w hich leads to meniscus solidification,inadequate flux infiltration,and surface defects). In this study,a Eulerian-Lagrangian approach is used to investigate the effects of EM Br and Ar bubble injection on the surface flow velocity. The results show that high Ar injection rates can lead to an increase in surface velocity.展开更多
During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the mold.Thus,the q...During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the mold.Thus,the quality of the final product can be improved considerably.A new electromagnetic braking(EMBr)method,named vertical-combined electromagnetic braking(VC-EMBr),is proposed to be applied to a flexible thin slab casting(FTSC)mold.To evaluate the beneficial effects of the VC-EMBr,the melt flow,heat transfer,and solidification processes in the FTSC mold are studied by means of numerical simulations.In detail,a Reynolds-averaged Navier–Stokes turbulence model together with an enthalpy-porosity approach was used.The numerical findings are compared with respective simulations using the traditional Ruler-EMBr.The results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab defects.In contrast to the Ruler-EMBr,the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus region.For instance,by applying a magnetic flux density of 0.3 T,the maximum amplitude of meniscus deflection reduces by about 80%.Moreover,the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting direction.On this basis,the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.展开更多
基金financially supported by the“National Natural Science Foundation of China”[Grant No.52105106]the“China National Postdoctoral Program for Innovative Talents”[Grant No.BX2021126]+2 种基金the“Jiangsu Province Natural Science Foundation”[Grant No.BK20210342]the“Jiangsu Planned Projects for Postdoctoral Research Funds”[Grant No.2021K008A]the“Nanjing Municipal Human Resources and Social Security Bureau”[Grant No.MCA21121]。
文摘With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electromagnetic braking technology to recoil mechanism.In this paper,prototype tests of a certain artillery were carried out to verify the feasibility of the electromagnetic brake(EMB)and obtain the electromagnetic braking force.Due to the brittleness of Nd Fe B,in order to eliminate the worry about the safety of EMB,SHPB experiments of Nd Fe B were carried out.Then,based on the assumption of uniform crack distribution,the law of crack propagation and damage accumulation was described theoretically,and the damage constitutive model suitable for brittle materials was proposed by combining the Zhu-Wang-Tang(ZWT)equation.Finally,the numerical simulation model of the artillery prototype was established and through calculation,the dynamic mechanical characteristics of Nd Fe B in the prototype were analyzed.The calculation results show that the strength of Nd Fe B can meet the requirements of the use in the working process.From the perspective of damage factor,the damage value of the permanent magnet on the far right is larger,and the damage value of the inner ring gradually decreases to the outer ring.
基金Item Sponsored by National Natural Science Foundation of China(59734080,59504006)Plan of National FundamentalResearch and Development of China(G1998061510)Postdoctoral Science Foundation of China(200217)
文摘Three-dimensional mathematical models were developed for studying the molten steel flow and the trajectories of inclusions and bubbles in continuous casting mold with electromagnetic brake.The results show that the effect of the electromagnetic brake on the molten steel flow and the movement of inclusions and bubbles depends on the position of electromagnetic brake.While EMBR Ruler is installed at the exit of the submerged entry nozzle,the velocity of the main jet of molten steel from the nozzle can be decreased effectively,the velocity of the molten steel streams near the free surface and the narrow face is reduced obviously;Meantime more inclusions and bubbles could float up to the slag layer.
基金Sponsored by the National Natural Science Foundation of China (Grants No. 50801019,51071062)the State Key Lab of Advanced Metals Materials(Grant No.2009ZD-06)the National Basic Research Program of China (Grant No. 2011CB605504)
文摘The present work numerically investigates two-dimensional (2-D) solidification transport phenomena (EM-STP) during continuous casting (CC) process in the absence and the presence of static magnetic fields (SMFs), based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake (EMBR) effects of various SMFs under the given depth of submerged entry nozzle (SEN) and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.
文摘Multiphase flow control w ith electromagnetic braking( EMBr) is w idely used in the continuous casting of steel slabs. The basic aim of the flow control system of the process is to deliver molten steel from the ladle through the tundish,upper tundish nozzle,slide gate,and submerged entry nozzle into the mold region w ith minimal defects. This requires the optimization of turbulence levels at a meniscus to avoid both an excessively fast flow( which creates high fluctuations of the meniscus level in addition to slag entrapment,surface nonuniformities,and surface defects) and insufficient slow flow( w hich leads to meniscus solidification,inadequate flux infiltration,and surface defects). In this study,a Eulerian-Lagrangian approach is used to investigate the effects of EM Br and Ar bubble injection on the surface flow velocity. The results show that high Ar injection rates can lead to an increase in surface velocity.
基金National Natural Science Foundation of China(Grant Nos.U1760206 and 51574083)the 111 Project(2.0)of China(No.BP0719037)for the financial support+1 种基金The first author is grateful for financial support provided by the Institute of Thermodynamics and Fluid Mechanics at Technische Universität Ilmenau,Germany,and the Verein zur Förderung der Thermo-und Fluiddynamik e.V.Furthermore,the authors are grateful to Deutsche Forschungsgemeinschaft(DFG)for the financial support in the framework of the Research Training Group Lorentz Force Velocimetry and Lorentz Force Eddy Current Testing(GRK 1567)Finally,the authors acknowledge support by the Computer Center at TU Ilmenau for providing the computational resources.
文摘During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the mold.Thus,the quality of the final product can be improved considerably.A new electromagnetic braking(EMBr)method,named vertical-combined electromagnetic braking(VC-EMBr),is proposed to be applied to a flexible thin slab casting(FTSC)mold.To evaluate the beneficial effects of the VC-EMBr,the melt flow,heat transfer,and solidification processes in the FTSC mold are studied by means of numerical simulations.In detail,a Reynolds-averaged Navier–Stokes turbulence model together with an enthalpy-porosity approach was used.The numerical findings are compared with respective simulations using the traditional Ruler-EMBr.The results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab defects.In contrast to the Ruler-EMBr,the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus region.For instance,by applying a magnetic flux density of 0.3 T,the maximum amplitude of meniscus deflection reduces by about 80%.Moreover,the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting direction.On this basis,the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.