Simulation on flow process of filtered molten metals

Vol. 12 No. 1Trans. Nonferrous Met. Soc. ChinaFeb.2002[ Article ID ] 1003 - 6326( 2002 )01 -0102 - 03Simulation on flow process of filtered molten metals LFANG Wen-bin(房文斌), GENG Yao-hong( 耿耀宏), WEI Zun-jie( 魏尊杰),AN Ge-ying安阁英), YE Rong-mad叶荣茂)( School of Materials Science and Engineering , Harbin Institute of Technology ,Harbin 150001 , China )[ Abstract ] Filtration and flow process of molten metals was analyzed by water simulation experiments. Fluid dynamicphenomena of molten metal cells through a foam ceramic filter was described and calculated by ERCOR equation as well.The results show that the filter is most useful for stable molten metals and the filtered flow is laminar , so that inclusionscan be removed more effectively.[ Key words ] molten metals ; filtration ; flow process ; dynamics[ CLC number ] TG146.2+ 1[ Document code ]A1 INTRODUCTIONAdding water and solid particles into the pouring bushand lifting the faucet，they can flow in the moldMolten metals( aluminum alloys , cast steels andchamber through pouring system and solid particlescast irons ) often fill in mold chambers as turbulencecan be stopped behind the foam ceramic filter. As the .in the pouring purification process through a foam ce-data obtained by water simulation experiments carramic filter. Due to turbulent influence , inclusions inapproximately visualize the flow process of moltencross gate have no chance to go up or dow n complete-metals ,it s an important preliminary examination ofly and lots of them are easily piled up at the filter in-the filling process of molten metals.let1-5]. To better understand the flowing rules ofConsidering that mechanical interception leads tomolten metals and refining mechanics of the inclu-more inclusions at the filter inlet w hen molten metalssions , the flow process of filtered molten metals areflow by，the complex net work structure of the filtertested theoretically and dynamics equations for thefunctions as a rectifier by refining currents and flowprocess are established , which is an important ratio-resistance is enhanced by the filter , filtered water innale for alloy filtration technology in production.the simulation experiment is calculated by secondaryAccording to similarity principle , M ach numberERGOR equation of hydromechanics to figure out the( M )of incompressible flow of water and molten met-low velocity variat ions and inclusion distribution ten-alsas well as Weber number( We ) are negligible ,dencies of filtered and unfiltered molten metals.since surface tension in large chambers isn' t appar-ent. Euler number( Eu ) of incompressible flow is aESTABLISHMENT OF DYNAMICS EQUA-functionofReandFr,i.e.Eu=f(Re，Fr),TIONSwhich indicates that Re and Fr of similarity canERGOR equation isbring Eu in the same condition. Therefore , plasticparticles used in hydraulics simulation ex periments are- VP= V(fi+ f2lo| )( 1)prepared by controlling foaming conditions to satisfywhere. fi , f2 are coefficients and can be ex pressedPinclusion : Pmolen metal = Pparicle : P waterAs for Froudenumber( Fr= V2/gL ),it' s necessarily unanimous if4.2nsK1 - fYfi =flow model of actual molten metals and simulation e-fiquipments are of the same size and flow velocity ,0. 292ρsch 1 - fi)fz =which means that water simulation experiments canfbe taken in emulating flow process of actual moltenUsing Cartesian coordinate in the bivariate equa-tions :中国煤化工(2)2 WATER SIMULATION EXPERIMENTSMHCNMHG(3)Fig.1 is a draft of water simulation apparatus.Derivations of Eqns.(2),( 3)are①[ Foundation itemlProjet supported by the Youth Fund of Harbin Institute of Technology[ Received dat826o1 - 08 - 30 ;[ Accepted date]2001- 11- 05Vol.12 No.1Simulation on flow process of filtered molten metalsPouringbush] Faucettuberetings,FilterMold chamberOverlow tubespout万Pool本CameraWater pump .channelFig.1 Draft of water simulation apparatus25= fzuu+(f1+f2 u )g"Suppose approximate central difference is takendxdy'dyon Eqn.( 8 ), then(4)φij+1-2φij+ 9ij-1A +一=f208 +(f1+fz u )"。(5)2p日uLet9i+1/-29;j+ 9i-1iB+c=o(9)|ul=√u2+ 02i.e.Then ,= V(Jq/axP +(Jq/yY，Pij =2 A△x2 + BOy2)1( Li+1+ iui-lA + Pi+1j + 9i-liB+ c)( 10)-axoy=f2ay2Oy-△x2According to flow velocity and direction at the“dxfilter inlet , fluidity behavior is complex while its hori-(22里. ?2q + 22φ?q)+zontal velocity( u ), vertical velocity( 0 ) are evenlyx dxdydy dy2distributed after it approaches stability condition ,(6)i.e. such filter is a useful rectifier and filtered water[/+12/(器》+(鄂门7器.is laminar so that inclusions of pouring system can be2p:r。aφ1removed more effectively.- ay0x =-f2x 2Fig.2 describes stratification in the filter. Whenit' s laid vertically , flow velocity reaches highest in(2?φ?∞+224?φ)_the middle of it and tend to slow down，w hich meansdx ax2Jy dxdymore inclusions will be piled up in middle and lower(7)part of it. At this time , the major mechanism for the[/+12/(器Y+(影门器filter is rectification deposition and the minor is me-where u =dφ,v=_dφ. ,φ is a function of flu-chanical intercept and absorption. All the conditions3y、mentioned above are shown in Fig.3 by flow velocity ,idity.that is the relative volume flow , and inclusion distri-Let Eqs.( 6),( 7) muliplybutions.then subtract each other , the result can be ex pressed中国煤化工asMolten.MYHCNMHG((++(98+1(器+摊Foam ceramic fiterx架川+影(n(器》+(器》,f5[x器场方败姆川}+29器器器=0(8)ax dy dxdyFig.2 Sketch of filter arrangement104.Trans. Nonferrous Met. Soc. ChinaFeb.20023 ) Flow velocity reaches highest in the middle ofhe vertical filter and tends to decrease slowly with30 Volume flow raterectification deposition as the major , mechanic inter-cept and absorption as the minor mechanicals in the昌2filter.。20-20. [ REFERENCES ]s 15-▲一Inclusion15[1] Glemings M C , Niiyama E, Taylor H F. Fluidity of alu-distributionminum alloys , an experimental and quantitative evalua-tion[J]. AFS Transactions , 1961 , 169 : 625.UpperMiddleLower[2] FANG W en-bin. Development and application of foamceramic filters used in cast irons[ J ] Mechanical Engi-neering Material ,( in Chinese), 1996 ,20( 6):48 - 50. .Fig.3 Calculated results[3] FANG Wen-bin , GENG Yao-hong. Development ofoam ceramic filters[J ]. Casting ,( in Chinese ), 1996 ,4 CONCLUSIONS9 :45- 49.[4] Wiser P E , Dutta. Priming and flow through filters[ J].1 ) Based on hydraulics simulation experiments ,AFS Transaction , 1986 : 85.dynamics equation on flow process of filtered molten[5] Sutton W H , Morris J R. Development of ceramic foammaterials for the filtration of high- temperature investmentmetals is given and can be used in liquid aluminum al-casting alloys[ A ] 31th Annual meeting ICI[ C] Dal-loys , cast steels and cast irons.las,TX ,1983. 901 -921.2 ) Analysis of flow process shows that the filter[6] PEI Qing-jan. Study on tridimensional numerical simula-is most useful for stable molten metals and filteredtion and casting process CAD system[ D ]. Bejing : Ts-flow is laminar so that inclusions of pouring systeminghua University , 1991.can be removed more effectively.( Edited by YUAN Sai-qian )中国煤化工YHCNMHG