شبيه سازي جريان سيال و انتقال گرما در قالب ريخته گري مداوم تختال

چكيده انگليسي :

Simulation of Fluid Flow and Heat Transfer in Continuous Slab Casting Mold Mohammad Khalilzadeh Milani m khalilzadehmilani@me iut ac ir August 16 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSuperviser Ahmad Saboonchi Prof ahmadsab@cc iut ac irAbstractIn the last three decades continuous casting has become increasingly important in steel production andnowadays it is the most important step in the manufacture of steel The fluid flow and heat transferphenomena in a continuous casting mold are very complex and these phenomena affect considerably on theproduct quality Therefore the understandings of the fluid flow and heat transfer phenomena in continuouscasting mold have become important Particularly value of solidified shell thickness in the mold outlet isvery important Becouse the solidified shell must be thick enough to withstand the ferrostatic pressure ofmolten steel Due to the very high temperature of process the direct measurement of velocity andtemperature distribution is difficult Thus numerical simulation is an important tool and provides morecomplete knowleges In this study a model is proposed on the basis of the technical and operationalconditions of the slab caster in the continuous casting unit of Mobarakeh Steel Company A threedimensional mathematical model using Fluent finite volume software was developed for simulation ofturbulent flow and heat transfer in continuous slab casting mold by bifurcated nozzle Gambit software wasused to create geometry and mesh generation To predict the correct flow pattern in the mold the solutiondomain including the nozzle mold and small part of secondary cooling zone was considered The turbulentflow is mathematically described by the Reynolds averaged Navier Stokes equations RANS The realizablek model and Reynolds stress model are used to close the RANS equations The non equilibrium wallfunctions near the wall are used to capture the steep gradients with accuracy on a coarse grid Enthalpy porosity technique has been used for solidification process In this method a source term derived fromDarcy s law of porous media is incorporated in the momentum and turbulence equations Due to theconvergence problems in simulation of solidification process as use of enthalpy porosity technique theproblem was solve in transient state Convergence criterion is establishment of the energy balance on theboundaries of solution area According to the results quantities as flow velocity height of free surfaceoscillation temperature and thickness of solidified shell were determined The upper recirculation and lowerrecirculation flows were predicted truly Level fluctuations of meniscus weas calculated using pressuredistribution along the free surface based upon potential energy conservation The temperature distribution isvigorously dependent to the velocity distribution The uniform distribution of temperature obtained that isimportant for slab quality Reynolds stress model didn t have any advantage toward k model although ithad more computational expense CPU time and memory This is due to the more sensibility of Reynolds stress model to the grid size equations discretization method and settings of multigrid solver In comparisonwith measured data thickness of solidified shell on the slab wide face was predicted truly However resultson slab narrow face have great error The parameters of flow velocity mushy zone constant and profile ofheat flux on the wall mold have the most effect on the solidification process Particularly the value of mushyzone constant has a great effect on the thickness of solidified shell and its growth rate Key WordsContinuous casting mold flow heat transfer turbulence solidification Fluent

خليل زاده، محمد

شبيه سازي جريان سيال و انتقال گرما در قالب ريخته گري مداوم تختال

تلاطم , انجماد , فلوئنت