Sami-Alex Zaïmi - Academia.edu (original) (raw)

Uploads

Papers by Sami-Alex Zaïmi

PARTICLES II : proceedings of the II International Conference on Particle-Based Methods : fundamentals and applications, 2011

A numerical study of the charging process of a full-scale blast furnace, based on the Discrete El... more A numerical study of the charging process of a full-scale blast furnace, based on the Discrete Element Method, is presented. This study concentrates on the granular flow in a rotating chute employed to distribute appropriately the charge in the furnace. Detailed analysis of the results of numerical simulations has been undertaken to determine specific phenomena of importance to the charging process. Validation of the numerical results is obtained by comparison with experimental measurements of the position of the charge stream after exiting from the chute. The numerical results are shown to be in excellent qualitative and quantitative agreement with the experimental observations.

材料とプロセス日本鉄鋼協会講演論文集 Current Advances in Materials and Processes Report of the Isij Meeting, Sep 1, 1999

Http Www Theses Fr, 1998

On utilise la methode des elements finis (a l'aide du code de calcul ABAQUS) afin de determin... more On utilise la methode des elements finis (a l'aide du code de calcul ABAQUS) afin de determiner l'ecoulement des matieres solides dans le haut fourneau. Cet ecoulement peut etre assimile a celui se produisant dans un silo a paroi divergente puis convergente, et a extraction peripherique. La loi de comportement utilisee appartient a la famille des lois dites hypo-plastiques, qui convient bien a la modelisation des ecoulements granulaires. Cette loi est calibree a l'aide d'essais triaxiaux sur des echantillons de coke et de minerai. Apres de multiples remaillages, on atteint un regime permanent des vitesses et des contraintes. Les cartes obtenues montrent, entre autres, les regions en poussee et en butee, les regions en ecoulement sablier et piston, et la forme de la zone stagnante appelee homme mort. La theorie de Cosserat a ete appliquee, et a permis de simuler la formation de bandes de cisaillement en paroi (conditions aux limites rugueuses). Des observations experimentales (appliquant la technique de l'analyse d'image) sur une maquette bidimensionnelle de haut fourneau sont venues etayer nos resultats sur le champ des vitesses.

Revue de Métallurgie, 2004

The solid flow inside a blast furnace is modelled using a standalone finite element program and a... more The solid flow inside a blast furnace is modelled using a standalone finite element program and a constitutive equation called hypo-plastic, in order to better simulate the granular material behaviour. The parameters of this constitutive equation are calibrated using data obtained from simple soil mechanics tests on coke and sinter materials, such as triaxial and oedometric devices. Steady velocity, stress and void fraction fields are obtained after several iterations of the code. Knowledge of the solids velocity field makes it possible to determine the dead man profile, as well as its renewal kinetics. Burden trajectories and time lines are also computed. Knowledge of the stress field makes it possible to compute pressures acting on the burden as well as on the walls. Finally, knowledge of void fraction field makes it possible to determine gas paths. The solid flow model was validated on 20 and 30 small-scale cold blast furnaces, but the simulations never required any tuning parameter. This code is in fact an invaluable tool to determine the effect of blast furnace profile on solid flow conditions, and reciprocally.

ISIJ International, 2000

The finite element method (FEM) is used in conjunction with plasticity theory in granular materia... more The finite element method (FEM) is used in conjunction with plasticity theory in granular materials to derive the stress field and velocity field inside a small experimental apparatus reproducing the blast furnace. The theory used, called hypo-plasticity, gave satisfactory agreement between numerical and experimental time lines, and was able to predict the shape of the stagnant region in the bottom part, the so called dead man, without any adjustable parameters. Specific numerical methods, like iterative remeshing, allowed it to reach steady flow conditions in an Eulerian frame. The stress field is characterized by a plastic active state in the upper part, and a plastic passive state in the lower part. The velocity field is characterized by a plug flow in the upper part, and a funnel flow in the lower part. This model can also simulate granular flows in all type of vessels, like silos. In modeling blast furnaces, its usefulness lies in its connection with a multi-phase total model.

ISIJ International, 2000

This article introduces an improvement of an existing blast furnace total model called the Four F... more This article introduces an improvement of an existing blast furnace total model called the Four Fluid Flow Model, maintained by the last author. The derivation of solid phase motion in the former model is now replaced by an external numerical code, which implements a very specific granular flow theory called hypoplasticity. The calculation method in the external solid flow model is based on the finite element method (FEM), and differs from the method used in the fluid flow model (finite volume method or FVM), hence their separation. Both models are run one after the other by exchanging data such as solid velocity field, drag forces and solid voidage, until convergence. One major issue of the additional solid flow model is its ability to calculate the shape of the dead man (the name of the stagnant zone inside the blast furnace), whereas its shape was prescribed in the fluid model. The solid flow model also introduces stress state dependence on voidage, and takes into account source and sink terms related to solid phase physical and chemical transformations.

Ironmaking & Steelmaking, 2003

Modelling of solid flow in the blast furnace As already indicated, current theories of ow in gran... more Modelling of solid flow in the blast furnace As already indicated, current theories of ow in granular A finite element method has been used to model solids are unable to accurately account for the behaviour solid flow inside a cold blast furnace, based on a of the blast furnace burden and various modelling attempts hypo-plastic constitutive equation. This equation in the past have led to con icting results.9 There are clearly was calibrated with data obtained from simple soil two main approaches to mathematical modelling of solid mechanics tests on coke material. The steady state ow, each with advantages and shortcomings. velocity and stress fields were determined after an The uid mechanics approach includes Tohoku University's iterative enmeshment procedure. The most well known 'four uid' model,4,10 which uses a nite volume significant results include the computed shapes of technique.11 Unfortunately, the pro le of the dead-man zone the deadman zone and the active and passive state cannot be correctly estimated when it is assumed that solids regions, the transition between plug flow in the behave like uids, and the pro le must be prescribed before shaft and funnel flow in the bosh, and the void ratio computation. Furthermore, the friction coeYcient at the distribution fields. I&S/1698 furnace wall cannot be taken into account in these models. The second approach consists of applying plasticity methods Dr Zaṏmi is in the Dé partement Fonte, IRSID (Arcelor Group), to the blast furnace. Some models thus assume that the Maiziè res-lè s-Metz, France

PARTICLES II : proceedings of the II International Conference on Particle-Based Methods : fundamentals and applications, 2011

材料とプロセス日本鉄鋼協会講演論文集 Current Advances in Materials and Processes Report of the Isij Meeting, Sep 1, 1999

Http Www Theses Fr, 1998

Revue de Métallurgie, 2004

ISIJ International, 2000

Ironmaking & Steelmaking, 2003