Numerická optimalizace kontilití ocelových bram a vliv termofyzikálních vlastností materiálů.

A numerical optimization of concast steel slab and influence of the material thermophysical proprerties

conference paper

en

The thermophysical properties of steels have a significant influence on the actual concasting process and on the accuracy of its numerical simulation and optimization. The determination of these properties (heat conductivity, specific heat capacity and density in the solid and liquid states) often requires more time than the actual numerical calculation of the temperature fields of a continuously cast steel billet, cylinder or slab. The influence of individual properties should be neither under- nor over-estimated. Therefore, an analysis/parametric study of these thermophysical properties was conducted. The order of importance within the actual process and the accuracy of simulation and optimization were also determined. Individual properties, which, in some cases, were obtained from tables and in others experimentally, were substituted by an approximation using orthogonal polynomials. The accuracy of each polynomial is dependent on the precision of individual values. The order of significance of individual thermophysical properties was determined with respect to the technological length and the minimum thickness of the solidified shell of the steel at the exit of the crystallizer. The analysis was performed by means of a so-called calculation experiment, i.e. by means of the original and universal numerical concasting model developed by the authors of this paper. The influence of each property has been studied separately within the range from 50 to 150% of its real value and also illustrated graphically. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of concasting, thus enhancing the process of optimization.

Termofyzikální vlastnosti ocelí mají zásadní význam pro proces kontilití a přesnost jeho numerického modelování a optimalizaci. Jejich určování někdy vyžaduje více času než vlastní numerický výpočet. Byla provedena parametrická analyza těchto termofyzikálních vlastností a jejich vlivu na přesnost výpočtu. Tato analyza byla provedena formou t.zv. výpočtového experimentu, za pomoci originálního univerzálního numerického modelu kontilití vyvinutého autory příspěvku. Vliv každé vlastnosti byl zkoumán samostatně v rozmezí 50 až 150% reálné hodnoty a výsledky byly vyjádřeny graficky.

The thermophysical properties of steels have a significant influence on the actual concasting process and on the accuracy of its numerical simulation and optimization. The determination of these properties (heat conductivity, specific heat capacity and density in the solid and liquid states) often requires more time than the actual numerical calculation of the temperature fields of a continuously cast steel billet, cylinder or slab. The influence of individual properties should be neither under- nor over-estimated. Therefore, an analysis/parametric study of these thermophysical properties was conducted. The order of importance within the actual process and the accuracy of simulation and optimization were also determined. Individual properties, which, in some cases, were obtained from tables and in others experimentally, were substituted by an approximation using orthogonal polynomials. The accuracy of each polynomial is dependent on the precision of individual values. The order of significance of individual thermophysical properties was determined with respect to the technological length and the minimum thickness of the solidified shell of the steel at the exit of the crystallizer. The analysis was performed by means of a so-called calculation experiment, i.e. by means of the original and universal numerical concasting model developed by the authors of this paper. The influence of each property has been studied separately within the range from 50 to 150% of its real value and also illustrated graphically. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of concasting, thus enhancing the process of optimization.

thermophysical properties of steels. accuracy of simulation, calculation experiment, universal numerical concasting model

2001

01.10.2001

Nakl. Ing. Jan Novosad, Procesní inženýrství, Praha

Praha

80-86059-32-4

CHISA 2001 Sborník 1

6