Význam termofyzikálních vlastností na přesnost výpočtu termokinetiky tuhnutí

Importance of Thermophysical Properties on Calculation Accuracy of Thermokinetics of Solidification

článek v časopise - ostatní, Jost

en

The thermophysical properties of steels have significant influence on the actual continuous and also gravitational casting 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 casting. 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 metallurgical length for concasting process and with respect to the total solidification time for gravitational casting process. The analysis was performed by means of a so-called calculation experiment, i.e., by means of the original and universal numerical casting model developed by the authors of this paper. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of casting, thus enhancing the process of optimization.

Termofyzikální vlastnosti ocelí mají významný vliv na průběh kontinuálního i gravitačního odlévání a přesnost jejich numerické simulace a optimalizace. Vliv jednotlivých vlastností by neměl být přeceňován ani podceňován. Proto je provedena parametrická studie těchto vlastností a stanovena přesnost simulace a optimalizace. Pořadí významnosti je stanoveno pro kontinuální lití s ohledem na velikost metalurgické délky, u gravitačního lití s ohledem na celkovou dobu tuhnutí. Použita je metoda t.zv. výpočtového experimentu.

The thermophysical properties of steels have significant influence on the actual continuous and also gravitational casting 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 casting. 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 metallurgical length for concasting process and with respect to the total solidification time for gravitational casting process. The analysis was performed by means of a so-called calculation experiment, i.e., by means of the original and universal numerical casting model developed by the authors of this paper. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of casting, thus enhancing the process of optimization.

Tuhnutí oceli, termokinetika, termofyzikální vlastnosti, přesnost výpočtu.

Steel solidification, thermokinetics, thermophysical properties, calculation accuracy.

2011

10.12.2011

David Publishing

1934-8959

A1, 2011

12

1037–1044

8