Key Engineering Materials Vol. 685

Abstract: Temperature and radiative characteristics of different regimes of premixed gas combustion in porous cylindrical burner are investigated numerically. Two-temperature thermal diffusion model with radiative heat transfer and external radiative heat losses described in the framework of Eddington model is applied. It is found that two different combustion regimes can be realized under the same mixture equivalence ratio and flow rate depends on ignition conditions. It is shown that total radiative heat flux from the external surface of the burner and burner’s radiative efficiency strongly depend on the combustion regime.

Abstract: The optimal control problem for evolution radiative heat transfer in SP₁ approximation is considered. The problem is solved by weak form technique and Lagrange method. Numerical experiments for real materials are done.

Abstract: Melting and solidification problems are important in applications of many industries. In the present work mathematical simulation of natural convection with phase transition inside an enclosure with a local heat source has been carried out. Partial differential equations with corresponding initial and boundary conditions have been solved using the finite difference method. The effect of temperature differences on fluid flow and heat transfer has been discussed.

Abstract: The 3-D OpenMP parallel version of an algorithm for modeling dynamic processes in porous media with heat-evolution sources is presented. Parallel methods and techniques which were used for significant speed up of final results obtaining are described in detail. The performance results of parallel program for specific configuration of porous object are presented.

Abstract: Two approaches for simulating the burning surface in gas dynamics by means boundary conditions and right sides in the equations involving Dirac delta function are discussed. A comparison of numerical steady-state solutions and the exact ones in one-dimensional approximation is performed for two approaches. It is shown that the numerical solutions obtained with the finite-difference scheme of first order accuracy on the base of two considered approaches converge to each other when the mesh refinement is applied. The numerical solution for the steady state problem coincides with the analytical one, if the pressure at the boundary cell face is set equal to the pressure in the center of the boundary cell.

Abstract: Results of modeling rheological properties (constitutive models) of composite material Victrex PEEK 90HMF20 by reversible analysis method at high-speed milling considering the direction of the reinforcing fiber are presented. Strain hardening until the moment of rupture was determined by the results of static tests of destruction at different temperatures. Coefficients of viscoplastic hardening and thermal softening were determined by the results of statistical processing of experimental milling samples of PEEK-based deformation velocity field obtained by simulation of the process of edge cutting machining in Deform 2D.

Abstract: In the framework of the generalized Kramers theory of physical and chemical kinetics the relation for the decay rate of the metastable state is obtained. The peculiarity of the system is the ratio of the potential barrier height to temperature of the system. This ratio is much less than unity. To study the process we introduce the concept of the effective square of the potential barrier. It is shown that in the limiting case the obtained relation becomes the standard formula (Kramers formula) for the decay rate.

Abstract: The work investigates the accuracy of the Kramers approximate formula describing the decay rate of a metastable state. The study was performed by comparing the rate obtained through Kramers formula with the quasistationary rate derived by dynamical modeling that was performed by solving the Langevin equation. We have demonstrated that the non-correlation between Kramers rate and dynamical rate reached 15%, while a better correlation was expected. The study allowed us to generate corrections to Kramers formula by accounting for the higher derivatives of the potential. The rate obtained by the corrected formula exhibits the correlation with the dynamic rate of better than 1%.

Abstract: We have simulated an aluminum workpiece tool bending process with and without consideration of the heat affected zone after laser cutting with PAM-STAMP 2G. To describe the heat affected zone we have used a customized software option for calculating welded materials and dissimilar ones. We have also provided an analysis of the stress-strain state with a different scale of mechanical properties of the material on its “edge” and in the center of the workpiece.

Abstract: This work considers performance identification by operation statistics aimed to mathematical descriptions of blast-furnace processes. In case of the blast-furnace process automation the operational task of process conditions optimization shall preferably be implemented based on the algorithm of performance identification by operation statistics alongside with control and stabilization of process conditions.