Numerical modeling of heat transfer at cooling a high-temperature steel cylinder by the flow of a water-air medium with account taken of the gamma - alpha transformation

Abstract

Based on the mathematical model of the conjugate heat transfer from a steel cylinder to a water-air medium, the results of the calculation of the cooling rate and the mass fraction of the α-phase in supercooled austenite during the γ → α transformation are obtained. To find the mass fraction of the α-phase in austenite during supercooling, a modified Kolmogorov – Johnson – Mel – Avrami equation is used. The calculation results have been obtained during the cooling of the high-temperature metal cylinder by the laminar gas-liquid flow in an annular channel with account taken of vaporization in the liquid. The regulation of the heat and mass transfer balance of the system during the vaporization is based on the energy model of the heat balance and is performed using the effective thermophysical parameters of the cooling medium. The mathematical model is presented in a two-dimensional non-stationary formulation taking into account the symmetry of the cooling medium flow relative to the longitudinal vertical axis of the cylinder. To solve the system of differential equations, the control volume method is used. The parameters of the cooling medium flow are calculated using an algorithm SIMPLE. For the iterative solution of the system of linear algebraic equations, the methods of Gauss-Seidel and under-relaxation are used. The calculations, are carried out using a grid with a condensing profile at the «metal cylinder – liquid» and «liquid - outer metal ring» boundaries on the liquid side and the metal side.