PERFORMANCE OF SIMPLE CONDENSATION MODEL IN HIGH-PRESSURES

In this article we deal with the numerical solution of two-phase flow with nonequilibrium condensation in high pressures. We test how simple homogeneous non-equilibrium mixture model (single-fluid model) performs in high-pressure conditions. For this purpose we used our in-house CFD code with the following limitation: time-dependent compressible Euler equations in 2D for mixture of dry steam and water droplets, standard method of moments for liquid phase, simple fitting of liquid saturation data, so-called special gas equation provided by Wagner and Pruss (IAPWS-95) used as real equation of state for both superheated and supersaturated dry steam, classical nucleation theory and droplet growth model with appropriate corrections. As a test case we used rapid expansion of high-pressure steam in convergent-divergent nozzle with supersonic outlet in which condensation occurs in the divergent part. Test cases come from work of Bakhtar et al [1], [2]. We used all three nozzle geometries and two distinct cases for each (six test cases in total). Results of our simulations are in a reasonable accordance with the experimental data, several simplifications taking into account.