Numerical Modelling of Cryogenic Two-phase Flow in the DLR TAU Code

Abstract

The present paper discusses work that has been conducted to extent the German Aerospace Center (DLR) TAU Code to simulate heat and mass transfer in two-phase systems in launcher cryogenic upper stages. Preceding work has been performed to extend the incompressible version of the DLR inhouse CFD Code TAU to simulate isothermal twophase flows. A Volume of Fluid (VOF) approach and a finite volume discretization are used. Due to the grid handling in TAU an algebraic solution of the interface position is necessary yielding shorter computation times compared to geometrical approaches on both structured and unstructured grids. This model is currently extended to simulate heat and mass transfer. Therefore, the energy conservation equation needs to be included. Density deviations are included via the Boussinesq-approximation and heat convection is modeled by Fouriers law. Basic test cases like laminar flow in a pipe were used to verify the proper functionality of the new implementation and show good agreements with analytically solutions.