Hem modeling for subcritical flows in liquid rocket engine cooling systems

During off-design operations of liquid rocket engines, the coolant operating conditions can easily extend from the subcritical to the supercritical regime. As a matter of fact, it is very useful to have a single software able to study the flow in this range of operating conditions, providing reliable simulations able to correctly estimate and assess the coolant temperature increase along the channel, as well as the wall temperature field. This objective is pursued by the extension of a 3D CFD software, which is available to the research team for the study of supercritical flows, to the case of subcritical heating (i.e. two-phase flow) with an approach based on the so-called Homogeneous Equilibrium Model (HEM), which has shown to be rather predictive and accurate in one-dimensional models. In this work, the selected approach is presented and described in detail. Some preliminary results concerning test cases like variable cross section ducts and heated pipes are shown.