  Under rocket-relevant conditions, real-gas effects and thermodynamic
non-idealities are prominent features of the flow field. Experimental
investigations indicate that phase separation can occur depending on the
operating conditions and on the involved species in the multicomponent flow.
During the past decades, several research groups in the rocket combustion
community have addressed this topic. In this contribution we employ a
high-fidelity thermodynamic framework comprising real-gas and multicomponent
phase separation effects to investigate liquid oxygen-methane and liquid
oxygen-hydrogen flames at high pressure. A thorough introduction and discussion
on multicomponent phase separation is conducted. The model is validated with
experimental data and incorporated in a reacting flow CFD code. Thermodynamic
effects are presented using one-dimensional counterflow diffusion flames. Both
real-gas and phase separation effects are present and quantified in terms of
derived properties. Finally, the method is applied in a three-dimensional large
eddy simulation of a single-element reference test case and the results are
compared to experimental data.
