The coaxial injection of cryogenic nitrogen and warm hydrogen into a supercritical nitrogen atmosphere is studied numerically by means of well resolved large-eddy simulation (LES). Numerical data for two operating conditions are compared both quantitatively and qualitatively with a series of experiments [Oschwald et al., 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 1999], A detailed thermodynamic analysis of phenomena associated with the binary mixing of nitrogen and hydrogen together with a systematic study of the thermodynamic state of cryogenic nitrogen prior to injection allows an assessment of uncertainties related to both numerical and experimental data. Trans- and supercritical mixing constitutes considerable challenges for numerical simulations with regard to physical modeling and numerical stability. We compare a fully conservative (FC) formulation to a quasi conservative (QC) formulation of the governing equation, which was recently proposed by Terashima and Koshi [J. Comput. Phys., 2012].

In a joint effort towards the development of robust numerical tools for Large-Eddy Simulations (LES) of the injection, mixing and combustion process in the high-pressure environments of liquid-propellant rocket engines, a consistent model of real-gas thermo-physical effects has been developed and implemented into two different CFD codes: INCA with a density-based approach and a pressure-based version of OpenFOAM. As part of the validation process, LES of trans- and supercritical nitrogen jets have been performed with different subgrid-scale modeling approaches. Despite the different code architecture and turbulence models, the numerical results are in excellent agreement with each other and with experimental reference data. Compared to experimental data, our results have the same or better quality as those from previous simulations.