In the present numerical study, implicit large eddy simulations (LES) of non-reacting multi-components mixing processes of cryogenic nitrogen and n-dodecane fuel injections under transcritical and supercritical conditions are carried out, using a modified reacting flow solver, originally available in the open source software OpenFOAM®. To this end, the Peng-Robinson (PR) cubic equation of state (EOS) is considered and the solver is modified to account for the real-fluid thermodynamics. At high pressure conditions, the variable transport properties such as dynamic viscosity and thermal conductivity are accurately computed using the Chung transport model. To deal with the multicomponent species mixing, molar averaged homogeneous classical mixing rules are used. For the velocity–pressure coupling, a PIMPLE based compressible algorithm is employed. For both cryogenic and non-cryogenic fuel injections, qualitative and quantitative analyses are performed, and the results show significant effects of the chamber pressure on the mixing processes and entrainment rates. The capability of the proposed numerical model to handle multicomponent species mixing with real-fluid thermophysical properties is demonstrated, in both supercritical and transcritical regimes.

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Complexity behind physical phenomena of supercritical and transcritical jet flows, still leaves an ambiguous understanding of such widespread technology, with applications ranging from diesel and liquid rocket engines to gas turbines. In this present numerical study, a new open-source CFD model construction is presented and validated using a liquid-rocket benchmark comprised of liquid-oxygen (LOX) and gaseous-hydrogen (H2) streams. Mixing process of liquid oxygenhydrogen streams under liquid rocket engine (LRE) relevant conditions is scrutinized using the pressure-based solution framework implemented in the versatile computation platform Open-FOAM. The model accounts for real fluid thermodynamics and transport properties, making use of the cubic Peng-Robinson equation of state (PR-EOS) and the Chung transport model. The solver capability to capture the mixing layer between the two separated streams is discussed as well as its capability to predict with adequate accuracy the thermophysical quantities. Following the thorough validation, a comparison of the contribution of the accurate laminar transport properties vs. the large eddy simulation (LES) subgrid scale (sgs) turbulent values is conducted in order to assess the relative importance of the turbulent viscosity. By means of an assessment of the pressure-based numerical framework with available data in the literature, this work contributes to a better understanding of well resolved simulations. In addition, it enables the further development of a real fluid pressure-based multi-species solver as an open-source code.

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