Large-Eddy Simulation of Coaxial LN2/GH2 Injection at Trans- and Supercritical Conditions

Abstract

Large-eddy simulations are carried out for the coaxial injection of liquid nitrogen and preheated hydrogen at supercritical pressures. The conditions are similar to that in typical liquid-propellant rocket combustors. By using nitrogen as a model gas, the mixing process is studied without the interference with chemical reactions. An analysis of the thermodynamic conditions that arise in the shear layer reveals that local phase separation may occur if the injection condition is transcritical. A novel volume-translation method on the basis of the cubic Peng–Robinson equation of state is introduced for the use in multispecies large-eddy simulations and is tested for both trans- and supercritical injection conditions. The new thermodynamic model corrects the deficiencies of the Peng–Robinson equation of state in the transcritical regime at minimal extra computational cost. Two independently developed large-eddy simulation codes are used for the simulations and the results are compared. The outcome indicates that the flowfield is mainly controlled by the turbulence on the resolved scales, and an accurate model for the fluid’s thermodynamic state is more important than the subgrid-scale turbulence model or the details of the code architecture. A comparison with available experimental data shows that important flow features are well predicted.