LES OF SUPERCRITICAL NITROGEN JETS AT HIGH SWIRL NUMBERS

Reactants are introduced into the combustion chambers of cryogenic liquid-propellant rocket engines (LREs) at supercritical conditions. At near-supercritical operating conditions, thermophysical properties change rapidly over short distances, which needs to be accurately modeled. In the present study, an OpenFOAM-based solver is developed inhouse and validated and is used to perform three-dimensional large-eddy simulation (LES) to study the effects of changing swirl numbers on the flow field. A precessing vortex core (PVC) is formed when the swirl number satisfies the condition S ≥ 1.29, and the frequency of PVC increases linearly with an increase in the swirl number. At these high swirl numbers, a nonmonotonic variation is observed in both the jet length and the jet cone angle. Thus, nonmonotonic behavior is shown to be due to the base of the PVC entering the injector.