Three-dimensional study of gas-centered, liquid-swirl coaxial injector flow dynamics at supercritical condition*

Supercritical fluid flow dynamics of a gas-centered, liquid-swirl coaxial injector are numerically investigated under conditions typical of contemporary oxidizer-rich staged-combustion cycle engines. Gaseous oxygen is injected into the center tube while kerosene is tangentially introduced into the coaxial annulus at pressure of 253 bar. Previous studies on axisymmetric configurations revealed distinctive flow characteristics and identified the importance of recess length to the mixing process.  The axisymmetric assumption, however, leads to the neglect of flow variations in the azimuthal direction and the exclusion of the vortex-stretching mechanism responsible for turbulent energy transfer from large to small eddies. The present three-dimensional work includes these features and employs a large-eddy-simulation technique. Instead of a slit entry, kerosene is injected through 12 tangential orifices. Complex vortical structures and flow dynamics are explored in detail. Various underlying mechanisms dictating the flow evolution are analyzed.