Effects of Geometric Change on Supercritical Fluid Flow Dynamics and Mixing in Gas-Centered Liquid-Swirl Coaxial Injectors

The present work investigates supercritical fluid flow dynamics and mixing in gas-centered liquid-swirl coaxial injectors, which are used in in the main chambers of oxidizer-rich staged-combustion engines. Gaseous oxygen (GOX) is axially directed through a center post at a temperature of 687.7 K. Kerosene is tangentially introduced into the outer coaxial swirler at a temperature of 492.2 K. The mean chamber pressure of 253.0 bar substantially exceeds the thermodynamic critical pressures of oxygen and kerosene. The end of the GOX post is recessed from the entrance of the taper region, which is connected downstream to an open domain. Changes in geometric parameters in recess lengths and in the taper regions are found to have noticeable influences on the flow and mixing fields.  The present abstract focuses on the latter case.  First, adjusting the injector geometry accelerates the development of the GOX-kerosene mixing layer. Second, stretching and amalgamation of vortices disturb the energy cascade toward high-wavenumber eddies. Third, flow recirculation and reduction in the bulk axial velocity increase the residence time of the reactive mixture, facilitating flame stabilization.  Results and discussions will be presented in detail at the meeting.