Study of hydrodynamic instability of shear coaxial flow in a recessed region

The hydrodynamic instability of a coaxial injector with recessed inner fluid posts has been investigated using a homogeneous flow method with pseudo-density model in a time-dependent, viscous calculation. The present study focuses on unsteady “self-oscillation” and “self-pulsation” modes of jet flow in the coaxial injector. The Kelvin-Helmholtz instability mechanism due to velocity discontinuity between gas and liquid phase is suggested as a source of the flow instability which may contribute to combustion instabilities.; A two-dimensional analogue is investigated first in this study. A series of parametric studies in the 2-D geometry has been completed to assess the amplitude and frequency of oscillations under a variety of design conditions. A full 3-D unsteady, parallelized model has been developed. Flow dynamics of the coaxial injectors in the Space Shuttle Main Engine (SSME) main burner and preburner has been investigated to verify the pulsation mode of coaxial jet flow along with the oscillation mode.