A mechanism for the acousticvortex interaction in a Ramjet dump combustor
Abstract
Recent numerical simulations of cold flow in a dump combustor show that pressure oscillations with a characteristic frequency different from that of the acoustic mode may be sustained in the dump. The unique characteristic of this mode of oscillation is that the frequency of the pressure oscillation in the dump is identical to the passage frequency of the vortices at a downstream section. Using this as the crucial evidence, a simple onedimensional model in which the vorticity fluctuation and the acoustic wave interact at the boundaries of the domain of interest has been constructed. The eigenvalue problem gives a frequency close to that observed in the simulations. Furthermore, the analysis reveals that there is a stability criterion on the 'overall interaction parameter' below which the oscillations of this class cannot be sustained. This criterion explains the absence of this class of oscillations in a numerical simulation in which the shear layer is thick and relatively stable. Additional numerical simulations with parameters ranging between the extreme cases also support the theoretical model.
 Publication:

Thermophysical Aspects of Reentry Flows
 Pub Date:
 July 1986
 Bibcode:
 1986aiaa.confQ....J
 Keywords:

 Dump Combustors;
 Pressure Oscillations;
 Ramjet Engines;
 Sound Waves;
 Vortices;
 Wave Interaction;
 Eigenvalues;
 Numerical Flow Visualization;
 Reynolds Number;
 Fluid Mechanics and Heat Transfer