Numerical simulation of the vortexacoustic wave interaction in a dump combustor
Abstract
Cold flow simulations are performed for the flow inside a ramjet combustor. The objective is to develop a numerical simulation code and to study the complex interaction between acoustic waves and large vortical structures in such a device. The compressible NavierStokes equations are solved using MacCormack's finite volume scheme. Vorticity contour plots reveal that the shear layer behind the backgroundfacing step rolls up into large vortices. Spectral analyses of the time history of vorticity and pressure fluctuations at several points are performed to examine the nature of the vortexacoustic wave interaction. The results indicate that, at low Reynolds numbers when the shear layer is thick, the acoustic resonant mode simply modulates the motion of the rolledup vortex. For high Reynolds numbers, when the shear layer is more unstable, the rolledup vortex and acoustic waves interact in a more complex manner. This interaction produces a low resonant frequency different from that of an acoustic eigenmode. A simple model is postulated to explain the possible interaction mechanism.
 Publication:

24th AIAA Aerospace Sciences Meeting
 Pub Date:
 January 1986
 Bibcode:
 1986aiaa.meetQ....J
 Keywords:

 Computational Fluid Dynamics;
 Computerized Simulation;
 Dump Combustors;
 Ramjet Engines;
 Sound Waves;
 Vortices;
 Finite Volume Method;
 NavierStokes Equation;
 Reynolds Number;
 Turbulent Flow;
 Wave Interaction;
 Fluid Mechanics and Heat Transfer