Thierry Poinsot
Institut de Mécanique des Fluides Allée du Pro Camille Soula 31400 Toulouse, FRANCE
Christian Angelberger
CERFACS, Toulouse France
Fokion Egolfopoulos
University of Southern California, USA
Denis Veynante
Ecole Centrale Paris CNRS, UPR 288, Laboratoire EM2C Grande Voie des Vignes 92290 Chatenay-Malabry, France
This paper describes a Large Eddy Simulation of acoustic combustion instabilities in a dump combustor. It is shown that the main effect of acoustic waves entering the combustion chamber is to create large vortices and unsteady heat release when these vortices burn. The fact that the equivalence ratio of incoming gas is also modulated by acoustic waves was tested through a special simulation where the inlet equivalence ratio fluctuates but the total flow rate remains constant. This mechanism was shown to induce less destabilizing effects than the purely aerodynamical mechanism due to vortex formation and combustion.