TABLE OF CONTENTS S bastien Ducruix, [*] Thierry Schuller, [ ] Daniel Durox, [ ] and S bastien Candel [ ]
CNRS and Ecole Centrale Paris, Ch tenay-Malabry, France
Copyright 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
[*]Research Scientist, Laboratoire EM2C.
[ ]Assistant Professor, ECP, Laboratoire EM2C.
[ ]Senior Research Engineer, Laboratoire EM2C.
[ ]Professor, ECP and Institut Universitaire de France, Laboratoire EM2C, Fellow AIAA.
Combustion instabilities constitute a central problem in many fields of application from aerospace propulsion, gas turbines operating in the premixed mode to domestic boilers and radiant heaters. Instabilities that result from resonant interactions lead to oscillations of the flow, inducing many undesirable effects: large-amplitude structural vibrations, increased heat fluxes at the system walls, flashback, and flame blowoff. In some extreme cases, the outcome is a spectacular failure. Much of the recent work in this field has relied on detailed experimentation with advanced optical diagnostics and on numerical simulation tools. In general, the objective of this work is to reveal the instability scenario and develop predictive models for combustion-dynamic phenomena. Schematically, a driving process generates perturbations of the flow, and a feedback process couples these perturbations to the driving mechanism and produces the resonant interaction that may lead to oscillations. The feedback (or coupling) process relates the downstream flow to the upstream region where the perturbations are initiated. As a consequence, acoustic-wave propagation is usually responsible for the feedback path. This coupling process may also involve convective modes, like entropy waves, which are associated...
