Seminars & Events
Argonne Leadership Computing Seminar
"Massively Parallel LES of Azimuthal Thermoacoustic Instabilities in Annular Gas Turbines"
DATE: November 11, 2008
TIME: 10:00 am
SPEAKER: Pierre Wolf, The European Centre for Research and Advanced Training in Scientific Computation, CERFACS
LOCATION: Building 360, Conference Room L119, Argonne National Laboratory
Description:
Increasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines, which are unfortunately more and more prone to combustion instabilities. In the particular field of annular combustion chambers,
these instabilities often take the form of azimuthal modes. To predict these modes, one must compute the full combustion chamber, which remained out of reach until very recently and the development of massively parallel computers, such as the BG/P.
Full annular Large Eddy Simulation (LES) of two helicopter combustors, which di ffer only on the swirlers' design, were recently performed. In both computations, LES captures self-
established rotating azimuthal modes. However, the two cases exhibit di fferent thermo-acoustic responses and the resulting limit-cycles are di fferent. With the fi rst design, a self-excited strong instability develops, leading to pulsating flames and local flashback. In the second case, the ames are much less a ected by the azimuthal acoustic mode and remain stable, allowing an acceptable operation. This study therefore highlights the potential of LES for discriminating injection system designs.
However, additional computations are required to enforce these results. More speci fically, the same case with a refined mesh is currently being computed on the BG/P to get better insights on the mesh dependency of such simulations. An other computation is also currently being calculated on the BG/P and aims at breaking the azimuthal periodicity of annular combustion chamber to see its e ffects on the mode.
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