ISSN:
1573-1987
Keywords:
LES
;
combustion
;
instabilities
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract This paper describes the first steps in the development of a large eddy simulation (LES) code able to compute combustion instabilities in gas turbines. This code was used to compute the forcing of an experimentally investigated premixed 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. Another effect of waves entering the combustor is to modulate the fuel and air flow rates produced by the feeding lines. In this case the equivalence ratio of the mixture entering the combustor may also vary. This was investigated in a “chemical effect” simulation where the inlet equivalence ratio fluctuates but the total flow rate remains constant. For perturbations from stoichiometric burning, this mechanism was shown to induce less destabilizing effects than the purely aerodynamical mechanism due to vortex formation and combustion. It is shown that the LES methodology developed is able to reproduce the experimentally observed phase shift between acoustic excitation and total reaction rate in the chamber.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1011477030619
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