In order to carry out reliable large-eddy simulation or Helmholtz solver computations in aeronautical combustion chambers, it is crucial to impose the right boundary conditions at both the inlet and outlet of the combustion system. This means providing acoustic boundary impedances that take into account all the stages in compressors and turbines. This study is a follow up of works in which the boundary conditions were derived from the isentropic and isenthalpic linearized Euler equations. Specific terms are added to the quasi-one-dimensional linearized Euler equation in order to account for enthalpy jumps induced by the rotor stages of the compressors and turbines. This system of equations also accounts for the entropy–acoustic coupling because, in addition to the continuity and momentum equations, the entropy equation is also considered. The numerical implementation is validated by comparing the numerical results with analytical solutions in several model problems. The effective impedance of the inlet air circuit of an actual helicopter engine is then computed in order to illustrate the potential of the method as well as the importance of the rotor terms added.
Boundary Conditions for the Computation of Thermoacoustic Modes in Combustion Chambers
AIAA Journal ; 52 , 6 ; 1180-1193
2014-02-28
14 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Boundary Conditions for the Computation of Thermoacoustic Modes in Combustion Chambers
Online Contents | 2014
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