Session: 04-20: Combustion Noise
Paper Number: 82637
82637 - A Novel Decomposition Approach Preventing Spurious Entropy Generation in Hybrid Thermoacoustic Stability Computations
Prominent approaches for the computation of thermoacoustic stability are hybrid methods like the linearized Navier-Stokes equations (LNSE) or the linearized Euler equations (LEE). The transient fluctuations around a precomputed steady-state mean flow field solved for with these sets of equations naturally include the energy transition between acoustic, vortical and entropic modes. It is common practice to account for flame-acoustic interactions by applying measured or computed flame transfer functions (FTF) as a volumetric source term proportional to the mean heat release rate in the energy equation. However, the underlying assumption of a static flame is the root-cause of spurious entropy production, which may ultimately falsify the thermoacoustic stability predictions. In the present paper, a methodology to include arbitrary flame movement to the governing set of equations is presented. The procedure makes use of an Arbitrary Lagrangian-Eulerian (ALE) description of conservation equations and is demonstrated for the Euler equations. The resulting set of linear perturbation equations is then applied to two test cases. First, the frequency response of a one-dimensional premixed air-methane flame is evaluated. Secondly, the first transversal eigenmode of an experimental premixed, swirl-stabilized combustor is computed. To demonstrate the suppression of spurious entropy waves, the results are compared to those of the classic LEE.
Presenting Author: Gerrit Heilmann Technical University of Munich
Presenting Author Biography: Gerrit Heilmann studied Mechanical Engineering at the Karlsruhe Institute of Technology (KIT) and obtained his M.Sc. in 2016.<br/>After numerically studying the damping capabilities of porous media in combustion chambers in his master's thesis he became a PhD student at the Chair of Thermodynamics at TUM.<br/>With his ongoing work he targets the reliable and low-cost numerical prediction of thermoacoustic instabilities.
Authors:
Gerrit Heilmann Technical University of MunichTong Liu Technical University of Munich
Pedro Romero Vega Technical University of Munich
Thomas Sattelmayer Technical University of Munich
A Novel Decomposition Approach Preventing Spurious Entropy Generation in Hybrid Thermoacoustic Stability Computations
Paper Type
Technical Paper Publication