ORCID Profile
0000-0003-1968-1611
Current Organisation
Siemens Corp Corporate Research
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Publisher: Elsevier BV
Date: 2014
Publisher: Wiley
Date: 15-06-2021
DOI: 10.1002/FLD.5021
Abstract: The goal of the present article is to understand the impact of numerical schemes for the reconstruction of data at cell faces in finite‐volume methods, and to assess their interaction with the quadrature rule used to compute the average over the cell volume. Here, third‐, fifth‐ and seventh‐order WENO‐Z schemes are investigated. On a problem with a smooth solution, the theoretical order of convergence rate for each method is retrieved, and changing the order of the reconstruction at cell faces does not impact the results, whereas for a shock‐driven problem all the methods collapse to first‐order. Study of the decay of compressible homogeneous isotropic turbulence reveals that using a high‐order quadrature rule to compute the average over a finite‐volume cell does not improve the spectral accuracy and that all methods present a second‐order convergence rate. However the choice of the numerical method to reconstruct data at cell faces is found to be critical to correctly capture turbulent spectra. In the context of simulations with finite‐volume methods of practical flows encountered in engineering applications, it becomes apparent that an efficient strategy is to perform the average integration with a low‐order quadrature rule on a fine mesh resolution, whereas high‐order schemes should be used to reconstruct data at cell faces.
Publisher: Elsevier BV
Date: 05-2016
Publisher: Informa UK Limited
Date: 15-01-2019
Publisher: Mathematical Sciences Publishers
Date: 19-11-2020
Publisher: Springer Science and Business Media LLC
Date: 05-07-2011
Publisher: Elsevier BV
Date: 2017
Publisher: Cambridge University Press (CUP)
Date: 16-05-2014
DOI: 10.1017/JFM.2014.245
Abstract: A combustion instability in a combustor terminated by a nozzle is analysed and modelled based on a low-order Helmholtz solver. A large eddy simulation (LES) of the corresponding turbulent, compressible and reacting flow is first performed and analysed based on dynamic mode decomposition (DMD). The mode with the highest litude shares the same frequency of oscillation as the experiment (approximately 320 Hz) and shows the presence of large entropy spots generated within the combustion chamber and convected down to the exit nozzle. The lowest purely acoustic mode being in the range 700–750 Hz, it is postulated that the instability observed around 320 Hz stems from a mixed entropy–acoustic mode, where the acoustic generation associated with entropy spots being convected throughout the choked nozzle plays a key role. The DMD analysis allows one to extract from the LES results a low-order model that confirms that the mechanism of the low-frequency combustion instability indeed involves both acoustic and convected entropy waves. The delayed entropy coupled boundary condition (DECBC) (Motheau, Selle & Nicoud, J. Sound Vib. , vol. 333, 2014, pp. 246–262) is implemented into a numerical Helmholtz solver where the baseline flow is assumed at rest. When fed with appropriate transfer functions to model the entropy generation and convection from the flame to the exit, the Helmholtz/DECBC solver predicts the presence of an unstable mode around 320 Hz, in agreement with both LES and experiments.
Publisher: ASME International
Date: 24-09-2012
DOI: 10.1115/1.4007198
Abstract: The present study is devoted to the modeling of mean flow effects while computing thermoacoustic modes under the zero Mach number assumption. It is first recalled that the acoustic impedance modeling of a compressor or a turbine must be prescribed under an energetical form instead of the classical acoustic variables. Then we demonstrate the feasibility to take into account the coupling between acoustic and entropy waves in a zero Mach number framework to capture a family of low frequency entropic modes. The proposed approach relies on a new delayed entropy coupled boundary condition (DECBC) and proves able to capture a family of low frequency entropic mode even though no mean flow term is included in the fluctuating pressure equation.
Publisher: Elsevier BV
Date: 11-2018
Publisher: American Society of Mechanical Engineers
Date: 03-06-2013
DOI: 10.1115/GT2013-94224
Abstract: A combustion instability in a combustor typical of aero-engines is analyzed and modeled thanks to a low order Helmholtz solver. A Dynamic Mode Decomposition (DMD) is first applied to the Large Eddy Simulation (LES) database. The mode with the highest litude shares the same frequency of oscillation as the experiment (approx. 350 Hz) and it shows the presence of large entropy spots generated within the combustion chamber and convected down to the exit nozzle. The lowest purely acoustic mode being in the range 650–700 Hz, it is postulated that the instability observed around 350 Hz stems from a mixed entropy/acoustic mode where the acoustic generation associated with the entropy spots being convected throughout the choked nozzle plays a key role. A Delayed Entropy Coupled Boundary Condition is then derived in order to account for this interaction in the framework of a Helmholtz solver where the baseline flow is assumed at rest. When fed with appropriate transfer functions to model the entropy generation and convection from the flame to the exit, the Helmholtz solver proves able to predict the presence of an unstable mode around 350 Hz, in agreement with both the LES and the experiments. This finding supports the idea that the instability observed in the combustor is indeed driven by the entropy/acoustic coupling.
Publisher: The Open Journal
Date: 31-10-2023
DOI: 10.21105/JOSS.05450
Publisher: American Society of Mechanical Engineers
Date: 11-06-2012
DOI: 10.1115/GT2012-68852
Abstract: The present study is devoted to the modeling of mean flow effects while computing thermoacoustic modes under the zero Mach number assumption. It is first recalled that the acoustic impedance modelling a compressor or a turbine must be prescribed under an energetical form instead of the classical acoustic variables. Then we demonstrate the feasibility to take into account the coupling between acoustic and entropy waves in a zero Mach number framework to capture a family of low frequency entropic modes. The proposed approach relies on a new Delayed Entropy Coupled Boundary Condition (DECBC) and proves able to capture a family of Low frequency entropic mode even though no mean flow term is included into the fluctuating pressure equation.
Publisher: ASME International
Date: 21-08-2013
DOI: 10.1115/1.4024953
Abstract: A combustion instability in a combustor typical of aero-engines is analyzed and modeled thanks to a low order Helmholtz solver. A dynamic mode decomposition (DMD) is first applied to the large eddy simulation (LES) database. The mode with the highest litude shares the same frequency of oscillation as the experiment (approximately 350 Hz) and it shows the presence of large entropy spots generated within the combustion chamber and convected down to the exit nozzle. With the lowest purely acoustic mode being in the range 650–700 Hz, it is postulated that the instability observed around 350 Hz stems from a mixed entropy/acoustic mode where the acoustic generation associated with the entropy spots being convected throughout the choked nozzle plays a key role. A delayed entropy coupled boundary condition is then derived in order to account for this interaction in the framework of a Helmholtz solver where the baseline flow is assumed to be at rest. When fed with the appropriate transfer functions to model the entropy generation and convection from the flame to the exit, the Helmholtz solver proves able to predict the presence of an unstable mode around 350 Hz, which is in agreement with both the LES and the experiments. This finding supports the idea that the instability observed in the combustor is indeed driven by the entropy/acoustic coupling.
Location: United States of America
No related grants have been discovered for Emmanuel Motheau.