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Two-way hybrid LES/CAA approach including acoustic feedback loop for the prediction of thermoacoustic instabilities in technical combustors

Klenke, T. C. and Lo Presti, F. and Lackhove, K. and di Mare, F. and Sadiki, A. and Janicka, J. (2017):
Two-way hybrid LES/CAA approach including acoustic feedback loop for the prediction of thermoacoustic instabilities in technical combustors.
In: Proceedings of the ASME Turbo Expo: Turbine technical conference and exposition 2017, New York, USA, American Society of Mechanical Engineers, [Conference or Workshop Item]

Abstract

Due to the reduction of fuel consumption and new global emission limits, especially for the pollutant emissions of NOx, improvements to lean combustion technologies in aeroengine combustors are unavoidable. Near to the lean limits, combustion tends to be unstable. A geometry related coupling between unsteady heat release and acoustic perturbations leads to thermoacoustic instabilities, which show an undesirable impact on pressure, velocity and heat release in the combustor Such instabilities occur when the unsteady heat release fluctuations are in phase with the acoustic pressure fluctuations. The. aim of this study is to find an industrially applicable, three-dimensional numerical model for the prediction of combustion noise, which can also provide insight in thermoacoustic instabilities and acoustic effects in a responsive environment in enclosed, technical combustion systems. The turbulent reacting flow in a realistic gas turbine combustor has been computed by means of Large Eddy Simulation coupled to a tabulated chemistry approach based on the Flamelet Generated Manifold ansatz. The reactive LES provides very well suited method to study the impact of unsteady heat release as a major source of acoustic noise in combustion. For the simultaneous treatment of the reacting flow and its acoustic features, a Computational Aero Acoustics (CAA) solver has been coupled with the LES solver following a hybrid approach. In this work the acoustic wave propagation is calculated by the Linearized Euler Equations (LEE). The interface between both codes is optimized for the realisation of an acoustic feedback loop in order to obtain a suitable representation of acoustically self-excited oscillations. To demonstrate the prediction capability of the hybrid LES/CAA approach, geometry-dependent thermoacoustic instabilities in a generic half-dump combustor, for which experimental data are available, are investigated. The numerical results are compared to measured pressure fluctuations under both thermoacoustically stable and unstable conditions.

Item Type: Conference or Workshop Item
Erschienen: 2017
Creators: Klenke, T. C. and Lo Presti, F. and Lackhove, K. and di Mare, F. and Sadiki, A. and Janicka, J.
Title: Two-way hybrid LES/CAA approach including acoustic feedback loop for the prediction of thermoacoustic instabilities in technical combustors
Language: English
Abstract:

Due to the reduction of fuel consumption and new global emission limits, especially for the pollutant emissions of NOx, improvements to lean combustion technologies in aeroengine combustors are unavoidable. Near to the lean limits, combustion tends to be unstable. A geometry related coupling between unsteady heat release and acoustic perturbations leads to thermoacoustic instabilities, which show an undesirable impact on pressure, velocity and heat release in the combustor Such instabilities occur when the unsteady heat release fluctuations are in phase with the acoustic pressure fluctuations. The. aim of this study is to find an industrially applicable, three-dimensional numerical model for the prediction of combustion noise, which can also provide insight in thermoacoustic instabilities and acoustic effects in a responsive environment in enclosed, technical combustion systems. The turbulent reacting flow in a realistic gas turbine combustor has been computed by means of Large Eddy Simulation coupled to a tabulated chemistry approach based on the Flamelet Generated Manifold ansatz. The reactive LES provides very well suited method to study the impact of unsteady heat release as a major source of acoustic noise in combustion. For the simultaneous treatment of the reacting flow and its acoustic features, a Computational Aero Acoustics (CAA) solver has been coupled with the LES solver following a hybrid approach. In this work the acoustic wave propagation is calculated by the Linearized Euler Equations (LEE). The interface between both codes is optimized for the realisation of an acoustic feedback loop in order to obtain a suitable representation of acoustically self-excited oscillations. To demonstrate the prediction capability of the hybrid LES/CAA approach, geometry-dependent thermoacoustic instabilities in a generic half-dump combustor, for which experimental data are available, are investigated. The numerical results are compared to measured pressure fluctuations under both thermoacoustically stable and unstable conditions.

Title of Book: Proceedings of the ASME Turbo Expo: Turbine technical conference and exposition 2017
Volume: 4A
Place of Publication: New York, USA
Publisher: American Society of Mechanical Engineers
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute for Energy and Power Plant Technology (EKT)
Date Deposited: 27 Mar 2019 06:22
Identification Number: 978-0-7918-5084-8
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