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Multiphase Flow Large-Eddy Simulation Study of the Fuel Split Effects on Combustion Instabilities in an Ultra-Low-NOxAnnular Combustor

Bauerheim, Michaël and Jaravel, Thomas and Esclapez, Lucas and Riber, Eleonore and Gicquel, Laurent Y.M. and Cuenot, Bénédicte and Cazalens, Michel and Bourgois, S. and Rullaud, M. Multiphase Flow Large-Eddy Simulation Study of the Fuel Split Effects on Combustion Instabilities in an Ultra-Low-NOxAnnular Combustor. (2016) In: ASME Turbo Expo 2015: Turbine Technical Conference and Exposition (GT2015), 15 June 2015 - 19 June 2015 (Montreal, Canada).

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Official URL: http://doi.org/10.1115/1.4031871

Abstract

This paper describes the application of a coupled Acoustic model/LES approach to assess the effect of fuel split on combustion instabilities in an industrial ultra low-NOx annular combustor. Multiphase flow LES and an analytical model (ATACAMAC) to predict thermoacoustic modes are combined to reveal and compare two mechanisms leading to thermoacoustic instabilities: 1) a gaseous type in the multi-point zone where acoustics generates vortex shedding, wrinkling the flame front and 2) a multiphase flow type in the pilot zone where acoustics can modify the liquid fuel transport and the evaporation process leading to gaseous fuel oscillations. The aim of this paper is to investigate these mechanisms by changing the fuel split (from 5% to 20%, mainly affecting the pilot zone and mechanism 2) and therefore assess which mechanism controls the flame dynamics. First, the eigenmodes of the annular chamber are investigated using the analytical model and validated by 3D Helmholtz simulations. Then, multiphase flow LES are forced at the eigenfrequencies of the chamber for three different fuel split values. Key features of the flow and flame dynamics are investigated. Results show that acoustic forcing generates gaseous fuel oscillations which strongly depend on the fuel split parameter. However, the global correlation between heat release fluctuations and acoustics highlights no dependency on the fuel split staging. It suggests that vortex shedding in the multi-point zone, almost not depending on the fuel split here, is the main feature controlling the flame dynamics for this LEMCOTEC engine.

Item Type:Conference or Workshop Item (Paper)
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Centre Européen de Recherche et Formation Avancées en Calcul Scientifique - CERFACS (FRANCE)
Other partners > Institut national des sciences de l'Univers - INSU (FRANCE)
Other partners > SAFRAN (FRANCE)
Other partners > Société nationale d'étude et de constructions de moteurs d'avion - SNECMA (FRANCE)
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Deposited On:14 Jun 2019 13:14

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