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Publication type: Conference paper
Type of review: Peer review (publication)
Title: Autoignition flame transfer matrix : analytical model versus large eddy simulations
Authors: Gant, Francesco
Cuquel, Alexis
Bothien, Mirko
et. al: No
DOI: 10.21256/zhaw-23280
Conference details: Symposium on Thermoacoustics in Combustion: Industry meets Academia (SoTiC 2021), 6-10 September 2021
Issue Date: Sep-2021
Publisher / Ed. Institution: ZHAW Zürcher Hochschule für Angewandte Wissenschaften
Language: English
Subjects: Autoignition; Flame transfer matrix; Sequential combustion; Gas turbines; Rankine-Hugoniot conditions
Subject (DDC): 629: Aeronautical, automotive engineering
Abstract: Modern gas turbines need to fulfill increasingly stringent emission targets on the one hand and exhibit outstanding operational and fuel flexibility on the other. Ansaldo Energia GT26 and GT36 gas turbine models address these requirements by employing a combustion system in which two lean premixed combustors are arranged in series. Due to the high inlet temperatures from the first stage, the second combustor stage predominantly relies on autoignition for flame stabilization. In this paper, the response of autoignition flames to temperature, pressure and velocity excitations is investigated. The gas turbine combustor geometry is represented by a backward-facing step. Based on the conservation equations an analytical model is derived by solving the linearized Rankine-Hugoniot conditions. This is a commonly used analytical approach to describe the relation of thermodynamic quantities up- and downstream of a propagation stabilized flame. In particular, the linearized Rankine-Hugoniot jump conditions are derived taking into account the presence of a moving discontinuity as well as upstream entropy inhomogeneities. The unsteady heat release rate of the flame is modeled as a linear superposition of flame transfer functions, accounting for velocity, pressure, and entropy disturbances, respectively. This results in a 3x3 flame transfer matrix relating both primitive acoustic variables and the temperature fluctuations across the flame. The obtained analytical expression is compared to large eddy simulations with excellent agreement. A discussion about the contribution of the single terms to the modeling effort is provided, with a focus on autoignition flames.
Further description: Paper number 8436
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute of Energy Systems and Fluid Engineering (IEFE)
Appears in collections:Publikationen School of Engineering

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