Interactions between Multiple Unstable Transversal Modes in High-Frequency Thermoacoustic Systems

• Applicant: Professor Dr.-Ing. Thomas Sattelmayer
• Subject Area: Technical Thermodynamics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 380974143

• Final Report Year: 2022

Final Report Abstract

This project deals with high-frequency thermoacoustic instabilities in lean-premixed gas turbine combustion systems. These instabilities increasingly often occur after commissioning of modern gas turbine combustors and may lead to hardware damage and/or decrease the operational window of the gas turbine. The research objective of this work represents the qualitative and quantitative prediction of thermoacoustic instabilities from a numerical and theoretical perspective. This allows systematic application of countermeasures to avoid or mitigate unstable behavior. An approach is introduced to predict thermoacoustic instabilities in three separated steps. These steps comprise 1.) the determination of the linear thermoacoustic stability limits, 2.) the identification of non-linear saturation mechanisms leading to the formation of limitcycle oscillations and 3.) the consideration of modal suppression phenomena between linearly unstable eigenmodes. The outcome of this project is an accurate, numerical prediction tool, which allows the efficient prediction of the temporal evolution of multiple, coupled acoustic eigenmodes. Additionally, fundamental numerical studies are carried out to enhance the understanding of the influence of vorticity perturbations on high-frequency thermoacoustic oscillations in general. To judge the performance of the computational tools and to validate numerical investigations, a lab-scale, swirl-stabilized combustor is used as benchmark system. For the first transversal (T1) eigenmode of this combustor extensive experimental data is available.

Publications

• Theory and Quantification of Energy Transformation Processes between Acoustic and Hydrodynamic Perturbation Modes in Non-Compact Thermoacoustic Systems via a Helmholtz-Hodge Decomposition Approach. ASME Turbomachinery Technical Conference & Exposition, 2019
  Hofmeister, T.; Hummel, T.; Schuermans, B.; Sattelmayer, T.
  
• Modeling and Quantification of Acoustic Damping Induced by Vortex Shedding in Noncompact Thermoacoustic Systems. Journal of Engineering for Gas Turbines and Power 142 (3), 2020, 031016
  Hofmeister, T.; Hummel, T.; Schuermans, B.; Sattelmayer, T.
  
• Elimination of Numerical Damping in the Stability Analysis of Noncompact Thermoacoustic Systems With Linearized Euler Equations. Journal of Engineering for Gas Turbines and Power 143 (3), 2021, Article number 031013
  Hofmeister, T.; Hummel, T.; Berger, F.; Klarmann, N.; Sattelmayer, T.
  
• Impact of the Stabilized Finite Element Method on Acoustic and Vortical Perturbations in Thermoacoustic Systems. Journal of Engineering for Gas Turbines and Power 143 (6), 2021, Article number 061012
  Hofmeister, T.; Hummel, T.; Sattelmayer, T.