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Technische Universität München
Technische Universität München

Advanced Stability Analysis

Self-excited instabilities are important in many fields of science and technology. Examples from fluid dynamics include jet break-up and mixing, aerodynamic flutter, combustion instabilities, and thermo-hydraulic instabilities in nuclear reactors or concentrated solar power. It is the goal of stability analysis to predict whether a small perturbation to a system will grow (instability) or decay (stability). The conventional approach is to represent a perturbation as a superposition of eigenmodes, and to study the temporal development of each mode separately. If all modes are stable, the system is argued to be stable as well. However, it has been learned quite recently that this argument is not valid for systems with a non-normal evolution operator. Then the eigenmodes will be non-orthogonal, such that they can exchange energy among each other by interaction with the base flow, even in the linear limit of small perturbation amplitudes. Such non-normal behaviour can result in strong transient growth, which in combination with nonlinear effects may completely invalidate conventional modal analysis.

In the last decade, there has been a surge of activity in non-modal (also called non-normal) stability analysis within the applied maths community. Many applications are concerned with the stability of shear flows in simple geometries. Prof. Sujith has discovered that thermoacoustic interactions are governed by a non-normal operator, and has worked out in a series of break-through papers the possible implications for the stability of combustion systems. These investigations made use of simplistic model problems. We are currently working on investigating how important the effects of non-normality are for realistic combustor configurations. Then methods of non-modal stability analysis have to be developed to a point, where they can be used as design tools for technical applications. It is also important to establish solid, quantitative experimental evidence for non-normality in thermoacoustics.

Dr. Bruno Schuermans is a Rudolf Diesel Industry Fellow and currently Team Leader for Scientific Methods and Thermoacoustics at the Combustor Department at Alstom Ltd.’s Switzerland branch in Baden. He has joined the Focus Group Advanced Stability Analysis together with his host Prof. Thomas Sattelmayer from the Thermodynamics department.

Prof. R. I. Sujith is a Professor at the Department of Aerospace Engineering at the Indian Institute of Technology Madras. As a Hans Fischer Senior Fellow of the IAS (2010-2013), he has intensified his collaboration with Prof. Wolfgang Polifke of the Chair for Thermodynamics at TUM.

TUM-IAS funded doctoral candidates:
Ralf Blumenthal, Thermodynamics
Sebastian Bomberg, Thermodynamics
Tobias Hummel, Thermodynamics

Publications by the Focus Group

2019

  • Hummel, Tobias Volkhard: Modeling and Analysis of High-Frequency Thermoacoustic Oscillations in Gas Turbine Combustion Chambers. Dissertation, 2019 mehr…

2017

  • Berger, Frederik M.; Hummel, Tobias; Hertweck, Michael; Kaufmann, Jan; Schuermans, Bruno; Sattelmayer, Thomas: High-Frequency Thermoacoustic Modulation Mechanisms in Swirl-Stabilized Gas Turbine Combustors—Part I: Experimental Investigation of Local Flame Response. Journal of Engineering for Gas Turbines and Power 139 (7), 2017, 071501 mehr…
  • Berger, Frederik M.; Hummel, Tobias; Schuermans, Bruno; Sattelmayer, Thomas: Pulsation-Amplitude-Dependent Flame Dynamics of High-Frequency Thermoacoustic Oscillations in Lean-Premixed Gas Turbine Combustors. Volume 4A: Combustion, Fuels and Emissions, ASME, 2017 mehr…
  • Emmert, T.; Bomberg, S.; Jaensch, S.; Polifke, W.: Acoustic and intrinsic thermoacoustic modes of a premixed combustor. Proceedings of the Combustion Institute 36 (3), 2017, 3835-3842 mehr…
  • Hummel, Tobias; Berger, Frederik; Hertweck, Michael; Schuermans, Bruno; Sattelmayer, Thomas: High-Frequency Thermoacoustic Modulation Mechanisms in Swirl-Stabilized Gas Turbine Combustors—Part II: Modeling and Analysis. Journal of Engineering for Gas Turbines and Power 139 (7), 2017, 071502 mehr…
  • Hummel, Tobias; Berger, Frederik; Stadlmair, Nicolai; Schuermans, Bruno; Sattelmayer, Thomas: Extraction of Linear Growth and Damping Rates of High-Frequency Thermoacoustic Oscillations From Time Domain Data. Volume 4A: Combustion, Fuels and Emissions, ASME, 2017 mehr…
  • Hummel, Tobias; Hammer, Klaus; Romero, Pedro; Schuermans, Bruno; Sattelmayer, Thomas: Low-Order Modeling of Nonlinear High-Frequency Transversal Thermoacoustic Oscillations in Gas Turbine Combustors. Journal of Engineering for Gas Turbines and Power 139 (7), 2017, 071503 mehr…
  • Romero, P.; Hummel, T.; Berger, F.; Schuermans, B.; Sattelmayer, T.: Damping due to Acoustic Boundary Layer in High-frequency Transverse Modes. 24th International Congress on Sound and Vibration, 2017ICSV 2017 mehr…
  • Stadlmair, Nicolai V.; Hummel, Tobias; Sattelmayer, Thomas: Thermoacoustic Damping Rate Determination From Combustion Noise Using Bayesian Statistics. Volume 4A: Combustion, Fuels and Emissions, ASME, 2017 mehr…

2016

  • Hummel, T.; Berger, F.; Schuermans, B.; Sattelmayer, T.: Theory and Modeling of Non-Degenerate Transversal Thermoacoustic Limit Cycle Oscillations. Proceedings of the International Symposium on Thermoacoustic Instabilities in Gas Turbines and Rocket Engines: Industry meets Academia, 2016 mehr…
  • Hummel, Tobias; Berger, Frederik; Hertweck, Michael; Schuermans, Bruno; Sattelmayer, Thomas: High-Frequency Thermoacoustic Modulation Mechanisms in Swirl-Stabilized Gas Turbine Combustors: Part Two — Modeling and Analysis. Volume 4B: Combustion, Fuels and Emissions, ASME International, 2016 mehr…
  • Hummel, Tobias; Berger, Frederik; Hertweck, Michael; Schuermans, Bruno; Sattelmayer, Thomas: High-Frequency Thermoacoustic Modulation Mechanisms in Swirl-Stabilized Gas Turbine Combustors: Part Two — Modeling and Analysis. Volume 4B: Combustion, Fuels and Emissions, ASME, 2016 mehr…
  • Hummel, Tobias; Hammer, Klaus; Romero, Pedro; Schuermans, Bruno; Sattelmayer, Thomas: Low-Order Modeling of Nonlinear High-Frequency Transversal Thermoacoustic Oscillations in Gas Turbine Combustors. Volume 4B: Combustion, Fuels and Emissions, ASME, 2016 mehr…
  • Schulze, Moritz; Hummel, Tobias; Klarmann, Noah; Berger, Frederik; Schuermans, Bruno; Sattelmayer, Thomas: Linearized Euler Equations for the Prediction of Linear High-Frequency Stability in Gas Turbine Combustors. Journal of Engineering for Gas Turbines and Power 139 (3), 2016, 031510 mehr…
  • Schulze, Moritz; Hummel, Tobias; Klarmann, Noah; Berger, Frederik; Schuermans, Bruno; Sattelmayer, Thomas: Linearized Euler Equations for the Prediction of Linear High-Frequency Stability in Gas Turbine Combustors. Volume 4B: Combustion, Fuels and Emissions, ASME, 2016 mehr…

2015

  • Blumenthal, Ralf: A Systems View on Non-Normal Transient Growth in Thermoacoustics. Dissertation, 2015 mehr…
  • Bomberg, S.; Emmert, T.; Polifke, W.: Thermal versus acoustic response of velocity sensitive premixed flames. Proceedings of the Combustion Institute 35 (3), 2015, 3185-3192 mehr…
  • Emmert, Thomas; Bomberg, Sebastian; Polifke, Wolfgang: Intrinsic thermoacoustic instability of premixed flames. Combustion and Flame 162 (1), 2015, 75-85 mehr…
  • Hummel, T.; Schulze, M.; Schuermans, B.; Sattelmayer, T.: Reduced Order Modeling of Transversal and Non-Compact Combustion Dynamics. 22nd International Congress on Sound and Vibration, 2015 mehr…
  • Hummel, Tobias; Temmler, Constanze; Schuermans, Bruno; Sattelmayer, Thomas: Reduced-Order Modeling of Aeroacoustic Systems for Stability Analyses of Thermoacoustically Noncompact Gas Turbine Combustors. Journal of Engineering for Gas Turbines and Power 138 (5), 2015, 051502 mehr…
  • Hummel, Tobias; Temmler, Constanze; Schuermans, Bruno; Sattelmayer, Thomas: Reduced Order Modeling of Aeroacoustic Systems for Stability Analyses of Thermoacoustically Non-Compact Gas Turbine Combustors. Volume 4B: Combustion, Fuels and Emissions, ASME, 2015 mehr…
  • Subramanian, Priya; Blumenthal, Ralf S.; Polifke, Wolfgang; Sujith, R.I.: Distributed time lag response functions for the modelling of combustion dynamics. Combustion Theory and Modelling 19 (2), 2015, 223-237 mehr…

2014

  • Albayrak, A.; Ulhaq, A.; Blumenthal, R. S.; Polifke, W.: Analytical derivation of laminar premixed flame impulse response to equivalence ratio perturbations. 21st International Congress on Sound and Vibration (ICSV21) , 2014 mehr…
  • L. Strobio-Chen, S. Bomberg, and W. Polifke: On the Jump Conditions for Flow Perturbations Across a Moving Heat Source. 21st International Congress on Sound and Vibration, 2014 mehr…

2013

  • Blumenthal, R. S.; Tangirala, A. K.; Sujith, R. I. Polifke, W.: A Contribution to the Discussion on Thermoacoustic Energy from a Systemic Perspective. n3l - Int’l Summer School and Workshop on Non-Normal and Nonlinear Effects In Aero- and Thermoacoustics, 2013, 10 mehr…
  • Blumenthal, Ralf S.; Subramanian, Priya; Sujith, R.I.; Polifke, Wolfgang: Novel perspectives on the dynamics of premixed flames. Combustion and Flame 160 (7), 2013, 1215-1224 mehr…
  • R. S. Blumenthal, P. Subramanian, R. I. Sujith, and W. Polifke: A time domain perspective on the response of premixed flames to flow perturbations. EUROMECH, Colloquium 546 - Combustion Dynamics and Combustion Noise, 2013 mehr…
  • Schmid, Martin; Blumenthal, Ralf S.; Schulze, Moritz; Polifke, Wolfgang; Sattelmayer, Thomas: Quantitative Stability Analysis Using Real-Valued Frequency Response Data. Journal of Engineering for Gas Turbines and Power 135 (12), 2013, 121601 mehr…
  • Schmid, Martin; Blumenthal, Ralf S.; Schulze, Moritz; Polifke, Wolfgang; Sattelmayer, Thomas: Quantitative Stability Analysis Using Real-Valued Frequency Response Data. Volume 1B: Combustion, Fuels and Emissions, ASME, 2013 mehr…
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