Intrinsic thermoacoustic feedback and its consequences for combustion noise and combustion dynamics

Combustion Webinar 04/30/2022, Speaker: Wolfgang Polifke

Thermoacoustic combustion instabilities represent a severe challenge for the development and reliable operation of efficient, flexible and low-emission combustion technology in gas turbines and rocket engines as well as industrial or domestic burners. Traditionally, thermoacoustic modes were understood to be associated with acoustic cavity modes of the combustion system. The discovery of the intrinsic thermoacoustic (ITA) feedback loop and associated eigenmodes shattered this paradigm: the complete set of eigenmodes of a combustor is now understood to be the aggregate of acoustic and ITA modes.
In this talk I will first reminisce from a personal perspective about the studies that led to the discovery of ITA feedback and ITA modes. Then I will present the current understanding of the structure and characteristic properties of ITA modes before exploring consequences of ITA feedback, such as convective scaling of thermoacoustic eigenfrequencies, resonant amplification of combustion noise, clusters of modes in annular and can-annular combustors, and exceptional points.

Wolfgang Polifke studied physics at the University of Regensburg, the University of Colorado in Boulder and the City College of New York (1981-87). His doctoral thesis dealt with the helicity of turbulent flows (City University of New York, 1990). He then spent almost a decade at ABB’s corporate research center in Baden-Dättwil, Switzerland, working on fundamental aspects of gas turbine combustion technology. In 1999, Prof. Polifke was appointed professor at TUM. His research areas include thermoacoustic combustion instabilities, aeroacoustics as well as mixing and reaction in turbulent flows. From 2016 to 2021 Prof. Polifke was Editor-in-Chief of the Int'l. J. for Spray and Combustion Dynamics. Since 2017 he has served as Associate Editor on the editorial board of Combustion and Flame. In 2021 he was elected as Fellow of the International Combustion Institute.