Nonlinear self-excited oscillations in a thermoacoustic system

Lipika Kabiraj, R. I. Sujith, Pankaj Wahi † ‡ Department of Aerospace Engineering Indian Institute of Technology Madras Chennai 600036, India [email protected], [email protected] Department of Mechanical Engineering Indian Institute of Technology Kanpur Kanpur-208016, India [email protected] ABSTRACT Spontaneous pressure and heat release rate oscillations can get excited in a confined combustion system (for example, gas turbines and furnaces) due to coupling between the acoustic modes of the system and unsteady heat release rate from the source of combustion. These self-excited oscillations result in high noise levels, increased emission of NOx gases and reduced life span of the combustion system. In extreme cases, the emergence of such oscillations can lead to complete system failure. Hence, there is a huge impetus for investigations on thermoacoustic instability in practical combustion systems.