Thermoacoustic instabilities – physical mechanisms and mathematical modelling
* Presenting author
If a flame is put into an acoustic resonator, an escalating interaction between the flame's heat release and the acoustic field can occur, giving rise to intense pressure oscillations. This phenomenon is termed "thermoacoustic instability". It occurs in combustion systems that have a continuously burning flame, such as gas turbines, jet aeroengines, boiler and heating systems, furnaces and rockets. Thermoacoustic instabilities are a serious problem because they can lead to excessive structural vibrations, fatigue, and even catastrophic hardware damage. The escalating flame-sound interaction occurs in tandem with other physical mechanisms, leading to a complex web of interactions, most of which are nonlinear. They include flame-vortex interactions, flame response to fluctuations in fuel concentration, entropy waves, flame-structure interactions, and others.The development of low-pollution combustion systems is very important for our environment. However, such combustion systems are particularly prone to thermoacoustic instabilities. Progress with developing combustion systems that are immune to these is hampered by insufficient physical insight. Efforts to gain further insight are going on by researchers worldwide using experimental, analytical and numerical tools. This talk aims to give an overview of the key physical mechanisms involved in thermoacoustic instabilities and will pay particular attention to mathematical modelling approaches.