A Thermoacoustic Instability Precursor Based on the Acoustic Flux at the Combustion Chamber Inlet

ABSTRACT

The acoustic flux at the inlet of the combustion chamber is used to indicate the proximity to impending thermo-acoustic instabilities (TAI) in a swirled spray combustor. This acoustic power is integrated over all frequencies and is deduced from acoustic pressure and velocity measurements made upstream the combustion chamber. Results with this TAI precursor are compared to those obtained by considering the root mean square value of the acoustic pressure inside the combustion chamber, the peak of the power spectral density of the combustion chamber acoustic pressure and the phase lag between the acoustic pressure inside the chamber and the OH* chemiluminescence. It is demonstrated that the acoustic flux outperforms the other indicators in terms of order of magnitude change and shape evolution when approaching TAI while being relatively insensitive to signal processing parameter modifications.

KEYWORDS:

• Combustion instabilities
• online monitoring
• acoustic flux
• swirl-spray flame
• gas turbine engines
• precursor

Acknowledgements

The authors would like to thank the IMFT technical team and in particular R. Soeparno, S. Lun, I. Loukili, G. Albert and L. Mouneix for their help on the burner design and its manufacturing. The authors report there are no competing interests to declare.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program Grant Agreement 832248, SCIROCCO and under the Horizon 2020, COEC (Center of Excellence in Combustion) program, Grant Agreement 952181. It has received support from SAFRAN AIRCRAFT ENGINES and ANRT (CIFRE n°2019/1654).