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

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.

Automated summary

The acoustic flux at the inlet of the combustion chamber is used as an indicator for impending thermo-acoustic instabilities (TAI) in a swirled spray combustor. The acoustic flux exhibits significant magnitude changes and shape evolutions when approaching TAI, while being relatively insensitive to modifications in signal processing parameters.