Together with my co-authors, Takaya Koda from Mitsubishi Heavy Industries, and Graham Pullan from the Whittle Lab, I have had a paper published in the Journal of Sound and Vibration, on the acoustic impedance of combustor–turbine gaps.

Motivated by the broader challenge of predicting thermoacoustic stability in gas turbines, we consider a mechanism of acoustic dissipation specific to can-annular combustors. Adjacent combustor cans oscillating in antiphase drive a fluctuating mass flow through the gap between combustor and turbine, converting acoustic energy into vorticity, and it is the magnitude of this dissipation that we seek to quantify to feed back into system stability modelling.

Our first contribution is demonstration of an experimentally validated computational approach for predicting gap acoustic resistance, where existing analytical models fail. Our second contribution is a systematic exploration of the sensitivity of resistance to gap geometry and mean flow conditions.

By quantifing the effects of combustor design changes on acoustic dissipation, and explaining the underlying physics, the paper should be of interest to those working on gas turbine thermoacoustic stability.

For details you can read the full paper (it is open-access).

On a meta note, the review, editing, and production process for this paper was unusually fast and smooth, and the running of the Journal of Sound and Vibration compares favorably to other turbomachinery-related journals.