Imperial College London
Alternate

ProfessorWilliamJones

Faculty of Engineering, Department of Mechanical Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 7037w.jones

 
 
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Assistant

 

Ms Fabienne Laperche +44 (0)20 7594 7033

 
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Location

 

607City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Fredrich:2021:10.1063/5.0057521,
author = {Fredrich, D and Jones, W and Marquis, A},
doi = {10.1063/5.0057521},
journal = {Physics of Fluids},
pages = {1--22},
title = {A combined oscillation cycle involving self-excited thermo-acoustic and hydrodynamic instability mechanisms},
url = {http://dx.doi.org/10.1063/5.0057521},
volume = {33},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The paper examines the combined effects of several interacting thermo-acoustic and hydrodynamic instability mechanisms that are known to influence self-excited combustion instabilities often encountered in the late design stages of modern low-emission gas turbine combustors. A compressible large eddy simulation approach is presented, comprising the flame burning regime independent, modeled probability density function evolution equation/stochastic fields solution method. The  approach is subsequently applied to the PRECCINSTA (PREDiction and Control of Combustion INSTAbilities) model combustor and successfully captures a fully self-excited limit-cycle oscillation without external forcing. The predicted frequency and amplitude of the dominant thermo-acoustic mode and its first harmonic are shown to be in excellent agreement with available experimental data. Analysis of the phase-resolved and phase- averaged fields leads to a detailed description of the superimposed mass flow rate and equivalence ratio fluctuations underlying the governing feedback loop. The prevailing thermo-acoustic cycle features regular flame liftoff and flashback events in combination with a flame angle oscillation, as well as multiple hydrodynamic phenomena, i.e., toroidal vortex shedding and a precessing vortex core. The periodic excitation and suppression of these hydrodynamic phenomena is confirmed via spectral proper orthogonal decomposition and found to be controlled by an oscillation of the instantaneous swirl number. Their local impact on the heat release rate, which is predominantly modulated by flame-vortex roll- up and enhanced mixing of fuel and oxidizer, is further described and investigated. Finally, the temporal relationship between the flame “surface area,” flame-averaged mixture fraction, and global heat release rate is  shown to be directly correlated.
AU  - Fredrich,D
AU  - Jones,W
AU  - Marquis,A
DO  - 10.1063/5.0057521
EP  - 22
PY  - 2021///
SN  - 1070-6631
SP  - 1
TI  - A combined oscillation cycle involving self-excited thermo-acoustic and hydrodynamic instability mechanisms
T2  - Physics of Fluids
UR  - http://dx.doi.org/10.1063/5.0057521
UR  - https://aip.scitation.org/doi/10.1063/5.0057521
UR  - http://hdl.handle.net/10044/1/91110
VL  - 33
ER  -
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