Imperial College London
Portrait Picture

Professor Aimee S. Morgans

Faculty of Engineering, Department of Mechanical Engineering

Professor of Thermofluids
 
 
 
//

Contact

 

+44 (0)20 7594 9975a.morgans

 
 
//

Location

 

621City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Li:2017:10.1016/j.combustflame.2017.06.018,
author = {Li, J and Xia, Y and Morgans, AS and Han, X},
doi = {10.1016/j.combustflame.2017.06.018},
journal = {Combustion and Flame},
pages = {28--43},
title = {Numerical prediction of combustion instability limit cycle oscillations for a combustor with a long flame},
url = {http://dx.doi.org/10.1016/j.combustflame.2017.06.018},
volume = {185},
year = {2017}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - A coupled numerical approach is investigated for predicting combustion instability limit cycle characteristicswhen the combustor contains a long flame. The test case is the ORACLES combustor, with aturbulent premixed flame a metre long: it exhibits limit cycle oscillations at ∼ 50 Hz and normalisedvelocity amplitude ahead of the flame of ∼ 0.29. The approach obtains the flame response to acousticexcitation using Large Eddy Simulations (LES), and couples this with a low-order wave-based networkrepresentation for the acoustic waves within the combustor. The flame cannot be treated as acousticallycompact; the spatial distribution of both its response and the subsequent effect on the acoustics mustbe accounted for. The long flame is uniformly segmented axially, each segment being much shorter thanthe flow wavelengths at play. A series of “local” flame describing functions, one for the heat release rateresponse within each segment to velocity forcing at a fixed reference location, are extracted from the LES.These use the Computational Fluid Dynamics toolbox, OpenFOAM, with an incompressible approximationfor the flow-field and combustion modelled using the Partially Stirred Reactor model with a global onestepreaction mechanism. For coupling with the low-order acoustic network modelling, compact acousticjump conditions are derived and applied across each flame segment, while between flame segments,wave propagation occurs. Limit cycle predictions from the proposed coupled method agree well withthose predicted using the continuous 1-D linearised Euler equations, validating the flame segmentationimplementation. Limit cycle predictions (frequency 51.6 Hz and amplitude 0.38) also agree well with experimentalmeasurements, validating the low-order coupled method as a prediction tool for combustorswith long flames. A sensitivity analysis shows that the predicted limit cycle amplitude decreases rapidlywhen acoustic losses at boundaries are accounted for, and inc
AU  - Li,J
AU  - Xia,Y
AU  - Morgans,AS
AU  - Han,X
DO  - 10.1016/j.combustflame.2017.06.018
EP  - 43
PY  - 2017///
SN  - 0010-2180
SP  - 28
TI  - Numerical prediction of combustion instability limit cycle oscillations for a combustor with a long flame
T2  - Combustion and Flame
UR  - http://dx.doi.org/10.1016/j.combustflame.2017.06.018
UR  - http://hdl.handle.net/10044/1/53012
VL  - 185
ER  -
Download