Indirect noise generated by the acceleration of combustion inhomogeneities is an important aspect in the design of aero-engines because of its impact on the overall noise emitted by an aircraft and the possible contribution to combustion instabilities. In this study, a realistic rich-quench-lean (RQL) combustor is numerically investigated, with the objective of quantitatively analyzing the formation and evolution of flow inhomogeneities and determining the level of indirect combustion noise in the nozzle guide vane (NGV). Both entropy and compositional noise are calculated in this work. A high-fidelity numerical simulation of the combustion chamber, based on the large-eddy simulation (LES) approach with the conditional moment closure (CMC) combustion model, is performed. The contributions of the different air streams to the formation of flow inhomogeneities are pinned down and separated with seven dedicated passive scalars. LES-CMC results are then used to determine the acoustic sources to feed an NGV aeroacoustic model, which outputs the noise generated by entropy and compositional inhomogeneities. Results show that non-negligible fluctuations of temperature and composition reach the combustor's exit. Combustion inhomogeneities originate both from finite-rate chemistry effects and incomplete mixing. In particular, the role of mixing with dilution and liner air flows on the level of combustion inhomogeneities at the combustor's exit is highlighted. The species that most contribute to indirect noise are identified and the transfer functions of a realistic NGV are computed. The noise level indicates that indirect noise generated by temperature fluctuations is larger than the indirect noise generated by compositional inhomogeneities, although the latter is not negligible and is expected to become louder in supersonic nozzles. It is also shown that relatively small fluctuations of the local flame structure can lead to significant variations of the nozzle transfer function, whose gain increases with the Mach number. This highlights the necessity of an on-line solution of the local flame structure, which is performed in this paper by CMC, for an accurate prediction of the level of compositional noise. This study opens new possibilities for the identification, separation, and calculation of the sources of indirect combustion noise in realistic aeronautical gas turbines.

References

References
1.
Motheau
,
E.
,
Nicoud
,
F.
, and
Poinsot
,
T.
,
2014
, “
Mixed Acoustic-Entropy Combustion Instabilities in Gas Turbines
,”
J. Fluid Mech.
,
749
, pp.
542
576
.
2.
Wassmer
,
D.
,
Schuermans
,
B.
,
Paschereit
,
C. O.
, and
Moeck
,
J. P.
,
2017
, “
An Acoustic Time-of-Flight Approach for Unsteady Temperature Measurements: Characterization of Entropy Waves in a Model Gas Turbine Combustor
,”
ASME J. Eng. Gas Turbines Power
,
139
(
4
), p. 041501.
3.
Dowling
,
A. P.
, and
Mahmoudi
,
Y.
,
2015
, “
Combustion Noise
,”
Proc. Combust. Inst.
,
35
(
1
), pp.
65
100
.
4.
Ihme
,
M.
,
2017
, “
Combustion and Engine-Core Noise
,”
Annu. Rev. Fluid Mech.
,
49
(
1
), pp. 277–310.
5.
Magri
,
L.
,
O'Brien
,
J.
, and
Ihme
,
M.
,
2016
, “
Compositional Inhomogeneities as a Source of Indirect Combustion Noise
,”
J. Fluid Mech.
,
799
, p.
R4
.
6.
Poinsot
,
T.
,
2017
, “
Prediction and Control of Combustion Instabilities in Real Engines
,”
Proc. Combust. Inst.
,
36
(
1
), pp.
1
28
.
7.
Morgans
,
A. S.
,
Goh
,
C. S.
, and
Dahan
,
J. A.
,
2013
, “
The Dissipation and Shear Dispersion of Entropy Waves in Combustor Thermoacoustics
,”
J. Fluid Mech.
,
733
, p.
R2
.
8.
Giusti
,
A.
,
Worth
,
N. A.
,
Mastorakos
,
E.
, and
Dowling
,
A. P.
,
2017
, “
Experimental and Numerical Investigation Into the Propagation of Entropy Waves
,”
AIAA J.
,
55
(
2
), pp.
446
458
.
9.
Xia
,
Y.
,
Duran
,
I.
,
Morgans
,
A. S.
, and
Han
,
X.
,
2018
, “
Dispersion of Entropy Perturbations Transporting Through an Industrial Gas Turbine Combustor
,”
Flow, Turbul. Combust.
,
100
(
2
), pp.
481
502
.
10.
Giusti
,
A.
,
2017
, “
Advances in the Modelling of Dispersion and Diffusion of Entropy Waves in Gas-Turbine Combustors
,” 24th International Congress on Sound and Vibration (
ICSV24
), London, July 23–27http://publications.eng.cam.ac.uk/939968/.
11.
Cuadra
,
E.
,
1967
, “
Acoustic Wave Generation by Entropy Discontinuities Flowing past an Area Change
,”
J. Acoust. Soc. Am.
,
42
(
4
), p.
725
.
12.
Marble
,
F. E.
, and
Candel
,
S. M.
,
1977
, “
Acoustic Disturbance From Gas Non-Uniformities Convected Through a Nozzle
,”
J. Sound Vib.
,
55
(
2
), pp.
225
243
.
13.
Bake
,
F.
,
Richter
,
C.
,
Mühlbauer
,
C.
,
Kings
,
N.
,
Röhle
,
I.
,
Thiele
,
F.
, and
Noll
,
B.
,
2009
, “
The Entropy Wave Generator (EWG): A Reference Case on Entropy Noise
,”
J. Sound Vib.
,
326
(
3–5
), pp.
574
598
.
14.
Duran
,
I.
, and
Moreau
,
S.
,
2013
, “
Solution of the Quasi-One-Dimensional Linearized Euler Equations Using Flow Invariants and the Magnus Expansion
,”
J. Fluid Mech.
,
723
, pp.
190
231
.
15.
Howe
,
M. S.
, and
Liu
,
J. T. C.
,
1977
, “
The Generation of Sound by Vorticity Waves in Swirling Duct Flows
,”
J. Fluid Mech.
,
81
(
2
), pp.
369
383
.
16.
Magri
,
L.
,
2017
, “
On Indirect Noise in Multi-Component Nozzle Flows
,”
J. Fluid Mech.
,
828
, p.
R2
.
17.
Magri
,
L.
,
O'Brien
,
J. D.
, and
Ihme
,
M.
,
2018
, “
Effects of Nozzle Helmholtz Number on Indirect Combustion Noise by Compositional Perturbations
,”
ASME J. Eng. Gas Turbines Power
,
140
(
3
), p.
031501
.
18.
O'Brien
,
J. D.
, and
Ihme
,
M.
,
2017
, “
Species Dependency of the Compositional Indirect Noise Mechanism
,”
ASME
Paper No. GT2017-63076.
19.
Rolland
,
E. O. D.
,
Domenico
,
F.
, and
Hochgreb
,
S.
,
2017
, “
Direct and Indirect Noise Generated by Injected Entropic and Compositional Inhomogeneities
,”
ASME
Paper No. GT2017-64428.
20.
Klimenko
,
A.
, and
Bilger
,
R.
,
1999
, “
Conditional Moment Closure for Turbulent Combustion
,”
Prog. Energy Combust. Sci.
,
25
(
6
), pp.
595
687
.
21.
Giusti
,
A.
, and
Mastorakos
,
E.
,
2017
, “
Detailed Chemistry LES/CMC Simulation of a Swirling Ethanol Spray Flame Approaching Blow-Off
,”
Proc. Combust. Inst.
,
36
(
2
), pp.
2625
2632
.
22.
Olguin
,
H.
, and
Gutheil
,
E.
,
2014
, “
Influence of Evaporation on Spray Flamelet Structures
,”
Combust. Flame
,
161
(
4
), pp.
987
996
.
23.
Giusti
,
A.
,
Mastorakos
,
E.
,
Hassa
,
C.
,
Heinze
,
J.
,
Magens
,
E.
, and
Zedda
,
M.
,
2018
, “
Investigation of Flame Structure and Soot Formation in a Single Sector Model Combustor Using Experiments and Numerical Simulations Based on the Large Eddy Simulation/Conditional Moment Closure Approach
,”
ASME J. Eng. Gas Turbines Power
,
140
(
6
), p. 061506.
24.
Mortensen
,
M.
, and
Bilger
,
R. W.
,
2009
, “
Derivation of the Conditional Moment Closure Equations for Spray Combustion
,”
Combust. Flame
,
156
(
1
), pp.
62
72
.
25.
Zhang
,
H.
,
Garmory
,
A.
,
Cavaliere
,
D. E.
, and
Mastorakos
,
E.
,
2015
, “
Large Eddy Simulation/Conditional Moment Closure Modeling of Swirl-Stabilized Non-Premixed Flames With Local Extinction
,”
Proc. Combust. Inst.
,
35
(
2
), pp.
1167
1174
.
26.
Zhang
,
H.
, and
Mastorakos
,
E.
,
2016
, “
Prediction of Global Extinction Conditions and Dynamics in Swirling Non-Premixed Flames Using LES/CMC Modelling
,”
Flow, Turbul. Combust.
,
96
(
4
), pp.
863
889
.
27.
Giusti
,
A.
, and
Mastorakos
,
E.
,
2016
, “
Numerical Investigation Into the Blow-Off Behaviour of Swirling Spray Flames Using the LES/CMC Approach
,” 11th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM-11), Palermo, Italy, Sept. 21–23.
28.
Tyliszczak
,
A.
,
Cavaliere
,
D. E.
, and
Mastorakos
,
E.
,
2014
, “
LES/CMC of Blow-Off in a Liquid Fueled Swirl Burner
,”
Flow, Turbul. Combust.
,
92
(
1–2
), pp.
237
267
.
29.
Ukai
,
S.
,
Kronenburg
,
A.
, and
Stein
,
O.
,
2015
, “
Large Eddy Simulation of Dilute Acetone Spray Flames Using Cmc Coupled With Tabulated Chemistry
,”
Proc. Combust. Inst.
,
35
(
2
), pp.
1667
1674
.
30.
Triantafyllidis
,
A.
, and
Mastorakos
,
E.
,
2010
, “
Implementation Issues of the Conditional Moment Closure Model in Large Eddy Simulations
,”
Flow, Turbul. Combust.
,
84
(
3
), pp.
481
512
.
31.
Nehse
,
M.
,
Warnatz
,
J.
, and
Chevalier
,
C.
,
1996
, “
Kinetic Modeling of the Oxidation of Large Aliphatic Hydrocarbons
,”
Proc. Combust. Inst.
,
26
(
1
), pp.
773
780
.
32.
Anand
,
M. S.
,
Eggels
,
R.
,
Staufer
,
M.
,
Zedda
,
M.
, and
Zhu
,
J.
,
2013
, “
An Advanced Unstructured-Grid Finite-Volume Design System for Gas Turbine Combustion Analysis
,”
ASME
Paper No. GTINDIA2013-3537.
33.
Pope
,
S. B.
,
2000
,
Turbulent Flows
,
Cambridge University Press
,
Cambridge, UK
.
34.
Perini
,
F.
,
2016
, “
The Speedchem Project
,” accessed Dec. 8, 2016, http://www.federicoperini.info/speedchem
35.
Abramzon
,
B.
, and
Sirignano
,
W.
,
1989
, “
Droplet Vaporization Model for Spray Combustion Calculations
,”
Int. J. Heat Mass Transfer
,
32
(
9
), pp.
1605
1618
.
36.
Chiu
,
H. H.
, and
Summerfield
,
M.
,
1974
, “
Theory of Combustion Noise
,”
Acta Astronaut.
,
1
(
7–8
), pp.
967
984
.
37.
Williams
,
F. A.
,
1985
,
Combustion Theory
,
Perseus Books
,
Reading, MA
.
38.
Strahle
,
W. C.
,
1976
, “
Noise Produced by Fluid Inhomogeneities
,”
AIAA J.
,
14
(
7
), pp.
985
987
.
39.
Sattelmayer
,
T.
,
2003
, “
Influence of the Combustor Aerodynamics on Combustion Instabilities From Equivalence Ratio Fluctuations
,”
ASME J. Eng. Gas Turbines Power
,
125
(
1
), pp.
11
19
.
You do not currently have access to this content.