This study deals with thermoacoustic instabilities in a generic sequential combustor. The thermoacoustic feedback involves two flames: the perfectly premixed swirled flame anchored in the first stage and the sequential flame established downstream of the mixing section, into which secondary fuel is injected in the vitiated stream from the first stage. It is shown that the large amplitude flapping of the secondary fuel jet in the mixing section plays a key role in the thermoacoustic feedback. This evidence is brought using high-speed background-oriented Schlieren (BOS). The fuel jet flapping is induced by the intense acoustic field at the fuel injection point. It has two consequences: first, it leads to the advection of equivalence ratio oscillations toward the sequential flame; second, it modulates the residence time of the ignitable mixture in the mixing section, which periodically triggers autoignition kernels developing upstream of the chamber. In addition, the BOS images are processed to quantify the flow velocity in the mixing section and these results are validated using particle image velocimetry (PIV). This study presents a new type of thermoacoustic feedback mechanism, which is peculiar to sequential combustion systems. In addition, it demonstrates how BOS can effectively complement other diagnostic techniques that are routinely used for the study of thermoacoustic instabilities.

References

References
1.
Pennell
,
D. A.
,
Bothien
,
M. R.
,
Ciani
,
A.
,
Granet
,
V.
,
Singla
,
G.
,
Thorpe
,
S.
,
Wickstroem
,
A.
,
Oumejjoud
,
K.
, and
Yaquinto
,
M.
,
2017
, “
An Introduction to the Ansaldo GT36 Constant Pressure Sequential Combustor
,”
ASME
Paper No. GT2017-64790
.
2.
Motheau
,
E.
,
Nicoud
,
F.
, and
Poinsot
,
T.
,
2014
, “
Mixed Acoustic-Entropy Combustion Instabilities in Gas Turbines
,”
J. Fluid Mech.
,
749
, pp.
542
576
.
3.
Poinsot
,
T.
,
2017
, “
Prediction and Control of Combustion Instabilities in Real Engines
,”
Proc. Combust. Inst.
,
36
(
1
), pp.
1
28
.
4.
Berger
,
F.
,
Hummel
,
T.
,
Romero Vega
,
P.
,
Schuermans
,
B.
, and
Sattelmayer
,
T.
,
2018
, “
A Novel Reheat Combustor Experiment for the Analysis of High-Frequency Flame Dynamics - Concept and Experimental Validation
,”
ASME
Ppaper No. GT2018-77101.
5.
Saurabh
,
A.
, and
Paschereit
,
C. O.
,
2017
, “
Dynamics of Premixed Swirl Flames Under the Influence of Transverse Acoustic Fluctuations
,”
Combust. Flame
,
182
, pp.
298
312
.
6.
Stöhr
,
M.
,
Yin
,
Z.
, and
Meier
,
W.
,
2017
, “
Interaction Between Velocity Fluctuations and Equivalence Ratio Fluctuations During Thermoacoustic Oscillations in a Partially Premixed Swirl Combustor
,”
Proc. Combust. Inst.
,
36
(
3
), pp.
3907
3915
.
7.
Severin
,
M.
,
Lammel
,
O.
,
Ax
,
H.
,
Lückenrath
,
R.
,
Meier
,
W.
,
Aigner
,
M.
, and
Heinze
,
J.
,
2017
, “
High Momentum Jet Flames at Elevated Pressure: B—Detailed Investigation of Flame Stabilization With Simultaneous PIV and OH-LIF
,”
ASME
Paper No. GT2017-64556
.
8.
Boxx
,
I.
,
Stöhr
,
M.
,
Carter
,
C.
, and
Meier
,
W.
,
2010
, “
Temporally Resolved Planar Measurements of Transient Phenomena in a Partially Pre-Mixed Swirl Flame in a Gas Turbine Model Combustor
,”
Combust. Flame
,
157
(
8
), pp.
1510
1525
.
9.
Petersson
,
P.
,
Olofsson
,
J.
,
Brackman
,
C.
,
Seyfried
,
H.
,
Zetterberg
,
J.
,
Richter
,
M.
,
Aldén
,
M.
,
Linne
,
M. A.
,
Cheng
,
R. K.
,
Nauert
,
A.
,
Geyer, D.
, and
Dreizler, A.
,
2007
, “
Simultaneous PIV/OH-PLIF, Rayleigh Thermometry/OH-PLIF and Stereo PIV Measurements in a Low-Swirl Flame
,”
Appl. Opt.
,
46
(
19
), pp.
3928
3936
.
10.
Stella
,
A.
,
Guj
,
G.
,
Kompenhans
,
J.
,
Raffel
,
M.
, and
Richard
,
H.
,
2001
, “
Application of Particle Image Velocimetry to Combusting Flows: Design Considerations and Uncertainty Assessment
,”
Exp. Fluids
,
30
(
2
), pp.
167
180
.
11.
Melling
,
A.
,
1997
, “
Tracer Particles and Seeding for Particle Image Velocimetry
,”
Meas. Sci. Technol.
,
8
(
12
), pp.
1406
1416
.
12.
Kobayashi
,
H.
,
Nakashima
,
T.
,
Tamura
,
T.
,
Maruta
,
K.
, and
Niioka
,
T.
,
1997
, “
Turbulence Measurements and Observations of Turbulent Premixed Flames at Elevated Pressures Up to 3.0 Mpa
,”
Combust. Flame
,
108
(
1–2
), pp. 104–110.
13.
Raffel
,
M.
,
2015
, “
Background-Oriented Schlieren (BOS) Techniques
,”
Exp. Fluids
,
56
(
3
), p.
60
.
14.
Richard
,
H.
, and
Raffel
,
M.
,
2001
, “
Principle and Applications of the Background Oriented Schlieren (BOS) Method
,”
Meas. Sci. Technol.
,
12
(
9
), p.
1576
.
15.
Lang
,
H. M.
,
Oberleithner
,
K.
,
Paschereit
,
C. O.
, and
Sieber
,
M.
,
2017
, “
Measurement of the Fluctuating Temperature Field in a Heated Swirling Jet With BOS Tomography
,”
Exp. Fluids
,
58
(
7
), p.
88
.
16.
Tan
,
D. J.
,
Edgington-Mitchell
,
D.
, and
Honnery
,
D.
,
2015
, “
Measurement of Density in Axisymmetric Jets Using a Novel Background-Oriented Schlieren (BOS) Technique
,”
Exp. Fluids
,
56
(
11
), p.
204
.
17.
Mizukaki
,
T.
,
Borg
,
S. E.
,
Danehy
,
P. M.
, and
Murman
,
S. M.
,
2014
, “
Visualization of Flow Separation Around an Atmospheric Entry Capsule at Low-Subsonic Mach Number Using Background-Oriented Schlieren (BOS)
,”
AIAA
Paper No. AIAA 2014-2521.
18.
Stadler
,
H.
,
Bauknecht
,
A.
,
Siegrist
,
S.
,
Flesch
,
R.
,
Wolf
,
C. C.
,
van Hinsberg
,
N.
, and
Jacobs
,
M.
,
2017
, “
Background-Oriented Schlieren Imaging of Flow Around a Circular Cylinder at Low Mach Numbers
,”
Exp. Fluids
,
58
(
9
), p.
114
.
19.
Bichal
,
A.
, and
Thurow
,
B.
,
2014
, “
On the Application of Background Oriented Schlieren for Wavefront Sensing
,”
Meas. Sci. Technol.
,
25
(
1
), p.
015001
.
20.
Ramanah
,
D.
,
Raghunath
,
S.
,
Mee
,
D.
,
Rösgen
,
T.
, and
Jacobs
,
P.
,
2007
, “
Background Oriented Schlieren for Flow Visualisation in Hypersonic Impulse Facilities
,”
Shock Waves
,
17
(
1–2
), pp.
65
70
.
21.
Elsinga
,
G.
,
Van Oudheusden
,
B.
,
Scarano
,
F.
, and
Watt
,
D.
,
2004
, “
Assessment and Application of Quantitative Schlieren Methods: Calibrated Color Schlieren and Background Oriented Schlieren
,”
Exp. Fluids
,
36
(
2
), pp.
309
325
.
22.
Atcheson
,
B.
,
Heidrich
,
W.
, and
Ihrke
,
I.
,
2009
, “
An Evaluation of Optical Flow Algorithms for Background Oriented Schlieren Imaging
,”
Exp. Fluids
,
46
(
3
), pp.
467
476
.
23.
Merzkirch
,
W.
, ed.,
1987
,
Flow Visualization
,
2nd ed.
,
Academic Press
,
San Diego, CA
.
24.
Sun
,
D.
,
Roth
,
S.
, and
Black
,
M. J.
,
2010
, “
Secrets of Optical Flow Estimation and Their Principles
,”
IEEE Conference on Computer Vision and Pattern Recognition
(
CVPR
), San Francisco, CA, June 13–18, pp.
2432
2439
.
25.
Meinhardt-Llopis
,
E.
,
Sánchez Pérez
,
J.
, and
Kondermann
,
D.
,
2013
, “
Horn-Schunck Optical Flow With a Multi-Scale Strategy
,”
Image Process. Line
,
3
, pp.
151
172
.
26.
Dennis
,
C. N.
,
Slabaugh
,
C. D.
,
Boxx
,
I. G.
,
Meier
,
W.
, and
Lucht
,
R. P.
,
2016
, “
5 Khz Thermometry in a Swirl-Stabilized Gas Turbine Model Combustor Using Chirped Probe Pulse Femtosecond CARS—Part 1: Temporally Resolved Swirl-Flame Thermometry
,”
Combust. Flame
,
173
, pp.
441
453
.
27.
Fan
,
L.
,
Gao
,
Y.
,
Hayakawa
,
A.
, and
Hochgreb
,
S.
,
2017
, “
Simultaneous, Two-Camera, 2d Gas-Phase Temperature and Velocity Measurements by Thermographic Particle Image Velocimetry With Zno Tracers
,”
Exp. Fluids
,
58
(
4
), p.
34
.
28.
Wassmer
,
D.
,
Schuermans
,
B.
,
Paschereit
,
C. O.
, and
Moeck
,
J. P.
,
2016
, “
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
.
29.
Sadanandan
,
R.
,
Stöhr
,
M.
, and
Meier
,
W.
,
2008
, “
Simultaneous oh-Plif and Piv Measurements in a Gas Turbine Model Combustor
,”
Appl. Phys. B
,
90
(
3–4
), pp.
609
618
.
30.
Schulz
,
O.
,
Doll
,
U.
,
Ebi
,
D.
,
Droujko
,
J.
,
Bourquard
,
C.
, and
Noiray
,
N.
,
2018
, “
Thermoacoustic Instability in a Sequential Combustor: Large Eddy Simulation and Experiments
,”
Proc. Combust. Inst.
, (in press).
31.
Temme
,
J. E.
,
Allison
,
P. M.
, and
Driscoll
,
J. F.
,
2014
, “
Combustion Instability of a Lean Premixed Prevaporized Gas Turbine Combustor Studied Using Phase-Averaged PIV
,”
Combust. Flame
,
161
(
4
), pp.
958
970
.
32.
Kheirkhah
,
S.
,
Cirtwill
,
J. D. M.
,
Saini
,
P.
,
Venkatesan
,
K.
, and
Steinberg
,
A. M.
,
2017
, “
Dynamics and Mechanisms of Pressure, Heat Release Rate, and Fuel Spray Coupling During Intermittent Thermoacoustic Oscillations in a Model Aeronautical Combustor at Elevated Pressure
,”
Combust. Flame
,
185
(
Suppl. C
), pp.
319
334
.
33.
Biswas
,
S.
, and
Qiao
,
L.
,
2017
, “
A Comprehensive Statistical Investigation of Schlieren Image Velocimetry (SIV) Using High-Velocity Helium Jet
,”
Exp. Fluids
,
58
(
3
), p.
18
.
34.
Schulz
,
O.
, and
Noiray
,
N.
,
2018
, “
Autoignition Flame Dynamics in Sequential Combustors
,”
Combust. Flame
,
192
, pp. 86–100.
You do not currently have access to this content.