Abstract

Experiments are performed in a partially premixed bluff body-stabilized turbulent combustor by varying the mean flow velocity. Simultaneous measurements obtained for unsteady pressure, velocity, and heat release rate are used to investigate the dynamic regimes of intermittency (10.1 m/s) and thermoacoustic instability (12.3 m/s). Using wavelet analysis, we show that during intermittency, modulation of heat release rate occurring at the acoustic frequency fa by the heat release rate occurring at the hydrodynamic frequency fh results in epochs of heat release rate fluctuations where the heat release rate is phase locked with the acoustic pressure. We also show that the flame position during intermittency and thermoacoustic instability are essentially dictated by saddle point dynamics in the dump plane and the leading edge of the bluff body.

References

References
1.
Lieuwen
,
T.
,
2013
, “
Combustion Driven Oscillations in Gas Turbines
,”
Turbomach. Int.
,
44
(
1
), pp.
16
18
.
2.
Brown
,
G. L.
, and
Roshko
,
A.
,
1974
, “
On Density Effects and Large Structure in Turbulent Mixing Layers
,”
J. Fluid Mech.
,
64
(
4
), pp.
775
816
.10.1017/S002211207400190X
3.
Schadow
,
K. C.
,
Gutmark
,
E.
,
Parr
,
T. P.
,
Parr
,
D. M.
,
Wilson
,
K. J.
, and
Crump
,
J. E.
,
1989
, “
Large-Scale Coherent Structures as Drivers of Combustion Instability
,”
Combust. Sci. Tech.
,
64
(
4–6
), pp.
167
186
.10.1080/00102208908924029
4.
Schadow
,
K. C.
, and
Gutmark
,
E.
,
1992
, “
Combustion Instability Related to Vortex Shedding in Dump Combustors and Their Passive Control
,”
Prog. Energy Combust. Sci.
,
18
(
2
), pp.
117
132
.10.1016/0360-1285(92)90020-2
5.
Nair
,
V.
,
Thampi
,
G.
, and
Sujith
,
R. I.
,
2014
, “
Intermittency Route to Thermoacoustic Instability in Turbulent Combustors
,”
J. Fluid Mech.
,
756
, pp.
470
487
.10.1017/jfm.2014.468
6.
Nair
,
V.
, and
Sujith
,
R. I.
,
2015
, “
Intermittency as a Transition State in Combustion Dynamics: An Explanation for Flame Dynamics Near Lean Blowout
,”
Combust. Sci. Technol.
,
187
(
11
), pp.
1821
1835
.10.1080/00102202.2015.1066339
7.
Tony
,
J.
,
Gopalakrishnan
,
E. A.
,
Sreelekha
,
E.
, and
Sujith
,
R. I.
,
2015
, “
Detecting Deterministic Nature of Pressure Measurements From a Turbulent Combustor
,”
Phys. Rev. E
,
92
(
6
), p.
062902
.10.1103/PhysRevE.92.062902
8.
Nair
,
V.
,
Thampi
,
G.
,
Karuppusamy
,
S.
,
Gopalan
,
S.
, and
Sujith
,
R. I.
,
2013
, “
Loss of Chaos in Combustion Noise as a Precursor of Impending Combustion Instability
,”
Int. J. Spray Combust.
,
5
(
4
), pp.
273
290
.10.1260/1756-8277.5.4.273
9.
Nair
,
V.
, and
Sujith
,
R. I.
,
2014
, “
Multifractality in Combustion Noise: Predicting an Impending Combustion Instability
,”
J. Fluid Mech.
,
747
, pp.
635
655
.10.1017/jfm.2014.171
10.
Unni
,
V. R.
, and
Sujith
,
R. I.
,
2015
, “
Multifractal Characteristics of Combustor Dynamics Close to Lean Blowout
,”
J. Fluid Mech.
,
784
, pp.
30
50
.10.1017/jfm.2015.567
11.
Haller
,
G.
,
2015
, “
Lagrangian Coherent Structures
,”
Annu. Rev. Fluid Mech.
,
47
(
1
), pp.
137
162
.10.1146/annurev-fluid-010313-141322
12.
Green
,
M.
,
Rowley
,
C.
, and
Smits
,
A.
,
2011
, “
The Unsteady Three-Dimensional Wake Produced by a Trapezoidal Pitching Panel
,”
J. Fluid Mech.
,
685
, pp.
117
145
.10.1017/jfm.2011.286
13.
Nair
,
V.
,
Alenius
,
E.
,
Boij
,
S.
, and
Efraimsson
,
G.
,
2016
, “
Inspecting Sound Sources in an Orifice-Jet Flow Using Lagrangian Coherent Structures
,”
Comput. Fluids
,
140
, pp.
397
405
.10.1016/j.compfluid.2016.09.001
14.
Peng
,
J.
, and
Dabiri
,
J.
,
2009
, “
Transport of Inertial Particles by Lagrangian Coherent Structures: Application to Predator-Prey Interaction in Jellyfish Feeding
,”
J. Fluid Mech.
,
623
, pp.
75
84
.10.1017/S0022112008005089
15.
Beron-Vera
,
F.
,
Olascoaga
,
M.
, and
Goni
,
G.
,
2008
, “
Oceanic Mesoscale Eddies as Revealed by Lagrangian Coherent Structures
,”
Geophys. Res. Lett.
,
35
, p.
L12603
.10.1029/2008GL033957
16.
Premchand
,
C. P.
,
George
,
N. B.
,
Raghunathan
,
M.
,
Unni
,
V. R.
,
Sujith
,
R. I.
, and
Nair
,
V.
,
2019
, “
Lagrangian Analysis of Intermittent Sound Sources in the Flow-Field of a Bluff-Body Stabilized Combustor
,”
Phys. Fluids
,
31
(
2
), p.
025115
.10.1063/1.5064862
17.
Sampath
,
R.
,
Mathur
,
M.
, and
Chakravarthy
,
S. R.
,
2016
, “
Lagrangian Coherent Structures During Combustion Instability in a Premixed-Flame Backward-Step Combustor
,”
Phys. Rev. E.
,
94
(
6
), p.
062209
.10.1103/PhysRevE.94.062209
18.
Schmid
,
P. J.
,
2010
, “
Dynamic Mode Decomposition of Numerical and Experimental Data
,”
J. Fluid Mech.
,
656
, pp.
5
28
.10.1017/S0022112010001217
19.
Komarek
,
T.
, and
Polifke
,
W.
,
2010
, “
Impact of Swirl Fluctuations on the Flame Response of a Perfectly Premixed Swirl Burner
,”
ASME J. Eng. Gas Turbines Power
,
132
, p.
061503
.10.1115/1.4000127
20.
Raffel
,
M.
,
Willert
,
C. E.
,
Wereley
,
S.
, and
Kompenhans
,
J.
,
2007
,
Particle Image Velocimetry: A Practical Guide
,
Springer,
Verlag Berlin Heidelberg.
21.
Strogatz
,
S. H.
,
1994
,
Nonlinear Dynamics and Chaos: With Applications to Physics, Biology, Chemistry, and Engineering
,
CRC press, Boca Raton, FL.
22.
Schmid
,
P. J.
,
Li
,
L.
,
Juniper
,
M. P.
, and
Pust
,
O.
,
2011
, “
Applications of the Dynamic Mode Decomposition
,”
Theor. Comput. Fluid Dyn.
,
25
(
1–4
), pp.
249
259
.10.1007/s00162-010-0203-9
23.
Alenius
,
E.
,
2012
, “
Flow Duct Acoustics—An LES Approach
,” Doctoral thesis, KTH Royal Institute of Technology, Stockholm, Sweden.
24.
Alenius
,
E.
,
2014
, “
Mode Switching in a Thick Orifice Jet, an LES and Dynamic Mode Decomposition Approach
,”
Comput. Fluids
,
90
, pp.
101
112
.10.1016/j.compfluid.2013.11.022
25.
Nair
,
V.
, and
Sujith
,
R. I.
,
2015
, “
A Reduced-Order Model for the Onset of Combustion Instability: Physical Mechanisms for Intermittency and Precursors
,”
Proc. Combust. Inst.
,
35
(
3
), pp.
3193
3200
.10.1016/j.proci.2014.07.007
26.
Matveev
,
K. I.
, and
Culick
,
F. E. C.
,
2003
, “
A Model for Combustion Instability Involving Vortex Shedding
,”
Combust. Sci. Technol.
,
175
(
6
), pp.
1059
1083
.10.1080/00102200302349
27.
Lieuwen
,
T.
,
2012
,
Unsteady Combustor Physics
,
Cambridge University Press
, New York.
You do not currently have access to this content.