During the design and testing process of swirl-stabilized combustors, it is often impractical to maintain identical outlet boundary conditions. Furthermore, it is a common practice to intentionally change the acoustic boundary conditions of the outlet in order to suppress thermoacoustic instabilities. In the presented work the susceptibility of the reacting flow field to downstream perturbations is assessed by the application of an area contraction at the outlet. Since combustion and fuel composition are shown to be important parameters for the influence of the boundary conditions on the flow field, highly steam diluted flames are investigated in addition to dry flames at different equivalence ratios and degrees of swirl. The applied measurement techniques include particle image velocimetry, laser doppler velocimetry, and emission analysis. The results reveal a clear correlation of the susceptibility of the flow field to downstream perturbations to both the inlet swirl number and the amount of dilatation caused by the flame. The concept of an effective swirl number downstream of the flame is applied to the results and is proven to be the dominating parameter. A theoretical explanation for the influence of this parameter is provided by the usage of the well known theory of subcritical and supercritical swirling flows, where perturbations can propagate upstream solely in subcritical flows via standing waves. Knowledge of the flow state is of particular importance for the evaluation of combustion tests with differing exit boundary conditions and the results emphasize the need for realistic exit boundary conditions for numerical simulations.

References

References
1.
Syred
,
N.
, and
Beér
,
J. M.
, 1974, “
Combustion in Swirling Flows: A Review
,”
Combust. Flame
,
23
(
2
), pp.
143
201
.
2.
Huang
,
Y.
, and
Yang
,
V.
, 2009, “
Dynamics and Stability of Lean-Premixed Swirl-Stabilzed Combustion
,”
Progress Energy Combust. Sci.
,
35
(
4
), pp.
293
364
.
3.
Lieuwen
,
T.
, and
Yang
,
V.
, 2005,
Combustion Instabilities in Gas Turbine Engines: Operational Experience, Fundamental Mechanisms, and Modeling
(Progress in Astronautics and Aeronautics), Vol. 210,
American Institute of Aeronautics and Astronautics
,
Reston, VA
.
4.
Zajadatz
,
M.
,
Lachner
,
R.
,
Bernero
,
S.
,
Motz
,
C.
, and
Flohr
,
P.
, 2007, “
Development and Design of Alstoms’s Staged Fuel Gas Injection EV Burner for NOx Reduction
,” Proceedings of GT2007 ASME Turbo Expo 2007: Power for Land, Sea and Air, Montreal, Canada, May 14–17,
ASME
Paper No.GT2007-27730.
5.
Schuermans
,
B.
,
Güthe
,
F.
,
Pennell
,
D.
,
Guyot
,
D.
, and
Paschereit
,
C. O.
, 2010, “
Thermoacoustic Modeling of a Gas Turbine Using Transfer Functions Measured Under Full Engine Pressure
,”
ASME J. Eng. Gas Turbines Power
,
132
(
11
), p.
111503
.
6.
Kim
,
K. T.
,
Lee
,
J. G.
,
Quay
,
B. D.
, and
Santavicca
,
D. A.
, 2010, “
Spatially Distributed Flame Transfer Functions for Predicting Combustion Dynamics in Lean Premixed Gas Turbine Combustors
,”
Combust. Flame
,
157
(
9
), pp.
1718
1730
.
7.
Mongia
,
H. C.
,
Held
,
T. J.
, and
Hsiao
,
G. C.
, 2003, “
Challenges and Progress in Controlling Dynamics in Gas Turbine Combustors
,”
J. Propul. Power
,
19
(
5
), pp.
822
829
.
8.
Ćosić
,
B.
,
Bobusch
,
B. C.
,
Moeck
,
J. P.
, and
Paschereit
,
C. O.
, 2012, “
Open-Loop Control of Combustion Instabilities and the Role of the Flame Response to Two-Frequency Forcing
,”
ASME J. Eng. Gas Turbines Power
,
134
(
6
), p.
061502
.
9.
Squire
,
H. B.
, 1962, “
Analysis of the Vortex Breakdown Phenomenon. Part I
,”
Miszellaneen der Angewandten Mechanik
,
Akademie
,
Berlin
, pp.
306
312
.
10.
Benjamin
,
T. B.
, 1962, “
Theory of the Vortex Breakdown Phenomenon
,”
J. Fluid Mech.
,
14
(
04
), pp.
593
629
.
11.
Escudier
,
M. P.
, and
Keller
,
J. J.
, 1985, “
Recirculation in Swirling Flow—A Manifestation of Vortex Breakdown
,”
AIAA J.
,
23
(
1
), pp.
111
116
.
12.
Altgeld
,
H.
,
Jones
,
W. P.
, and
Wilhelmi
,
J.
, 1983, “
Velocity Measurements in a Confined Swirl Driven Recirculating Flow
,”
Exp. Fluids
,
1
(
2
), pp.
73
78
.
13.
Li
,
G.
, and
Gutmark
,
E. J.
, 2005, “
Effect of Exhaust Nozzle Geometry on Combustor Flow Field and Combustion Characteristics
,”
Proc. Combust. Inst.
,
30
(
2
), pp.
2893
2901
.
14.
Weber
,
R.
, and
Dugué
,
J.
, 1992, “
Combustion Accelerated Swirling Flows in High Confinements
,”
Progress Energy Combust. Sci.
,
18
(
4
), pp.
349
367
.
15.
Soares
,
C.
, 2007,
Gas Turbines: A Handbook of Air, Land and Sea Applications
.
Butterworth
Heinemann, London
.
16.
Bartlett
,
M. A.
, and
Westermark
,
M. O.
, 2005, “
A Study of Humidified Gas Turbines for Short-Term Realization in Midsized Power Generation—Part I: Nonintercooled Cycle Analysis
,”
ASME J. Eng. Gas Turbines Power
,
127
(
1
), pp.
91
99
.
17.
Bartlett
,
M. A.
, and
Westermark
,
M. O.
, 2005, “
A Study of Humidified Gas Turbines for Short-Term Realization in Midsized Power Generation—Part II: Intercooled Cycle Analysis and Final Economic Evaluation
,”
ASME J. Eng. Gas Turbines Power
,
127
(
1
), pp.
100
108
.
18.
Göke
,
S.
,
Göckeler
,
K.
,
Krüger
,
O.
, and
Paschereit
,
C. O.
, 2010, “
Computational and Experimental Study of Premixed Combustion at Ultra Wet Conditions
,” Proceedings of GT2010 ASME Turbo Expo 2010: Power for Land, Sea and Air, Glasgow, Scotland, June 14–18,
ASME
Paper No. GT2010-23417.
19.
Göke
,
S.
,
Terhaar
,
S.
,
Schimek
,
S.
,
Göckeler
,
K.
, and
Paschereit
,
C. O.
, 2011, “
Combustion of Natural Gas, Hydrogen and Bio-Fuels at Ultra-Wet Conditions
,” Proceedings of ASME Turbo Expo 2011: Power for Land,
Sea and Air
, Vancouver, Canada, June 6–10,
ASME
Paper No. GT2011-45696.
20.
Terhaar
,
S.
,
Göckeler
,
K.
,
Schimek
,
S.
,
Göke
,
S.
, and
Paschereit
,
C. O.
, 2011, “
Non-Reacting and Reacting Flow in a Swirl-Stabilized Burner for Ultra-Wet Combustion
,” Proceedings of 41st AIAA Fluid Dynamics Conference and Exhibit, Honolulu, HI, June 27–30, AIAA Paper No. 2011-3584.
21.
Leuckel
,
W.
, 1967, “
Swirl Intensities, Swirl Types and Energy Losses of Different Swirl Generating Devices
,”
IFRF Doc. Nr. G
,
2
(
0
).
22.
Smith
,
G. P.
,
Golden
,
D. M.
,
Frenklach
,
M.
,
Moriarty
,
N. W.
,
Eiteneer
,
B.
,
Goldenberg
,
M.
,
Bowman
,
C. T.
,
Hanson
,
R. K.
,
Song
,
S.
,
Gardiner
,
W. C.
,
Lissianski
,
V. V.
, and
Qin
,
Z.
, “
GRI-Mech 3.0
,” http://www.me.berkeley.edu/gri_mech/http://www.me.berkeley.edu/gri_mech/, accessed February 2, 2012.
23.
Göke
,
S.
, and
Paschereit
,
C. O.
, 2012, “
Influence of Steam Dilution on NOx Formation in Premixed Natural Gas and Hydrogen Flames
,” 50th AIAA Aerospace Science Meeting, AIAA-2012-1272, Nashville, TN, January 9–12.
24.
Escudier
,
M. P.
,
Nickson
,
A. K.
, and
Poole
,
R. J.
, 2006, “
Influence of Outlet Geometry on Strongly Swirling Turbulent Flow Through a Circular Tube
,”
Phys. Fluids
,
18
(
12
), p.
125103
.
25.
Leschziner
,
M. A.
, and
Hogg
,
S.
, 1989, “
Computation of Highly Swirling Confined Flow With a Reynolds Stress Turbulence Model
,”
AIAA J.
,
27
(
1
), pp.
57
63
.
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