Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor

被引:92
作者
Altay, H. Murat [1 ]
Speth, Raymond L. [1 ]
Hudgins, Duane E. [1 ]
Ghoniem, Ahmed F. [1 ]
机构
[1] MIT, Dept Mech Engn, Cambridge, MA 02139 USA
关键词
Thermoacoustic instability; Combustion dynamics; Flame-vortex interactions; GAS-TURBINE COMBUSTORS; PRESSURE OSCILLATIONS; PREMIXED COMBUSTION; INSTABILITY; MECHANISM; SIMULATION; MODEL; MIXTURES; METHANE;
D O I
10.1016/j.combustflame.2009.02.003
中图分类号
O414.1 [热力学];
学科分类号
摘要
The combustion dynamics of propane-hydrogen Mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure. velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed names can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel composition separately. We formulate a theory for predicting the critical values of the heat release parameter at which quasi-stable to unstable and unstable to high-frequency unstable modes take place. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
引用
收藏
页码:1111 / 1125
页数:15
相关论文
共 41 条
[1]   Instability mechanisms in a premixed prevaporized combustor [J].
Bernier, D ;
Lacas, F ;
Candel, S .
JOURNAL OF PROPULSION AND POWER, 2004, 20 (04) :648-656
[2]   FLAME STRETCH AND THE BALANCE EQUATION FOR THE FLAME AREA [J].
CANDEL, SM ;
POINSOT, TJ .
COMBUSTION SCIENCE AND TECHNOLOGY, 1990, 70 (1-3) :1-15
[3]   Instability in lean premixed combustors [J].
Dowling, AP ;
Hubbard, S .
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY, 2000, 214 (A4) :317-332
[4]   Acoustic analysis of gas turbine combustors [J].
Dowling, AP ;
Stow, SR .
JOURNAL OF PROPULSION AND POWER, 2003, 19 (05) :751-764
[5]   Combustion dynamics and instabilities: Elementary coupling and driving mechanisms [J].
Ducruix, S ;
Schuller, T ;
Durox, D ;
Candel, S .
JOURNAL OF PROPULSION AND POWER, 2003, 19 (05) :722-734
[6]  
FIGURA L, 2007, 52 ASME TURB EXP C
[7]   An experimental investigation of thermoacoustic instabilities in a premixed swirl-stabilized flame [J].
Fritsche, D. ;
Fueri, M. ;
Boulouchos, K. .
COMBUSTION AND FLAME, 2007, 151 (1-2) :29-36
[8]   A computational study of combustion instabilities due to vortex shedding [J].
Fureby, C .
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2000, 28 :783-791
[9]   A numerical study of lean CH4/H2/air premixed flames at high pressure [J].
Gauducheau, JL ;
Denet, B ;
Searby, G .
COMBUSTION SCIENCE AND TECHNOLOGY, 1998, 137 (1-6) :81-99
[10]   Mechanism of combustion dynamics in a backward-facing step stabilized premixed flame [J].
Ghoniem, AF ;
Park, S ;
Wachsman, A ;
Annaswamy, A ;
Wee, D ;
Altay, HM .
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2005, 30 :1783-1790