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An experimental study of effects of confinement ratio on swirl stabilized flame macrostructures

Tong, Yiheng LU ; Li, Mao LU ; Thern, Marcus LU and Klingmann, Jens LU (2017) ASME 2017 Power Conference Joint with ICOPE 2017, POWER 2017-ICOPE 2017, collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum In Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant 1.
Abstract

Swirl stabilized premixed flames are common in industrial gas turbines. The flame shape in the combustor is highly related to the combustion stability and the performance of the gas turbine. In the current paper, the effects of confinement on the time averaged flame structures or flame macrostructures are studied experimentally. Experiments are carried out with swirl number S = 0.66 in two cylindrical confinements with diameters of d1 = 39 mm and d2 = 64 mm and confinement ratio c1 = 0.148 and c2 = 0.0567. All the experiments were carried out in atmospheric. CH chemiluminescence from the flame was recorded to visualize the flame behavior. An inverse Abel image reconstruction method... (More)

Swirl stabilized premixed flames are common in industrial gas turbines. The flame shape in the combustor is highly related to the combustion stability and the performance of the gas turbine. In the current paper, the effects of confinement on the time averaged flame structures or flame macrostructures are studied experimentally. Experiments are carried out with swirl number S = 0.66 in two cylindrical confinements with diameters of d1 = 39 mm and d2 = 64 mm and confinement ratio c1 = 0.148 and c2 = 0.0567. All the experiments were carried out in atmospheric. CH chemiluminescence from the flame was recorded to visualize the flame behavior. An inverse Abel image reconstruction method was employed to better distinguish the flame macrostructures. Different mechanisms forming the time averaged M shape flames are proposed and analyzed. It is found that the confinement wall plays an important role in determining the flame macrostructures. The flow structures including the inner and outer recirculation zones formed in the confinement are revealed to be the main reasons that affects different flame macrostructures. Meanwhile, the alternation of flame shapes determines the flame stability characteristics. A smaller confinement diameter forced the flame front to bend upstream into the outer recirculation zone hence forming a M shape flame. A strong noise caused by the interaction of the flame front in the outer recirculation zone with the combustor wall was observed. Another unsteady behavior of the flame in the bigger combustor, which was caused by the alternation of the flame root position inside and outside the premixing tube, is also presented. The V shape flame in the two combustors radiated weaker chemiluminescence but the main heat release zone was elongated than the M shape flame. Other operating conditions, i.e. total mass flow rate of the air flow and the equivalence ratio also affect the flame macrostructures. The flame blowout limits were also altered under different test conditions. The bigger confinement has better performance in stabilizing the flame by having lower lean blowout limits.

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author
organization
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publication status
published
subject
in
Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant
volume
1
publisher
American Society Of Mechanical Engineers (ASME)
conference name
ASME 2017 Power Conference Joint with ICOPE 2017, POWER 2017-ICOPE 2017, collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum
external identifiers
  • scopus:85029828867
ISBN
9780791857601
DOI
10.1115/POWER-ICOPE2017-3064
language
English
LU publication?
yes
id
6762cef1-5b00-48cc-90d0-a623e1125d65
date added to LUP
2017-10-09 13:08:07
date last changed
2018-04-08 05:01:22
@inproceedings{6762cef1-5b00-48cc-90d0-a623e1125d65,
  abstract     = {<p>Swirl stabilized premixed flames are common in industrial gas turbines. The flame shape in the combustor is highly related to the combustion stability and the performance of the gas turbine. In the current paper, the effects of confinement on the time averaged flame structures or flame macrostructures are studied experimentally. Experiments are carried out with swirl number S = 0.66 in two cylindrical confinements with diameters of d<sub>1</sub> = 39 mm and d<sub>2</sub> = 64 mm and confinement ratio c<sub>1</sub> = 0.148 and c<sub>2</sub> = 0.0567. All the experiments were carried out in atmospheric. CH<sup>∗</sup> chemiluminescence from the flame was recorded to visualize the flame behavior. An inverse Abel image reconstruction method was employed to better distinguish the flame macrostructures. Different mechanisms forming the time averaged M shape flames are proposed and analyzed. It is found that the confinement wall plays an important role in determining the flame macrostructures. The flow structures including the inner and outer recirculation zones formed in the confinement are revealed to be the main reasons that affects different flame macrostructures. Meanwhile, the alternation of flame shapes determines the flame stability characteristics. A smaller confinement diameter forced the flame front to bend upstream into the outer recirculation zone hence forming a M shape flame. A strong noise caused by the interaction of the flame front in the outer recirculation zone with the combustor wall was observed. Another unsteady behavior of the flame in the bigger combustor, which was caused by the alternation of the flame root position inside and outside the premixing tube, is also presented. The V shape flame in the two combustors radiated weaker chemiluminescence but the main heat release zone was elongated than the M shape flame. Other operating conditions, i.e. total mass flow rate of the air flow and the equivalence ratio also affect the flame macrostructures. The flame blowout limits were also altered under different test conditions. The bigger confinement has better performance in stabilizing the flame by having lower lean blowout limits.</p>},
  author       = {Tong, Yiheng and Li, Mao and Thern, Marcus and Klingmann, Jens},
  booktitle    = {Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant},
  isbn         = {9780791857601},
  language     = {eng},
  publisher    = {American Society Of Mechanical Engineers (ASME)},
  title        = {An experimental study of effects of confinement ratio on swirl stabilized flame macrostructures},
  url          = {http://dx.doi.org/10.1115/POWER-ICOPE2017-3064},
  volume       = {1},
  year         = {2017},
}