It explains about flames, types of flames, flame instabilities, stability techniques, and some CFD result of stabilized flame after using different techniques.

1. Seminar-III
ROSHAN SAH
USN :- 17AE60R01
M.Tech (1st Year)
Dept. of Aerospace Engg.
Indian Institute of Technology
Kharagpur (IIT KGP)
Flame Stabilization Techniques

2. Contents:
• Flame.
• Classification of flames
• Flame instabilities.
• Flame stabilization techniques.
• Some of CFD results.
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3. Definition
Flame :-
• It is a self-sustaining propagation of a localized
combustion zone at required velocity.
• Deflagration :- Discrete combustion wave that
travel subsonic.
• Detonation :- Discrete combustion wave that
travel supersonic.
Bunsen Burner
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4. Classification of Flame :-
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5. Flame Instabilities :-
They are:-
o Instability due to fuel droplets size and its distribution.
o Fuel-air mixing problem (Turbulent mixing problem).
o Ignition instabilities.
o Instability due to flame holder .
o Aerodynamics effects of heat release.
o Thermo-acoustic instability.
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6. Flame stabilization techniques:-
They are as follows:
 Low Velocity bypass ports.
 Refractory Burners tiles.
 Bluff-body flame holders.
 Swirls-jet inducedrecirculating flows.
 Rapid increase in flow area creating recirculating separated
flows.
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7. Low Velocity bypass ports:-
• This techniqueis used to stabilized an industrial burner flame.
• Similar to the modern laboratory Bunsen burner.
Flame-retention type industrialflame.
Source: from Ref[1]
Bypass port
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8. Refractory Burners tiles:-
• This techniqueis also used to stabilizedan
industrialflame.
• Flame is stabilizedwithin refractory
passageway.
• Refractory tiles helps to maintain near-
adiabatic flame temperatures.
• It has large divergence angle , therefore it
is possible that the boundary layer separates
and creates a recirculationzone within the
tiles.
Refractory tile burner
Source: from Ref[1]
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9. Bluff-body flame holders:-
• This techniques is used to stabilize turbulent flames.
• Bluff body may be V-gutter, rod, wedge, plate.
• Principle: The existence of a strong recirculation zone behind the flame
holding devices which causes uniform burned product reach nearly
adiabatic flame temperature.
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10. Bluff-body flame holders
• The presence of a strong recirculation zone of hot products ignites the
unburnedgases and provides a region where the local turbulent flame
speed matches to local flow velocity.
• Example :- premixed gas-turbine combustion, premixed industrial
combustion
Turbulent flame stabilized in the wake of a bluff
body.
Source: from Ref[2]
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11. Bluff-body flame holders:-
Some of CFD results:-
Source: from Ref[3]
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12. Swirls-jet induced recirculating flows :-
• Recirculation zone is created in
combustion chamber by introducing a
swirl component to the incoming gases.
• This techniques is frequently used in
industrial burners and gas turbine
combustion for both premixed and non-
premixed mode of combustion.
• Swirl induced flow patterns affects
mixing of fuel and air.
Flow patterns for a flame
with inlet swirl.
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13. Some CFD results
Swirls-jet induced recirculating flows:-
Swirl Annular flow
Source: from Ref[4]
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14. Swirls-jet induced recirculating flows
Swirl and bluff body stabilization design
Source: from Ref[4]
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15. References:-
[1] North America manufacturing Co. North America Combustion
Handbook, The North America Manufacturing Co, Cleveland, OH, 1952.
[2]Zukoski, E. E. and Marble, F. E., “The Role of Wake Transition in the
Process of Flame Stabilization in the Bluff Bodies,” AGARD Combustion
Researches and Reviews, Butterworth Scientific Publishers, London, 1954,
pp. 167-180.
[3] Ghobad Bagheri, Seyed Ehsan Hosseini*, Mazlan Abdul Wahid “Effects
of bluff body shape on the flame stability in premixed micro-combustion of
hydrogen-air mixture”. Elsevier, Applied Thermal Engineering 67 (2014)
266-272.
[4] Yiheng Tonga, Xiao Liub, Zhenkan Wang, Mattias Richter, Jens
Klingmanna. “Experimental and numerical study on bluff-body and swirl
stabilizeddiffusion flames.” Fuel 217 (2018) 352–364.
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