The effects of changes in the jet nozzle geometry, i.e., nozzle shape and lip thickness, on the blowout limits of jet diffusion flames in a co-flowing air stream were experimentally investigated for a range of co-flow air stream velocities. Circular and elongated nozzles of different axes rations were employed. Preliminary results showed that nozzles with low major-to-minor axes ratios improved, while high ratios reduced, the blowout limit of attached flames compared with that for an equivalent circular nozzle. The nozzle shape had no apparent influence on the blowout limits lifted flames and the limiting stream velocity. The experimental blowout limits of lifted flames were found to be a function of the co-flowing stream velocity and jet discharge area. On the other hand, the stability of attached flames was a function of the co-flowing stream velocity, jet discharge area as well as the nozzle shape. The effect of premixing a fuel with the surrounding air was also studied. Generally, the introduction of auxiliary fuel into the surrounding stream either increased or decreased the blowout limit depending on the type of flame stabilization mechanism prior to blowout. The stability mechanism of the flame was found to be a function of the co-flow stream velocity and the auxiliary fuel employed.

Issue Section:
Technical Papers
Topics:
Diffusion flames, Geometry, Nozzles, Flames, Fuels, Shapes, Flow (Dynamics), Stability
1.
Broadwell, J. E., Dahm, W. J. A., and Mungal, M. G., 1984, “Blowout of Turbulent Diffusion Flames,” Twentieth Symposium (International) on Combustion, The Combustion Institute, pp. 303–310.
2.
Coats, C. M., and Zhao, H., 1988, “Transition and Stability of Turbulent Jet Diffusion Flames,” Twenty-Second Symposium (International) on combustion, The Combustion Institute, pp. 685–692.
3.
Dahm, W. J. A., and Dibble, R. W., 1988, “Co-flowing Turbulent Jet Diffusion Flame Blowout,” Twenty-Second Symposium (International) on Combustion, The Combustion Institute, p. 801.
4.
Dahm
W. J. A.
, and
Mayman
A. G.
,
1990
, “
Blowout Limits of Turbulent Jet Diffusion Flames for Arbitrary Source Conditions
,”
AIAA Journal
, Vol.
28
, pp.
1157
–
1162
.
5.
Dhanak
M. R.
, and
De Bernardinis
B.
,
1981
, “
The Evolution of an Elliptic Vortex Ring
,”
Journal of Fluid Mechanics
, Vol.
109
, pp.
189
–
216
.
6.
Eickhoff, H., Lenze, B., and Leuckel, W., 1984, “Experimental Investigation of the Stabilization Mechanism of Jet Diffusion Flames,” Twentieth Symposium (International) on Combustion, The Combustion Institute, pp. 311–318.
7.
Feikema
D.
,
Chen
R. H.
, and
Driscoll
J. F.
,
1991
, “
Blowout of Non-Premixed Flames: Maximum Co-Axial Air Velocities Achievable, with and Without Swirl
,”
Combustion and Flame
, Vol.
86
, pp.
347
–
358
.
8.
Gollahalli
S. R.
,
Khanna
T.
, and
Prabhu
N.
,
1992
, “
Diffusion Flames of Gas Jets Issued from Circular and Elliptic Nozzles
,”
Combustion Science and Technology
, Vol.
86
, pp.
267
–
288
.
9.
Gutmark, E., and Ho, C. M., 1983, “On a Forced Elliptic Jet,” Fourth Symposium on Turbulent Shear Flows, p. 7.13.
10.
Ho
C. M.
, and
Gutmark
E.
,
1987
, “
Vortex Induction and Mass Entrainment in a Small-Aspect-Ratio Elliptic Jet
,”
Journal of Fluid Mechanics
, Vol.
179
, pp.
383
–
405
.
11.
Hussain
F.
, and
Husain
H. S.
,
1989
, “
Elliptic Jets. Part 1. Characteristics of Unexcited and Excited Jets
,”
Journal of Fluid Mechanics
, Vol.
208
, pp.
257
–
320
.
12.
Kalghatgi
G. T.
,
1981
a, “
Blowout Stability of Gaseous Jet Diffusion Flames. Part 1: In Still Air
,”
Combustion Science and Technology
, Vol.
26
, pp.
233
–
239
.
13.
Kalghatgi
G. T.
,
1981
b, “
Blowout Stability of Gaseous Jet Diffusion Flames. Part 2: Effect of Cross Wind
,”
Combustion Science and Technology
, Vol.
26
, pp.
241
–
244
.
14.
Karim
G. A.
,
Wierzba
I.
, and
Hanna
M.
,
1984
, “
The Blowout Limit of a Jet Diffusion Flame in a Co-flowing Stream of Lean Gaseous Fuel-Air Mixtures
,”
Combustion and Flame
, Vol.
57
, pp.
283
–
288
.
15.
Namazian, M., Kelly, J. T., and Schefer, R. W., 1988, “Near-Field Instantaneous Flame and Fuel Concentration Structures,” Twenty-Second Symposium (International) on Combustion, The Combustion Institute, pp. 627–634.
16.
Pitts, W. M., 1988, “Assessment of Theories for the Behaviour and Blowout of Lifted Turbulent Jet Diffusion Flames,” Twenty-Second Symposium (International) on Combustion, The Combustion Institute, pp. 809–816.
17.
Roquemore
W. M.
,
Chen
L-D.
,
Goss
L. P.
, and
Lynn
W. F.
,
1989
, “
The Structure of Jet Diffusion Flames
,”
Lecture Notes in Engineering: Turbulent Reactive Flows
, Vol.
40
, pp.
49
–
63
.
18.
Savas
O.
, and
Gollahalli
S. R.
,
1986
, “
Flow Structure in Near-Nozzle Region of Gas Jet Flames
,”
AIAA Journal
, Vol.
24
, p.
1137
1137
.
19.
Schadow, K. C., Wilson, K. J., Lee, M. J., and Gutmark, E., 1984, “Enhancement of Mixing in Ducted Rockets with Elliptic Gas-Generator Nozzles,” AIAA Paper No. 84-1260.
20.
Takahashi, F., and Goss, L. P., 1992, “Near-Field Turbulent Structures and Local Extinction of Jet Diffusion Flames,” Twenty-Fourth Symposium (International) on Combustion, The Combustion Institute, pp. 351–359.
21.
Takahashi, F., Mizomoto, M., Ikai, S., and Tsuruyama, K., 1990, “Stability Limits of Hydrogen/Air Co-Flow Jet Diffusion Flames,” AIAA Paper No. 90-0034.
22.
Vanquickenbourne
L.
, and
van Tiggelen
A.
,
1966
, “
The Stabilization Mechanism of Lifted Diffusion Flames
,”
Combustion and Flame
, Vol.
10
, pp.
59
–
69
.
23.
Wierzba
I.
,
Kar
K.
, and
Karim
G. A.
,
1993
, “
An Experimental Investigation of Blowout Limits of a Jet Diffusion Flame in Co-flowing Streams of Different Velocity and Composition
,”
ASME JOURNAL OF ENERGY RESOURCES TECHNOLOGY
, Vol.
115
, pp.
142
–
147
.
24.
Wierzba
I.
, and
Oladipo
A. B.
,
1994
, “
Blowout of Jet Diffusion Flames in Co-flowing Air Stream
,”
ASME Emerging Energy Technology
, Vol.
57
, pp.
29
–
33
.
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