The effect of centrifugal force on flame propagation velocity of stoichiometric propane–, kerosene–, and n-octane–air turbulent premixed flames was numerically examined. The quasi-turbulent numerical model was set in an unsteady two-dimensional (2D) geometry with finite length in the transverse and streamwise directions but with infinite length in the spanwise direction. There was relatively good comparison between literature-reported measurements and predictions of propane–air flame propagation velocity as a function of centrifugal force. It was found that for all mixtures the flame propagation velocity increases with centrifugal force. It reaches a maximum, then falls off rapidly with further increases in centrifugal force. The results of this numerical study suggest that there are no distinct differences among the three mixtures in terms of the trends seen of the effect of centrifugal force on the flame propagation velocity. There are, however, quantitative differences. The numerical model is set in a noninertial, rotating reference frame. This rotation imposes a radially outward (centrifugal) force. The ignited mixture at one end of the tube raises the temperature and its heat release tends to laminarize the flow. The attained density difference combined with the direction of the centrifugal force promotes Rayleigh–Taylor instability. This instability with thermal expansion and turbulent flame speed constitute the flame propagation mechanism towards the other tube end. A wave is also generated from the ignition zone but propagates faster than the flame. During propagation the flame interacts with eddies that wrinkle and/or corrugate the flame. The flame front wrinkles interact with streamtubes that enhance Landau–Darrieus (hydrodynamic) instability, giving rise to a corrugated flame. Under strong stretch conditions the stabilizing equidiffusive-curvature mechanism fails and the flame front breaks up, allowing inflow of unburned mixture into the flame. This phenomenon slows down the flame temporarily and then the flame speeds up faster than before. However, if corrugation is large and the inflow of unburned mixture into the flame is excessive, the latter locally quenches and slows down the flame. This occurs when the centrifugal force is large, tending to blowout the flame. The wave in the tube interacts continuously with the flame through baroclinic torques at the flame front that further enhances the above mentioned flame–eddy interactions. Only at low centrifugal forces, the wave intermingles several times with the flame before the averaged flame propagation velocity is determined. The centrifugal force does not substantially increase the turbulent flame speed as commented by previous experimental investigations. The results also suggest that an ultracompact combustor (UCC) with high-g cavity (HGC) will be limited to centrifugal force levels in the 2000–3000 g range.

References

References
1.
Burrus
,
D.
,
2013
, internal communication.
2.
Lewis
,
G. D.
,
Shadowen
,
J. H.
, and
Thayer
,
E. B.
,
1977
, “
Swirling Flow Combustion
,”
J. Energy
,
1
(
4
), pp.
201
205
.10.2514/3.62330
3.
Lewis
,
G. D.
,
1973
, “
Centrifugal-Force Effects on Combustion
,”
Symp. (Int.) Combust.
,
14
(1), pp.
413
419
.10.1016/S0082-0784(73)80040-2
4.
Lewis
,
G. D.
,
1971
, “
Combustion in a Centrifugal-Force Field
,”
Symp. (Int.) Combust.
,
13
(1), pp.
625
629
.10.1016/S0082-0784(71)80064-4
5.
Katta
,
V. R.
,
Blunck
,
D.
, and
Roquemore
,
W. M.
,
2013
, “
Effect of Centrifugal Effects on Flame Stability in an Ultra-Compact Combustor
,”
AIAA
Paper No. 2013-1046. 10.2514/6.2013-1046
6.
Katta
,
V. R.
,
Zelina
,
J.
, and
Roquemore
,
W. M.
,
2008
, “
Numerical Studies on Cavity-Inside-Cavity-Supported Flames in Ultra Compact Combustor
,”
ASME
Paper No. GT2008-50853. 10.1115/GT2008-50853
7.
Gokulakrishnan
,
P.
,
Fuller
,
C. C.
,
Klassen
,
M. S.
, and
Huang
,
H.
,
2011
, “
Kinetic Modeling of Thermal and Catalytic Cracking of Paraffinic Surrogate Fuels Relevant to Supersonic Applications
,”
AIAA
Paper No. 2011-6106. 10.2514/6.2011-6106
8.
ANSYS, 2013, ANSYS FLUENT 14.5, Theory Guide, ANSYS, Inc., Canonsburg, PA.
9.
Kader
,
B.
,
1981
, “
Temperature and Concentration Profiles in Fully Turbulent Boundary Layers
,”
Int. J. Heat Mass Transfer
,
24
(
9
), pp.
1541
1544
.10.1016/0017-9310(81)90220-9
10.
Barth
,
T. J.
, and
Jespersen
,
D.
,
1989
, “
The Design and Application of Upwind Schemes on Unstructured Meshes
,”
AIAA
Paper No. 89-0366. 10.2514/6.1989-366
11.
Anderson
,
W.
, and
Bonhus
,
D. L.
,
1994
, “
An Implicit Upwind Algorithm for Computing Turbulent Flows on Unstructured Grids
,”
Comput. Fluids
,
23
(
1
), pp.
1
21
.10.1016/0045-7930(94)90023-X
12.
Hinze
,
J. O.
,
1975
,
Turbulence
,
McGraw-Hill
,
New York
.
13.
Law
,
C. K.
,
2006
,
Combustion Physics
,
Cambridge University
,
Cambridge, UK
.
14.
Westbrook
,
C. K.
, and
Dryer
,
F. L.
,
1981
, “
Simplified Reaction Mechanisms for the Oxidation of Hydrocarbon Fuels in Flames
,”
Combust. Sci. Technol.
,
27
(1–2), pp.
31
43
.10.1080/00102208108946970
15.
Landau
,
L. D.
, and
Lifshitz
,
E. M.
,
1959
,
Fluid Mechanics
,
Addison-Wesley
,
Reading, MA
.
You do not currently have access to this content.