The objective of this study is to investigate the sensitivity and accuracy of the reaction flow-field prediction for the LIMOUSINE combustor with regard to choices in computational mesh and turbulent combustion model. The LIMOUSINE combustor is a partially premixed, bluff body-stabilized natural gas combustor designed to operate at 40–80 kW and atmospheric pressure and used to study combustion instabilities. The transient simulation of a turbulent combusting flow with the purpose to study thermoacoustic instabilities is a very time-consuming process. For that reason, the meshing approach leading to accurate numerical prediction, known sensitivity, and minimized amount of mesh elements is important. Since the numerical dissipation (and dispersion) is highly dependent on, and affected by, the geometrical mesh quality, it is of high importance to control the mesh distribution and element size across the computational domain. Typically, the structural mesh topology allows using much fewer grid elements compared to the unstructured grid; however, an unstructured mesh is favorable for flows in complex geometries. To explore computational stability and accuracy, the numerical dissipation of the cold flow with mixing of fuel and air is studied first in the absence of the combustion process. Thereafter, the studies are extended to combustible flows using standard available ansys-cfx combustion models. To validate the predicted variable fields of the combustor's transient reactive flows, the numerical results for dynamic pressure and temperature variations, resolved under structured and unstructured mesh conditions, are compared with experimental data. The obtained results show minor dependence on the used mesh in the velocity and pressure profiles of the investigated grids under nonreacting conditions. More significant differences are observed in the mixing behavior of air and fuel flows. Here, the numerical dissipation of the (unstructured) tetrahedral mesh topology is higher than in the case of the (structured) hexahedral mesh. For that reason, the combusting flow, resolved with the use of the hexahedral mesh, presents better agreement with experimental data and demands less computational effort. Finally, in the paper, the performance of the combustion model for reacting flow is presented and the main issues of the applied combustion modeling are reviewed.

References

References
1.
Weatherill
,
N. P.
,
1988
, “
A Method for Generating Irregular Computational Grids in Multiply Connected Planar Domains
,”
Int. J. Numer. Methods Fluids
,
8
(
2
), pp.
181
197
.10.1002/fld.1650080206
2.
Koomullil
,
R.
,
Soni
,
B.
, and
Singh
,
R.
,
2008
, “
A Comprehensive Generalized Mesh System for CFD Applications
,”
Math. Comput. Simul.
,
78
(
5–6
), pp.
605
617
.10.1016/j.matcom.2008.04.005
3.
Mavriplis
,
D. J.
,
1997
, “
Unstructured Grid Techniques
,”
Ann. Rev. Fluid Mech.
,
29
, pp.
473
514
.10.1146/annurev.fluid.29.1.473
4.
Kikuchi
,
N.
,
1986
, “
Adaptive Grid-Design Methods for Finite Element Analysis
,”
Comput. Methods Appl. Mech. Eng.
,
55
(
1–2
). pp.
129
160
.10.1016/0045-7825(86)90089-7
5.
Beam
,
R. M.
, and
Warming
,
R.
,
1982
, “
Implicit Numerical Method for the Compressible Navier–Stokes and Euler Equations
,”
lecture notes, Von Karman Institute for Fluid Dynamics
, Sint-Genesius-Rode, Belgium.
6.
Caughey
,
D. A.
, and
Hafez
,
M. M.
,
1994
,
Frontiers of Computational Fluid Dynamics
,
Wiley
,
New York
.
7.
Çete
,
A. R.
,
Yükselen
,
M. A.
, and
Kaynak
,
Ü.
,
2008
, “
A Unifying Grid Approach for Solving Potential Flows Applicable to Structured and Unstructured Grid Configurations
,”
Comput. Fluids
,
37
(
1
), pp.
35
50
.10.1016/j.compfluid.2007.01.011
8.
Hansen
,
R. P.
, and
Forsythe
,
J. R.
,
2003
, “
A Comparison of Structured and Unstructured Grid Solutions for Flow Over a Circular Cylinder
,”
Proceedings of the 2003 DoD User Group Conference
, Bellevue, WA, June 9–13, pp. 104–112.10.1109/DODUGC.2003.1253382
9.
Hua
,
Z.-L.
,
Xing
,
L.-H.
, and
Gu
,
L.
,
2008
, “
Application of a Modified Quick Scheme to Depth-Averaged κ–ε Turbulence Model Based on Unstructured Grids
,”
J. Hydrodynam.
,
20
(
4
), pp.
514
523
.10.1016/S1001-6058(08)60088-8
10.
Tomita
,
J. T.
,
Silva
,
L. M. D.
, and
Silva
,
D. T. D.
,
2012
, “
Comparison Between Unstructured and Structured Meshes With Different Turbulence Models for a High Pressure Turbine Application
,”
Proceedings of ASME Turbo Expo
,
Copenhagen
,
Denmark
, June 11–15,
ASME
Paper No. GT2012-69990.10.1115/GT2012-69990
11.
Rijke
,
P. L.
,
1859
, “
On the Vibration of the Air in a Tube Open at Both Ends
,”
Philos. Mag.
,
17
, pp.
419
422
.10.1080/14786445908642701
12.
Patankar
,
S. V.
,
1980
,
Numerical Heat Transfer and Fluid Flow
,
Hemisphere
, New York.
13.
Rhie
,
C. M.
, and
Chow
,
W. L.
,
1982
, “
A Numerical Study of Turbulent Flow Past an Isolated Airfoil With the Trailing Edge Separation
,”
AIAA J.
,
21
, pp.
1525
1532
.10.2514/3.8284
14.
Majumdar
,
S.
,
1988
, “
Role of Underrelaxation in Momentum Interpolation for Calculation of Flow With Nonstaggered Grids
,”
Numer. Heat Transfer
,
13
(
1
), pp.
125
132
.10.1080/10407788808913607
15.
Menter
,
F. R.
,
1994
, “
2-Equation Eddy-Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
,
32
(
8
), pp.
1598
1605
.10.2514/3.12149
16.
Menter
,
F. R.
and
Egorov
,
Y.
,
2010
, “
The Scale-Adaptive Simulation Method for Unsteady Turbulent Flow Predictions. Part 1: Theory and Model Description
,”
Flow Turbul. Combust.
,
85
(
1
), pp.
113
138
.10.1007/s10494-010-9264-5
17.
Combest
,
D. P.
,
Ramachandran
,
P. A.
, and
Dudukovic
,
M. P.
2011
, “
On the Gradient Diffusion Hypothesis and Passive Scalar Transport in Turbulent Flows
,”
Ind. Eng. Chem. Res.
,
50
(
15
), pp.
8817
8823
.10.1021/ie200055s
18.
Liu
,
M.
,
2012
, “
Age Distribution in the Kenics Static Micromixer With Convection and Diffusion
,”
Ind. Eng. Chem. Res.
,
51
(
20
), pp.
7081
7094
.10.1021/ie200716v
19.
Pozarlik
,
A.
,
2010
,
Vibro-Acoustical Instabilities Induced by Combustion Dynamics in Gas Turbine Combustors
,
University of Twente
,
Enschede, Netherlands
.
20.
Heckl
,
M.
,
2010
, “
The Rijke Tube: A Green's Function Approach in the Frequency Domain
,”
Acta Acust. Acust.
,
96
(
4
), pp.
743
752
.10.3813/AAA.918328
21.
Roman Casado
,
J. C.
, and
Kok
,
J. B. W.
,
2012
, “
Non-Linear Effects in a Lean Partially Premixed Combustor During Limit Cycle Operation
,”
Proceeding of ASME Turbo Expo 2012
,
Copenhagen
,
Denmark
, June 11–15,
ASME
Paper No. GT2012-69164.10.1115/GT2012-69164
22.
Altunlu
,
A. C.
,
Shahi
,
M.
,
Pozarlik
,
A. K.
,
van der Hoogt
,
P. J. M.
,
Kok
,
J. B. W.
, and
de Boer
,
A.
,
2012
, “
Fluid-Structure Interaction on the Combustion Instability
,” 19th International Congress on Sound and Vibration (ICSV19), Vilnius, Lithuania, July 8–12.
23.
Vera
,
I. H.
,
2011
, “
Soot Modeling in Flames and Large-Eddy Simulations of Thermo-Acoustic Instabilities
,” Ph.D. thesis, Universite de Toulouse, Toulouse, France.
24.
Ozcan
,
E.
,
2012
, “
Tuning the Self-Excited Thermo-Acoustic Oscillations of a Gas Turbine Combustor to Limit Cycle Operations by Means of Numerical Analysis
,” Master's thesis, University of Twente, Enschede, Netherlands.
25.
Rayleigh
,
J.
,
1878
, “
The Explanation of Certain Acoustic Phenomena
,”
Nature
,
18
, pp.
319
321
.10.1038/018319a0
26.
Shahi
,
M.
,
Kok
,
J. B. W.
, and
Alemela
,
P. R.
,
2012
, “
Simulation of 2-Way Fluid Structure Interaction in a 3D Model Combustor
,”
Proceedings of ASME Turbo Expo
,
Copenhagen
,
Denmark
, June 11–15,
ASME
Paper No. GT2012-69681.10.1115/GT2012-69681
27.
Ansys
,
2010
,
Release 11.0 Documentation for ANSYS
, Ansys Inc., Canonsburg, PA.
28.
Veynante
,
D.
, and
Vervisch
,
L.
,
2002
, “
Turbulent Combustion Modeling
,”
Prog. Energy Combust. Sci
,
28
, pp.
193
266
.10.1016/S0360-1285(01)00017-X
You do not currently have access to this content.