Large-eddy Simulation of Triangular-stabilized Lean Premixed Turbulent Flames: Quality and Error Assessment

In this numerical study, an algebraic flame surface wrinkling (AFSW) reaction submodel based on the progress variable approach is implemented in the large-eddy simulation (LES) context and validated against the triangular stabilized bluff body flame configuration measurements i.e. in VOLVO test rig. The quantitative predictability of the AFSW model is analyzed in comparison with another well validated turbulent flame speed closure (TFC) combustion model in order to help assess the behaviour of the present model and to further help improve the understanding of the flow and flame dynamics. Characterization of non-reacting (or cold) and reacting flows are performed using various subgrid scale models for consistent grid size variation with 300,000 (coarse), 1.2 million (intermediate) and 2.4 million (fine) grid cells. For non-reacting flows at inlet velocity of 17 m/s and inlet temperature 288 K, coarse grid leads to over prediction of turbulence quantities due to low dissipation at the early stage of flow development behind the bluff body that convects downstream eventually polluting the resulting solution. The simulated results with the intermediate (and fine) grid for mean flow and turbulence quantities, and the vortex shedding frequency (fs) closely match experimental data. For combusting flows for lean propane/air mixtures at 35 m/s and 600 K, the vortex shedding frequency increase threefold compared with cold scenario. The predicted results of mean, rms velocities and reaction progress variable are generally in good agreement with experimental data. For the coarse grid the combustion predictions show a shorter recirculation region due to higher turbulent burning rate. Finally, both cold and reacting LES data are analyzed for uncertainty in the solution using two quality assessment techniques: two-grid estimator by Celik, and model and grid variation by Klein. For both approaches, the resolved turbulent kinetic energy is used to estimate the grid quality and error assessment. The quality assessment reveals that the cold flows are well resolved even on the intermediate mesh, while for the reacting flows even the fine mesh is locally not sufficient in the flamelet region. The Klein approach estimates that depending on the recirculation region in cold scenario both numerical and model errors rise near the bluff-body region, while in combusting flows these errors are significant behind the stabilizing point due to preheating of unburned mixture and reaction heat release. The total error mainly depends on the numerical error and the influence of model error is low for this configuration.

[1]  Large-eddy simulation of a counterflow configuration with and without combustion , 2000 .

[2]  B. Geurts,et al.  A framework for predicting accuracy limitations in large-eddy simulation , 2002 .

[3]  A. Sjunnesson,et al.  CARS measurements and visualization of reacting flows in a bluff body stabilized flame , 1992 .

[4]  Akira Yoshizawa,et al.  A Statistically-Derived Subgrid-Scale Kinetic Energy Model for the Large-Eddy Simulation of Turbulent Flows , 1985 .

[5]  Johannes Janicka,et al.  Prediction of finite chemistry effects using large eddy simulation , 2002 .

[6]  A. D. Gosman,et al.  Application of a flame-wrinkling les combustion model to a turbulent mixing layer , 1998 .

[7]  Denis Veynante,et al.  Turbulent combustion modeling , 2002, VKI Lecture Series.

[8]  Friedrich Dinkelacker,et al.  A test of validation of turbulent premixed models for high-pressure bunsen flames , 2005 .

[9]  I. Porumbel,et al.  Large eddy simulation of bluff body stabilized premixed and partially premixed combustion , 2006 .

[10]  Thierry Poinsot,et al.  Diagrams of premixed turbulent combustion based on direct simulation , 1991 .

[11]  Claudio Bruno,et al.  The coupling of turbulence and chemistry in a premixed bluff-body flame as studied by LES , 2004 .

[12]  T. Poinsot,et al.  Theoretical and numerical combustion , 2001 .

[13]  Norbert Peters,et al.  A spectral closure for premixed turbulent combustion in the flamelet regime , 1992, Journal of Fluid Mechanics.

[14]  J. Smagorinsky,et al.  GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS , 1963 .

[15]  B. Hjertager,et al.  On mathematical modeling of turbulent combustion with special emphasis on soot formation and combustion , 1977 .

[16]  Christer Fureby,et al.  Large eddy simulation of unsteady combustion , 1996 .

[17]  Thierry Poinsot,et al.  Effects of mesh resolution on large eddy simulation of reacting flows in complex geometry combustors , 2008 .

[18]  P. Moin,et al.  A dynamic subgrid‐scale eddy viscosity model , 1990 .

[19]  M. Haq,et al.  Turbulent burning velocity, burned gas distribution, and associated flame surface definition , 2003 .

[20]  Christer Fureby,et al.  Large Eddy Simulation of Reacting Flows Applied to Bluff Body Stabilized Flames , 1995 .

[21]  S. Pope.  Turbulent Flows: FUNDAMENTALS , 2000 .

[22]  Markus Klein,et al.  An Attempt to Assess the Quality of Large Eddy Simulations in the Context of Implicit Filtering , 2005 .

[23]  Ismail Celik,et al.  Index of resolution quality for large eddy simulations , 2005 .

[24]  D. Brian Spalding,et al.  Development of the eddy-break-up model of turbulent combustion , 1977 .

[25]  Friedrich Dinkelacker,et al.  Modelling and simulation of lean premixed turbulent methane/hydrogen/air flames with an effective Lewis number approach , 2011 .

[26]  Friedrich Dinkelacker,et al.  Development of an algebraic reaction rate closure for the numerical calculation of turbulent premixed methane, ethylene, and propane/air flames for pressures up to 1.0 MPa , 2005 .

[27]  Liu Tao,et al.  Application of the elliptic conditional moment closure model to a two-dimensional nonpremixed methanol bluff-body flame , 2000 .

[28]  S. Menon,et al.  Large Eddy Simulation of Bluff Body Stabilized Premixed Flame , 2006 .

[29]  Large-Eddy Simulation of Lean Premixed Turbulent Flames of Three Different Combustion Configurations using a Novel Reaction Closure , 2008 .

[30]  Johan Meyers,et al.  A computational error-assessment of central finite-volume discretizations in large-eddy simulation using a Smagorinsky model , 2007, J. Comput. Phys..