Largeeddy simulation of a bluffbody stabilized nonpremixed flame
Abstract
Largeeddy simulations have been performed for a turbulent nonpremixed bluffbody stabilized CH{sub 4}:H{sub 2} (50:50 vol.) flame at a Reynolds number of 15,800. The corresponding isothermal flow has also been computed. The Sydney bluffbody burner under consideration has been investigated experimentally by Masri and coworkers, who obtained velocity and scalar statistics. The focus of the current work is on flow and mixing effects with the thermochemistry evaluated using a steadystate laminar flamelet approach. The incompressible (lowMachnumber) governing equations for mass, momentum, and mixturefraction have been solved on a structured cylindrical grid and resolution effects investigated using up to 3.643x10{sup 6} nodes. The corresponding nonreactive case was resolved by 5.76x10{sup 5} nodes, resulting in a resolution of more than 80% of the turbulence kinetic energy. The reacting case yields a resolution in excess of 75% on the finest gridarguably sufficient to permit conclusions regarding the accuracy of submodels. Comparisons with experimental data show that for high resolutions comparatively good agreement is obtained for the flow field and for species other than nitric oxide. However, resolution effects are important and results obtained with 4.51x10{sup 5} nodes show that a resolution of less than 70% of the turbulent kinetic energy is insufficient inmore »
 Authors:
 Thermofluids Division, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)
 Chair for Energy and Powerplant Technology, Department of Mechanical Engineering, Darmstadt Technical University, Petersenstr. 30, 64287 Darmstadt (Germany)
 Publication Date:
 OSTI Identifier:
 20685985
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Combustion and Flame; Journal Volume: 144; Journal Issue: 12; Other Information: Elsevier Ltd. All rights reserved
 Country of Publication:
 United States
 Language:
 English
 Subject:
 42 ENGINEERING; FLAMES; BURNERS; COMPUTERIZED SIMULATION; TURBULENCE; METHANE; HYDROGEN; GAS FLOW; COMBUSTION KINETICS; CALCULATION METHODS; ACCURACY
Citation Formats
Kempf, A., Lindstedt, R.P., and Janicka, J. Largeeddy simulation of a bluffbody stabilized nonpremixed flame. United States: N. p., 2006.
Web. doi:10.1016/j.combustflame.2005.07.006.
Kempf, A., Lindstedt, R.P., & Janicka, J. Largeeddy simulation of a bluffbody stabilized nonpremixed flame. United States. doi:10.1016/j.combustflame.2005.07.006.
Kempf, A., Lindstedt, R.P., and Janicka, J. Sun .
"Largeeddy simulation of a bluffbody stabilized nonpremixed flame". United States.
doi:10.1016/j.combustflame.2005.07.006.
@article{osti_20685985,
title = {Largeeddy simulation of a bluffbody stabilized nonpremixed flame},
author = {Kempf, A. and Lindstedt, R.P. and Janicka, J.},
abstractNote = {Largeeddy simulations have been performed for a turbulent nonpremixed bluffbody stabilized CH{sub 4}:H{sub 2} (50:50 vol.) flame at a Reynolds number of 15,800. The corresponding isothermal flow has also been computed. The Sydney bluffbody burner under consideration has been investigated experimentally by Masri and coworkers, who obtained velocity and scalar statistics. The focus of the current work is on flow and mixing effects with the thermochemistry evaluated using a steadystate laminar flamelet approach. The incompressible (lowMachnumber) governing equations for mass, momentum, and mixturefraction have been solved on a structured cylindrical grid and resolution effects investigated using up to 3.643x10{sup 6} nodes. The corresponding nonreactive case was resolved by 5.76x10{sup 5} nodes, resulting in a resolution of more than 80% of the turbulence kinetic energy. The reacting case yields a resolution in excess of 75% on the finest gridarguably sufficient to permit conclusions regarding the accuracy of submodels. Comparisons with experimental data show that for high resolutions comparatively good agreement is obtained for the flow field and for species other than nitric oxide. However, resolution effects are important and results obtained with 4.51x10{sup 5} nodes show that a resolution of less than 70% of the turbulent kinetic energy is insufficient in the context of the Smagorinsky subgrid model combined with the dynamic procedure of Germano. The latter result is consistent with the analysis of Pope.},
doi = {10.1016/j.combustflame.2005.07.006},
journal = {Combustion and Flame},
number = 12,
volume = 144,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

A largeeddy simulation (LES) of a bluffbodystabilized flame has been carried out using a new strategy for LES grid generation. The recursive filterrefinement procedure (RFRP) has been used to generate optimized clustering for variable density combustion simulations. A methanehydrogen fuelbased bluffbodystabilized experimental configuration has been simulated using stateoftheart LES algorithms and subfilter models. The combustion chemistry is described using a precomputed, laminar flamelet modelbased lookup table. The GRI2.11 mechanism is used to build the lookup table parameterized by mixture fraction and scalar dissipation rate. A beta function is used for the subfilter mixture fraction filtered density function (FDF). The simulationsmore »

Large Eddy Simulations of forced ignition of a nonpremixed bluffbody methane flame with Conditional Moment Closure
Large Eddy Simulations (LES) of forced ignition of a bluffbody stabilised nonpremixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A threedimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonablemore » 
Twodimensional large eddy simulation of soot formation in the nearfield of a strongly radiating nonpremixed acetyleneair turbulent jet flame
A numerical study of soot formation in the nearfield of a strongly radiating, nonpremixed, acetyleneair planar jet flame is conducted using Large Eddy Simulation in two dimensions to examine coupled turbulence, soot chemistry, and radiation effects. The twodimensional, Favrefiltered, compressible NavierStokes, total sensible energy and mixture fraction equations are closed using the Smagorinsky subgridscale (SGS) turbulence model. Major species of gasphase combustion are obtained using a laminar flamelet model by employing experimentally obtained laminar flame state relationships for the major species mass fractions as a function of gasphase mixture fraction. A combination of a presumed Beta filtered density function andmore » 
Premixed and nonpremixed generated manifolds in largeeddy simulation of Sandia flame D and F
Premixed and nonpremixed flameletgenerated manifolds have been constructed and applied to largeeddy simulation of the piloted partially premixed turbulent flames Sandia Flame D and F. In both manifolds the chemistry is parameterized as a function of the mixture fraction and a progress variable. Compared to standard nonpremixed flamelets, premixed flamelets cover a much larger part of the reaction domain. Comparison of the results for the two manifolds with experimental data of flame D show that both manifolds yield predictions of comparable accuracy for the mean temperature, mixture fraction, and a number of chemical species, such as CO{sub 2}. However, themore » 
Large eddy simulation of forced ignition of an annular bluffbody burner
The optimization of the ignition process is a crucial issue in the design of many combustion systems. Large eddy simulation (LES) of a conical shaped bluffbody turbulent nonpremixed burner has been performed to study the impact of spark location on ignition success. This burner was experimentally investigated by Ahmed et al. [Combust. Flame 151 (2007) 366385]. The present work focuses on the case without swirl, for which detailed measurements are available. First, coldflow measurements of velocities and mixture fractions are compared with their LES counterparts, to assess the prediction capabilities of simulations in terms of flow and turbulent mixing. Timemore »