Simulation of finite-rate chemical kinetics in a turbulent bluff body flame

2004 ◽  
Vol 4 (3/4/5) ◽  
pp. 264
Author(s):  
B. Wilmes ◽  
L. Rackwitz ◽  
M. Pfitzner
Keyword(s):  
Chemical Kinetics ◽  
Bluff Body ◽  
Finite Rate

Modelling finite-rate chemistry effects in nonpremixed turbulent combustion: Test on the bluff-body stabilized flame

1997 ◽  
Vol 110 (3) ◽  
pp. 298-318 ◽  
Author(s):  
L. Fallot ◽  
M. Gonzalez ◽  
R. Elamraoui ◽  
M. Obounou
Keyword(s):  
Turbulent Combustion ◽  
Bluff Body ◽  
Finite Rate

Large eddy simulation of spark ignition of a bluff-body stabilized burner using a subgrid-ignition model coupled with FGM-based combustion models

2017 ◽  
Vol 27 (2) ◽  
pp. 400-427 ◽  
Author(s):  
Alain Fossi ◽  
Alain DeChamplain
Keyword(s):  
Bluff Body ◽  
Mixture Fraction ◽  
Aircraft Engines ◽  
Simulation Approach ◽  
Finite Rate ◽  
Content Type ◽  
Combustion Models ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Ignition Kernel

Purpose Safety improvement and pollutant reduction in many practical combustion systems and especially in aero-gas turbine engines require an adequate understanding of flame ignition and stabilization mechanisms. Improved software and hardware have opened up greater possibilities for translating basic knowledge and the results of experiments into better designs. The present study deals with the large eddy simulation (LES) of an ignition sequence in a conical shaped bluff-body stabilized burner involving a turbulent non-premixed flame. The purpose of this paper is to investigate the impact of spark location on ignition success. Particular attention is paid to the ease of handling of the numerical tool, the computational cost and the accuracy of the results. Design/methodology/approach The discrete particle ignition kernel (DPIK) model is used to capture the ignition kernel dynamics in its early stage of growth after the breakdown period. The ignition model is coupled with two combustion models based on the mixture fraction-progress variable formulation. An infinitely fast chemistry assumption is first done, and the turbulent fluctuations of the progress variable are captured with a bimodal probability density function (PDF) in the line of the Bray–Moss–Libby (BML) model. Thereafter, a finite rate chemistry assumption is considered through the flamelet-generated manifold (FGM) method. In these two assumptions, the classical beta-PDF is used to model the temporal fluctuations of the mixture fraction in the turbulent flow. To model subgrid scale stresses and residual scalars fluxes, the wall-adapting local eddy (WALE) and the eddy diffusivity models are, respectively, used under the low-Mach number assumption. Findings Numerical results of velocity and mixing fields, as well as the ignition sequences, are validated through a comparison with their experimental counterparts. It is found that by coupling the DPIK model with each of the two combustion models implemented in a LES-based solver, the ignition event is reasonably predicted with further improvements provided by the finite rate chemistry assumption. Finally, the spark locations most likely to lead to a complete ignition of the burner are found to be around the shear layer delimiting the central recirculation zone, owing to the presence of a mixture within flammability limits. Research limitations/implications Some discrepancies are found in the radial profiles of the radial velocity and consequently in those of the mixture fraction, owing to a mismatch of the radial velocity at the inlet section of the computational domain. Also, unlike FGM methods, the BML model predicts the overall ignition earlier than suggested by the experiment; this may be related to the overestimation of the reaction rate, especially in the zones such as flame holder wakes which feature high strain rate due to fuel-air mixing. Practical implications This work is adding a contribution for ignition modeling, which is a crucial issue in various combustion systems and especially in aircraft engines. The exclusive use of a commercial computational fluid dynamics (CFD) code widely used by combustion system manufacturers allows a direct application of this simulation approach to other configurations while keeping computing costs at an affordable level. Originality/value This study provides a robust and simple way to address some ignition issues in various spark ignition-based engines, namely, the optimization of engines ignition with affordable computational costs. Based on the promising results obtained in the current work, it would be relevant to extend this simulation approach to spray combustion that is required for aircraft engines because of storage volume constraints. From this standpoint, the simulation approach formulated in the present work is useful to engineers interested in optimizing the engines ignition at the design stage.

On the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustors

2017 ◽  
Author(s):  
Nadim W. Chakroun ◽  
Santosh J. Shanbhogue ◽  
Gaurav Kewlani ◽  
Soufien Taamallah ◽  
Dan Michaels ◽  
...  
Keyword(s):  
Chemical Kinetics ◽  
Bluff Body ◽  
Backward Facing Step ◽  
Kinetics Modeling

scholarly journals Coupled Lagrangian Monte Carlo PDF–CFD Computation of Gas Turbine Combustor Flowfields With Finite–Rate Chemistry

1996 ◽  
Author(s):  
Anil K. Tolpadi ◽  
Iris Z. Hu ◽  
Sanjay M. Correa ◽  
David L. Burrus
Keyword(s):  
Monte Carlo ◽  
Gas Turbine ◽  
Bluff Body ◽  
Aircraft Engine ◽  
Reacting Flow ◽  
Gas Turbine Combustor ◽  
Finite Rate ◽  
Reduced Chemistry ◽  
Rate Effects ◽  
Fast Chemistry

A coupled Lagrangian Monte Carlo Probability Density Function (PDF)–Eulerian Computational Fluid Dynamics (CFD) technique is presented for calculating steady three–dimensional (3–D) turbulent reacting flow in a gas turbine combustor. PDF transport methods model turbulence–combustion interactions more accurately than conventional turbulence models with an assumed shape PDF. The PDF transport equation was solved using a Lagrangian particle tracking Monte Carlo (MC) method. The PDF modeled was over composition only. This MC module has been coupled with CONCERT, which is a fully elliptic 3–D body–fitted CFD code based on pressure correction techniques. In an earlier paper [Tolpadi et al, 1995], this computational approach was described but only fast chemistry calculations were presented in a typical aircraft engine combustor. In the present paper, reduced chemistry schemes were incorporated into the MC module that enabled the modeling of finite rate effects in gas turbine flames and therefore the prediction of CO and NOx emissions. With the inclusion of these finite rate effects, the gas temperatures obtained were also more realistic. Initially, a two scalar scheme was implemented that allowed validation against Raman data taken in a recirculating bluff body stabilized CO/H2/N2–air flame. Good agreement of the temperature and major species were obtained. Next, finite rate computations were performed in a single annular aircraft engine combustor by incorporating a simple three scalar reduced chemistry scheme for Jet A fuel. This three scalar scheme was an extension of the two scalar scheme for CO/H2/N2 fuel. The solutions obtained using the present approach were compared with those obtained using the fast chemistry PDF transport approach [Tolpadi et al, 1995] as well as the presumed shape PDF method. The calculated exhaust gas temperatures using the finite rate model showed the best agreement with measurements made by a thermocouple rake. In addition, the CO and NOx emission indices were also computed and compared with corresponding data.

Coupled Lagrangian Monte Carlo PDF–CFD Computation of Gas Turbine Combustor Flowfields With Finite-Rate Chemistry

1997 ◽  
Vol 119 (3) ◽  
pp. 519-526 ◽  
Author(s):  
A. K. Tolpadi ◽  
I. Z. Hu ◽  
S. M. Correa ◽  
D. L. Burrus
Keyword(s):  
Monte Carlo ◽  
Gas Turbine ◽  
Bluff Body ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Gas Turbine Combustor ◽  
Finite Rate ◽  
Reduced Chemistry ◽  
Rate Effects ◽  
Fast Chemistry

A coupled Lagrangian Monte Carlo Probability Density Function (PDF)-Eulerian Computational Fluid Dynamics (CFD) technique is presented for calculating steady three-dimensional turbulent reacting flow in a gas turbine combustor. PDF transport methods model turbulence-combustion interactions more accurately than conventional turbulence models with an assumed shape PDF. The PDF transport equation was solved using a Lagrangian particle tracking Monte Carlo (MC) method. The PDF modeled was over composition only. This MC module has been coupled with CONCERT, which is a fully elliptic three-dimensional body-fitted CFD code based on pressure correction techniques. In an earlier paper (Tolpadi et al., 1995), this computational approach was described, but only fast chemistry calculations were presented in a typical aircraft engine combustor. In the present paper, reduced chemistry schemes were incorporated into the MC module that enabled the modeling of finite rate effects in gas turbine flames and therefore the prediction of CO and NOx emissions. With the inclusion of these finite rate effects, the gas temperatures obtained were also more realistic. Initially, a two scalar scheme was implemented that allowed validation against Raman data taken in a recirculating bluff body stabilized CO/H2/N2-air flame. Good agreement of the temperature and major species were obtained. Next, finite rate computations were performed in a single annular aircraft engine combustor by incorporating a simple three scalar reduced chemistry scheme for Jet A fuel. This three scalar scheme was an extension of the two scalar scheme for CO/H2/N2 fuel. The solutions obtained using the present approach were compared with those obtained using the fast chemistry PDF transport approach (Tolpadi et al., 1995) as well as the presumed shape PDF method. The calculated exhaust gas temperature using the finite rate model showed the best agreement with measurements made by a thermocouple rake. In addition, the CO and NOx emission indices were also computed and compared with corresponding data.

scholarly journals Accelerating finite-rate chemical kinetics with coprocessors: Comparing vectorization methods on GPUs, MICs, and CPUs

2018 ◽  
Vol 226 ◽  
pp. 18-29 ◽  
Author(s):  
Christopher P. Stone ◽  
Andrew T. Alferman ◽  
Kyle E. Niemeyer
Keyword(s):  
Chemical Kinetics ◽  
Finite Rate
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