RANS Simulations of Statistically Stationary Premixed Turbulent Combustion Using Flame Speed Closure Model

2014 ◽  
Vol 94 (2) ◽  
pp. 381-414 ◽  
Author(s):  
E. Yasari ◽  
S. Verma ◽  
A. N. Lipatnikov
Keyword(s):  
Turbulent Combustion ◽  
Flame Speed ◽  
Closure Model ◽  
Premixed Turbulent Combustion ◽  
Rans Simulations

An Efficient Computational Model for Premixed Turbulent Combustion at High Reynolds Numbers Based on a Turbulent Flame Speed Closure

1997 ◽  
Author(s):  
Vladimir Zimont ◽  
Wolfgang Polifke ◽  
Marco Bettelini ◽  
Wolfgang Weisenstein
Keyword(s):  
Computational Model ◽  
Transport Equation ◽  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Reynolds Numbers ◽  
Flame Speed ◽  
Closed Form Expression ◽  
Turbulent Length Scale ◽  
Premixed Turbulent Combustion ◽  
Turbulent Flame Speed

Theoretical background, details of implementation and validation results of a computational model for turbulent premixed gaseous combustion at high turbulent Reynolds numbers are presented. The model describes the combustion process in terms of a single transport equation for a progress variable; closure of the progress variable’s source term is based on a model for the turbulent flame speed. The latter is identified as a parameter of prime significance in premixed turbulent combustion and is determined from theoretical considerations and scaling arguments, taking into account physico-chemical properties of the combustible mixture and local turbulent parameters. Specifically, phenomena like thickening, wrinkling and straining of the flame front by the turbulent velocity field are considered, yielding a closed form expression for the turbulent flame speed that involves, e.g., speed, thickness and critical gradient of a laminar flame, local turbulent length scale and fluctuation intensity. This closure approach is very efficient and elegant, as it requires only one transport equation more than the non-reacting flow case, and there is no need for costly evaluation of chemical source terms or integration over probability density functions. The model was implemented in a finite-volume based computational fluid dynamics code and validated against detailed experimental data taken from a large scale atmospheric gas turbine burner test stand. The predictions of the model compare well with the available experimental results. It has been observed that the model is significantly more robust and computationally efficient than other combustion models. This attribute makes the model particularly interesting for applications to large 3D problems in complicated geometries.

A Modeling Approach for Hydrogen-Doped Lean Premixed Turbulent Combustion

2006 ◽  
Author(s):  
Siva P. R. Muppala ◽  
Miltiadis V. Papalexandris
Keyword(s):  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Turbulent Flames ◽  
Flame Speed ◽  
Hydrocarbon Mixtures ◽  
Empirical Constant ◽  
Premixed Turbulent Combustion ◽  
Turbulent Flame Speed ◽  
Preferential Diffusion ◽  
Model Predictions

In this study, we investigate some preliminary reaction model predictions analytically in comparison with experimental premixed turbulent combustion data from four different flame configurations, which include i) high-jet enveloped, ii) expanding spherical, iii) Bunsen-like, and iv) wide-angled diffuser flames. The special intent of the present work is to evaluate the workability range of the model to hydrogen and hydrogen-doped hydrocarbon mixtures, emphasizing on the significance of preferential diffusion, PD, and Le effects in premixed turbulent flames. This is carried out in two phases: first, involving pure hydrocarbon and pure hydrogen mixtures from two independent measured data, and second, with the blended mixtures from two other data sets. For this purpose, a novel reaction closure embedded with explicit high-pressure and exponential Lewis number terms developed in the context of hydrocarbon mixtures is used. These comparative studies based on the global quantity, turbulent flame speed, indicate that the model predictions are encouraging yielding proper quantification along with reasonable characterization of all the four different flames, over a broad range of turbulence, fuel-types and for varied equivalence ratios. However, with each flame involved the model demands tuning of the (empirical) constant to allow for either or both of these effects, or for the influence of the burner geometry. This provisional stand remains largely insufficient. Therefore, a submodel for chemical time scale from the leading point analysis based on the critically curved laminar flames employed in earlier studies for expanding spherical flames is introduced here. By combining the submodel and the reaction closure, the dependence of turbulent flame speed on physicochemical properties of the burning mixtures including the strong dependence of preferential diffusion and/or Le effects can be determined.

An Efficient Computational Model for Premixed Turbulent Combustion at High Reynolds Numbers Based on a Turbulent Flame Speed Closure

1998 ◽  
Vol 120 (3) ◽  
pp. 526-532 ◽  
Author(s):  
V. Zimont ◽  
W. Polifke ◽  
M. Bettelini ◽  
W. Weisenstein
Keyword(s):  
Computational Model ◽  
Transport Equation ◽  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Reynolds Numbers ◽  
Flame Speed ◽  
Closed Form Expression ◽  
Turbulent Length Scale ◽  
Premixed Turbulent Combustion ◽  
Turbulent Flame Speed

Theoretical background, details of implementation, and validation results for a computational model for turbulent premixed gaseous combustion at high turbulent Reynolds numbers are presented. The model describes the combustion process in terms of a single transport equation for a progress variable; turbulent closure of the progress variable’s source term is based on a model for the turbulent flame speed. The latter is identified as a parameter of prime significance in premixed turbulent combustion and determined from theoretical considerations and scaling arguments, taking into account physico-chemical properties and local turbulent parameters of the combustible mixture. Specifically, phenomena like thickening, wrinkling, and straining of the flame front by the turbulent velocity field are considered, yielding a closed form expression for the turbulent flame speed that involves, e.g., speed, thickness, and critical gradient of a laminar flame, local turbulent length scale, and fluctuation intensity. This closure approach is very efficient and elegant, as it requires only one transport equation more than the non reacting flow case, and there is no need for costly evaluation of chemical source terms or integration over probability density functions. The model was implemented in a finite-volume-based computational fluid dynamics code and validated against detailed experimental data taken from a large-scale atmospheric gas turbine burner test stand. The predictions of the model compare well with the available experimental results. It has been observed that the model is significantly more robust and computationally efficient than other combustion models. This attribute makes the model particularly interesting for applications to large three-dimensional problems in complicated geometries.

scholarly journals Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2425-2438 ◽  
Author(s):  
Mohammed Alhumairi ◽  
Özgür Ertunç
Keyword(s):  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Jet Flow ◽  
Flame Speed ◽  
Premixed Combustion ◽  
Grid Turbulence ◽  
Closure Model ◽  
Lean Premixed Combustion ◽  
Turbulent Flame Speed ◽  
Combustion Models

Lean premixed combustion under the influence of active-grid turbulence was computationally investigated, and the results were compared with experimental data. The experiments were carried out to generate a premixed flame at a thermal load of 9 kW from a single jet flow combustor. Turbulent combustion models, such as the coherent flame model and turbulent flame speed closure model were implemented for the simulations performed under different turbulent flow conditions, which were specified by the Reynolds number based on Taylor?s microscale, the dissipation rate of turbulence, and turbulent kinetic energy. This study shows that the applied turbulent combustion models differently predict the flame topology and location. However, similar to the experiments, simulations with both models revealed that the flame moves toward the inlet when turbulence becomes strong at the inlet, that is, when Re? at the inlet increases. The results indicated that the flame topology and location in the coherent flame model were more sensitive to turbulence than those in the turbulent flame speed closure model. The flame location behavior on the jet flow combustor significantly changed with the increase of Re?.

Premixed, turbulent combustion of a sudden-expansion flow

1983 ◽  
Vol 50 ◽  
pp. 153-165 ◽  
Author(s):  
Y.El Banhawy ◽  
S. Sivasegaram ◽  
J.H. Whitelaw
Keyword(s):  
Turbulent Combustion ◽  
Sudden Expansion ◽  
Premixed Turbulent Combustion

scholarly journals A Similarity Subgrid Model for Premixed Turbulent Combustion

2008 ◽  
Vol 82 (2) ◽  
pp. 233-248 ◽  
Author(s):  
A. W. Vreman ◽  
R. J. M. Bastiaans ◽  
B. J. Geurts
Keyword(s):  
Turbulent Combustion ◽  
Premixed Turbulent Combustion ◽  
Subgrid Model
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