LES Combustion Model With Stretch and Heat Loss Effects for Prediction of Premix Flame Characteristics and Dynamics

2017 ◽  
Author(s):  
Luis Tay-Wo-Chong ◽  
Alessandro Scarpato ◽  
Wolfgang Polifke
Keyword(s):  
Flow Field ◽  
Heat Loss ◽  
Turbulent Combustion ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Swirl Burner ◽  
Combustion Models ◽  
Variable Approach ◽  
Large Eddy ◽  
Good Agreement

The present paper extends an approach to include effects of stretch and heat losses into turbulent combustion models from the RANS framework to the LES framework. This approach has shown the potential to improve the prediction of flame stabilization by considering these combined effects. The model is based on the calculation of the consumption speed of laminar premixed flames influenced by variations in strain and heat loss in asymmetric counterflow configurations. The consumption speed depending on strain and heat loss is introduced into a turbulent combustion model based on a progress variable approach. Large Eddy Simulations of a fully-premixed axial swirl burner with and without the influence of stretch and heat loss effects are carried out and validated against flow field and OH* chemiluminescence measurements for different power ratings and equivalence ratios. Flame dynamics are also investigated by extracting the Flame Transfer Function of the fully-premixed axial swirl burner with System Identification methods. Good agreement on the flow field, flame characteristics and dynamics between experiment and simulation was obtained with the inclusion of stretch and heat loss effects into the combustion model. Results show the importance of including these effects into turbulence combustion models for the design of premix burners for gas turbine combustors.

scholarly journals Understanding the diesel-like spray characteristics applying a flamelet-based combustion model and detailed large eddy simulations

2019 ◽  
Vol 21 (1) ◽  
pp. 134-150 ◽  
Author(s):  
Eduardo J Pérez-Sánchez ◽  
Jose M Garcia-Oliver ◽  
Ricardo Novella ◽  
Jose M Pastor
Keyword(s):  
Flame Stabilization ◽  
Large Eddy Simulations ◽  
Combustion Model ◽  
Progress Variable ◽  
Auto Ignition ◽  
Large Eddy ◽  
Engine Combustion ◽  
Spatial Fields ◽  
Lift Off ◽  
Good Agreement

This investigation analyses the structure of spray A from engine combustion network (ECN), which is representative of diesel-like sprays, by means of large eddy simulations and an unsteady flamelet progress variable combustion model. A very good agreement between modelled and experimental measurements is obtained for the inert spray that supports further analysis. A parametric variation in oxygen concentration is carried out in order to describe the structure of the flame and how it is modified when mixture reactivity is changed. The most relevant trends for the flame metrics, ignition delay and lift-off length are well-captured by the simulations corroborating the suitability of the model for this type of configuration. Results show that the morphology of the flame is strongly affected by the boundary conditions in terms of the reactive scalar spatial fields and Z–T maps. The filtered instantaneous fields provided by the simulations allow investigation of the structure of the flame at the lift-off length, whose positioning shows low fluctuations, and how it is affected by turbulence. It is evidenced that small ignition kernels appear upstream and detached from the flame that eventually merge with its base in agreement with experimental observations, leading to state that auto-ignition plays a key role as one of the flame stabilization mechanisms of the flame.

scholarly journals Study of the Wall Thermal Condition Effect in a Lean-Premixed Downscaled Can Combustor Using Large-Eddy Simulation

2016 ◽  
Author(s):  
D. Mira ◽  
M. Vázquez ◽  
G. Houzeaux ◽  
S. Gövert ◽  
J. W. B. Kok ◽  
...  
Keyword(s):  
Turbulent Combustion ◽  
Mixture Fraction ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Laminar Flames ◽  
Combustion Model ◽  
Test Case ◽  
Eddy Simulation ◽  
Condition Effect ◽  
Large Eddy

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame.

scholarly journals Large Eddy Simulation of a Bluff Body Stabilized Lean Premixed Flame

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
A. Andreini ◽  
C. Bianchini ◽  
A. Innocenti
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Bluff Body ◽  
Sensitivity Study ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lean Premixed

The present study is devoted to verify current capabilities of Large Eddy Simulation (LES) methodology in the modeling of lean premixed flames in the typical turbulent combustion regime of Dry LowNOxgas turbine combustors. A relatively simple reactive test case, presenting all main aspects of turbulent combustion interaction and flame stabilization of gas turbine lean premixed combustors, was chosen as an affordable test to evaluate the feasibility of the technique also in more complex test cases. A comparison between LES and RANS modeling approach is performed in order to discuss modeling requirements, possible gains, and computational overloads associated with the former. Such comparison comprehends a sensitivity study to mesh refinement and combustion model characteristic constants, computational costs, and robustness of the approach. In order to expand the overview on different methods simulations were performed with both commercial and open-source codes switching from quasi-2D to fully 3D computations.

Modelling of Turbulent Premixed CH4/H2/Air Flames Including the Influence of Stretch and Heat Losses

2021 ◽  
Author(s):  
Halit Kutkan ◽  
Alberto Amato ◽  
Giovanni Campa ◽  
Giulio Ghirardo ◽  
Luis Tay Wo Chong Hilares ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Loss ◽  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Heat Losses ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Flame Stretch ◽  
Turbulent Combustion Model ◽  
Turbulent Premixed

Abstract This paper presents a RANS turbulent combustion model for CH4/H2/air mixtures which includes the effect of heat losses and flame stretch. This approach extends a previous model concept designed for methane/air mixtures and improves the prediction of flame stabilization when hydrogen is added to the fuel. Heat loss and stretch effects are modelled by tabulating the consumption speed of laminar counter flow flames in a fresh-to burnt configuration with detailed chemistry at various heat loss and flame stretch values. These computed values are then introduced in the turbulent combustion model by means of a turbulent flame speed expression which is derived as a function of flame stretch, heat loss and H2 addition. The model proposed in this paper is compared to existing models on experimental data of spherical expanding turbulent flame speeds. The performance of the model is further validated by comparing CFD predictions to experimental data of an atmospheric turbulent premixed bluff-body stabilized flame fed with CH4/H2/air mixtures ranging from pure methane to pure hydrogen.

Including Heat Loss and Quench Effects in Algebraic Models for Large Eddy Simulation of Premixed Combustion

2012 ◽  
Author(s):  
Roman Keppeler ◽  
Michael Pfitzner ◽  
Luis Tay Wo Chong ◽  
Thomas Komarek ◽  
Wolfgang Polifke
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Heat Loss ◽  
Combustion Model ◽  
Algebraic Models ◽  
Combustion Models ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Wall Interaction ◽  
Swirl Flame

In technically relevant combustion devices, combustion can take place in the vicinity of walls which can significantly affect the reaction and the heat transfer. However, only few studies focus on modelling of flame-wall interaction (FWI) for algebraic combustion models and virtually none consider FWI for algebraic Large Eddy Simulation combustion models. In the present work heat loss models, as previously published in the literature, are employed to extend a LES algebraic combustion model. The performance of the FWI models is evaluated by simulations of a nonadiabatic swirl flame. The simulation results are compared with experimental data of velocity field and heat release. The extent of the quenching zone and heat loss effects are determined in the simulations and compared with data from direct numerical simulations. Comparison of simulation and experimental data shows a significant improvement when heat loss effects are incorporated. Also the characteristic Peclet numbers are correctly predicted by FWI models.

Modelling of Turbulent Premixed CH4/H2/Air Flames Including the Influence of Stretch and Heat Losses

2021 ◽  
Author(s):  
Halit Kutkan ◽  
Alberto Amato ◽  
Giovanni Campa ◽  
Giulio Ghirardo ◽  
Luis Tay Wo Chong ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Loss ◽  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Heat Losses ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Flame Stretch ◽  
Turbulent Combustion Model ◽  
Turbulent Premixed

Abstract This paper presents a RANS turbulent combustion model for CH4/H2/air mixtures which includes the effect of heat losses and flame stretch. This approach extends a previous model concept designed for methane/air mixtures and improves the prediction of flame stabilization when hydrogen is added to the fuel. Heat loss and stretch effects are modelled by tabulating the consumption speed of laminar counter flow flames in a fresh-to-burnt configuration with detailed chemistry at various heat loss and flame stretch values. These computed values are then introduced in the turbulent combustion model by means of a turbulent flame speed expression which is derived as a function of flame stretch, heat loss and H2 addition. The model proposed in this paper is compared to existing models on experimental data of spherical expanding turbulent flame speeds. The performance of the model is further validated by comparing CFD predictions to experimental data of an atmospheric turbulent premixed bluff-body stabilized flame fed with CH4/H2/air mixtures ranging from pure methane to pure hydrogen.

Application of Various Combustion Models to a Generic Combustor

2003 ◽  
Author(s):  
Lei-Yong Jiang ◽  
Ian Campbell
Keyword(s):  
Experimental Tests ◽  
Combustion Model ◽  
Discrete Ordinates ◽  
Experimental Measurements ◽  
Finite Rate ◽  
Zone Length ◽  
Combustion Models ◽  
The Mean ◽  
Heat Transfers ◽  
Good Agreement

The flow-field of a generic gas combustor with interior and exterior conjugate heat transfers was numerically studied. Results obtained from three combustion models, combined with the re-normalization group (RNG) k-ε turbulence model, discrete ordinates radiation model, and partial equilibrium NOx model are presented and discussed. The numerical results are compared with a comprehensive database obtained from a series of experimental tests. The flow patterns and the recirculation zone length are excellently predicted, and the mean axial velocities are in fairly good agreement with the experimental measurements, particularly at downstream sections for all three combustion models. The mean temperature profiles are also fairly well captured by the probability density function (PDF) and eddy dissipation (EDS) combustion models. The EDS-finite-rate combustion model fails to provide acceptable temperature field. In general, the PDF shows some superiority over the EDS and EDS-finite-rate models. NOx levels predicted by the EDS model are in reasonable agreement with the experimental measurements.

Modeling of Turbulent Combustion and Radiative Heat Transfer in a Object-Oriented CFD Code for Gas Turbine Application

2008 ◽  
Author(s):  
Antonio Andreini ◽  
Matteo Cerutti ◽  
Bruno Facchini ◽  
Luca Mangani
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Radiative Heat Transfer ◽  
Turbulent Combustion ◽  
Radiative Heat ◽  
Object Oriented ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Combustion Models

One of the driving requirements in gas turbine design is the combustion analysis. The reduction of exhaust pollutant emissions is in fact the main design constraint of modern gas turbine engines, requiring a detailed investigation of flame stabilization criteria and temperature distribution within combustion chamber. At the same time, the prediction of thermal loads on liner walls continues to represent a critical issue especially with diffusion flame combustors which are still widely used in aeroengines. To meet such requirement, design techniques have to take advantage also of the most recent CFD tools that have to supply advanced combustion models according to the specific application demand. Even if LES approach represents a very accurate approach for the analysis of reactive flows, RANS computation still represents a fundamental tool in industrial gas turbine development, thanks to its optimal tradeoff between accuracy and computational costs. This paper describes the development and the validation of both combustion and radiation models in a object-oriented RANS CFD code: several turbulent combustion models were considered, all based on a generalized presumed PDF flamelet approach, valid for premixed and non premixed flames. Concerning radiative heat transfer calculations, two directional models based on the P1-Approximation and the Finite Volume Method were treated. Accuracy and reliability of developed models have been proved by performing several computations on well known literature test-cases. Selected cases investigate several turbulent flame types and regimes allowing to prove code affordability in a wide range of possible gas turbine operating conditions.

Large Eddy Simulation of an Enclosed Turbulent Reacting Methane Jet With the Tabulated Premixed Conditional Moment Closure Method

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Carlos Velez ◽  
Scott Martin ◽  
Aleksander Jemcov ◽  
Subith Vasu
Keyword(s):  
Turbulent Combustion ◽  
Moment Closure ◽  
Scalar Dissipation ◽  
Combustion Model ◽  
Conditional Moment ◽  
Eddy Simulation ◽  
Conditional Moment Closure ◽  
Major Species ◽  
Large Eddy ◽  
Closure Method

The tabulated premixed conditional moment closure (T-PCMC) method has been shown to provide the capability to model turbulent, premixed methane flames with detailed chemistry and reasonable runtimes in Reynolds-averaged Navier–Stokes (RANS) environment by Martin et al. (2013, “Modeling an Enclosed, Turbulent Reacting Methane Jet With the Premixed Conditional Moment Closure Method,” ASME Paper No. GT2013-95092). Here, the premixed conditional moment closure (PCMC) method is extended to large eddy simulation (LES). The new model is validated with the turbulent, enclosed reacting methane backward facing step data from El Banhawy et al. (1983, “Premixed, Turbulent Combustion of a Sudden-Expansion Flow,” Combust. Flame, 50, pp. 153–165). The experimental data have a rectangular test section at atmospheric pressure and temperature with an inlet velocity of 10.5 m/s and an equivalence ratio of 0.9 for two different step heights. Contours of major species, velocity, and temperature are provided. The T-PCMC model falls into the class of table lookup turbulent combustion models in which the combustion model is solved offline over a range of conditions and stored in a table that is accessed by the computational fluid dynamic (CFD) code using three controlling variables: the reaction progress variable (RPV), variance, and local scalar dissipation rate. The local scalar dissipation rate is used to account for the affects of the small-scale mixing on the reaction rates. A presumed shape beta function probability density function (PDF) is used to account for the effects of subgrid scale (SGS) turbulence on the reactions. SGS models are incorporated for the scalar dissipation and variance. The open source CFD code OpenFOAM is used with the compressible Smagorinsky LES model. Velocity, temperature, and major species are compared to the experimental data. Once validated, this low “runtime” CFD turbulent combustion model will have great utility for designing the next generation of lean premixed (LPM) gas turbine combustors.

Sign in / Sign up

Export Citation Format

Share Document