scholarly journals Numerical Simulations of a Turbulent High-Pressure Premixed Cooled Jet Flame With the Flamelet Generated Manifolds Technique

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Andrea Donini ◽  
Robert J. M. Bastiaans ◽  
Jeroen A. van Oijen ◽  
L. Philip H. de Goey
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Heat Loss ◽  
Computational Effort ◽  
Navier Stokes ◽  
Combustion Model ◽  
Jet Flame ◽  
Progress Variable ◽  
Air Jet ◽  
Flamelet Generated Manifold

In the present paper, a computational analysis of a high pressure confined premixed turbulent methane/air jet flames with heat loss to the walls is presented. In this scope, chemistry is reduced by the use of the flamelet generated manifold (FGM) method and the fluid flow is modeled in an large eddy simulation (LES) and Reynolds-averaged Navier–Stokes (RANS) context. The reaction evolution is described by the reaction progress variable, the heat loss is described by the enthalpy and the turbulence effect on the reaction is represented by the progress variable variance. A generic lab scale burner for methane high-pressure (5 bar) high-velocity (40 m/s at the inlet) preheated jet is adopted for the simulations, because of its gas-turbine relevant conditions. The use of FGM as a combustion model shows that combustion features at gas turbine conditions can be satisfactorily reproduced with a reasonable computational effort. Furthermore, the present analysis indicates that the physical and chemical processes controlling carbon monoxide (CO) emissions can be captured only by means of unsteady simulations.

Numerical Simulations of a Premixed Turbulent Confined Jet Flame Using the Flamelet Generated Manifold Approach With Heat Loss Inclusion

2013 ◽  
Author(s):  
A. Donini ◽  
S. M. Martin ◽  
R. J. M. Bastiaans ◽  
J. A. van Oijen ◽  
L. P. H. de Goey
Keyword(s):  
Heat Loss ◽  
Computational Effort ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Conductive Heat ◽  
Jet Flame ◽  
Reaction Progress ◽  
Progress Variable ◽  
Air Jet ◽  
Flamelet Generated Manifold

In the present paper a computational analysis of a confined premixed turbulent methane/air jet flame is presented. In this scope, chemistry is reduced by the use of the Flamelet Generated Manifold (FGM) method [1, 2], and the fluid flow is modeled in a RANS context. In the FGM technique the reaction progress of the flame is generally described by a few control variables, for which a transport equation is solved during runtime. The flamelet system is computed in a pre-processing stage, and a manifold with all the information about combustion is stored in a tabulated form. In the present implementation the reaction evolution is described by the reaction progress variable, the heat loss is described by the enthalpy and the turbulence effect on the reaction is represented by the progress variable variance. The turbulence-chemistry interaction is considered through the use of a presumed pdf approach. A generic lab scale burner for high-velocity preheated jets is used for validation [3, 4]. It consists of a rectangular confinement, and an off-center positioning of the jet nozzle enables flame stabilization by recirculation of hot combustion products. The inlet speed is appropriately high, in order to be close to the blow out limit. Flame structures were visualized by OH* chemiluminescence imaging and planar laser-induced fluorescence of the OH radical. Laser Raman scattering was used to determine concentrations of the major species and the temperature. Velocity fields were measured with particle image velocimetry. The important effect of conductive heat loss to the walls is included in the FGM chemistry reduction method in a RANS context, in order to predict the evolution and description of a turbulent jet flame in high Reynolds number flow conditions. Comparisons of various mean fields (velocities, temperatures) with RANS results are shown. The use of FGM as a combustion model shows that combustion features at gas turbine conditions can be satisfactorily reproduced with a reasonable computational effort.

Comparison of Performance of Flamelet Generated Manifold Model With That of Finite Rate Combustion Model for Hydrogen Blended Flames

2021 ◽  
Author(s):  
Sourabh Shrivastava ◽  
Ishan Verma ◽  
Rakesh Yadav ◽  
Pravin Nakod ◽  
Stefano Orsino
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Characteristics ◽  
Combustion Model ◽  
Finite Rate ◽  
Reaction Progress ◽  
Progress Variable ◽  
Combustion Models ◽  
Flamelet Generated Manifold ◽  
Chemistry Modeling

Abstract International Air Transport Association (IATA) sets a 50% reduction in 2005 CO2 emissions levels by 2050, with no increase in net emissions after 2020 [1]. The association also expects the global aviation demand to double to 8.2 billion passengers per year by 2037. These issues have prompted the aviation industry to focus intensely on adopting sustainable aviation fuels (SAF). Further, reduction in CO2 emission is also an active area of research for land-based power generation gas turbine engines. And fuels with high hydrogen content or hydrogen blends are regarded as an essential part of future power plants. Therefore, clean hydrogen and other hydrogen-based fuels are expected to play a critical role in reducing greenhouse gas emissions in the future. However, the massive difference in hydrogen’s physical properties compared to hydrocarbon fuels, ignition, and flashback issues are some of the major concerns, and a detailed understanding of hydrogen combustion characteristics for the conditions at which gas turbines operate is needed. Numerical combustion analyses can play an essential role in exploring the combustion performance of hydrogen as an alternative gas turbine engine fuel. While several combustion models are available in the literature, two of the most preferred models in recent times are the flamelet generated manifold (FGM) model and finite-rate (FR) combustion model. FGM combustion model is computationally economical compared to the detailed/reduced chemistry modeling using a finite-rate combustion model. Therefore, this paper aims to understand the performance of the FGM model compared to detailed chemistry modeling of turbulent flames with different levels of hydrogen blended fuels. In this paper, a detailed comparison of different combustion characteristics like temperature, species, flow, and NOx distribution using FGM and finite rate combustion models is presented for three flame configurations, including the DLR Stuttgart jet flame [2], Bluff body stabilized Sydney HM1 flame [3] and dry-low-NOx hydrogen micro-mix combustion chamber [4]. One of the FGM model’s essential parameters is to select a suitable definition of the reaction progress variable. The reaction progress variable should monotonically increase from the unburnt region to the burnt region. The definition is first studied using a 1D premixed flame with different blend ratios and then used for the actual cases. 2D/3D simulations for the identified flames are performed using FGM and finite rate combustion models. Numerical results from both these models are compared with the available experimental data to understand FGM’s applicability. The results show that the FGM model performs reasonably well for pure hydrogen and hydrogen blended flames.

Turbulent Combustion Modeling Using Flamelet-Generated Manifolds for Gas Turbine Applications in OpenFOAM

2014 ◽  
Author(s):  
A. Fancello ◽  
L. Panek ◽  
O. Lammel ◽  
W. Krebs ◽  
R. J. M. Bastiaans ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Computational Effort ◽  
Navier Stokes ◽  
Test Case ◽  
Combustion System ◽  
Data Set ◽  
Detailed Chemistry ◽  
Jet Flame ◽  
Controlling Variables ◽  
Extensive Experimental Data

The continuous interest in reducing pollutions and developing both an efficient and clean combustion system require large attention in the design requirements, especially when related to industrial gas turbine application. Although in recent years the advancements in modelling have increased dramatically, combustion still needs a huge computational effort. The Flamelet-Generated Manifolds (FGM) method is considered a suitable solution with an accuracy that can be comparable with detailed chemistry simulations results. The full combustion system can be described by few controlling variables while the chemical details are stored in a database (manifold) as function of controlling variables. Transport equations are solved for the Navier-Stokes system and the controlling variables. The detailed chemistry code Chem1D is used to create the manifolds. Turbulence can be modeled using a PDF approach for the subgrid modeling of the chemistry terms. The OpenFOAM open source CFD package is used as CFD tool for the simulations. The aim of this work is to demonstrate the usage of FGM with OpenFOAM and figure out the status of the implementation. To achieve this goal, the work employs as test case a confined lean jet flame is used. For the case presented, an extensive experimental data set exist, including PIV and Raman data. Results are further compared with traditional methods, while FGM method might be easily extended to other scenarios.

The Implementation of Five-Dimensional FGM Combustion Model for the Simulation of a Gas Turbine Model Combustor

2015 ◽  
Author(s):  
Andrea Donini ◽  
Robert J. M. Bastiaans ◽  
Jeroen A. van Oijen ◽  
L. Philip H. de Goey
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Heat Loss ◽  
Gas Turbines ◽  
Mixture Fraction ◽  
Combustion Model ◽  
Control Variables ◽  
Progress Variable ◽  
Gas Turbine Combustion ◽  
Turbine Model

Gas turbines are one of the most important energy conversion methods in the world today. This is because using gas turbines, large scale, high efficiency, low cost and low emission energy production is possible. For this type of engines, low pollutants emissions can be achieved by very lean premixed combustion systems. Numerical simulation is foreseen to provide a tremendous increase in gas turbine combustors design efficiency and quality over the next future. However, the numerical simulation of modern stationary gas-turbine combustion systems represents a very challenging task. Several numerical models have been developed in order to reduce the costs of flame simulations for engineering applications. In the present paper the Flamelet-Generated Manifold (FGM) chemistry reduction method is implemented and extended for the inclusion of all the features that are typically observed in stationary gas-turbine combustion. These consist of stratification effects, heat loss and turbulence. The latter is included by coupling FGM with the Reynolds Averaged Navier Stokes (RANS) model. Three control variables are included for the chemistry representation: the reaction evolution is described by the reaction progress variable, the heat loss is described by the enthalpy and the stratification effect is expressed by the mixture fraction. The interaction between chemistry and turbulence is considered through a presumed probability density function (PDF) approach, which is considered for progress variable and mixture fraction. This results in two extra control variables: progress variable variance and mixture fraction variance. The resulting manifold is therefore five-dimensional, in which the dimensions are progress variable, enthalpy, mixture fraction, progress variable variance and mixture fraction variance. A highly turbulent and swirling flame in a gas turbine model combustor is computed in order to test the 5-D FGM implementation. The use of FGM as a combustion model shows that combustion features at gas turbine conditions can be satisfactorily reproduced with a reasonable computational effort. The implemented combustion model retains most of the physical accuracy of a detailed simulation while drastically reducing its computational time, paving the way for new developments of alternative fuel usage in a cleaner and more efficient combustion.

Monte Carlo Simulation for Radiative Transfer in a High-Pressure Industrial Gas Turbine Combustion Chamber

2017 ◽  
Author(s):  
Tao Ren ◽  
Michael F. Modest ◽  
Somesh Roy
Keyword(s):  
Monte Carlo ◽  
Gas Turbine ◽  
Radiation Effects ◽  
Swirling Flow ◽  
Calculation Model ◽  
Navier Stokes ◽  
Combustion Model ◽  
Stirred Reactor ◽  
Industrial Gas Turbine ◽  
Gas Turbine Burner

Radiative heat transfer is studied numerically for reacting swirling flow in an industrial gas turbine burner operating at a pressure of 15 bar. The reacting field characteristics are computed by Reynolds-averaged Navier-Stokes (RANS) equations using the k-ε model with the partially stirred reactor (PaSR) combustion model. The GRI-Mech 2.11 mechanism, which includes nitrogen chemistry, is used to demonstrate the the ability of reducing NOx emissions of the combustion system. A Photon Monte Carlo (PMC) method coupled with a line-by-line spectral model is employed to accurately account for the radiation effects. CO2, H2O and CO are assumed to be the only radiatively participating species and wall radiation is considered as well. Optically thin and PMC-gray models are also employed to show the differences between the simplest radiative calculation models and the most accurate radiative calculation model, i.e., PMC-LBL, for the gas turbine burner. It was found that radiation does not significantly alter the temperature level as well as CO2 and H2O concentrations. However, it has significant impacts on the NOx levels at downstream locations.

Assessment of Scale-Resolved Computational Fluid Dynamics Methods for the Investigation of Lean Burn Spray Flames

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Stefano Puggelli ◽  
Davide Bertini ◽  
Lorenzo Mazzei ◽  
Antonio Andreini
Keyword(s):  
Detailed Comparison ◽  
Navier Stokes ◽  
Combustion Model ◽  
Experimental Investigations ◽  
Lean Burn ◽  
Two Phase ◽  
Physical Description ◽  
Spray Flames ◽  
Flamelet Generated Manifold ◽  
Modeling Strategy

Incoming standards on NOx emissions are motivating many aero-engines manufacturers to adopt the lean burn combustion concept. However, several technological issues have to be faced in this transition, among which limited availability of air for cooling purpose and thermoacoustics phenomena. In this scenario, standard numerical design tools are not often capable of characterizing such devices. Thus, considering also the difficulties of experimental investigations in a highly pressurized and reactive environment, unsteady scale-resolved CFD methods are required to correctly understand the combustor performances. In this work, a set of scale-resolved simulations have been carried out on the Deutsches Zentrum für Luft- und Raumfahrt (DLR) generic single-sector combustor spray flame for which measurements both in nonreactive and reactive test conditions are available. Exploiting a two-phase Eulerian–Lagrangian approach combined with a flamelet generated manifold (FGM) combustion model, LES simulations have been performed in order to assess the potential improvements with respect to steady-state solutions. Additional comparisons have also been accomplished with scale-adaptive simulation (SAS) calculations based on eddy dissipation combustion model (EDM). The comparison with experimental results shows that the chosen unsteady strategies lead to a more physical description of reactive processes with respect to Reynolds-averaged Navier–Stokes (RANS) simulations. FGM model showed some limitations in reproducing the partially premixed nature of the flame, whereas SAS–EDM proved to be a robust modeling strategy within an industrial perspective. A new set of spray boundary conditions for liquid injection is also proposed whose reliability is proved through a detailed comparison against experimental data.

Investigation of Flamelet Generated Manifold Reaction Source Term Closure Models Applied to an Industrial Gas Turbine

2019 ◽  
Author(s):  
George Mallouppas ◽  
Graham Goldin ◽  
Yongzhe Zhang ◽  
Piyush Thakre ◽  
Jim Rogerson
Keyword(s):  
Gas Turbine ◽  
Source Term ◽  
Mixture Fraction ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Turbulent Flame Speed ◽  
Progress Variable ◽  
Flamelet Generated Manifold ◽  
Reactor Types ◽  
Industrial Gas Turbine

Abstract Three Flamelet Generated Manifold reaction source term closure options and two different reactor types are examined with Large Eddy Simulation of an industrial gas turbine combustor operating at 3 bar. This work presents the results for the SGT-100 Dry Low Emission (DLE) gas turbine provided by Siemens Industrial Turbomachinery Ltd. The related experimental study was performed at the German Aerospace Centre, DLR, Stuttgart, Germany. The FGM model approximates the thermo-chemistry in a turbulent flame as that in a simple 0D constant pressure ignition reactors and 1D strained opposed-flow premixed reactors, parametrized by mixture fraction, progress variable, enthalpy and pressure. The first objective of this work is to compare the flame shape and position predicted by these two FGM reactor types. The Kinetic Rate (KR) model, studied in this work, uses the chemical rate from the FGM with assumed shapes, which are a Beta function for mixture fraction and delta functions for reaction progress variable and enthalpy. Another model investigated is the Turbulent Flame-Speed Closure (TFC) model with Zimont turbulent flame speed, which propagates premixed flame fronts at specified turbulent flame speeds. The Thickened Flame Model (TFM), which artificially thickens the flame to sufficiently resolve the internal flame structure on the computational grid, is also explored. Therefore, a second objective of this paper is to compare KR, TFC and TFM with the available experimental data.

Design Improvement Survey for NOx Emissions Reduction of a Heavy-Duty Gas Turbine Partially Premixed Fuel Nozzle Operating With Natural Gas: Numerical Assessment

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Alessandro Innocenti ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Matteo Cerutti ◽  
Gianni Ceccherini ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbulent Combustion ◽  
Operating Conditions ◽  
Combustion Model ◽  
Formation Mechanisms ◽  
Heavy Duty ◽  
Flamelet Generated Manifold ◽  
Fuel Nozzle ◽  
Partially Premixed ◽  
Heavy Duty Gas Turbine

A numerical investigation of a low NOx partially premixed fuel nozzle for heavy-duty gas turbine applications is presented in this paper. Availability of results from a recent test campaign on the same fuel nozzle architecture allowed the exhaustive comparison study presented in this work. At first, an assessment of the turbulent combustion model was carried out, with a critical investigation of the expected turbulent combustion regimes in the system and taking into account the partially premixed nature of the flame due to the presence of diffusion type pilot flames. In particular, the fluent partially premixed combustion model and a flamelet approach are used to simulate the flame. The laminar flamelet database is generated using the flamelet generated manifold (FGM) chemistry reduction technique. Species and temperature are parameterized by mixture fraction and progress variable. Comparisons with calculations with partially premixed model and the steady diffusion flamelet (SDF) database are made for the baseline configuration in order to discuss possible gains associated with the introduced dimension in the FGM database (reaction progress), which makes it possible to account for nonequilibrium effects. Numerical characterization of the baseline nozzle has been carried out in terms of NOx. Computed values for both the baseline and some alternative premixer designs have been then compared with experimental measurements on the reactive test rig at different operating conditions and different split ratios between main and pilot fuel. Numerical results allowed pointing out the fundamental NOx formation processes, both in terms of spatial distribution within the flame and in terms of different formation mechanisms. The obtained knowledge would allow further improvement of fuel nozzle design.

Computational Fluid Dynamics Study of a Nonpremixed Turbulent Flame Using openfoam: Effect of Chemical Mechanisms and Turbulence Models

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Hermann Chopkap Noume ◽  
Valentin Bomba ◽  
Marcel Obounou ◽  
Henri Ekobena Fouda ◽  
Flavian Emmanuel Sapnken
Keyword(s):  
Turbulent Flame ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Combustion Model ◽  
Turbulent Diffusion Flame ◽  
Elementary Reactions ◽  
Jet Flame ◽  
Chemical Mechanisms ◽  
High Reynolds ◽  
Skeletal Mechanism

Abstract This article presents a study of the influence of chemical mechanisms and turbulence models on Reynolds-averaged Navier–Stokes (RANS) simulations of the CH4/H2/N2-air turbulent diffusion flame, i.e., the so-called DLR-A flame. The first part of this study is focused on the assessment of the influence of four chemical models on predicted profiles of the DLR-A flame. The chemical mechanisms considered are as follows: (i) a C2 compact skeletal mechanism, which is derived from the GRI3.0 mechanism using an improved multistage reduction method, (ii) a C1 skeletal mechanism containing 41 elementary reactions amongst 16 species, (iii) the global mechanism by Jones and Lindstedt, (iv) and a global scheme consisting of the overall reactions of methane and dihydrogen. RANS numerical results (e.g., velocities, temperature, species, or the heat production rate profiles) obtained running the reactingFOAM solver with the four chemical mechanisms as well as the standard k − ɛ model, the partially stirred reactor (PaSR) combustion model, and the P − 1 radiation model indicate that the C2 skeletal mechanism yields the best agreement with measurements. In the second part of this study, four turbulence models, namely, the standard k − ɛ model, the renormalization group (RNG) k − ɛ model, realizable k − ɛ model, and the k − ω shear stress transport (SST) model, are considered to evaluate their effects on the DLR-A flame simulation results obtained with the C2 skeletal mechanism. Results reveal that the predictions obtained with the standard k − ɛ and the RNG k − ɛ models are in very good agreement with the experimental data. Hence, for simple jet flame with moderately high Reynolds number such as the DLR-A flame, the standard k-epsilon can model the turbulence with a very good accuracy.

Prediction of CO Emission Index for Aviation Gas Turbine Combustor Using Flamelet Generated Manifold Combustion Model

2021 ◽  
Author(s):  
Saurabh Patwardhan ◽  
Pravin Nakod ◽  
Stefano Orsino ◽  
Rakesh Yadav ◽  
Fang Xu ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Combustion Model ◽  
Gas Turbine Engines ◽  
Gas Turbine Combustor ◽  
Flamelet Generated Manifold ◽  
Emission Index ◽  
Co Emission

Abstract Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.

Sign in / Sign up

Export Citation Format

Share Document