| 1. |
- Abou-Taouk, Abdallah, et al.
(författare)
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A Four-Step Global Reaction Mechanism for CFD Simulations of Flexi-Fuel Burner for Gas Turbines
- 2011
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Ingår i: Turbulence, Heat and Mass Transfer 7. - 9781567003017 ; , s. 785-788
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Konferensbidrag (refereegranskat)abstract
- A reduced four-step scheme for Computational Fluid Dynamics (CFD) analysis is presented here in the context of industrial type laboratory combustor. The present scheme has been optimized for a syngas mixture consisting of 10% CH4, 22.5% CO and 67.5% H2 by volume, and for a methane-air mixture. The optimization of the global scheme is done by comparing with the detailed San Diego mechanism using perfectly stirred reactor (PSR) and laminar flame speed calculations. The four-step global scheme has been applied to the CFD analysis of a swirl-stabilized flexi-fuel burner. Both reacting and non-reacting cases has been computed, using a hybrid Unsteady RANS/Large Eddy Simulation (URANS/LES) technique. Comparisons between CFD results and experimental data in the form of Particle Image Velocimetry (PIV) data, Planar Laser Induced Fluorescence (pLIF) and Proper Orthogonal Decomposition (POD) analysis from an atmospheric burner test rig at Lund University are presented. The CFD results scheme show good agreement with the experimental data.
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| 2. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
-
A Four-Step Global Reaction Mechanism for CFD Simulations of Flexi-Fuel Burner for Gas Turbines
- 2012
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Ingår i: Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer. - 2377-2816. ; Volume 2012-September, s. 616-627
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Konferensbidrag (refereegranskat)abstract
- A reduced four-step scheme for Computational Fluid Dynamics (CFD) analysis is presented here in the context of industrial type laboratory combustor. The present scheme has been optimized for a syngas mixture consisting of 10% CH4, 22.5% CO and 67.5% H2 by volume, and for a methane-air mixture. The optimization of the global scheme is done by comparing with the detailed San Diego mechanism using perfectly stirred reactor (PSR) and laminar flame speed calculations. The four-step global scheme has been applied to the CFD analysis of a swirl-stabilized flexi-fuel burner. Both reacting and non-reacting cases has been computed, using a hybrid Unsteady RANS/Large Eddy Simulation (URANS/LES) technique. Comparisons between CFD results and experimental data in the form of Particle Image Velocimetry (PIV) data, Planar Laser Induced Fluorescence (pLIF) and Proper Orthogonal Decomposition (POD) analysis from an atmospheric burner test rig at Lund University are presented. The CFD results scheme show good agreement with the experimental data.
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| 3. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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CFD analysis and application of dynamic mode decomposition for resonant-mode identification and damping in an SGT-100 DLE combustion system
- 2015
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Ingår i: Proceedings of the 7th European Combustion Meeting. - 9789631212570
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Konferensbidrag (refereegranskat)abstract
- This paper presents result of a turbulent reacting flow simulation based on a hybrid Unsteady Reynolds Averaged Navier Stokes/Large Eddy Simulation model (Menter’s SAS-SST model) applied to an experimental version of an industrial gas turbine combustion chamber at a pressure of 6 bar. The kinetics were represented by a recently developed in-house 4-step reaction mechanism using 7 species. A reasonably good agreement with measurements is found concerning velocity, temperature, pressure loss, mixture fraction and fuel mass fraction. The dynamic mode decomposition algorithm is also used here in order to identify some resonant modes and to quantify their respective frequency and damping. A number of low frequency modes with combustion dynamics included are observed and compared with the measurements.
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| 4. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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CFD analysis of a SGT-800 burner in a combustion RIG
- 2016
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Ingår i: ASME Turbo Expo, June 13 – 17, 2016, Seoul, South Korea. ; 4B-2016
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Konferensbidrag (refereegranskat)abstract
- This work focuses on 3D turbulent reacting flow modeling of a SGT-800 3rd generation dry low emission (DLE) burner at both atmospheric and engine-like conditions. At atmospheric pressure the burner is fitted in a test rig with high pre-heating of the incoming air. To reduce the computational cost, the M4 mechanism previously developed by Abou-Taouk et al. (2013) is used for operating pressure of 1 bar. A new novel optimized 4-step reaction mechanism for methane-air mixture is developed in the present work at an operating pressure of 20 bar. The mechanism is based on a large sample of detailed chemistry solutions that are processed by an iterative optimization procedure. This leads to a reduced 4-step mechanism, reproducing the targeted detailed chemistry solutions in terms of laminar flame speeds, species profiles and temperatures. The CFD simulations are performed using the combined eddy dissipation model / finite rate chemistry (EDM/FRC) turbulence chemistry interaction model. The turbulence is modeled using both the k-ω SST and the scale adaptive simulation (SAS) turbulence models. A comprehensive testing and measurement campaign carried out at atmospheric pressure for this burner was previously performed in a combustion test rig. The CFD results are compared to measurement data which includes for example flame position and pressure drop.
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| 5. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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CFD investigation of a Stirling engine f exi-fuel burner based on MILD combustion
- 2015
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Ingår i: Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer. - 2377-2816. ; 0, s. 855-858
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Konferensbidrag (refereegranskat)abstract
- This paper presents the comparison of results from tests and 3D CFD combustion simulations based on both RANS and hybrid URANS/LES (SAS-SST model) turbulence models applied to an industrial Stirling engine combustion chamber at atmospheric pressure. Both natural gas and landf ll gas mixture were simulated. The combustor is designed to operate in the MILD combustion mode which is characterized by low f ame temperatures and low NOX emissions. The kinetics for the landf ll gas was represented by a new optimized 4-step global mechanism, named AAT4NR, which was optimized for the present landf ll mixture. The new mechanism is developed using well-established optimization tools, where the coeff cients of the 4-step global chemistry are determined from a set of reference detailed chemistry solutions. A good agreement with measurements is found concerning major emissions, temperatures and NOX-levels.
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| 6. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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CFD investigation of a Stirling engine flexi-fuel burner based on MILD combustion
- 2015
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Ingår i: Turbulence, Heat and Mass Transfer 8. - 2377-2816. - 9781567004274 ; 8
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Konferensbidrag (refereegranskat)abstract
- This paper presents comparisons of results from tests and 3D CFD combustion simulations based on both RANS and hybrid URANS/LES (SAS-SST model) turbulence models applied to an industrial Stirling engine combustion chamber at atmospheric pressure. Both methane gas and landfill gas were simulated. The combustor is designed to operate in the MILD combustion mode which is characterized by low flame temperatures and low NOx emissions. A 4-step reduced reaction mechanism, named AAT4NR, involving seven species was developed to represent the landfill gas. The optimization was performed at atmospheric pressure for a range of fresh gas temperatures [300 K - 1000 K] and equivalence ratios [0.15 - 1]. Comparisons with detailed chemistry solutions of a planar propagating flame front show that the laminar flame speed, the adiabatic flame temperature, the ignition delay time and the species concentration at equilibrium are adequately predicted. There is good agreement between the quantities predicted with URANS/LES and experimental data, in terms of flow and flame dynamics, averaged temperatures, NOX-levels and the concentrations of some major species.
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| 7. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
-
CFD INVESTIGATION OF SWIRL-STABILIZED FLEXI-FUEL BURNER USING METHANE-AIR MIXTURE FOR GAS TURBINES
- 2011
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Ingår i: International Society for Airbreathing Engines, ISABE, Gothenburg, 2011. ; 1, s. 160-172
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Konferensbidrag (refereegranskat)abstract
- Combustion modeling based on a multi-step global reaction mechanism [1] is applied to CFD (Computational Fluid Dynamics) analysis of a scaled swirl-stabilized 4th generation premixed DLE (Dry Low Emission) burner for gas turbines. The flexi-fuel burner consists of a MAIN pre-mixed flame, a premixed PILOT flame and a confined RPL (Rich Pilot Lean) flame. Both steady-state RANS (Reynolds Averaged Navier Stokes) and hybrid URANS/LES (Unsteady RANS/Large Eddy Simulation) results have been computed. The results are compared with high quality experimental data in the form of emission data, PIV (Particle Image Velocimetry) data and OH-PLIF (Planar Laser Induced Fluorescence Imaging) from an atmospheric burner test rig at Lund University [2-3]. There is a good agreement between the CFD simulations and measurements of emissions, velocity field and flame visualization.
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| 8. |
- Abou-Taouk, Abdallah, 1982
(författare)
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CFD Modeling of Combustion in Flexi-Fuel Burners at Gas Turbine Conditions
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main source of energy in the nearest future will come from fossil fuels. Increasing demands on environmentally friendly energy conversion implies that pollutants, such as CO and NOx, need to be reduced. This project aims to investigate recent developments in combustion modeling and turbulence modeling in the context of engineering type Computational Fluid Dynamics (CFD) analysis tools, applied to the main problem area of swirl-stabilized flexi-fuel flames. To perform a CFD simulation of reacting flows, kinetic information needs to be provided to the CFD code. Fully detailed kinetic mechanisms are expensive in terms of computer time when coupled with CFD and hence the use of global reaction mechanisms is preferable. Global mechanismsconsist of a reduced number of reactions mostly one-way reactions which are governed by tuned Arrhenius rate expressions. The optimization at each equivalence ratio is here done by comparing results from Perfectly Stirred Reactor (PSR) calculations for both a detailed reference mechanism and the chosen multi-step global reaction mechanisms.Steady-state Reynolds Averaged Navier Stokes (RANS), hybrid Unsteady RANS/Large Eddy Simulation (URANS/LES) and LES turbulence models have been used in the CFD work. This thesis includes the development and derivation of new 3-step global reaction mechanism for methane-air flames, which has been implemented and evaluated in the CFD analysis for two different burner configurations. In papers I and II an atmospheric burner test rig at Lund University (LTH) has been modeled and the results have been compared to high quality experimental data (emission and Particle Image Velocimetry (PIV) data). There is good agreement between the CFD simulations and measurements of emissions, velocity field and flame visualization. The second configuration that has been modeled and compared with experimental data is the Sandia Flame D test case, which is reported in paper III.Keywords: CFD, Chemistry, Combustion, RANS, LES, SAS-SST, PSR, Global reaction mechanism
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| 9. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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CFD study on a Stirling burner based on MILD combustion and diluted mixtures
- 2016
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Ingår i: 17th International Stirling Engine Conferenc, 24-26 August 2016, Newcastle Upon Tyne, UK.. - 9781861354693 ; , s. 319-330
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Konferensbidrag (refereegranskat)abstract
- The work presented in this paper presents comparison of results from the experimental facility in Chalmers University of Technology and 3D CFD combustion simulations based on both RANS and hybrid URANS/LES (SAS-SST model) turbulence models applied to the GasBox combustion chamber at atmospheric pressure. The combustion is modelled using the Eddy Dissipation Model coupled with Finite Rate Chemistry using different optimized global reaction mechanisms. The gas composition has been varied from pure methane gas to low energy content, such as landfill gas mixture consisting of 26.8% CH4, 32.2% CO2, 2.0% O2 and 39.0% N2 by volume. There is a good agreement between the quantities predicted with hybrid URANS/LES and the experimental data, in terms of flow and flame dynamics, averaged temperatures and the concentrations of some major species.
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| 10. |
- Abou-Taouk, Abdallah, 1982
(författare)
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Challenges in kinetic optimization
- 2015
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Ingår i: 1st General Meeting & SECs for Power, Industry and Engines Workshop, 20150825, Thessaloniki, Greece..
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Konferensbidrag (refereegranskat)abstract
- Computational fluid dynamics (CFD) is an important tool for designing and optimizing combustion systems. However, CFD modeling of industrial combustion applications is a computationally demanding task. Today the integration of kinetics into turbulent flame simulations is one of the most difficult challenges in the combustion community. Numerous methods have been proposed for integrating kinetics into turbulent reaction flow, such as tabulation ideas [1] and trajectories in composition space [2]. However, run-time and computational power becomes a more difficult issue when such methods must be used in unsteady simulations such as hybrid URANS/LES and LES models where the conservation equations must be solved at each time step. For this reason, it is often necessary to apply simplified reaction mechanisms to reduce the computing effort. Given a detailed mechanism for a specific fuel mixture, a global mechanism can then be generated for a wide range of operating conditions matching any number of combustion parameters. To simplify the reaction mechanism it is necessary to determine which parameters may be important for the specific combustion case. For example, when generating a global mechanism for use in premixed CFD simulations, laminar flame speed is important. Other parameters may be important, such as the species production rates, the temperature and the species concentrations at equilibrium, the residence time for ignition and the 1D profiles for species and temperatures for a wide range of initial temperature, ϕ and pressures.
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