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flamelet-models
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Numerical Analysis of Effects of Twin Swirler Injector on Turbine Combustion Chamber Performance
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
The objective of current research is to investigate the effects of Twin Swirler Injector on performance of turbine combustor. For this purpose, the swirlcup is assessed in a dump combustion chamber. The resultant simplicity in geometry leads to a facilitation in parametric studies as well as a reduction in modeling and meshing time. The target swirlcup, is a simplified model of CFM56 engine’s swirlcup.
Standard k-ε model is established to take into account turbulence effects. The non-reacting flow is at first simulated for capturing and recognising different phenomena. Adiabatic reacting flow simulations are conducted with Probability Distribution Function using Steady Laminar Flamelet...
Standard k-ε model is established to take into account turbulence effects. The non-reacting flow is at first simulated for capturing and recognising different phenomena. Adiabatic reacting flow simulations are conducted with Probability Distribution Function using Steady Laminar Flamelet...
Flamelet Modeling in Large-eddy Simulation of Turbulent Premixed
Flames
,
M.Sc. Thesis
Sharif University of Technology
;
Farshchi, Mohammad
(Supervisor)
;
Salehi, Mohammad Mahdi
(Co-Supervisor)
Abstract
The purpose of this study is to investigate the efficiency of a flamelet method along with the LES1 approach in the modeling of a turbulent premixed flame behind the bluff-body. In this flame ,because of the high turbulence intensity and fuel dilution, there is a significant interaction between the turbulence and chemical kinetics. In this study, first, the cold flow is modeled using LES and RANS2 approaches. Then, using the Flame-Generated Manifold (FGM) model and a presumed PDF model, the turbulent reacting flow is simulated.Comparison of the results of the LES and RANS showed that the accuracy of the LES method in simulating the physics of turbulent flow is much higher than RANS, but its...
Optimization of Design Parameters for NOx Reduction in Combustion Process of an Effective Power Plants Burner
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
In recent decade, pollution reduction is one of challenges in front of engineers. Nowadays accurate prediction of temperature and harmful Pollutants is vital, this leads to various models for turbulent combustion to predict combustion-generated pollutants. One of the most widely used models for simulating turbulent combustion is Flamelet because of separating the chemical reactions and the turbulent flow field. The unsteady state assumption of Flamelet model is capable of reasonably predict complicated phenomenon such as slow chemical reaction and radiation. The purpose of this study is to calculate combustion-generated emissions by Flamelet model and reduce these emissions by engineering...
Assessment of optimal reaction progress variable characteristics for partially premixed flames
, Article Combustion Theory and Modelling ; Volume 26, Issue 5 , 2022 , Pages 797-830 ; 13647830 (ISSN) ; Ommi, F ; Farshchi, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
The reaction progress variable is a crucial concept in the advanced flamelet combustion models. As a controlling variable, a well-defined progress variable must consider the essential features of the combustion process. It is usually a heuristically defined linear combination of some major chemical species mass fractions. However, such a simple definition could lead to inaccurate results for the fuel-rich reactive mixtures or complicated fuels, due to the vast number of chemical species in the combustion process. In this paper, a new method for generating a reaction progress variable is proposed through solving a constrained optimisation problem. The proposed method uses a genetic algorithm...
Supercritical Combustion Simulation
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Combustion in supercritical conditions (thermodynamic) is one of the most important applications of today's systems. One of the reasons for the increased use of combustion in supercritical conditions is the need to develop high pressure combustion systems, such as liquid fuel engines, gas turbines and internal combustion engines. Combustion is a technique in which the fuel is injected into the combustion chamber with its supercritical state (Any substance at a temperature and pressure above its critical point). Fuels in the supercritical conditions exhibit new features such as low viscosity, high diffusivity and low surface tension, which lead to higher efficiency, high power generation and...
Modeling of Turbulent Combustion at Supercritical Condition, Using Flamelet Based Models
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Turbulent combustion at supercritical condition have a considerable effect in modern high performance rocket propulsion systems, gas turbines and diesel engines. In such a reaction conditions, an abrupt changes occur in thermodynamics and transport properties of fluid. So numerically modeling of a real fluid behavior of the cryogenic propellants and the turbulent trans-critical mixing and combustion processes faces serious challenges.In this study, in order to realistically represent turbulence–chemistry interactions, detailed chemical kinetics and real-fluid thermodynamic behaviors related to the gaseous hydrogen and cryogenic liquid oxygen combustion under supercritical pressures, the...
Finite element volume analysis of propane preheated air flame passing through a minichannel
, Article ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting ; 2014 ; Ghafourizadeh, M ; Schneider, G. E ; Sharif University of Technology
Abstract
A hybrid finite-element-volume FEV method is extended to simulate turbulent non-premixed propane air preheated flame in a minichannel. We use a detailed kinetics scheme, i.e. GRI mechanism 3.0, and the flamelet model to perform the combustion modeling. The turbulence-chemistry interaction is taken into account in this flamelet modeling using presumed shape probability density functions PDFs. Considering an upwind-biased physics for the current reacting flow, we implement the physical influence upwinding scheme PIS to estimate the cell-face mixture fraction variance in this study. To close the turbulence closure, we employ the two-equation standard κ-ε turbulence model incorporated with...
Numerical study on the effects of fuel injector on carbonaceous pollutants in a kerosene combustor
, Article 13th International Energy Conversion Engineering Conference, 27 July 2015 through 29 July 2015 ; July , 2015 ; 9781624103766 (ISBN) ; Ghafourizadeh, M ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc, AIAA
2015
Abstract
A gaseous-kerosene/air turbulent nonpremixed flame in a combustion chamber is simulated to investigate the effects of fuel-injector cone-angle on the pollutions of soot nano-particles, carbon monoxide, and carbon dioxide. We use a two-equation soot model in our studying, consider a detailed chemical scheme consisting of 121 species and 2613 elementary reactions, use the flamelet model, employ the presumed-shape probability density functions PDFs, apply the two-equation κ-ε turbulence model with round-jet corrections, and take into account the radiation effects assuming optically-thin flame in our numerical modeling. This research concentrates on investigating the impacts of kerosene injector...
Numerical study of inlet turbulators effect on the thermal characteristics of a jet propulsion-fueled combustor and its hazardous pollutants emission
, Article Journal of Heat Transfer ; Volume 139, Issue 6 , 2017 ; 00221481 (ISSN) ; Ghafourizadeh, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2017
Abstract
This work numerically studies the effects of inlet air and fuel turbulators on the thermal behavior of a combustor burning the jet propulsion (JP) (kerosene-surrogate) fuel and its resulting pollutants emission including the nanoparticulate soot aerosols and aromatic compounds. To model the soot formation, the method employs a semi-empirical two-equation model, in which the transport equations for soot mass fraction and soot number density are solved considering soot nanoparticles evolutionary process. The soot nucleation is described using the phenyl route in which the soot is formed from the polycyclic aromatic hydrocarbons. Incorporating a detailed chemical mechanism described by 200...