K. K. Kuo,“Principle of Combustion – second edition”, Wiley
C. Law, Combustion Physics, Cambridge
J. Warnatz, U.Maas, R. Dibble, Combustion 3rd edition, Springer
I. Glassmann, R. Yetter, Combustion 4th edition, Academic Press - Elsevier
Poinsot, Veynante, “Theoretical and numerical combustion”, Edwards
A. Lefebvre, Atomizations and Sprays, Taylor&Francis
Mathieu, J., Scott, J., “An Introduction to Turbulent Flow”, Cambridge University Press,2000.
“Introduction to Turbulence Modelling”, Lecture series by the Von Karman Institute for Fluid Dynamics, Bruxelles, 2002
“LES and related techniques”, Lecture series by the Von Karman Institute for Fluid Dynamics, Bruxelles, 2007
S. Pope, 2000, “Turbulent flows”, Cambridge Univesrity Press
R. Cant, E. Mastorakos, Turbulent Reacting Flows, Imperial college press
A. M. Mellor, 1990, “Design of modern gas turbine combustors”, Academic Press
A. H. Lefebvre, 1999, “Gas Turbine Combustion”, 2° Edition, Taylor and Francis
F. Williams, Combustion Theory Second Edition, Benjamin Cummings Publishing
N. Peters, B. Rogg, Reduced Kinetic Mechanism for Applications in Combustion Systems, Springer
R. Kee, F. Rupley, E. Meeks, J. Miller, Chemkin-III: a Fortran chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics, Sandia National Lab - UC-405 SAND96-8216
Learning Objectives
1) General objectives of the course
This course aims at providing the basic knowledge for the understanding of combustion process in gas turbine with particular focus on aeroengine combustors. A particular attention will be given to the description of the modern methodology for numerical simulation of turbulent combustion process, deepening all the aspects related to liquid fuel injection, pollutant emissions formation, the onset of combustion instabilities and heat transfer process (convection and radiation). The most update methodology for the aero-thermal design of combustor will also be faced.
2)Provided knowledge
In-depth knowledge and understanding of the theoretical-scientific aspects of engineering, with a specific reference to mechanical engineering, in which students are able to identify, formulate and solve, even in an innovative way, complex and/or interdisciplinary problems. The ability to understand a multidisciplinary context in the engineering field and to work with a problem solving approach.
Knowledge and understanding of numerical methods for the design and verification of mechanical components and/or systems, including numerical models for the correct representation of material behaviour. Knowledge of analysis types necessary to carry out the aforesaid design and verification activity according to the most recent requirements of the industrial world.
Knowledge and understanding of the machinery sector deepening the aspects properly connected with systems for energy production and transformation, with reference also to renewable energies and/or aspects related to propulsion systems. Understanding the role of different energy technologies in ensuring the environmental and economic sustainability of production.
3) Applying knowledge
Applying knowledge and understanding related to the choice and application of appropriate analytical and modelling methods, based on mathematical and numerical analysis, in order to better simulate the behavior of components and plants in order to predict and improve their performance.
Applying in-depth knowledge and understanding related to the choice and use of appropriate equipment, tools, procedures and methods, knowing their limits and potential; in particular the ability to conduct even complex experiments, manage and employ advanced instrumentation and software, with appropriate analytical capabilities.
Applying knowledge and understanding related to the appropriate interpretation of the results of experimental tests, verification calculations and complex theoretical simulation processes, through the use of the computer, applying the acquired experimental, modeling, mathematical and informatics bases.
Applying knowledge and understanding to achieve adequate preparation for tertiary level university studies (frequency to post-master's degree courses and doctoral schools) in order to further deepen knowledge and skills in research.
Teaching Methods
Oral lectures and practical exercises in laboratory
Further information
For any additional information please contact the Lecturer: antonio.andreini@unifi.it
Type of Assessment
Evaluation of the student will be based on an oral examination with a possible practical exercise. Proposed topics are:
Physical process involving lquid fuel preparation and injection (spray). Hydrocarbon fuel claissification. Reaction mechanisms. Stochiometry. Laminar premxed and non-premixed flames. Turbulence-chemistry interaction. Basic CFD modelling. Turbulent combustion modelling: local source models, flamelet models, LES modelling. Two-phase flow modeling with CFD. Combustor cooling. Aerodynamic preiminary design. Injection system. Ignition. Stability. Thermoacoustics.
The examination usually consists in three questions on each fundamental part of the course (basic combustion knowledge and liquid fuel, combustors design, CFD modelling). Student must show an adequate knowledge of the different topics pointing out the capability to cross relate the various notions.
Course program
COMBUSTION FUNDAMENTALS
Thermochemistry and thermodynamics
Stoichiometry, chemical equilibrium, chmical kinetics
Fuels
Transport mechanisms
Laminar premixed flames
Laminar diffusive flames
NOx, CO and soot emissions
Ignition and stability limits
Liquid fuel evaporation
Liquif fuel combustion
INTRODUCTION TO TURBULENT FLOWS
Physics of turbulence
Energy cascade and characteristics scales
Navier-Sotkes equations for turbulent flows
Computational approaches: DNS, LES, RANS
Turbulence models for RANS
Eddy viscosity models, Near wall treatments
LES (Large Eddy Simulation)
Filtered Navier-Sotkes equations
SubGridScale models
Scheme and BC for LES analysis
Hybrid models DES, SAS
INTRODUCTION TO TURBULENT COMBUSTION
Probability Density Function concept
Damkholer number
Turbulent premixed flames - stabilization, characteristics scales, regimes
Non premixed turbulent flames - stabilization, characteristics scales, regimes
Numerical solution of reactive turbulent flows
RANS
Classification of turbulent combustion models
GAS TURBINE COMBUSTORS
layouts and fundamentals dimensions
Classification and design requirements
Diffusers - design
Airflow Split
Swirler
Fuel injection system
Liner cooling
Thermal design of GT combustor liner
Stability
Emissions
International standards on GT emisisons
Combustor perfomance
Ignition and altitude relight
LIQUID FUEL PREPARATION
Detailed analysis of liquid fuel evaporation
Multicomponent fuels
Atomization process
GT combusto injection system
Correlations
TERMOACUSTICS
General overview – Rayleigh criterion
Flame Transfer Function
Liner and BC impendance
Calculation example
TURBULENCE COMBUSTION MODELS
Local Source models
EDC fast chemistry and finite rate chemistry models
Chemistry acceleration
Flamelet models – premixed flames
Modelli Flamelet Fiamme premiscelate
BML theory
Eddy BreakUp model
FSD model
TFC model
G-Equation model
Partially premixed flames
Nox emissions – modeling in turbulent flows
Soot emissions – modeling in turbulent flows
PDF Transport models
FGM models
Dscrete Particle Modelling
Advanced multi-phase modelling
Turbulent combustion models for LES
CHEMICAL KINETICS EXERCISES
Chemkin package
Chemical equilibrium
Stanjan for Chemkin
Chemical reactors
Laminar flames
Fluent Flamelet module
CFD EXERCISES
Overview of Fluent turbulent combustion capabilities
Premixed flame example
Non premixed free jet flame example - EDC
Non premixed free jet flame example - Laminar Flamelet
Partially Premixed flame combustor
Liquid Fuel
Overview of OpenFOAM turbulent combustion capabilities
Application test