Iran First International Combustion School (ICS2019)
2019 Lecture notes will be available after the summer school:
Titles of the lectures:
University of Brighton, Brighton, UK
Fuel Droplet and Spray Modelling
(ICS2019 missed Prof. Sazhin Presentation Unwillinglessly.)
During the course, students will learn fundamental principles of the modelling of the processes leading to mixture preparation preceding ignition and combustion of fuel sprays. The focus will be on fundamentals of spray formation and heating/evaporation of mono- and multi-component fuel droplets. The discussion of fundamental principles will be supplemented by brief presentations of the most recent developments in these fields.
The course will include the following tree lectures.
Lecture 1 (1.5 hours + 2 hours)
The lecture will start with a general introduction to fuel spray phenomena and the results of automotive fuel spray observations obtained at the University of Brighton. This introduction will be followed by an analysis of the phenomena leading to spray formation, mainly linked with the development of instabilities of jets emerging from a nozzle. Basic principles on which the instability theory is based will be discussed in detail. The WAVE model and its recent modifications, and classical droplet break-up models will be discussed. Finally, the lecture will refocus on simplified models for spray penetration and vortex-ring-like structures in sprays.
Lecture 2 (1.5 hours + 2 hours)
The lecture will focus on the analysis of fuel droplet heating due to convection and thermal radiation, ignoring and taking into account the effects of droplet evaporation. The effect of temperature gradient inside droplets will be taken into account based on the analytical solution to the spherically symmetric heat conduction equation with the source term. This approach will be complemented by a simplified model, based on the parabolic approximation of the temperature profile inside droplets. The classical (Abramzon and Sirignano model) and the most recent developments in the modelling of heating and evaporation of mono-component droplets will be presented. The predictions of the models will be compared with experimental data where appropriate. The most recent approaches to modelling non-spherical droplet heating and evaporation will be discussed.
Lecture 3 (1.5 hours + 2 hours)
The lecture will focus on the analysis of multi-component droplet heating and evaporation and
the applications of the models to the analysis of automotive fuel droplets. In most models to be discussed the effects of species diffusion inside droplets will be taken into account based on the analytical solution to the species diffusion equation incorporated into a numerical code. The heating and evaporation of realistic Diesel and gasoline fuel droplets will be analysed based on the recently developed multi-dimensional quasi-discrete model. The most recent developments in modelling of multi-component fuel film heating and evaporation, and micro-explosions in fuel/water mixtures will be discussed. Time permitting, basic principle and recent developments in kinetic and molecular dynamics modelling of fuel droplet heating and evaporation will be discussed.
The contents of all lectures is tentative and is subject to possible modifications/adjustments depending on familiarity by the students with the background of the phenomena.
TU Darmstadt, Germany
Spray Combustion
Sprays and droplets are involved in a variety of important industrial processes, such as spray combustion, spray drying, spray cooling, spray atomization, spray deposition, spray cleaning/surface treatment, spray inhalation, agricultural sprays, paint spray, and many others.
During the course students will learn especially fundamentals of spray combustion. In many spray combustion based applications (e.g. gas turbine, rocket combustion and internal combustion engines), the liquid fuel is injected into the combustion chamber resulting in fuel spray. Thereby, the liquid atomization, the droplet break-up and the subsequent interacting multiscale processes that govern the spray propagation and combustion play an important role in determining efficiency of the combustion systems.
The course will therefore include the (six) lectures on
(1) liquid fuel atomization
(2) typical spray parameters for spray characterization
(3) spray transport and inter-phase coupling
(4) phase change phenomena and mixture formation
(5) turbulent combustion of spray
(6) numerical description techniques of spray combustion, numerical simulations and experimental validation issues
Appropriate examples will be provided throughout the lectures. After the course students will be able to identify the role of the interacting multiscale processes that govern the spray evolution downstream from the near-injector atomization region in liquid-fueled combustion systems. They will be able to choose a suitable method for numerically simulating spray propagation and spray combustion. They will be aware on the experimental validation issues and the modern approaches in the field of turbulent spray combustion
Politecnico di Milano, Italy
Combustion Modelling
Day 1
Lesson 1: Governing equations, thermodynamics, kinetics, and transport properties (~1.5 h)
• Presentation of the course, learning objectives, organization
• Transport equations
- Continuity and momentum equations
- Conservation of species; diffusion fluxes (Stefan-Maxwell theory, Fick diffusion, Soret effect)
- Energy equation: enthalpy and temperature formulations
• Basics of thermodynamics, kinetics, and transport properties
- Enthalpy and specific heats, NASA polynomial formalism
- Kinetic parameters, reaction rate, reversible reactions, equilibrium constant, examples of kinetic mechanisms in CHEMKIN format, pressure-dependent reactions (third-body, fall-off reaction, Chebyshev formalism, PLOG formalism)
- Kinetic theory of gases (viscosity, mass diffusion coefficients, thermal conductivity, Lewis number)
• Introduction to the CHEMKIN formalism
Lesson 2: Numerical algorithms for reactive flows (~2 h)
• Introduction: complexity of reacting flows and combustion
- Detailed kinetics and combustion
- Non-linearity, coupling, stiffness
• The 0D reacting system model
- Governing equations
- Numerical solution of ODE systems
- The Jacobian matrix and the sparsity of kinetic mechanisms
• Ideal reacting systems in combustion
- Batch Reactor
- Shock Tube Reactor
- Perfectly Stirred Reactor
- Plug Flow Reactor
Day 2
Lessons 3: Numerical methods for 1D and multi-dimensional flames (~2 h)
• Introduction: Combustion and transport phenomena & laminar flames
• Numerical solution of 1D flames
- Premixed laminar flames
- Burner stabilized unstretched (or flat) flame
- Governing equations and modeling aspects
- Numerical solution
- Freely-propagating unstretched (or flat) flame
- Governing equations and modeling aspects
- Counterflow diffusion flames
- Governing equations and modeling aspects
• Multidimensional flames
- Introduction and examples
- Governing equations
- Numerical algorithms for multidimensional flames
- The operator-splitting method
Lesson 4: Advanced techniques for reacting flows with detailed kinetics (~1.5 h)
• Acceleration of simulations by reduction of specie
- Skeletal reduction
- Quasi Steady-State Approximation (QSSA)
- Dynamic Stiffness Removal (DSR)
- Dynamic Adaptive Chemistry (DAC)
• Acceleration of simulation by reduction of reacting environments
- Reaction Network Analysis (RNA) and Kinetic Post-Processor (KPP)
- Dynamic Adaptive Clustering
- ISAT (In Situ Adaptive Tabulation)
• Species bundling for diffusion coefficient reduction
• Computation Cost Minimization
• Numerical tools for analysis of kinetic mechanisms
- Sensitivity Analysis
- Rate of Production and Reaction Path Analyses
Day 3
Lessons 5 and 6: Turbulent combustion (~3.5 h)
• Turbulent flows
- Introduction to modeling of turbulent flows (statistical description, Reynolds'/Favre's averaging, mean flow equations, Kolmogorov's theory)
- Mean flow equations (short introduction)
- Scalar transport equations
- Interactions between turbulence and chemistry: the need of closure models
• Premixed turbulent flames
- Turbulent burning velocity
- Bray-Moss-Libby (BML) Model
- Eddy-Break-Up (EBU) Model
- Level Set Approach / G-equation
• Non-premixed turbulent flames
- Conserved scalar based models
- Flamelet Model
- Finite-rate models: EBU, ED, ED/FR, EDC
University of Naples Federico II, Italy
Combustion Fundamentals
DAY 1
1. Introduction Lecture 1 - 24/08/2019 (1.5 h)
a. Definition and relevance of Combustion Science. Applications.
b. Governing equations of multi-component chemically-reacting gas mixtures
c. Thermodynamics, transport, flame temperature and equilibrium
2. Homogeneous Combustion – AutoIgnition Lecture 2 - 24/08/2019 (2 h)
a. Chain-branching and Thermal Explosions, H2/O2 System
b. Auto-ignition. CH4/O2 system.
c. Stratified AutoIgnition. Dilution effects.
d. Back-Mixed Ignition. Steady and Unsteady conditions.
e. Heat loss effects. High molecular weight paraffin systems nC7H16, iC8H18
DAY 2
3. Combustion with Flame Propagation Lecture 3 - 25/08/2019 (1.5 h)
a. One Dimensional Steady Flow formulation.
b. Rayleigh and Rankine-Hugoniot equations.
c. Detonation.
d. Deflagration. Thermal theory. Flame Speed Dependencies.
4. Laminar Diffusion Flames (2 h) Lecture 4 - 25/08/2019 (2 h)
a. Flame Structure and Mixture Fraction.
b. Infinitely fast chemistry. Flamelet concept.
c. 1D Steady Diffusion flames. Strained/Unstrained.
d. 1D Unsteady Diffusion flames. Strained/Unstrained.
e. Diluted conditions. Diffusion Ignition processes.
DAY 3
5. Complex Flame Structures Lecture 5 - 26/08/2019 (1.5 h)
a. Partially-premixed flames
b. The Structure of Triple Flames
c. Stabilization, propagation and instability of tribrachial triple flames
6. Turbulence, Mixing and Aerodynamics Lecture 6 - 26/08/2019 (2 h)
a. Characteristics and Description of Turbulent Flows
b. Turbulent Premixed Combustion. Scales and Dimensionless Quantities.
c. Borghi Diagram
d. Flame stabilization, Ignition and Extinction
e. Flashback and Blowoff
f. Swirl and reverse flows
Prof. Sorrentino 2019 lectures notes:
© 2019 Iran Combustion School