Course: 2020/2021

Combustion and transport phenomena

(12442)

Requirements (Subjects that are assumed to be known)

Students are suggested to review their knowledge on the following Bachelor subjects:
- Thermal Engineering: thermodynamic properties, internal combustion engines, heat transfer
- Fluid Mechanics: Navier-Stokes equations , subsonic/supersonic flows, waves and discontinuities
- Advanced Mathematics: solving of differential equations

Understanding of and ability to solve problems and cases related to
- Processes of mass and heat transfer in aerospace propulsion systems
- Fundamentals of a combustion processes: fuels, stoichiometry, thermochemistry, chemical kinetics, mass diffusion
- Navier-Stokes equations for reacting mixtures: convection vs. diffusion, combustion source terms, dimensionless numbers, energy equations,
- Simple reacting systems: global combustors, well-stirred reactors
- Combustion fronts: deflagrations and detonations
- Structure ans properties of premixed flames
- Structure ans properties of non-premixed (diffusion) flames
- Experimentation and diagnosis of combustion phenomena

Description of contents: programme

1. Combustion fundamentals.
Thermodynamics of mixtures. Reactions and species in combustion processes.
Major and minor species. Global reaction mechanism.
Non-stoichiometric mixtures. Flame temperature and fuel specific energy.
Chemical kinetics: global reaction rate.
2. Navier-Stokes equations of reacting mixtures.
Length and time scales. Mass conservation and diffusion; Fick's law.
Momentum equation. Energy equation: enthalpy and temperature forms; combustion heat rate.
Dimensionless parameters. Application to simple combustors.
A purely diffusive application: liquid droplet evaporation.
3. Premixed flames.
Introduction. The heating/burning/post-burning region structure.
Planar 1D model with constant coefficients.
Solution of the heating and burning regions.
Flame velocity, temperature, and thickness.
Anchored flames.
Influence of main parameters. Flammability range.
Flame cooling and quenching in a tube. Ignition.
4. Combustion fronts.
Jump conditions across reacting fronts.
The Raleigh and Hugoniot curves.
Deflagrations and detonations.
Chapman-Jouguet fronts.
Deflagrations in open and semi-closed tubes.
The double ZND structure of a detonation.
Combustion fronts in practice.
5. Non-premixed flames.
Introduction. Flame configurations.
The fuel/burning/air region structure. Fuel aeration
Spherical 1D model with constant coefficients.
Determination of the flame length and temperature.
Introduction to a jet flame model: the conserved scalars.
Influence of main parameters; empirical correlations.
Droplet burning. 1D vaporization-controlled spray combustion.
6. Introduction to advanced topics and experimentation.
Radiation. Turbulence.
Visualization of different flame regimes.
Experimental diagnosis of flames.

Learning activities and methodology

The methodology combines
1) lecture classes presenting the different subjects
2) exercise and problem solving sessions
3) laborotary sessions
4) homework assignements
5) several quizzes
Tutorials can be both personally or through Aula Global

Assessment System

- % end-of-term-examination 60
- % of continuous assessment (assigments, laboratory, practicals...) 40

Basic Bibliography

- GLASSMAN. Combustion, 4th edition. Elsevier. 2008
- TURNS. An introduction to combustion concepts and applications, 3rd edition. McGraw Hill. 2012

Additional Bibliography

- F. WILLIAMS. COMBUSTION THEORY. PERSEUS BOOKS. 1985