Fundamentals of Explosions: Natural, Accidental and Controlled
Deadline for registration: 15 days before the starting date of each training
Duration : 3 days
An explosion occurs when energy is released locally into a physical system faster than it can be smoothly equilibrated. The result is that the local pressure increases rapidly and shock waves form and propagate throughout the system. This general description covers scenarios including astrophysical events such as supernovae or solar magnetic eruptions, accidents such as vapor-cloud or coal mine explosions, and purposely created energetic processes in engines for high-speed propulsion. All of these events are based on similar principles of compressible flow, energy release into this flow, the formation and propagation of shock waves, and the creation of specific kinds of reactions waves, ranging from laminar flame to deflagrations to detonations.
This course introduces the physics and chemistry of explosions and investigates how they occur naturally (e.g., volcanoes and stars), accidentally (e.g., vapor cloud explosions, unsuccessful rocket launch, hydrogen accumulation from meltdowns), and by engineering design (e.g., detonation engines, air bags, shaped charges). We will cover the basics needed to understand these phenomena, and then take a forensics approach to understanding specific types of scenarios of interest to the class.
Scientific contact : Elaine S. Oran
Pr Elaine Oran is Glenn L. Martin Institute Professor of Engineering at A. James Clark School of Engineering.
For more details : download synopsis here
(Every day from 9h to 17h00, to be confirmed)
The session will present a point of view that sets the stage for the remainder of the course.
This session will:
- Review the fundamental definition of an explosion.
- Discuss possible methods of classifying explosions, such as by type and intensity of energy source, level and type of confinement, or level of human control on the event.
- Discuss what we need to know to understand an explosion in terms of the physics, mechanisms of energy release, and control.
A quick reprise of the “point of view” and material in Session 1 will be given, now with a little more detail in areas of specific interest to the students.
The first new topic to discuss is shock waves: what they are, how they form, how they are used, how do they arise naturally? Specifically, we will review the physics and theory of shock waves, blast waves, complex shock-wave structure, and shock interactions with boundary layers. This will be begin with the history of the development of concepts of shock waves and show how they are an integral part of so many physical processes and events.
Fundamental principles of flames and detonation are introduced, first through zero-th order approximations, such as summarized in p-v diagrams, and then through a more detailed insight into steady flame and detonation structure and their controlling processes. Then backtracking somewhat, there will be a discussion of how varying the amount of energy release affects fluids, ignition, and the state of combustion.
The deflagration-to-detonation process is discussed. Recent concepts are described, ranging from hot-spot ignition and where and how it occurs, through to shock focusing, through to “direct” ignition. Time permitting, background in turbulence, as it applies to these events, will be discussed. Turbulence in exploding systems is very different from standard, equilibrium, homogeneous turbulence.
Supernovae explosions will be discussed as examples of explosions that are unconfined, nuclear, accidental (?), and defining our environment. Then a summary of technical, legal, ethical, and environmental issues will lead to class discussions. This may be deal with in terms of breakout groups presenting their findings.
Material from the last five sessions will be reviewed. A selection of case studies will be introduced and this will lead to class discussions. Case studies include fuel storage plants (e.g., Buncefield or Jaipur), nuclear facilities (Fukushima or Chernobyl), Astrophysical explosions.
Trainees/PhDs/PostDocs : 150 €
CERFACS shareholders/CNRS/INRIA : 450 €
Public : 900 €