Projet Feux | UMR SPE 6134
Productions  |
Theses

Link to Albert Simeoni’s thesis: "The spread of forest fires: improvement of semi-physical models using a multiphase approach" (in French: "Propagation des feux de forêt : Amélioration des modèles demi-physiques à l'aide de l'approche multiphasique") defended on 21 December 2000

Link to Thierry Marcelli’s thesis: "The spread of forest fires: improvement of semi-physical models using a multiphase approach" (in French: "Propagation des feux de forêt : Modélisation et étude expérimentale de la transition d'un feu de surface vers un feu de cime" defended on 3 January 2002

Link to Toussaint Barboni’s thesis: "The contribution of analytical chemistry methods for improvement of the quality of fruits and the determination of mechanisms (EGE) and fire risks" (in French: "Contribution de méthodes de la chimie analytique à l'amélioration de la qualité de fruits et à la détermination de mécanismes (EGE) et de risques d'incendie") defended on 12 December 2006

Link to Virginie Tihay’s thesis: "Experimental and theoretical contribution towards the modelling of combustion in forest fires" (in French: "Contribution expérimentale et théorique pour la modélisation de la combustion dans les feux de forêt") defended on 23 November 2007

Link to Valérie Leroy’s thesis: "Contribution to the modelling of forest fires: thermal degradation kinetics and plant combustion kinetics" (in French: "Contribution à la modélisation des feux de forêt : Cinétique de dégradation thermique et Cinétique de combustion de végétaux") defended on 19 November 2007

Link to Pauline Bartoli’s thesis:  "Forest fires: developing knowledge about fuel-flame coupling" (in French: "Feux de forêt : amélioration de la connaissance du couplage combustible-flamme") defended on 13 July 2011

Link to Elodie Romagnoli’s thesis: "The combustion dynamics of vegetation and an analysis of the smoke released: the impact of level and system" (in French: "Dynamique de combustion des végétaux et analyse des fumées émises : effets de l’échelle et du système") defended on 11 December 2014

Link to Basiliu Moretti’s thesis: "Modelling of the behaviour of forest fires for decision-making support tools" (in French: "Modélisation du comportement des feux de forêt pour des outils d'aide à la décision") defended on 7 July 2015

Link to Baha Nader’s thesis: "Evaluation of forest fire simulations" (in French: "Evaluation des simulations de feux de forêt") defended on 28 November 2016

Link to Tom Toulouse’s thesis: "An estimation of the geometric characteristics of a spreading wildland fire"(in French: "Estimation par stéréovision multimodale de caractéristiques géométriques d'un feu de végétation en propagation") defended on 13 November 2015

 


Toussaint Barboni’s thesis: "The contribution of analytical chemistry methods for improvement of the quality of fruits and the determination of mechanisms (EGE) and fire risks" (in French: "Contribution de méthodes de la chimie analytique à l'amélioration de la qualité de fruits et à la détermination de mécanismes (EGE) et de risques d'incendie") defended on 12 December 2006

This study comprises two parts: the first concerns an analysis of the aromas and flavonoids of two island fruits, while the second focuses on a study of the risks to which firefighters are exposed during forest fires. These two topics meet a certain expectation in terms of the various stakeholders and fall within the framework of the various projects with which the laboratory is associated.
The first part concerns analysis of volatile compounds and flavonoids for a Citrus genus hybrid as well as common myrtle berries. In Corsica, the annual production of clementines is high – it is the leading export product – while myrtle berries are used in the production of liqueurs and wines. These two fruits are key economic drivers for the island. Aromas are substances that constitute the taste properties of food. We have identified 44 volatile compounds in the juice of clementines, mandarins and hybrids. The most abundant molecules are hydrocarbon monoterpenes, mainly limonene and -terpinene. Flavonoids are substances with high antioxidant potential; we have identified two polymethoxylated flavones and three flavone glycosides. Myrtle berries are characterised by 36 volatile compounds with mainly pinene, eucalyptol, hex-3-en-1-ol and 14 phenolic compounds, amongst which myricetin and its glycoside derivatives are the most abundant.
The second part covers another concern for the island during the summer months: forest fires. Each year, thousands of hectares of forest burn in Europe, and specifically in the Mediterranean basin.
Generalised blaze phenomena were observed, but the mechanism remains poorly defined. The aim of this research work is to identify the terpene molecules that are emitted by five plant types representative of the Corsican canopy, namely Pinus laricio, Pinus pinaster, Montpellier cistus, Erica arborea and Arbutus. Initially it is a question of ascertaining the possibility of the instant combustion of a gas pocket of biogenic volatile organic compounds (VOCs). The analyses carried out show that -pinene is the main component emitted by the pines, while diterpines are mainly emitted by the Montpellier cistus. Next, we were interested in the pollutant emissions from wildland fires and the toxic effect they have on personnel involved. To do this, we analyse the molecules in the smoke and the BTEX (benzene, toluene, ethylbenzene and xylenes) and then compare them to permissible exposure levels (PELs). We demonstrated that the concentration of benzene is higher than the PEL, meaning firefighters are exposed to a toxic environment.

His thesis can be downloaded here 


Pauline Bartoli’s thesis: "Forest fires: developing knowledge about the fuel-flame coupling" (in French: "Feux de forêt : amélioration de la connaissance du couplage combustible-flamme")

In Mediterranean regions, forest fires are a common occurrence. These fires have an economic impact and an impact on the environment and human populations. Studies into forest fires require consideration of numerous complex phenomena such as the thermal degradation of combustible plant matter, combustion in
the gaseous phase, heat transfer and atmosphere coupling, amongst others. The aim of this thesis is to develop basic knowledge of the issue of fuel-flame coupling. We performed work where the strong experimental dominance was at the level of the particle and the plant complex. The originality of this thesis resides in the fact that we adapted and applied the tools and methods used up until now in the fire safety research field to the combustion of forest combustible matter. For each of the experimental studies presented, specific experimental protocols were used and/or implemented. Where necessary, dedicated experimental mechanisms were developed. We performed the physical and chemical characterisation of the fine particles of six plant species representative of the Mediterranean ecosystem, namely Pinus halepensis, Pinus laricio, Pinus pinaster, Avena fatua, Erica arborea and Cistus monspeliensis. The usefulness of this characterisation is two-fold: it constitutes an input basis for propagation models and offers us greater insight and better means of analysis of the phenomena observed in the combustion phase. Next, we considered the arrangement of these particles between themselves, constituting a porous fuel medium such as the bed covering a forest floor. We determined the permeability of the various fuel loads commonly found on the floor. A simple empirical law linking the permeability of pine needle beds to its porosity and the geometric characteristics of the needles that constitute it was put forward. The combustion study of the fuel-flame coupling was carried out using oxygen consumption calorimetry tools. For this, we used calorimetry instruments, namely the FTT Cone Calorimeter and FM Global’s Fire Propagation Apparatus. The main study underpinning this thesis concerned the combustion dynamics of pine needle beds. We demonstrated that the flow, the overall properties of pine needle beds and the pine needle characteristics that constitute them have a clear influence on their combustion dynamics. The ignition times were greatly influenced by the air flow rate within the porous matter but not by their porosity and/or their permeability. For the same permeability and the same flow rate, the ignition time is influenced by the physical and geometric characteristics of the plant species concerned. In terms of heat output, this increases with the flow imposed on the fuel bed. Two combustion regimes were demonstrated, a sub-ventilated regime in the case of low flow and a ventilated regime in the case of high flow. The same applies to ignition, the
combustion dynamics of the studied plants and the power released by them will depend on the plant species concerned. The final part of the thesis concerned a study of the influence of the incident radiative flux on the combustion dynamics of the vegetation bedding and surface plants. It was demonstrated that the incident radiative flux as well as physical and geometric characteristics of plant particles and their status (dead or alive) have a clear impact on the ignition time of fuels. In terms of the heat output, for dead fuel matter, the density of the flow had little impact. However, for living fuel matter such as bush, high radiative flux causes a lowered heat output.

Her thesis can be downloaded here


Thierry Marcelli’s thesis: "The spread of forest fires: improvement of semi-physical models using a multiphase approach" (in French: "Propagation des feux de forêt : Modélisation et étude expérimentale de la transition d'un feu de surface vers un feu de cime" defended on 3 January 2002

This work focuses on the modelling of the surface fire - crown fire transition. To this end, we developed a semi-physical transition model. This model is based on the propagation model of a fuel bed fire developed at the University of Corsica; as this model does not take into account the transition towards a higher layer of fuel we decided to use a method of improvement based on the reduction of the complete model, specifically that of the IUSTI of Marseilles. This reduction showed a transition period between the convective hot column and the upper stratum fuel, and allowed us to improve our model by adding an additional period representing this transition. In order to evaluate this period, we set up a measurement campaign at the laboratory. Being the first ones to carry out this type of experiment at the University of Corsica, we were first required to develop a protocol enabling us to access the characteristic data of the fire: temperature and propagation rate. Temperatures were measured using thermocouples, in the combustion and smoke plume zone. We developed an original method of numerical temperature compensation in the flame zone, as the thermocouples used did not adequately represent temperature fluctuations. This compensation made it possible to replicate the dynamics of the phenomena, and thus, using the calculation of the transit time between two sensors, to calculate the upward velocity of the combustion gases. Another series of experiments conducted on the transition allowed for the calculation of a transition period allowing us to carry out simulations of our model. The results obtained are encouraging, they clearly represent the stages and trends relating to the transition of a surface fire to a crown fire.

His thesis can be downloaded here 


Basiliu Moretti’s thesis: "Modelling of the behaviour of forest fires for decision-making support tools" (in French: "Modélisation du comportement des feux de forêt pour des outils d'aide à la décision")

The modelling of the propagation of forest fires is a complex topic which can be addressed in various ways (a physical, semi-physical or empirical approach). A number of simulators exist, each with their own specific features, advantages and drawbacks. The work conducted in writing this thesis aims to improve the simplified physical propagation model of Balbi et al, 2007, and to lay the foundation for the development of a behaviour fire model. The work focused on three key aspects: The first is the modelling of surface fire spread with the transfer of radiative heat being the main driver. This modelling led to improvements in terms of the formulation of flat speed without wind. It also ultimately led to the characterisation of two extinction criteria for the critical values ??of two fuel parameters (leaf surface area index and the fuel’s moisture content). The second is the quantification of the energy emitted by the flame front. This quantification was realised using the solid flame model as the hypothesis. This approach allowed for an analytical relationship to be obtained allowing for an evaluation of Permitted Safety Distances (DSAs) in a very short amount of time. The third is the sensitivity study of the various results obtained so as to validate all of them and identify the relative impact of the various parameters.

Her thesis can be downloaded here 


Baha Nader’s thesis: "Evaluation of forest fire simulations" (in French: "Evaluation des simulations de feux de forêt")

Evaluation of the performance of models is a fundamental step in their development and improvement. The research work presented in this manuscript is dedicated to evaluating simulation models on the spread of forest fires. A review of the research revealed that, although many elements were available, no standardised solution that could be automated had been put forward in this field of application. A solution to this
problem would be the development of a formal approach within the framework of modelling and simulation theory. This step made it possible to conceptually determine which components should be developed and how they should be interlinked.
The development of this framework firstly required the standardisation of data available for forest fires, since no file standard or even list is available and/or used by modellers or engineers (observation or simulation). To this end, we proposed a set of names, scoring and data encoding formats in a NetCDF unit.
A second step entailed determining the metrics required to quantify simulation errors (simulation scores). Although four standard methods could be identified in the literature, we were able to show that they were limited to comparison at a given moment, so they could not take account of the performance of the dynamics of a fire simulation. This issue has been handled by putting forward two new specific score calculation methods. These various evaluation methods have been incorporated in a calculation library.
Finally, the models were evaluated by applying the abovementioned framework. This evaluation entailed comparing four flame front velocity model formulations performed on 80 real fire simulations in a completely automated manner. The automation and non-adjustment of the parameters made it possible to get closer to the operational context where little local information is available, shortly after the fire outbreak warning. The results showed that this approach is likely to reveal a hierarchy of parametrisation or formulation performance relative to another, without, however, being able to give an absolute and objective measurement of the model error. 

Her thesis can be downloaded here  


Elodie Romagnoli’s thesis: "The combustion dynamics of vegetation and an analysis of the smoke released: the impact of level and system" (in French: "Dynamique de combustion des végétaux et analyse des fumées émises : effets de l’échelle et du système")

Wildland fires are characterised by several different levels in time and space. A multi-physical, multi-level approach is therefore required to address the complexity of these phenomena. This thesis makes an experimental contribution to the study of level and system effects on the combustion dynamics of plants and emitted smoke. Our main objective was to ascertain which experimental protocols, and specifically which levels, would allow for the best characterisation of plant combustion in the laboratory. To this end, we studied the behaviour of fire on the needles of two pine species representative of the Mediterranean ecosystem, Pinus pinaster and Pinus laricio. Pine needle forest beds pose a significant threat as they are responsible for fire spread and the transition of surface fire to full fire.
Three experimental configurations were studied in this thesis, the level of the cone calorimeter, that of the large calorimeter or LSHR (allowing the static combustion of matter larger than the cone) and finally, propagation in the LSHR allowing us to study the effect of the system on combustion dynamics and the production of smoke. In order to compare these three configurations, the experimental protocols were adapted, while the fuel load was maintained. Various parameters were studied to analyse combustion dynamics, such as combustion efficiency, the energy emitted and the rate of loss of matter. The production of smoke was studied by measuring the extinction coefficient characterising their opacity and allowed for the soot emission factor to be obtained. The emission factors of the main compounds emitted during the combustion of these two types of pine needles were measured continuously using a Fourier Transform Infrared analyzer and a Non-Dispersive Infrared analyzer. Gas chromatographic analyses coupled with a flame ionization detector and mass spectrometer enabled us to complete the full set of measurements. Carbon
mass balance was calculated in order to quantify the total carbon measured in our analyses. The main contribution made by our work is the following: the study of the behaviour of fire in P. pinaster needles revealed significant differences in terms of the heat emitted at the level of the cone calorimeter and the LSHR. On the other hand, the combustion system (propagation) does not influence this quantity. The level and combustion system concerned appears to have little
effect on combustion efficiency. We observed an influence at combustion level on the total production of smoke (RSR) and on the soot emission factor. We also noted that the combustion system (propagation) influences the dynamics and value of carbon dioxide and carbon monoxide emission factors, the main compounds emitted through this combustion. An influence exerted by the scale and system can also be noted for the emission factors of nitrogen compounds and VOCs emitted for the three experimental configurations. We attributed the observed differences to the smoke temperature values. Finally, an influence exerted by the geometry of the particles was also noted through a comparison of the combustion realised through the cone calorimeter and the LSHR for the two types of pine needle. The combustion dynamics of Pinus laricio needles is less affected by the change of level than that of the Pinus pinaster (lower variation in the combustion output). We also noted that the Pinus laricio needles, which are thermally thinner than those of the Pinus pinaster, present a lower value in terms of the soot emission factor.

Her thesis can be downloaded here


 

 

Virginie Tihay’s thesis: "Experimental and theoretical contribution towards the modelling of combustion in forest fires" (in French: "Contribution expérimentale et théorique pour la modélisation de la combustion dans les feux de forêt") defended on 23 November 2007

This study presents an analysis of the behaviour of fire on the various plant species. The aim is to define plant properties in terms of their combustion and to offer an oxidation model in the gaseous phase that is sufficiently simple to serve as a point of departure for a propagation model. The plant species are shredded so as to limit the influence of the surface-volume ratio on their behaviour in a fire. The combustion of these crushed products generates laminar flames. The experimental study includes characterisation of the thermophysical and physico-chemical properties of combustible matter, an analysis of degradation gas and determination of the behaviour of solid and gas phases and their coupling. In the numerical study, various skeleton and global mechanisms were tested in order to define a simple model of gas oxidation degradation. This model is applied to the flames of plant fuels.

Her thesis can be downloaded here  


Tom Toulouse’s thesis: "An estimation of the geometric characteristics of a spreading wildfire through multimodal stereovision" (In French: "Estimation par stéréovision multimodale de caractéristiques géométriques d'un feu de végétation en propagation")

The work conducted for this thesis concerns the development of a visual mechanism allowing for the geometric characteristics of a spreading wildfire to be estimated. This mechanism is comprised of several systems of multimodal stereovision generating stereoscopic pairs of images from which three-dimensional points can be calculated and geometric characteristics of the fire such as its position, speed, height, depth, slope, surface area and volume can be estimated.
The first key contribution made by this thesis is the detection of wildfire pixels. All the algorithms for the detection of fire pixels in the literature as well as those developed within the framework of this thesis were evaluated based on a database of 500 images of wildland fires acquired in the visual range and characterised according to the fire’s properties as seen in the image (colour, smoke, brightness). Five wildland fire pixel detection algorithms based on a combination of information drawn from the images acquired in the visual range and the near infrared range were also developed and evaluated based on another database comprised of 100 multimodal characterised images.
The second significant contribution made by this thesis concerns the use of image fusion methods for the optimisation of paired points between stereoscopic multimodal images.
The third significant contribution made by this thesis concerns an estimation of the geometric characteristics of fire based on three-dimensional points obtained using several pairs of stereoscopic images which are registered using GPS and slope coordinates from all the viewing mechanisms.
The mechanism for estimating geometric characteristics based on stereovision systems was evaluated on rigid objects of known dimensions and has made it possible to obtain the desired information in an accurate manner. The results of the data obtained for spreading wildland fires are also presented.

His thesis can be downloaded here 


Albert Simeoni’s thesis: "The spread of forest fires: improvement of semi-physical models using a multiphase approach" (in French: "Propagation des feux de forêt : Amélioration des modèles demi-physiques à l'aide de l'approche multiphasique") 

The long-term goal of our research team (UMR fire brigade CNRS 6134 - SPE) is to propose a forest fire simulator that can serve both as a tool for decision-making support during firefighting and for the management of woodlands. Within this perspective, we defined a simple model that we qualified as semi-physical as it addresses the issue of fire spread from a more physical perspective than semi-empirical models do, yet its parameters are identified dynamically. This model firstly allowed for the prediction of the development of laboratory fires through beds of pine needles, both on steep slopes and at low wind speeds. However, it fell short of being able to accurately represent the behaviour of fires in the presence of strong winds. We therefore proved the need to develop it in order to enable it to take into account the physical phenomena that had been previously neglected, and first and foremost its convective effects. In order to implement an improvement method for the model, we drew inspiration from one of the most comprehensive models available today, which is the multiphase model of the USTI of Marseille. In fact, the model takes into account all the physical phenomena involved in fire spread, at an in-depth level. We therefore wanted to reduce the multiphase model so as to give it an expression similar to that of the semi-physical model, particularly owing to the hypothesis of thermal equilibrium between the solid and gaseous phases. This was done in an effort to gain the missing information we needed to improve our model. We applied this method to take into account the effects of wind, which led us to add a convection term in the energy equation of our model and to define a local wind sub-model to describe the variation of the speed of gases in the combustion zone. 
The results obtained in this study are encouraging in the sense that they have enabled significant improvements to be made in detecting the fire front’s rate of spread, and the fact that it takes into account effects which were largely unknown up until now, such as the combustion zone’s aspiration of fresh gas. In addition to this, the theoretical method of improving the semi-physical models that we propose could apply, beyond our simple model, to other models of the same type, and even lead to the creation of new models specially designed for forest fire simulators.

His thesis can be downloaded here 


Valérie Leroy’s thesis: "Contribution to the modelling of forest fires: thermal degradation kinetics and plant combustion kinetics" (in French: "Contribution à la modélisation des feux de forêt : Cinétique de dégradation thermique et Cinétique de combustion des végétaux")

Fire modelling work conducted on an international scale demonstrates that little is known about issues relating to plant chemistry under fire conditions The objective of this thesis was therefore to make a contribution towards an understanding of:

  • The kinetics of the thermal degradation of plants,
  • The kinetics of gas combustion emitted during pyrolysis.

The thermal degradation of Mediterranean plants was studied through thermogravimetry. The use of a hybrid kinetic method has contributed knowledge relating to the quantification of the loss of matter and the kinetic model of thermal degradation of combustible matter. On the other hand, the combustion of a CH4/CO/CO2 mixture was studied in a gas-jet self-agitating reactor. Initially we developed an outline mechanism based on a recognised comprehensive kinetic mechanism causing the oxidation of methane. Thereafter, application of the AEQS led to a simplified mechanism encompassing four global reactions. This simplified mechanism can now be introduced into a larger simulation code of reactive flow.

His thesis can be downloaded here 


Page mise à jour le 04/12/2017 par MATTHIEU VAREILLE