Turbulent buoyant jets are a major feature in fire hazards. The solution of the Reynolds Averaged Navier-Stokes (RANS) equations through computational fluid dynamic (CFD) techniques allow such flows to be simulated. The use of Reynolds averaging requires an empirical model to close the set of equations, this is known as the turbulence model. This thesis undertakes to investigate linear and nonlinear approaches to turbulence modelling and to apply the knowledge gained to the simulation of compartment fires. The principle contribution of this work is the reanalysis of the standard k- ε turbulence model and the implementation and application of more sophisticated models as applied to thermal plumes. Validation in this work, of the standard k- ε model against the most recent experimental data, counters the established view that the model is inadequate for the simulation of buoyant flows. Examination of previous experimental data suggests that the measurements were not taken in the self-similar region resulting in misleading comparisons with published numerical solutions. This is a significant conclusion that impacts of the general approach taken to modelling turbulence in this field. A number of methods for modelling the Reynolds stresses and the turbulent scalar fluxes have been considered and, in some cases for the first time, are applied to nonisothermal flows. The relative influence of each model has been assessed enabling its performance to be gauged. The results from this have made a valuable contribution to the knowledge in the field and have enabled the acquired experience to be applied to the simulation of compartment fires. The overall conclusion drawn from this thesis is that for the simulation of compartment fires, the most appropriate approach with current computational resources, is still the buoyancy corrected standard k- ε model. However, the turbulence scalar flux should be modelled by the generalised gradient diffusion hypothesis (GGDH) rather than the eddy-diffusivity assumption.

Social and organisation theorists have become increasingly interested in studying information and communication technologies over the last two decades. This thesis examines how information and communication technologies are organised, and what is organised by information and communication technologies. The thesis contributes to the interest in detailed studies of information and communication technology through an analysis of the implementation and deployment of a mobile data system-the Vehicle Mounted Data System (VMDS)-by firefighters, fire crews and officers at a United Kingdom fire brigade. This thesis examines what becomes of the Vehicle Mounted Data System when it is introduced into a UK fire brigade. This includes an exposition of how recurring issues including the boundaries of the brigade, what is meant by standardisation and risk, what counts as information, and what is understood by devolved incident management is reordered as the VMDS becomes a constitutive part of the problematic fire service provision. The VMDS is bound up with reality constituting effects and this means that what is meant by technology and organisation becomes an important topic of scholarly study. This thesis develops a non-essentialist ontology of technology and organisation-an ontological turn in organisation theory. It is argued that the VMDS is a relational effect that is aligned with existing boundaries and assumptions at Hereford and Worcester Fire Brigade, that the VMDS is a multiple object that is a mutable mobile and is deployed not only to manage safety at incidents but also for managing performance and organisational flexibility, and that the instabilities of the VMDS are responded to ambivalently by various actors as they are enrolled in the collective upkeep of the VMDS. In analysing the Vehicle Mounted Data System a range of analytical resources are drawn upon, including, most significantly, actor-network theory, but also the writings of Deleuze and Guattari. The thesis concludes with a discussion of the politics of theory and suggests that researchers would remain faithful to their intellectual tradition and a sense of critical and creative purpose if they engaged with and helped to construct the heterogeneous ways in which technological devices such as the Vehicle Mounted Data System transform what organisation theorists understand by organisation.

Ce travail, mené conjointement entre CNPP et le Laboratoire d’Énergétique et de Mécanique Théorique et Appliquée, est consacré à la mise en place d’un modèle d’évacuation de personnes, dans l’optique d’une application en Ingénierie de Sécurité Incendie. Le modèle de cheminement de personnes développé dans ce manuscrit est un modèle physique reposant sur une équation de conservation de la densité de personnes. Il est basé sur des hypothèses simples et réalistes résultant de l’observation de mouvements de foule, et utilise une vision macroscopique des personnes caractérisées par une densité moyenne. Ce modèle est mis en œuvre sur des cas de vérification et de comparaison issus de la littérature. Des expériences d’évacuation sont réalisées à échelle réelle afin de récolter des données quantitatives sur le mouvement des personnes et de valider de façon pertinente le modèle de cheminement de personnes. En outre, une stratégie est proposée afin d’intégrer dans la modélisation les contraintes thermiques et optiques liées au feu ainsi que leur impact sur le processus d’évacuation. Enfin, des simulations d’évacuation intégrant les effets du feu sont effectuées sur une configuration à grande échelle / This work was conducted as a collaboration between CNPP and the laboratory LEMTA. It was devoted to the implementation of an emergency egress model offering prospects for use in Fire Safety Engineering. The pedestrian movement model described in this manuscript is a physical model relying on a people density balance equation. This model is based on three fundamental assumptions resulting from pedestrian phenomena commonly observed, especially in crowds. Its mathematical formulation assumes that people are regarded as a mean density in a macroscopic way. The pedestrian model was tested on verification and comparison cases extracted from literature. Evacuation drills were also performed at real scale without fire constraints to collect some quantitative data like egress times or flows, and to validate the people motion model. Furthermore, a mathematical strategy is propounded in order to integrate thermal and optical stresses into the evacuation model and to take into consideration their incidence on evacuation processes. Finally, egress simulations are achieved on a large-scale configuration considering different scenarios involving fires

Ce travail est consacré à l'étude des interactions eau/fumée dans un couloir, lors du déclenchement d'un système d'aspersion dans un environnement enfumé. Il s'attache à évaluer les effets thermiques et optiques induits par une pulvérisation d'eau par sprinkler et par brouillard d'eau sur une couche de fumée générée à partir d'un foyer type bac d'heptane. Une synthèse bibliographique permet de faire l'état des travaux concernant la recherche sur l'aspersion d'eau pour le contrôle du feu lors d'un incendie en bâtiment et sur les notions de stratification des fumées. Une étude expérimentale basée sur 50 essais en grandeur réelle est présentée, impliquant des mesures thermiques et optiques. Un système d'opacimétrie laser spécifique a notamment été développé, permettant de mesurer l'opacité des fumées et les effets des interactions eau/fumée sur l'opacité et la visibilité. La partie numérique s'appuie sur le code FDS version 6 (Fire Dynamics Simulator) pour la simulation des essais et sur un module spécifique consacré à l'évaluation de la visibilité en parallèle. Utilisant les valeur extraites de la simulation par FDS pour les concentrations en gouttes et en suie, ce code calcule les propriétés optiques du milieu absorbant-diffusant considéré, puis combine une méthode de Monte-Carlo et des techniques de PSF (Point Spread Function) et MTF (Modulation Transfer Function) pour évaluer l'intensité et le contraste d'images reconstruites. Les effets de déstratification thermique et optique sont comparés pour chaque technologie d'aspersion expérimentalement et numériquement. / This work was devoted to the study of water/smoke interactions in the case of water mist activation on a smoke layer. The aim was to investigate the effects observed on thermal and optical properties when injecting water particles using sprinkler or water mist devices through a smoke layer generated with an heptane pool fire. A first review was reported in order to highlight the researches devoted to water aspersion for firefighting and the smoke stratification phenomena. An experimental study based on 50 runs at real scale was presented, involving optical and thermal measurements. In particular, a laser opacimeter system was developed, which allowed measuring the smoke opacity and the effects of smoke/water interactions on opacity and visibility. Afterwards, a numerical study was conducted. On the one hand fire tests were simulated using the FDS 6th version (Fire Dynamics Simulator) and on the other hand a dedicated code allowed us to evaluate the visibility. The values of the soot and droplet concentrations were extracted from FDS and used into the code dedicated to visibility to calculate the optical properties of the corresponding absorbing-scattering environment. Those properties are then used in a Monte Carlo approach combined with PSF (Point Spread Function) and MTF (Modulation Transfer Function) methods to evaluate the intensity and the contrast of reconstructed images. The destratification effects based on thermal and optical criteria were compared experimentally and numerically for each technology.

La propagation d’un incendie dans un espace clos s’explique par l’inflammation de matières combustibles. Un cas important est celui de la propagation d’une flamme sur une paroi verticale. En effet si la flamme progresse dans le même sens que l’écoulement (cas co-courant), la croissance est rapide. Dans ce cas, l’émission des vapeurs combustibles (pyrolyse) et le dégagement de la chaleur apportée par la combustion sont couplés par les flux convectés et rayonnés à la paroi. Ces flammes de paroi verticale sont pilotées par les forces de flottabilité, et se caractérisent par un régime de basse vitesse et avec une forte production de suie. Bien que de nombreux travaux aient été consacrés à l’étude des flammes de paroi verticale [1-3], peu d’entre eux ont été dédiés à l’étude de l’écoulement dans la couche limite proche de la paroi et à l’étude des zones de production de suie, lesquels sont des données nécessaires pour la validation des codes de calcul. Pour cela, des mesures simultanées de vitesse par PIV et de concentration de suie par LII ont été réalisées sur un brûleur gaz en configuration paroi-verticale. Dans un premier temps, ces mesures ont permis l’analyse de la forme, de la taille et de la concentration des zones de formation de suies (poches de suie) à différentes hauteurs dans la flamme. Ensuite, les champs 2D de vitesses moyennes (horizontales et verticales) ont été étudiés, ainsi que leurs fluctuations (densités de probabilité et écart-type). Une description de la couche limite réactive, à l’aide d’une échelle caractéristique obtenue avec des mesures de vitesse plus résolues spatialement (PIV « zoomé »), a également été réalisée. Finalement, les mesures de LII et PIV couplées ont permis d’étudier l’influence du champ de vitesse sur la distribution des suies dans la flamme, ainsi que le transport et le flux turbulent de la fraction volumique de suie dans la couche limite réactive. / The fire growth and spread on a confined space depends on the inflammation and combustion of combustible materials. An important case is the fire propagation on a vertical wall configuration, in which the pyrolysis gas and the total heat flux released by the flame are coupled by convective and radiative heat flux from the flame to the wall. This kind of flame is piloted by the buoyancy forces, and is characterized by a low velocity regime and a strong generation of soot particles. Although numerous works have been devoted on the study of vertical wall flames, few have been carried out on the analysis of the flame within the reactive boundary layer and the study of the zones of production of soot particles, which is data necessary for fire simulation codes validation. In this aim, simultaneous measurements of velocity by Particle Image Velocity (PIV) and of soot volume fraction by planar laser induced incandescence (LII) have been carried out on vertical wall fire generated by a vertical porous burner fed with a CH4/C2H4 mixture. First, the characteristics of soot sheet (shape, size, thickness, and peak concentration) have been studied at different heights into the flame, as well as the average and RMS soot volume fraction fields. Then, average and RMS fields of velocity and their probability density function have been analyzed. A description of the reactive boundary layer, through the definition of a characteristic velocity scale in the near-wall zone (viscous sub-layer), has been carried out by using a « PIV Zoom » set-up. Finally, simultaneous LII/PIV measurements have been carried out in order to study the influence of the aerodynamics of the flow on the soot volume fraction distribution, as well as the transport and turbulent flux of soot into the reactive boundary layer.

S’intéressant aux interactions entre la formulation, le procédé et le produit, ce travail original axé sur la fonctionnalisation ignifuge de textiles utilisés dans les transports et le bâtiment porte sur le développement de poudres non feu. La ligne conductrice de cette étude étant de comprendre comment les propriétés ignifuges du textile technique peuvent être influencées par les choix de formulation ou de procédé de mélange. L'identification des besoins, c.-à-d. la réalisation d’un produit fini ignifuge, la conception de mélanges de granulométrie définie qui s’écoulent facilement et qui possèdent une sensibilité à l’inflammation faible, a permis de proposer et d’examiner diverses formulations. En matière de méthodologie ce projet combine l’approche sécurité à l’ingénierie produit. La sélection finale des mélanges sera fonction des résultats de cette analyse technique globale. Le travail expérimental a permis de sélectionner le polymère et l’agent ignifuge à la concentration de 40 % pour l’obtention en mélangeur interne de particules bifonctionnelles répondant aux spécifications fixées. Contrairement aux mélanges à retournement ou haute vitesse, les grains préparés par granulation Hot-Melt ont des liaisons mécaniques renforcées. Ce résultat semble s’expliquer par la bonne affinité, le bon rapport en termes de taille de particules entre les composants et une morphologie favorable à la formation de ce type de structures. Ce mode de fabrication a également permis de lever les deux principaux verrous à savoir préparer une poudre bifonctionnelle à haute teneur en agent ignifuge et réaliser un mélange qui ne se démélange pendant l’étape d’imprégnation du procédé DPreg / This original work deals with the functionalization of textile fire retardant used in transport and the building focused on the development of fire retardant powders while studying the interactions of three criteria: the formulation, process and product. The main line of this study is the understanding and quantification of the flame retardant properties of the textile, which can be influenced by the choice of formulation or mixing process. The identification of needs, i.e. the realization of a finished fire retardant, the design of defined particle size mixtures, which flow easily and possess low sensitivity to inflammation, allowed to propose and consider various formulations. This project methodology is a good example of the combination between two approaches: the product engineering and a safety approach. The final selection of mixtures will be based on the results of a comprehensive technical analysis. The experimental work allows us to select the polymer and the flame retardant at a concentration of 40% in order to obtain in an internal mixer of bifunctional particles meet the specifications set out in this study. Unlike conventional mixtures by inversion or high speed, the grains prepared by Hot-Melt granulation have enhanced mechanical linkages. This result seems to be due to the good affinity and good particle size ratio between the components and a good morphology to the formation of such structures. This manufacturing method also overcomes two obstacles; the preparation of a bifunctional powder with high content of flame retardant and the realization of a mixture which does not demix under the action of the electric field of the DPreg impregnation process