Un des objectifs a consisté à développer une étude systématique des caractéristiques d'allumage, depropagation et de combustion massique de combustibles liquides. La ré-inflammation des fumées riches estplus spécialement pris en compte. La recherche porte essentiellement sur les propriétés des feux dans uneenceinte avec ventilation contrôlée, sous ventilée. Les facteurs dominants à la ré-inflammation des fuméesriches est la quantité minimale d'hydrocarbures totaux et la température. Grâce à la Simulation Numériquedes Grandes Echelles, nous sommes allés à un niveau de détail permettant de prendre en compte l'influencede la ventilation sur la propagation de la flamme en milieu confiné. Les modèles numériques permet deprévoir les aspects aussi bien chimiques de la combustion (pyrolyse du combustible liquide, réaction dans laflamme), que thermodynamiques (transfert de chaleur et de masse flamme-liquide). L'enjeu est de concevoirun modèle de feu encore plus général, capable de traiter aussi les feux à grande échelle. Ce type de modèleest consacré à la mise en équations du problème et à la faisabilité d'une simulation numérique complexe.Les résultats obtenus sur les feux sur-ventilés sont en accord avec les résultats expérimentaux. Outre lesdifficultés théoriques de ce type de problème, il faut ajouter les difficultés pratiques liées à la durée trèsimportante des simulations sur ordinateur, et le coût de calcul élevé.

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Os métodos para se projetar um edifício com segurança adequada para a situação de incêndio são pouco estudados e aplicados no Brasil. Essa falta de estudo é ainda mais visível quando nos deparamos com o assunto compartimentação, tópico pouco desenvolvido e ainda não normatizado pela ABNT. A compartimentação, especialmente a vertical, é fundamental para a segurança à vida, pois minimiza a propagação do incêndio entre pavimentos de edifícios. Para validar os procedimentos normatizados de dimensionamento de estruturas em situação de incêndio é necessário considerar que as edificações são compartimentadas. Atualmente as exigências sobre compartimentação são apresentadas apenas em Instruções Técnicas do Corpo de Bombeiros, variando de estado para estado. Neste trabalho é apresentado um estudo sobre a compartimentação, uma análise de sua influência na segurança contra incêndio das edificações e a comparação da visão do assunto em países de quatro continentes distintos. Após um estudo comparativo entre a visão e normatização do Brasil, Portugal, Inglaterra, Hong Kong e Estados Unidos foram realizadas simulações computacionais com base na teoria dos volumes finitos e da fluidodinâmica computacional de forma a se tentar verificar de forma mais aprofundada a influência das exigências de compartimentação na real propagação de um incêndio. Por fim, o principal foco deste trabalho é demonstrar que é possível utilizar a Dinâmica dos Fluidos Computacionais (CFD) de maneira a auxiliar o estudo do incêndio, e possibilitar uma análise mais aprofundada do assunto. / Methods for designing a building with adequate fire safety are poorly studied and applied in Brazil. This lack of study is even more present in the compartmentation subject, much-undeveloped topic and not yet standardized by ABNT. The compartmentation, especially the vertical, is critical to life safety, since it minimizes the spread of fire between building floors, and to validate the standardized procedures for structures in fire situation, because an important hypothesis of design methods is the vertical compartmentation. Currently the requirements of compartmentation are only present in the Technical Instructions of the States Fire Department, varying from state to state. This paper presents a study on compartmentation, its influence on the fire safety of buildings and a comparison of the vision of some countries of four different continents on this subject. After a comparative study of the vision and standardization between countries such as Brazil, Portugal, England, Hong Kong and the United States, computer simulation based on the theory of the finite volumes and computational fluid dynamics were carried out in order to try to check thoroughly the influence of compartmentation requirements in a real fire spread. Ultimately, the main focus of this work is to demonstrate that the Computational Fluid Dynamics (CFD) can be used in order to assist the study of fire, in order to allow a more in-depth analysis of the subject.

Os métodos para se projetar um edifício com segurança adequada para a situação de incêndio são pouco estudados e aplicados no Brasil. Essa falta de estudo é ainda mais visível quando nos deparamos com o assunto compartimentação, tópico pouco desenvolvido e ainda não normatizado pela ABNT. A compartimentação, especialmente a vertical, é fundamental para a segurança à vida, pois minimiza a propagação do incêndio entre pavimentos de edifícios. Para validar os procedimentos normatizados de dimensionamento de estruturas em situação de incêndio é necessário considerar que as edificações são compartimentadas. Atualmente as exigências sobre compartimentação são apresentadas apenas em Instruções Técnicas do Corpo de Bombeiros, variando de estado para estado. Neste trabalho é apresentado um estudo sobre a compartimentação, uma análise de sua influência na segurança contra incêndio das edificações e a comparação da visão do assunto em países de quatro continentes distintos. Após um estudo comparativo entre a visão e normatização do Brasil, Portugal, Inglaterra, Hong Kong e Estados Unidos foram realizadas simulações computacionais com base na teoria dos volumes finitos e da fluidodinâmica computacional de forma a se tentar verificar de forma mais aprofundada a influência das exigências de compartimentação na real propagação de um incêndio. Por fim, o principal foco deste trabalho é demonstrar que é possível utilizar a Dinâmica dos Fluidos Computacionais (CFD) de maneira a auxiliar o estudo do incêndio, e possibilitar uma análise mais aprofundada do assunto. / Methods for designing a building with adequate fire safety are poorly studied and applied in Brazil. This lack of study is even more present in the compartmentation subject, much-undeveloped topic and not yet standardized by ABNT. The compartmentation, especially the vertical, is critical to life safety, since it minimizes the spread of fire between building floors, and to validate the standardized procedures for structures in fire situation, because an important hypothesis of design methods is the vertical compartmentation. Currently the requirements of compartmentation are only present in the Technical Instructions of the States Fire Department, varying from state to state. This paper presents a study on compartmentation, its influence on the fire safety of buildings and a comparison of the vision of some countries of four different continents on this subject. After a comparative study of the vision and standardization between countries such as Brazil, Portugal, England, Hong Kong and the United States, computer simulation based on the theory of the finite volumes and computational fluid dynamics were carried out in order to try to check thoroughly the influence of compartmentation requirements in a real fire spread. Ultimately, the main focus of this work is to demonstrate that the Computational Fluid Dynamics (CFD) can be used in order to assist the study of fire, in order to allow a more in-depth analysis of the subject.

"Understanding fire behavior is critical to effective tactical decision making on the fireground, particularly since fireground operations significantly impact the growth and spread of the fire. Computer-based simulation is a flexible, low-cost training methodology with proven success in fields such as pilot training, space, and military applications. Computer-based simulation may enhance fire behavior training and promote effective fireground decision making. This study evaluates the potential of the NIST Fire Dynamics Simulator (FDS) and Smokeview to be utilized as a part of a computer-based fire fighter trainer. Laboratory compartment fire experiments and full-scale fire experiments in a live-fire training facility were both conducted as part of the NIST Multiphase Study on Fire Fighter Safety and the Deployment of Resources. The laboratory experiments characterized the burning behavior of wood pallets to design a repeatable fire for use in the field experiments. The field experiments observed the effects of varying fire fighter deployment configurations on the performance times of fire fighter actions at a live fire training facility. These actions included opening the front door and fire suppression. Because the field experiments simulated numerous fire department responses to a repeatable fire, data were available to evaluate FDS simulation of heat and smoke spread, and changes in the thermal environment after the front door is opened and fire suppressed. In simulating the field experiments, the laboratory-measured heat release rate was used as an input. Given this assumption, this study has two objectives: 1) to determine if simulations accurately spread heat and smoke through a multi-level, multi-compartment live fire training facility 2) to determine if the simulations properly reproduce changes in the thermal environment that result from two typical fire fighter actions: opening the front door and fire suppression. In simulation, heat and smoke spread to measurement locations throughout the test structure at times closely matching experimentally measured times. Predictions of peak temperatures near the ceiling were within approximately 20% for all measurement locations. Hot gas layer temperature and depth were both predicted within 10% of the floor to ceiling height. After the front door was opened, temperature changes near the door at the highest and lowest measurement locations matched with temperature changes in the experiments. After fire suppression, FDS simulated temperature decay at a rate within the range measured in the field experiments and approximated the total rise of the hot gas layer interface in the burn compartment 250 seconds after suppression."

The Fire Dynamics Simulator (FDS) code recently developed by the National Institute of Standards and Technology (NIST) is particularly well-suited for use by fire protection engineers for studying fire behavior. It makes use of Large Eddy Simulation (LES) techniques to directly calculate the large-scale fluid motions characteristic of buoyant turbulent diffusion flames. However, the underlying model needs further development and validation against experiment in the areas of soot formation/oxidation and radiation before it can be used to calculate flame heat transfer and predict the burning of solid or liquid fuels. WPI, Factory Mutual Research, and NIST have undertaken a project to make FDS capable of calculating the flame heat transfer taking place in fires of hazardous scale. The temperatures predicted by the FDS code were generally too high on the fuel side and too low on the oxidant side when compared to experimental data from small-scale laminar diffusion flames. For this reason, FDS was reformulated to explicitly solve the conservation of energy equation in terms of total (chemical plus sensible) enthalpy. This allowed a temperature correction to be applied by removing enthalpy from the fuel side and adding it to the oxidant side. This reformulation also has advantages when using probability density function (PDF) techniques in larger turbulent flames because the radiatively-induced nonadiabaticity is tracked locally with each fluid parcel. The divergence of the velocity field, required to obtain the flow-induced perturbation pressure, is calculated from an expression derived from the continuity equation. A new approach to soot modeling in diffusion flames was developed and added to the FDS code. The soot model postulated as part of this work differs from others because it is intended for engineering calculations of soot formation and oxidation in an arbitrary hydrocarbon fuel. Previous models contain several fuel-specific constants that generally can only be determined by calibration experiments in laminar flames. The laminar smoke point height, an empirical measure of a fuel?s sooting propensity, is used in the present model to characterize fuel-specific soot chemistry. Two separate mechanisms of soot growth are considered. The first is attributed to surface growth reactions and is dependent on the available surface area of the soot aerosol. The second is attributed to homogeneous gas-phase reactions and is independent of the available soot surface area. Soot oxidation is treated empirically in a global (fuel-independent) manner. The local soot concentration calculated by the model drives the rate of radiant emission. Calibration against detailed soot volume fraction and temperature profiles in laminar axisymmetric flames was performed. This calibration showed that the general approach postulated here is viable, yet additional work is required to enhance and simplify the model. The essential mathematics for modeling larger turbulent flames have also been developed and incorporated into the FDS code. An assumed-beta PDF is used to approximate the effect of unresolved subgrid-scale fluctuations on the grid-scale soot formation/oxidation rate. The intensity of subgrid-scale fluctuations is quantified using the principle of scale similarity. The modified FDS code was used to calculate the evolution of soot in buoyant turbulent diffusion flames. This exercise indicated that the subgrid-scale fluctuations are quantitatively important in LES of turbulent buoyant diffusion flames, although no comparison of prediction and experiment was performed for the turbulent case.

This research report examines the use of zone modelling compared with CFD modelling to determine when zone model approximation is valid and when a CFD model might be required. A series of computer simulations with enclosures and fires of various sizes was performed to compare the capabilities and limitations of the two computer methods. The relationship between the size of the enclosure space and the size of the fire has been demonstrated in a dimensionless form. The zone model BRANZFIRE and the CFD model FDS were used for simulating smoke development. The simulations included various full-scale experimental data on both small and large spaces found in the literature. Further simulations of large exemplar spaces with a range of fire sizes were performed to investigate different variables, which have not been examined in full-scale experiments. The simulation results have been compared based on the smoke layer height and the average layer temperature. Zukoski’s smoke filling equation was also used to compare the layer height predictions against BRANZFIRE and FDS. It was found that different data reduction techniques gave different approximations to the layer height. A perfect match between the experimental data and the model output was very difficult to achieve. FDS showed a large uncertainty of the smoke layer height and temperature in the early stages of fire across the enclosure space. In the later stages, this uncertainly became minimised where the smoke layer height and temperature were fairly uniformly developed across the space. For fire enclosures with instantaneous steady-state fires, the predictions between BRANZFIRE and FDS agreed well with each other if the fire size and the enclosure size were within a reasonable range. From the modelling of the full-scale experiments, FDS showed favourable layer-height comparisons against the full-scale experimental tests. However, the output results from BRANZFIRE are less comparable with those of FDS for the experiments with fire growth. An appropriate smoke transport time lag should be included for Zukoski’s smoke filling equation and BRANZFIRE; otherwise, they gave conservative estimates of the layer height to smaller fires with a growth phase. In general, the data reduction methods and zone models should not be used if the fire is too small relative to the enclosure size. A very low temperature rise within the enclosure space would give invalid predictions of the layer height and average layer temperature. This is because there is no clear indication of a separation between the upper and lower smoke layers or temperatures. Single point data of smoke concentrations and temperatures from CFD models should be considered through the entire space or at the specified location of interest. This also applies to an extremely large fire relative to the enclosure size where temperature distribution across the space might not be very homogenous. CFD models could also be used to investigate the details of the smoke properties in the early stages of growing fires, in which the smoke transport lag and the plume effects cannot be seen in BRANZFIRE. This research is intended to provide guidance for fire engineers by determining which of the computer methods can be used confidently and appropriately as a design tool.

The direct exposure to fire is not the most immediate threat to passengers&amp / #8217 / life in case of fire in an underground transportation system. Most of the casualties in fire are the results of smoke-inhalation. Numerical simulation of fire and smoke propagation provides a useful tool when assessing the consequence and deciding the best evacuation strategy in case of a train fire inside the underground transportation system. In a station fire the emergency ventilation system must be capable of removing the heat, smoke and toxic products of combustion from the evacuation routes to ensure safe egress from the underground transportation system station to a safe location. In recent years Computational Fluid Dynamics has been used as a tool to evaluate the performance of emergency ventilation systems. In this thesis, Computational Fluid Dynamics technique is used to simulate a fire incidence in underground transportation systems station. Several case studies are performed in two different stations in order to determine the safest evacuation scenario in CFDesign 7.0. CFD simulations utilize three dimensional models of the station in order to achieve a more realistic representation of the flow physics within the complex geometry. The steady state and transient analyses are performed within a simulation of a train fire in the subway station. A fire is represented as a source of smoke and energy. In transient analyses, a fast t2 growth curve is used for the heat release rate and smoke release rate. The results of the studies are given as contour plots of temperature, velocity and smoke concentration distributions. One of the case studies is compared with a code well known in the discipline, the Fire Dynamics Simulator, specifically developed for fire simulation. In selection of the preferred direction of evacuation, fundamental principles taken into consideration are stated.

In daily activities, hand use is dominated by individuated thumb and finger movements, and by grasping. This thesis focused on the level of ???independence??? of the digits and its relationship to hand grasps, from the level of the motor units to the level of synergistic grasping forces. Four major studies were conducted in healthy adult volunteers. First, spike-triggered averages of forces produced by single motor units in flexor pollicis longus (FPL) in a grasp posture showed small but significant loading of the index, but not other fingers. This reflected a neural rather than anatomical coupling, as intramuscular stimulation produced minimal effect in any finger. Also, FPL had a surprisingly large number of low-force motor units and this may account for the thumb???s exceptional dexterity and force stability compared with the fingers. Second, independent control of extensor digitorum (ED) was more limited than flexor digitorum profundus (FDP), as more ED motor units of a ???test??? finger were recruited inadvertently by extension than by flexion of adjacent digits. Third, ???force enslavement??? in maximal voluntary tasks was greater in digit extension than flexion. The distribution of force enslavement (and deficits) matched the pattern of daily use of the digits (alone and in combination), and reveals a neural control system which preferentially lifts fingers together from an object by extension but allows an individual digit to flex to contact an object so the finger pads can engage in exploration and grasping. Finally, during grasping, irrespective of whether a digit had been lifted from the object, coherence among forces generated by the digits was similar. In addition, the coherence between finger forces was independent of any contraction of the thumb, was stable over 2 months, and required no learning. The pattern of coherence between digital grasping forces may be closely related to the level of digit independence and daily use. Overall, the grasp synergy was remarkably invariant over the various tasks and over time. In summary, this thesis demonstrates novel aspects of the properties of FPL, the lack of complete independence of the digits, and robustness in the production of flexion forces in hand grasps.

Devant le besoin de nouveaux outils d’aide à l’investigation post-incendie, cette thèse se propose d’évaluer le recours à des modèles numériques pour apprécier un scénario proposé par un expert. Pour cela, les conditions d’utilisation de la version 4 de Fire Dynamics Simulator (FDS) ont été déterminées dans une optique de reconstitution de sinistres. Une méthode a ensuite été développée afin de confronter les résultats des simulations aux observations faites lors de l’investigation : cette méthode se base sur l’utilisation de multiples points de comparaison qui sont des effets thermiques ou mécaniques remarquables sur un matériau. Les résultats obtenus ont ensuite été utilisés pour la simulation de deux cas réels. Le premier s’attache à comparer, à des simulations, des mesures de propagation de flammes à la surface d’un matelas dans deux configurations différentes. Cela est réalisé afin d’évaluer le modèle de combustion solide de FDS dans différentes conditions de ventilation. La seconde application est la reconstitution d’un incendie ayant fait une victime dans un appartement. Ce second cas a été choisi dans le but d’évaluer les méthodes de simulation et d’utilisation des points de comparaison établies dans les premiers chapitres. / This work is intended to evaluate the use of numerical models to assess fire scenarios proposed by investigators. First chapter of this thesis is about theoretical fire phenomenon useful in the investigation frame. The second chapter is devoted to the validation of a CFD tool named Fire Dynamics Simulator (FDS) for fire reconstruction purposes. Guidance is developed in the third chapter in order to compare modelling results to degradations observed on fire scenes. It is explained how the accuracy of a scenario could be assessed using several comparison points, the thermal or mechanical effects on materials after a fire. Results obtained in previous chapters are finally applied on two cases. The first one is the comparison of fire spread velocities measured on two different experiments with simulations. This study is carried out to test FDS combustion model under ventilated and underventilated conditions. The second case is the reconstruction of a fire which killed the occupant of an apartment, the purpose of this work being to apply modelling and investigation guidance to a real case.