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Local wind fields that account for topographic interaction are a key element for any wildfire spread simulator. Currently available tools to generate near-surface winds with acceptable accuracy do not meet the tight time constraints required for data-driven applications. This article presents the specific problem of data-driven wildfire spread simulation (with a strategy based on using observed data to improve results), for which wind diagnostic models must be run iteratively during an optimisation loop. An interpolation framework is proposed as a feasible alternative to keep a positive lead time while minimising the loss of accuracy. The proposed methodology was compared with the WindNinja solver in eight different topographic scenarios with multiple resolutions and reference – pre-run– wind map sets. Results showed a major reduction in computation time (~100 times once the reference fields are available) with average deviations of 3% in wind speed and 3° in direction. This indicates that high-resolution wind fields can be interpolated from a finite set of base maps previously computed. Finally, wildfire spread simulations using original and interpolated maps were compared showing minimal deviations in the fire shape evolution. This methodology may have an important effect on data assimilation frameworks and probabilistic risk assessment where high-resolution wind fields must be computed for multiple weather scenarios., Peer Reviewed, Postprint (author's final draft)

The mechanical effects of a BLEVE are overpressure and ejection of fragments. Although fragments reach much longer distances, peak overpressure can be very strong over a certain area. Diverse authors have proposed methodologies for the estimation of the explosion energy and peak overpressure from these type of explosions, based on different thermodynamic and physical assumptions. Here these methodologies are commented and compared. Their predictions, which show an important scattering, are checked by comparison with two sets of experimental data taken from the literature. The results obtained indicate that none of the models take into account Reid’s theory. The models based on ideal gas behaviour and constant volume energy addition, isentropic expansion and isothermal expansion give quite conservative (i.e., high) values of both energy released and overpressure, while those assuming real gas behaviour and adiabatic irreversible expansion give lower values, much closer to the real/experimental ones. The diverse uncertainty factors affecting the prediction of peak overpressure are also commented., Postprint (published version)

En el present treball es porta a terme un estudi de la combustió dels contenidors de brossa analitzant els diferents tipus de dipòsits que hi ha al mercat i els tipus de residus que es poden trobar en aquests. D’altra banda, també s’estudiar{ la resistència al foc dels mateixos i es detallar{ diferents maneres d’evitar la crema d’aquests. En primer lloc, s’ha realitzat una petita revisió de diferents accidents ocorreguts que estan directament relacionats amb la crema de contenidors per poder extreure diferents factors que es repeteixen en tots ells. S’han descrit els diferents contenidors que es poden trobar en el mercat depenent de la marca que els fabriqui, que en aquest cas són Thesal y Ros Roca i, amb diferents contenidors de segona marca, s’ha realitzat dos probes de resistència al foc amb l’ajuda dels bombers. També s’ha calculat les característiques d’un incendi d’aquest tipus de manera teòrica per poder relacionar-lo amb les dades experimentals. A continuació, es presenten diferents propostes preventives per evitar que els contenidors de brossa siguin objecte d’actes vand{lics o que en el cas que ho siguin, els desperfectes causats sobre aquests i sobre l’entorn siguin mínims. També s’estudia tant com els fums produïts en un incendi així com els efectes negatius que aquests provoquen als éssers humans. Finalment, es pot afirmar que la crema de contenidors generalment, no només afecta al dipòsit en si, sinó que també afecta a qualsevol mobiliari que hi hagi al voltant ja siguin vehicles, altres contenidors o arbres i per evitar-ho el sistema de protecció més comú consisteix en enterrar els dipòsits construint emmagatzematges subterranis. D’altre banda, els retardants del foc com la llana de roca o la fibra de vidre resulten especialment útils per evitat tant com la propagació del foc com per minimitzar els efectes d’aquest inclús si només s’incorporen en la tapa del dipòsit.

Fire is the most common phenomenon that characterizes major accidents that take place in both industrial establishments and in the transport of dangerous goods by road and rail. The formation of a fireball, with or without a BLEVE, is characterized by the strong emission of thermal radiation, capable of causing lethal damage and irreversible injuries to people located at a significant distance. Although the knowledge about this type of accident has improved substantially, are still occurring eventually, so it is necessary to develop proposals aimed at reducing the effects of their consequences. This thesis has as main objective the development of new configuration factors between a fireball and a vulnerable target, considering the shadow effect of a third surface interposed between them. This approach defines a scenario of great practical utility, such as it is the implementation of physical barriers, not considered so far for the prediction of the consequences of major accidents of fireballs over their surroundings. In the literature review, no references has been found related with the raised hypothesis, so it will be in this research the first time they are published, for two particular cases: aboveground and elevated fireball. A novel mathematical method has been developed to determine the configuration factor under the conditions described above, which provides accurate results with reduced execution time and computational cost. Moreover, mathematical equations have been derived, through a semi-analytical method, that allow an acceptable approximation of these factors. The results of this research have allowed the development of a new mathematical model of dynamic fireball considering the shadow effect, whose m a in novelty is that the transitory regime of the fireball evolves through different regions in which the relative visibility can be total, partial and null. Physical barrier design criteria are established to limit the effects of thermal radiation, whic, El incendio es el fenómeno más frecuente que caracteriza a los accidentes graves que tienen lugar tanto en establecimientos industriales como en el transporte de mercancías peligrosas por carretera y ferrocarril. La formación de una bola de fuego, aislada o como parte de una BLEVE, se caracteriza por la emisión de una intensa radiación térmica, capaz de causar daños letales e irreversibles a personas situadas a una distancia significativa. A pesar de que el conocimiento acerca de este tipo de accidente ha mejorado de forma sustancial, se siguen produciendo eventualmente, por lo que es necesario desarrollar propuestas encaminadas a reducir los efectos de sus consecuencias. Esta tesis tiene como objetivo principal el desarrollo de factores de configuración entre una bola de fuego y un receptor vulnerable, considerando el efecto sombra que ejerce una tercera superficie interpuesta entre ambos. Este planteamiento define un escenario de gran utilidad práctica, como es la implantación de barreras físicas, no considerado hasta el momento para la predicción de las consecuencias de accidentes graves con bolas de fuego sobre su entorno próximo. No se han encontrado en la bibliografía factores de configuración para la hipótesis planteada, por lo que será en esta tesis la primera vez que se publiquen, para dos casos particulares: de bola de fuego a ras de suelo y elevada. Se ha desarrollado un método matemático propio para determinar el factor de configuración en las condiciones descritas anteriormente, que proporciona unos resultados de gran precisión, con reducido tiempo de ejecución y coste computacional. También se han obtenido ecuaciones matemáticas, a través de un método semi-analítico, que permiten realizar una aproximación aceptable de dichos factores. Los resultados de esta investigación han permitido desarrollar un nuevo modelo matemático de bola de fuego dinámica considerando el efecto sombra, cuya principal novedad es que el régimen transitorio de la bola de fuego e, Postprint (published version)

Wind turbines are generally considered cost-effective, reliable and sustainable energy sources. Fires are not common in wind turbines, but a significant number of fires occur every year due to the large number of turbines installed. Wind turbine fires are difficult to extinguish hence significant damage is expected. Due to the unmanned operation, the probability of a turbine being occupied during a fire is very low. However, operators can do several tasks every week, and hence be exposed to a certain risk. Moreover, there is a general lack of information about how a fire develops inside a wind turbine and the subsequent evolution of the tenability conditions during the time required for an eventual evacuation. Gamesa has been working on fire safety since 2013, using CFD fire modelling to provide insights on wind turbine fire development for the design of emergency procedures. The paper describes a fire hazard analysis performed in a Gamesa’s 2.5 MW turbine. A CFD simulation is carried out to estimate the effects during the first minutes of a typical wind turbine fire in an electrical cabinet. Results show that average oxygen concentration at the nacelle remains above 19.5% during the first 10 min; temperature remains below 60°C for 12 min if measured at 1.5 m; and visibility is on average assured at heights lower than 1.5 m, with values above 5 m during the first 8 min in worse locations, implying no danger for personnel. The potential of this type of analysis to design safer wind turbines under performance-based approaches is clearly demonstrated., Peer Reviewed, Postprint (author's final draft)

Several methodologies, based on different thermodynamic assumptions and requiring substance properties and thermodynamic data, have been proposed in the literature for the prediction of the mechanical energy released by a Boiling Liquid Expanding Vapour Explosion (BLEVE) and the associated overpressure. A new method, simple and easy to use, is presented which only requires the vessel filling degree and the temperature at failure as input variables to estimate this energy. The polynomial approach has been used to obtain the equation corresponding to the diverse substances most commonly involved in these explosions. The comparison of the predicted values with experimental data shows a good agreement., Peer Reviewed, Postprint (author's final draft)

Airborne thermal infrared (TIR) imaging systems are being increasingly used for wild fire tactical monitoring since they show important advantages over spaceborne platforms and visible sensors while becoming much more affordable and much lighter than multispectral cameras. However, the analysis of aerial TIR images entails a number of difficulties which have thus far prevented monitoring tasks from being totally automated. One of these issues that needs to be addressed is the appearance of flame projections during the geo-correction of off-nadir images. Filtering these flames is essential in order to accurately estimate the geographical location of the fuel burning interface. Therefore, we present a methodology which allows the automatic localisation of the active fire contour free of flame projections. The actively burning area is detected in TIR georeferenced images through a combination of intensity thresholding techniques, morphological processing and active contours. Subsequently, flame projections are filtered out by the temporal frequency analysis of the appropriate contour descriptors. The proposed algorithm was tested on footages acquired during three large-scale field experimental burns. Results suggest this methodology may be suitable to automatise the acquisition of quantitative data about the fire evolution. As future work, a revision of the low-pass filter implemented for the temporal analysis (currently a median filter) was recommended. The availability of up-to-date information about the fire state would improve situational awareness during an emergency response and may be used to calibrate data-driven simulators capable of emitting short-term accurate forecasts of the subsequent fire evolution., Postprint (author's final draft)

Huge amounts of hazardous materials are transported by rail and road, being from time to time involved in traffic accidents. In these cases, flammable materials such as, for example, LPG, can originate a severe accident if a loss of containment takes place: a BLEVE explosion usually followed by a fireball. This type of accident, which often follows the domino effect sequence of fire¿explosion, has caused the death of many people, including firefighters and spectators, the mechanical and thermal effects reaching significant distances. A historical survey has been performed on 167 accidents obtained from diverse databases. The results thus obtained have been used, together with the adequate mathematical models, to analyze the time to failure that can be expected and to estimate the lethality reach of the diverse effects-overpressure, ejected fragments, thermal radiation. Finally, a set of considerations concerning the safety and emergency measures that should be adopted in these accidents are commented, Postprint (published version)

In recent times there have been increasing efforts to integrate technology into wildfire management, especially in the fields of tactical monitoring and simulation. On the one hand, thermal infrared imaging (TIR) systems have been installed aboard surveillance aircraft including unmanned systems (UAS). On the other, there exists a variety of models and simulators able to forecast the fire spread. However, both fields currently present significant limitations. While relevant information is still extracted manually from aerial thermal imagery and is most times merely qualitative, simulators’ accuracy on fire spread prediction has proved insufficient. To solve these issues, this article presents a twofold methodology to couple meaningful automated wildfire monitoring with accurate fire spread forecasting. The main goals are to, firstly, automatically process aerial TIR imagery so that valuable information can be produced in real time during the event and, secondly, use this information to adjust a Rothermel-based simulator in order to improve its accuracy on-line. The fire perimeter location is tracked automatically through an unsupervised edge detector. Afterwards, an assimilation module uses the remotely sensed data to optimise the simulator's fuel and wind parameters, which are assumed to remain constant for a certain period of time. Subsequently, the optimum parameters’ values are used to issue a fire evolution forecast. All outputs are projected onto the corresponding Digital Terrain Model (DTM) and integrated into a Geographic Information System (GIS) for visualization. The global system was validated using two large-scale experiments. If these algorithms can be applied to a sufficiently rich and varied set of experimental data and further developed to cope with more complex scenarios, they could eventually be incorporated into a fire management decision support system., Peer Reviewed, Postprint (author's final draft)

Smouldering ground fires have severe environmental implications. Their main effects are the release of large amounts of carbon to the atmosphere with loses of organic soil and its biota. Quantitative data on the behaviour of smouldering wildfires are very scarce and are needed to understand its ecological effects, to validate fuel consumption and smouldering propagation models and to develop danger-rating systems. We present, for the first time, a methodology for conducting smouldering experiments in field conditions. This method provides key data to investigate smouldering combustion dynamics, acquire fire behaviour metrics and obtain indicators for ecological effects of smouldering fires. It is to be applied in all types of undisturbed soils. The experimental protocol is based on a non-electric ignition source and the monitoring system relies on combining both point and surface specific temperature measurements. The methodology has been developed and applied by means of large series of replicate experiments in highly organic soils at the forest–grassland treeline of the Peruvian Andes. The soil tested exhibited weak ignition conditions. However, transition to oxidation phase was observed, with smouldering combustion during 9¿h at 15-cm depth and residence times at temperatures above dehydration of ~22¿h., Peer Reviewed, Preprint

Residential occupancies are the most common type of buildings where compartment fires occur. In order to provide fire protection in these occupancies and thus to significantly reduce the number of future victims, the prediction of the fire effects during the first minutes becomes crucial. Particularly, forecasting fire dynamics (i.e. fire growth, smoke dispersion, etc.) may send early warnings to occupants and may provide important information for the fire service rescue team. Nevertheless, validation analysis should be previously performed to assess the predictive capabilities of different modelling tools when determining the harmful fire effects in residential compartments. The present paper describes three fire experiments undertaken in naturally-ventilated residential compartments. The aim of current work is to assess the fire effects prediction performance by means of different fire models compared to experimental data. The Q ¿ curves, which are derived from the temperatures measured inside the compartments, are employed as input data for the fire models used: an analytical model, a two-zone model (CFAST) and a field model (FDS). Recommendations on models choice are provided according to the results accuracy and the computational time required for the modelling tools employed. Preliminary outcomes reveal similar experimental fire behaviour in terms of temperatures, heat release rates and smoke layer heights among the three fire scenarios analysed. In addition, gas temperatures were correctly predicted with FDS; whereas the analytical model and CFAST were the most appropriate methods to forecast the smoke layer heights according to the experimental data collected., Peer Reviewed, Postprint (author's final draft)

Fires have been object of study over the last decades due to their destructive power. Fire’s hazardous nature and its ability to inflict damage to property, the environment and people, has produced a need to understand how it works in every aspect. Currently, the main focus is to estimate the fire characteristics and main effects, in order to accurately design emergency plans and prevention measures. Due to the needs previously stated, fires have been studied and analyzed mainly from an experimental point of view. However, experimental data is arduous and extremely expensive to obtain due to the amount of resources needed. Additionally, small-scale models, which are generally easier to be undertaken, cannot be extrapolated to full-scale models. Considering this, semi-empirical methods were developed, but can only be applied to simple scenarios and they cannot fully model them. To achieve complete models of fires, CFD (Computational Fluid Dynamics) modeling has been recently used as a way to achieve a cheaper and easier method to study the fire development of full-scale fires in a wide range of conditions. Nevertheless, CFD models require a huge validation effort before they could be widely applied. The main objective of this thesis is to analyze the performance and if possible validate the CFD code FLACS-Fire v10.5 (Flame Accelerator Simulator) for pool-fires. FLACS is a Computational Fluid Dynamic (CFD) program, which solves the compressible conservation equations for mass, momentum, enthalpy, and mixture fraction using a finite volume method. To model a fire it is necessary to include, among others, processes that involve submodels for: turbulence, combustion, thermal radiation, and soot generation. It is of utmost importance, while developing fire models, to validate them against experimental data in pursuance of being able to conclude whether the simulation is valid or not, and to determine the inherent error in comparison with reality. This process consists in

This project has as a main target to determine the validity of data provided by FDS simulator in function of its similitude with experimental data obtained through different PhD thesis. To start with, in a background section, is explained what is understand for fire and flames, which are the main types of fires that can occur in industry and, finally, which are the main features that define pool fires, which are object of study of this project. In this section, a brief introduction of computational fluids dynamic (CFD) has also been described, as the main simulation strategies in CFD (RANS, LES and DNS). Finally, the used simulation tools have been described. A whole chapter has been dedicated to the description of the different mathematical models FDS uses in order to perform its calculations, regarding to fluids hydrodynamics, combustion and thermal radiation transport. A brief summary of found validation results performed previously with FDS and which are related to the matter of this project have been summarized. After FDS introduction, a chapter has been dedicated to the description of the installation where the experiments were performed, the results of which will be compared with simulation data provided by FDS. Besides the description of the experimental scenario, the different measurement methods used experimentally to catch the registered variables are also described, and experimental results obtained have been compiled. Described the experimental installation and the measurement methods, it has been explained how experimental scenario has been implemented into FDS (originally, the reproduced scenario has been set as similar as possible to the real installation), and which have been the measurement methods for the output variables. Later, emplacement studies have been carried out, in order to find which domain and grid size (symmetry has also been studied) can provide the data which is most nearby to experimental results and, at the meantime, does not requ

Boiling Liquid Expanding Vapor Explosions keep occurring from time to time in process plants, storage areas and transportation by road or rail, often with severe effects. There is no doubt that a better knowledge of their main features will help in decreasing both their frequency and their consequences. This is the main aim of this thesis: the analysis of the main causes of BLEVEs, the improvement in the prediction of their effects and consequences and, finally, the definition of simple measures to be applied in the management of emergencies associated to these events. Historical analyses have been performed to determine the prevalence of BLEVEs among all major accidents in fixed plants and in the transportation of hazardous materials, as well as their main causes; the action of fire as domino effect escalation has also been studied, with special attention to the time to failure of a vessel in such a situation. The different existing methodologies for the estimation of the peak overpressure are presented and compared, and the diverse uncertainty factors affecting the prediction of BLEVE mechanical effects are analyzed. A new and relatively simple methodology has been proposed to predict the blast effects of these explosions, which allows a quick and accurate estimation. Finally, based on all these analyses, simple emergency management measures are proposed which could reduce significantly the consequences of BLEVEs on people., Encara avui, en plantes de procés, àrees d’emmagatzematge o en el transport per carretera o ferrocarril, de tant en tant es continuen produint les explosions anomenades BLEVE (Boiling Liquid Expanding Vapor Explosion, en català explosió del vapor en expansió d’un líquid bullent), sovint amb efectes molt severs. No hi ha cap mena de dubte que conèixer millor les principals característiques d’aquestes explosions permetrà reduir-ne tant la seva freqüència com les seves conseqüències. Aquesta és precisament la principal finalitat d’aquesta tesi: l’anàlisi de les causes principals de les BLEVEs, la millora en la predicció dels seus efectes i conseqüències i, finalment, la definició de mesures que siguin senzilles d’aplicar quan es produeixen emergències associades a aquest tipus d’esdeveniment. S’han dut a terme anàlisis històriques per a determinar la prevalença de les BLEVEs d’entre tots els accidents greus que es poden produir en instal·lacions fixes i durant el transport de mercaderies perilloses, així com també per a determinar-ne les causes principals. També s’ha analitzat l’acció que exerceix el foc com a element desencadenant d’efecte dominó, fent especial atenció al temps que trigarà un dipòsit en esclatar quan es veu sotmès a la seva acció. També es presenten i comparen les diverses metodologies existents per a l’estimació del pic de sobrepressió produït en una BLEVE, i s ¿analitzen els diversos factors d’incertesa que afecten la predicció dels efectes mecànics generats en una BLEVE. S’ha presentat una metodologia nova i relativament simple per predir els efectes d’aquest tipus d’explosions, que permet fer estimacions ràpides i acurades. Finalment, en base a totes aquestes anàlisis, s’han proposat mesures senzilles per a la gestió d’aquest tipus d’emergències que poden ajudar a reduir significativament les conseqüències de les BLEVEs sobre les persones., Postprint (published version)

A wildfire forecasting tool capable of estimating the fire perimeter position sufficiently in advance of the actual fire arrival will assist firefighting operations and optimise available resources. However, owing to limited knowledge of fire event characteristics (e.g. fuel distribution and characteristics, weather variability) and the short time available to deliver a forecast, most of the current models only provide a rough approximation of the forthcoming fire positions and dynamics. The problem can be tackled by coupling data assimilation and inverse modelling techniques. We present an inverse modelling-based algorithm that uses infrared airborne images to forecast short-term wildfire dynamics with a positive lead time. The algorithm is applied to two real-scale mallee-heath shrubland fire experiments, of 9 and 25 ha, successfully forecasting the fire perimeter shape and position in the short term. Forecast dependency on the assimilation windows is explored to prepare the system to meet real scenario constraints. It is envisaged the system will be applied at larger time and space scales., Peer Reviewed, Postprint (author's final draft)

El projecte que s’exposa a continuació és un treball desenvolupat a conseqüència d’un conjunt d’estudis duts a terme per el cos de Servei Tècnic dels Bombers de la Generalitat de Catalunya i experts en simulació, els quals es van plantejar la idoneïtat del reglament que regeix sobre la seguretat en incendis en naus industrials – Reglament de Seguretat Contra Incendis en Establiments Industrials (RSCIEI) – i, en concret, sobre els establiments categoritzats dins del tipus A horitzontal. Els tècnics del cos de bombers van observar i concloure que la normativa que s’aplica pel control i seguretat contra incendis en naus industrials (RSCIEI) estipulava condicions dures (tant tècnicament com econòmicament) als propietaris d’establiments que es classificaven com a tipus A horitzontals, doncs es determina que la tipologia d’aquest format d’establiment (que ocupa parcialment un edifici on, a més a més, es realitzen altres activitats) es pot assimilar a un establiment tipus B (edifici d’ús industrial adossat o distància màxima de 3 metres a d’altres) sempre i quan es presenti un estudi de viabilitat. Aquest estudi ha d'estar bastat en una argumentació sòlida basada en càlculs i anàlisis molt detallats, els quals conclouen en alternatives – per exemple, instal·lació de ruixadors automàtics –que suposen costos molt elevats als propietaris dels establiments. En aquest context, els tècnics proposen una alternativa menys costosa basada en un sistema de ventilació forçada el qual, després de completar aquest estudi, es va concloure que complementat amb protecció estructural, establiments de tipologia A horitzontal podien resistir incendis sense la necessitat d’implementar mesures tant costoses com les exposades anteriorment. Tanmateix, aquest estudi va utilitzar un format d’establiment industrial concret i, per tant, cal determinar si els resultats obtinguts a partir de les simulacions fetes pels tècnics són estables al variar paràmetres de l’escenari patró (com, per exemple, la v

Amb aquest projecte es pretén estudiar les atribucions que té l’enginyeria en el camp de la investigació dels incendis, concretament en la investigació d’incendis en vehicles. Per fer-ho, s’ha comptat amb la col·laboració directa de l’empresa ABP Investigación de Siniestros, en la que aquest estudiant ha realitzat les seves pràctiques curriculars. En un inici s’ha requerit estudiar els conceptes primaris de la generació del foc, la transmissió de la calor generada durant un incendi i les fonts de calor més comunes en la gran majoria d’incendis. A partir d’aquest punt, conegudes les característiques que poden desenvolupar un incendi i estudiades les diverses maneres de com aquest es pot originar, s’ha procedit a conèixer la metodologia bàsica en la investigació d’un incendi. Donat que la investigació d’incendis és una tasca multi-disciplinar en la que es requereixen diversos coneixements en diferents camps relacionats amb l’enginyeria per tal de determinar correctament l’origen i la causa de l’incendi, no es pot atribuir una única metodologia en la investigació d’un sinistre causat pel foc. Per aquest motiu, s’ha decidit enfocar el projecte a partir de la investigació dels incendis en vehicles, acotant les seves tècniques d’investigació, i centrant els esforços en entendre el procediment necessari per tal de realitzar correctament qualsevol tipus d’investigació en un vehicle. A partir d’un dels incendis que l’empresa ABP Investigación de Siniestros va haver d’investigar, comptant també amb la col·laboració d’aquest estudiant, s’ha procedit a realitzar la part pràctica del projecte, estudiant un cas real d’un incendi d’un camió. D’aquesta manera es pretén fer veure d’una forma més pràctica els conceptes comentats anteriorment, tant pel que fa als tipus de combustibles presents en un vehicle, les fonts de calor més comunes, la transmissió de la calor durant un incendi, així com la metodologia emparada en aquests tipus d’investigacions. En aquest cas concret, l’incendi

En aquest treball es pretén formular un coeficient de seguretat que permeti dimensionar la zona d'intervenció a partir de l'abast visible d'un núvol inflamable de gas liquat. Aquest coeficient es desenvoluparà tot fent ús de tècniques de simulació CFD mitjançant el programari d'anàlisi de risc FLACS. Les principals tasques són: 1. Anàlisi bibliografia: Recopilació de dades experimentals de fuites inflamables de gasos liquats; procediments d'intervenció en fuites inflamables; modelització CFD del comportament de fuites de gasos pesants. 2. Validació FLACS per a predir l'abast visible del núvol inflamable i l'abast del LEL: - Confrontació de dades experimentals de la mida del núvol visible amb el perfil simulat del llindar de temperatura de rosada. - Confrontació de dades experimentals de concentració amb els perfils simulats dels llindars del 10%, 60% i 100% del LEL. 3. Definició escenaris de simulació de fuites inflamables que puguin cobrir diferents rangs de cabals, substàncies i condicions atmosfèriques. 4. Estudi de la sensibilitat per a diferents variables que configuren el terme font i les condicions atmosfèriques. 5. Estudi estadístic de la significança dels diferents paràmetres considerats en l'anàlisi de sensibilitat i proposta d'un model per calcular la zona d'intervenció.

Aquest projecte té com a objectiu desenvolupar una metodologia, a partir de dades obtingudes per teledetecció, que permeti detectar i quantificar les àrees cremades, causades pels incendis, que es produeixen en un dels ecosistemes coneguts més sensibles al foc. Aquests són els boscos de boira tropical d’alta muntanya (Tropical Mountain Cloud Forest, TMFC), localitzats a la regió peruana dels Andes. El projecte està compost, a grans trets, per tres parts diferenciades. En la primera d’elles es realitza una definició entorn el concepte de teledetecció, els diversos tipus que existeixen i una descripció de les principals característiques dels sistemes utilitzats en el present projecte. En la segona part es presentaran les bases conceptuals de la metodologia de correcció topogràfica utilitzada, la qual s’ha aplicat a les imatges obtingudes per satèl·lit, per tal d’eliminar les ombres causades per l’orografia del terreny. S’ha posat a prova la metodologia aplicant-la a la zona d’estudi, i s’ha comprovat que aquesta és capaç d’eliminar en gran part les ombres del terreny, podent així pal·liar un dels principals factors causants d’interferències en la teledetecció d’àrees cremades. Finalment, la tercera part es centra en la descripció i implementació de la metodologia d’anàlisi de les imatges, provinents del sensor de Landsat, per tal de detectar les àrees cremades. Aquesta metodologia està basada en una adequació i pretractament de les imatges per tal de poder eliminar qualsevol tipus d’interferència per poder aplicar, posteriorment, la descomposició espectral a les imatges. La metodologia ha estat implementada en l’entorn de programació matemàtica MATLAB® i també s’ha utilitzat el programari d’informació geogràfica QGIS. Els resultats obtinguts demostren que és factible detectar àrees cremades en els TMFC’s mitjançant dades de Landsat.

Forecasting the behaviour of a flammable or toxic cloud is a critical challenge in quantitative risk analysis. Recent literature shows that empirical and integral models are unable to model complex dispersion scenarios, like those occurring in semi-confined spaces or with the presence of physical barriers. Although CFD simulators are promising tools in this regard, they still need to be fully validated with comprehensive datasets coming from experimental campaigns designed ad-hoc. In this paper, we present an experimental campaign carried out by a joint venture between University of Sao Paulo and Universitat Politecnica de Catalunya to investigate CFD tools performance when used to analyse clouds dispersion. The experiments consisted on propane cloud dispersion field tests (unobstructed and with the presence of a fence obstructing the flow) of releases up to 0.5 kg s(-1) of 40s of duration in a discharge area of 700 m(2). We provide a full 1-s averaged propane concentration evolution dataset of two experiments, extracted from 29 points located at different positions within the cloud, with which we have tested FLACS (R) CFD-software performance. FLACS reproduces successfully the presence of complex geometry, showing realistic concentration decreases due to cloud dispersion obstruction by the existence of a fence. However, simulated clouds have not represented the whole complex accumulation dynamics due to wind variation. (C) 2015 Elsevier Ltd. All rights reserved., Peer Reviewed, Postprint (published version)

The road accident of a tanker transporting liquefied natural gas (LNG) originated a fire and, finally, the BLEVE of the tank. This accident has been analyzed, both from the point of view of the emergency management and the explosion and fireball effects. The accidental sequence is described: fire, LNG release, further safety valves release, flames impingement on vessel unprotected wall, vessel failure mode, explosion and fireball. According to the effects and consequences observed, the thermal radiation and overpressure are estimated; a mathematical model is applied to calculate the probable mass contained in the vessel at the moment of the explosion. The peak overpressure predicted from two models is compared with the values inferred from the accident observed data. The emergency management is commented. (C) 2015 Elsevier Ltd. All rights reserved., Peer Reviewed, Postprint (author's final draft)

The domino sequences found in major accidents have been analyzed for a large set of cases (330); the first event triggering the domino effect was an explosion or a fire, both with approximately the same contribution; the same proportion has been found when all domino effect steps were considered. Although fire effects usually reach a distance much shorter than those of an explosion, as fire is the most frequent major accident it is often found as the first step of domino sequences. This is especially true in the case of BLEVEs. Both in fixed plants and in the transportation of hazardous materials, in the event of a fire, if flames affect a vessel and the fireproofing layer has been damaged, a BLEW can occur at any moment 127 BLEW accidents involving domino effect have been analyzed. It has been found that fire is significantly more frequent than explosion, both in triggering the domino effect sequence and in intermediate steps. The time to failure can range from 1 min or even less up to several hours, an aspect that should be very important for the management of the emergency. A set of conclusions are inferred from this survey. (C) 2015 Elsevier Ltd. All rights reserved., Postprint (author's final draft)

Fire safety community is currently concerned about the response of some widely used insulating materials in case of fire, due to the fact that existing regulations do not show how these materials behave in real conditions, which in some applications may be indeed critical. Within this context, several institutions have recently carried out large-scale tests with the aim of testing such insulator’s contribution to fire growth. In this paper we present a set of large scale tests of compartment and façade fires involving materials and configurations of different nature. Our experiments provided evidence that mineral wool insulator preserves its properties in case of fire, whilst other polymeric-type insulators contribute to fire growth in conditions close to the ones present in real fires., Postprint (published version)

The BLEVE (boiling liquid expanding vapor explosion) can occur with almost any liquid contained in a closed vessel, at a temperature well above its boiling point at atmospheric pressure. If the vessel fails, the vapor will expand and the superheated liquid will undergo a quick flash vaporization; the associated sudden increase in volume will originate an overpressure wave, that is, an explosion. This explosion can occur with any liquid, be it flammable or not, but if flammable then it will be followed by a fireball. The couple BLEVE-fireball can occur both in fixed plants and in transportation by rail or road. Knowledge of this type of accident has improved significantly during past decades, and measures to reduce its risk have consequently improved. Nevertheless, it still occurs from time to time and its consequences can still be very severe. In this chapter, a description of this phenomenon is provided, together with a review of the diverse methods employed to evaluate the mechanical, thermal and fragment rocket effects associated with this accident. Some recommendations concerning the management of these types of emergency are also provided., Postprint (published version)

L’Objectiu d’aquest projecte és dissenyar una base de dades sobre matèries perilloses que permeti optimitzar les intervencions dels equips del Cos de Bombers de la Generalitat de Catalunya en accidents de risc químic on actuar amb rapidesa pot ser un factor determinant. El projecte consta de tres parts clarament diferenciades. En la primera es defineix què és una matèria perillosa i s’estudia la importància d’aquestes substàncies en el territori català, tant a nivell industrial com a nivell de transport. Finalment, es descriuen els tipus de riscs que es poden derivar dels diferents escenaris accidentals que es poden produir. En la segona part s’estudien a fons diferents bases de dades especialitzades en matèries perilloses i, més concretament, orientades a la intervenció dels equips d’emergència i a la prevenció d’accidents. El total de bases de dades estudiades és de 14. Durant el transcurs de l’estudi es comparen diferents paràmetres representatius de les mateixes, s’estableixen criteris de classificació i es conclou com seria una base de dades ideal dissenyada de forma teòrica. Les dades extretes d’aquest estudi comparatiu, juntament amb les característiques bàsiques que ha de complir una base de dades permeten proposar diverses opcions de disseny. A partir de les dades extretes de les enquestes realitzades a bombers es pot decidir quina és la millor alternativa i efectuar-ne el disseny òptim. Un cop decidit el disseny que ha de presentar la base de dades, s’elabora un procediment per tal de poder omplir cada una de les fitxes trobant de forma senzilla la informació i corroborant que aquesta és correcta. S’elabora, també, el disseny d’un sistema comparatiu per a substàncies inflamables basant-se en substàncies amb un comportament conegut, com són el gasoil i la gasolina, que permetrà identificar de manera visual el comportament d’una substància inflamable. Finalment, en la darrera fase, es procedeix a fer una implementació mitjançant el programa Microsoft® Acces

Infrared (IR) imagery presents a great applicability in the field of wildland fires. However, most of the research conducted thus far has either focused on pre- and post- fire applications or relied on sophisticated technology. Despite the benefits it would potentially bring to operational fire management teams, real time active fire monitoring has not been achieved yet. The present article proposes a preliminary algorithm to detect and locate the fuel burning interface from thermal IR images. Since it is based on gradient instead of intensity thresholds, those images could ideally be captured with a simple low-cost camera without thermogrammetry capacities, i.e. no absolute temperature values are needed. First results are encouraging and suggest a further developed system could be deployed under operational conditions., Postprint (published version)

Preprint

The consequence analysis is used to define the extent and nature of effects caused by undesired events being of great help when quantifying the damage caused by such events. For the case of leaking of flammable and/or toxic materials, effects are analyzed for explosions, fires and toxicity. Specific models are used to analyze the spills or jets of gas or liquids, gas dispersions, explosions and fires. The central step in the analysis of consequences in such cases is to determine the concentration of the vapor cloud of hazardous substances released into the atmosphere, in space and time. With the computational advances, CFD tools are being used to simulate short and medium scale gas dispersion events, especially in scenarios where there is a complex geometry. However, the accuracy of the simulation strongly depends on diverse simulation parameters, being of particular importance the grid resolution. This study investigates the effects of the computational grid size on the prediction of a cloud dispersion considering both the accuracy and the computational cost. Experimental data is compared with the predicted values obtained by means of CFD simulation, exploring and discussing the influence of the grid size on cloud concentration the predicted values. This study contributes to optimize CFD simulation settings concerning grid definition when applied to analyses of consequences in environments with complex geometry., Postprint (published version)

Even though BLEVEs have been studied by a number of authors, there are still significant gaps in their knowledge and in the prediction of their physical effects. Diverse methodologies have been proposed to calculate the peak overpressure of the explosion, but their results sh ow an important scattering. Most of them assume a reversible, isentropic phenomenon, not at all logical for an explosion. Instead, some recent papers have assumed an irreversible process, much closer to the real phenomenon. This communication analyses these aspects, comparing the results obtaine d by applying the diverse methodologies to data obtained from a real case. The uncertainties found (v essel failure mode, directional effects) are also commented. Finally, some conclusions are derived on the best way to estimate the overpressure., Postprint (published version)

A key factor in decision-making process during a wildfire incident is counting on the forecast of how the fire is likely to behave in different fuels, weather conditions and terrain. Wildfire models and simulators attempt to assist fire responders in gaining understanding of the fire behaviour. The main hurdle to overcome when applying such technologies at operational level is the lack of a complete model that describes wildfire governing physics and the trade-off between accuracy and computing time. A forecasting prediction must be delivered within a positive lead time and current physical models are far beyond this requirement. Inverse modelling and data assimilation techniques offer a great potential of operational applicability in wildfires, coupling fire monitoring and fire behaviour forecast at real time. With this approach, a better description of the processes simulated by the fire behaviour models can be achieved when adding real-state information of the system, since discrepancies between simulated fire behaviour variables and observed variables are minimized. The use of this approach accelerates fire simulations without loss of forecast accuracy. In this paper we explore the adaptation to real fire scenarios of a synthetic-data-based inverse modelling structure for fire behaviour forecast. Improvements are investigated to extrapolate the already existing algorithm to real data assimilation from IR aerial monitoring. The technique explores elliptical Huygens expansion coupled with simple -yet effective- semi-empirical wildfire models. The algorithm assimilates fire fronts positions extracted from airborne thermal imaging and additional available data as wind speed and direction or fuel characteristics. The invariants -set of governing parameters that are mutually independent and constant for a significant amount of time- are resolved by means of forward model and linear tangent minimization. The technique has been adapted to be employed in large-scale mall, Postprint (published version)

Creació d'una metodologia operacional per a la recollida de dades en emergències en incendis d'interior, Preprint

In order to quantify the damage caused by undesired events involving leakages of flammable materials, specific models are used to analyze the spills or jets of gas and liquid, gas dispersion, explosions and fires. The main step of this analysis is to estimate the concentration, in space and time, of the vapor cloud of hazardous substances released into the atmosphere; the purpose is to determine the area where a fire or explosion might occur and the quantity of flammable material in that area. Recently with the computational advances, CFD tools are used to short and medium range gas dispersion scenarios, especially in scenarios where there is a complex geometry. However, the accuracy of the simulating strongly depends on the boundary conditions. Therefore, this study investigates the sensitivity degree of the prediction of cloud dispersion to changes in values of wind speed, ambient temperature, atmospheric pressure and ground roughness. This paper con-tributes to an appropriate assessment of the effects of these environment conditions to perform an accurate dispersion simulation using CFD tools and therefore contributes to a more effective analysis of the consequences., Postprint (published version)

Incoming