Search

Community structure is a common phenomenon observed in various social networks. In this work, a novel community detection algorithm is proposed by estimating the effect of community structure on the average path length of a network. The Erdos-Renyi graph model is used as a reference to compute the change in the average path length of a network due to community formation. By experimenting with artificial networks, it is found that community structure in a social network contributes towards the lengthening of the average shortest path length. A random graph is found to have a lesser average shortest path length than a social network with community structure. As the size of individual communities increases, there is a decrease in the difference of average shortest path lengths, compared with a random graph containing an equal number of nodes and edges. This relationship is used to predict the average community size and their numbers in a network. The findings mentioned above are applied to the proposed algorithm. The proposed community detection algorithm is an enhancement over Fire Spread community detection algorithm (Pattanayak, 2019), in which the value of R for the R-radius neighborhood subgraph is automatically calculated.

Indonesia is a tropical country that experiences forest fires every year. Forest fires occur due to a prolonged summer season. A major effect of forest fires that commonly occurred in Indonesia is the respiratory disorder and the visual impairment caused by the thick smoke that can experienced by the people who lives around the forest. The effects of forest fire fumes when the forest fire spread across the bigger land or area are also experienced by neighboring countries such as Malaysia, Singapore and Brunei Darussalam. Forest is a habitat for many animals, one of which is a bird. Birds are able to communicate with their colonies through sound. The bird sound during communication to the group can be in the form of calls, marriage invitations, and warnings of danger or threat of forest fires. This paper presents bird sounds classification study using one of Deep Learning (DL) algorithms i.e. Convolutional Neural Network (CNN) method. The CNN method is used to classify bird sounds in the two conditions: (1) under normal circumstances or conditions, and (2) under threated or panic condition. The bird sound data used in this study were collected from the local birds in Indonesia. The classification result of two bird sounds based on CNN method achieved up to 96.45%. This paper is a preliminary study for bio inspired early warning of forest fires based on the sound of birds.

A fact often overlooked is that large-scale wildfires, although occurring infrequently, are responsible for the overwhelming majority of fire-related suppression costs, economic losses, and natural resources damages. Fortunately, the increasingly severe problems of large-scale wildfires worldwide have been receiving ever-growing academic attention. The high-intensity burning behaviors in wildfires stem from the significant interaction of combustion with heat transfer and atmospheric flow under complicated fuel, meteorology, and topography conditions. Therefore, mitigating measures against large-scale wildfire disasters have grown into a challenging research focus for combustion scientists. Research over the past century has resulted in incrementally enhanced insights into the mechanisms of combustion dynamics underlying the various erratic behaviors in large-scale wildfires, with theories and models of fire accelerations developed and validated. These advances are expected to improve the efficacy of large-scale wildfire predictions significantly. Nevertheless, the physical interpretation of the acceleration of large-scale wildfires is far from adequate and complete. This paper intends not to make a comprehensive review of the entire wildfire research field, but to depict an overall pattern of the essential factors that lead an initial small-scale spreading flame to a large-scale wildfire beyond control. It is outlined that the complicated transformation of fuel preheating mechanisms determines the growth of surface fire spread, while varied large-size flame fronts and unique spread modes induced in specific fire environments play an essential role in fire spread acceleration. Additionally, multiple fires burning and merging often act as crucial steps for accelerating surface fire spread, generating large-size flames, and triggering unique spread modes. These major potential factors strike the energy balance of a low-intensity wildfire and push it to a high-intensity state. Several issues regarding intensely burning behaviors in large-scale wildfires are selected for in-depth discussions, for which an overview of the progress and challenges in research is presented. It is concluded that the fundamental exploration targeted at developing application tools capable of dealing with large-scale wildfires remains at its early stages. Opportunities for innovation are abundant, yet systematic and long-term research programs are required.

At present, the fire safety of double skin facades (DSFs) is an important research area due to recent spikes in fires in high rise buildings involving glass DSF systems, and also due to our limited understanding of the thermal behavior of these systems. To overcome this lack of knowledge, a numerical framework is proposed for simulating the thermal performance of DSFs under fire conditions. The framework is based on the smoothed particle hydrodynamics technique and it can be used to compute numerical solutions and simulate the thermal degradation of DSFs under fire conditions. The numerical model was validated by comparing the predicted response parameters in a fire exposed DSF system with those measured in fire experiments. The validated numerical model was then employed to derive empirical equations linking temperature with both the time and location along the interior and exterior glass panes of DSFs. Finally, numerical simulations were conducted for the same DSF configuration but equipped with venetian blinds in order to examine the influence of the blinds on the fire performance of glass DSFs. An in-house MATLAB code was developed and implemented to conduct these numerical simulations. The results obtained from these numerical simulations clearly indicated that the “blind tilt angle” can significantly affect the fire spread characteristics and temperature distribution in DSFs, and thus it should be considered in the design of DSF systems for high rise buildings.

In response to the transboundary haze problem in Southeast Asia, a physical model is adopted to simulate the spread and extinguishing of fire. This study is done in the context of Dumai, Indonesia, as it is one of the areas that significantly contribute to the haze problem. This model aims to provide perspectives on the persistence of forest fires despite fire-fighting efforts. While existing models using Huygens’ principle of wave propagation allow an understanding of the natural spread of fire, our model applies cellular automata to predict and analyse the effects of fire-fighting intervention strategies, with the spatial and propagation dynamics of fire considered. Cellular automata is an active area of research among physicists, and is widely used by chemists and biologists to model many types of natural phenomena. We note similarities between our model predictions and observations of real-world phenomena. Analyses on the factors that affect the spread of fire are presented, in order to understand which ones are dominant in differing situations. This provides insights on optimum conditions for fire-fighting efforts, and suggests guidelines that may be considered for fire control in future forest fires.

A new global sensitivity analysis has been conducted of fuel-type-dependent input variables of the simplified physical fire spread model (PhyFire) to understand how the use of spatial averages, that is, fuel models, influences the results of PhyFire with a view to enhancing its understanding and improving its design. The model’s simplicity, the numerical techniques used, and a recent code optimisation, allow undertaking the analysis with very competitive computational times. The fuel data used correspond to grasslands, shrublands and forest in the Spanish region of Galicia. The analysis results validate the flame length sub-model proposed in the paper, which significantly improves the model’s efficiency.

A learning-based wildfire spread model was developed in this study to predict short-term wildfire spread. Real-time rate of spread (RoS) measurement was first conducted by calculating normal movements of fire fronts. Subsequently, machine learning was employed to correlate the local RoS and environmental parameters and predict the RoS in the unburnt area. After that, a narrow-band level-set method was utilized to simulate the evolution of fire front. RoS measurement, machine learning, and level-set method were individually verified with numerically generated fire fronts, and applied in a real scale shrubland fire scenario. Results show that the proposed learning-based method is capable of predicting short-term fire spread without employing an empirical RoS model, which is beneficial for modeling spreading of a real wildfire.

This work investigates the fire line evolution in canyon fire spread by analytical and experimental means. The purpose is to understand the mechanism of fire spread acceleration associated with eruptive fire in canyon terrain. A symmetrical model canyon is used for experiments, and in each test the fire is initiated by a point ignition using dead pine needles as the fuels. By experimental observations and data, three distinct types of fire line contour are identified under different central slope angles (the angle between the canyon centerline and the horizontal ground), resulting in different variation modes of rate of spread along the canyon centerline. It is found that the trace of fire head deviates from the line of maximum slope for non-zero central slope angles, and such a deviation increases with increasing central slope angle. The fire spread acceleration associated with eruptive fire occurs when the central slope angle reaches a certain critical value. Experimental data confirm that under higher slope conditions, the significant interaction between the two lateral flame fronts induces marked convective heating ahead of the flame front, which is inferred to be the potential mechanisms of eruptive fire in canyon topography. A model analysis further elucidates how the deflection of the trace of fire head, induced by the fire interaction effect, influences the acceleration of fire spread under higher slope conditions.

The temperature heterogeneity due to fire in large open-plan office compartments is closely associated with fire spread behaviour and has been historically limited to experimental investigations using timber cribs. This study explores the ability of Computational Fluid Dynamics (CFD) models, specifically the Fire Dynamics Simulator (FDS), to reproduce the results of full-scale tests involving fire spread over timber cribs for continuous fuel-beds. Mesh schemes are studied, with a fine mesh over the crib and 2 × 2 cells in the wood stick cross-section by default, this being relaxed in the surrounding regions to enhance computational efficiency. The simple pyrolysis model considers the charring phase and moisture. In application to the TRAFIR-Liège LB7 test, this calibrated “stick-by-stick” representation shows a good agreement for interrelated parameters of heat release rate, fire spread, gas phase temperature, and burn-away, a set of agreements which has not been demonstrated in previous studies. Fire spread shows relatively high sensitivities to: heat of combustion, ignition temperature, thermal inertia, radiation fraction, heat release rate per unit area, and the fuel load density. An approximately linear regression was found between the different fire modes and the thermal exposures, with “travelling” (and decaying) fires characterised by heat fluxes associated with the fire plume, while the growing fires were associated with proportionally higher heat fluxes on the horizontal surfaces of the sticks, in conditions where these receive more pre-heating. The trends in the overall HRR are more dependent on the fire spread rates than variations in the stick burning rates.

The 3D structure of a fire front propagating through a homogeneous porous solid-fuel layer was studied numerically at laboratory and field scales. At laboratory scale, wind-tunnel fires propagating through laser-cut cardboard fuel were numerically reproduced, while at field scale, simulations of grassland fires with quasi-infinite fire front were carried out for different wind speeds. These simulations were performed using FIRESTAR3D, based on a multiphase formulation that includes the main physical phenomena governing fire behavior. An unsteady RANS approach and a Large Eddy Simulation (LES) approach were used to simulate the reactive turbulent flow, whereas turbulent combustion was modeled using Eddy Dissipation Concept (EDC). Unlike other 3D wildfire tools available in the community, such as FIRETEC and WFDS, the model is based on an implicit, low-Mach number resolution of the governing equations, and makes no empirical assumptions in the resolution of the radiative transfer equation. The comparison with the experimental data concerned mainly the Rate of Spread (ROS) of fire, the fireline intensity, the flame-zone depth, and the wavelength characterizing the crest-and-trough structure of the fire front along the transverse direction. Particular attention was drawn to the similitude in the fire front dynamics between small and large scales. In order to highlight the physical mechanisms responsible for this dynamics, a dimensional analysis was carried out by introducing Byram's convection number NC based on the fireline intensity and Froude's numbers Fr based on the characteristic wavelength of the fire-front structure. The analysis shows that all the results (wind-tunnel fires and grassland fires, experimental and numerical) collapsed on a single scaling law in the form F r = N C − 2 / 3 .

The paper presented the main results of large-scale fire tests with different types of fixed firefighting systems (FFFS) conducted in the Runehamar tunnel in June 2016. The background to the tests, the performance of the different systems, and conclusions regarding the efficiency of the systems were presented. The fire load consisted of 420 standardised wooden pallets and a target of 21 wooden pallets. Five of the tests were carried out with a 30 m long deluge zone delivering varying water densities using three different types of side-wall nozzles with an interval distance of 5 m. One test with 93 °C glass-bulb automatic sprinklers in the same zone was also conducted. In the five deluge tests, the detection system was simulated using thermocouples in the tunnel ceiling. The alarm was registered when the ceiling gas temperature reached 141 °C, and the system was activated manually after a delay of 4 min. The protection goal of the system was to prevent fire spread to a target positioned 5 m from the rear of the main fuel area, and to ensure that the fire did not exceed 30 MW in size. The system setups tested were found to meet these goals.

Internationally, informal settlements (also known as slums, favelas, shantytowns, ghettos, etc.) are expanding rapidly which have been associated with numerous large fires (where more than 10,000 people can be left homeless in a single disaster [ 1 ]), and an increase in fire related injuries and deaths. As a result of an increase in fire related incidences, various proposed interventions have been funded from governmental or private sources. However, many interventions have been unsuccessful because of technical, political, economic, social or practical issues. It is with the above mentioned in mind that this paper seeks to provide an understanding of fire behavior between multiple informal settlement dwellings (ISDs) as a baseline for future research and experiments. The paper starts by defining informal settlements in terms of construction and continues to look at the potential causes and hazards associated with informal settlement fires. The following two full-scale informal settlement dwelling burn experiments were conducted; (a) three ISDs clad with steel sheeting and (b) three ISDs clad with timber. The heat fluxes and temperatures of both experiments are shown and compared to understand the effect of cladding materials (i.e. timber cladding versus steel cladding, which are mostly used in informal settlements) on fire spread. Some general behavioral observations made during the full-scale experiments are given and discussed (i.e. how fire spreads, collapse mechanisms, etc.). Fire spread times are reported for both experiments, and range between 4 and 9 min (i.e. from the start of flashover in the first dwelling to the end of flashover in the last dwelling). These experiments are one of the bigger ISD experiments conducted to date and are the first experiments that measured heat fluxes for ISDs, which is crucial to understand fire spread. An important finding in this paper is that there is a critical separation distance of 3.8 m needed to prevent fire spread between dwellings.

The fire behaviour involving multiple fires in a mine drift with longitudinal ventilation was analysed. The conditions and fire phenomena occurring were described. The analysis was based upon experimental data from model-scale fire experiments. A fire involving several fuel items may lead to flames tilted horizontally and filling up the entire cross section, leading to earlier ignition, higher fire growth rates, higher fire spread rate and severe fire behaviour. Longer flame lengths will also result due to decreased air entrainment. A correlation for the continuous flame length was proposed. The results of the analysis will help identifying and preventing potentially dangerous fire situations with several large combustible items distributed along a mine drift. Keywords: Multiple fires, Mine drift, Fire spread, Flame length, Fire growth

Fire simulators allow predicting fire spread and behavior and some of which in real-time. Both strategies and tactics to suppress wildland fires depend on fire analysis which is generally based on fire simulations that need to be accurate for a proper decision making. However, limitations and assumptions of the fire models and uncertainties in input data may induce errors in the simulated fire growth and, therefore, fire simulations do not always match actual fire spread. In this paper, we show an innovative method implemented in Wildfire Analyst to adjust fire simulations in real-time. The method determines the adjustment factors needed for the optimal rate of spread by fuel model in order to minimize the arrival time error between the simulated fire and a set of control points where the arrival time of the observed (real) fire is known. Two case studies were used to present the method, showing robust results in reducing the error and fitting the simulated fire growth to the real fire spread, with practical real-time implications. The method presented may be solved in real-time and used with any empirical fire propagation.

Large wildfires can cover millions of hectares of forest every year worldwide, causing losses in ecosystems and assets. Fire simulation and modeling provides an analytical scheme to characterize and predict fire behavior and spread in several and complex environments. Spatial dynamics of large wildfires can be analyzed using satellite active fire data, a cost-effective way to acquire information systematically worldwide. The simulated growth of three large wildland fires from the USA, Chile and Spain with different fire spread pattern, duration and size has been compared to satellite active fire data. Additionally, a new approach to reinitialize fire simulations in near real-time and predict a more accurate fire spread is shown in this work. Discrepancies between the simulated fire growth and satellite active data were measured spatially and temporally in the three fires, increasing along the fire duration. The reinitialization approach meaningfully improved the accuracy of fire simulations in all case studies. Satellite active fire data showed a high potential to be used in real fire incidents, improving fire monitoring and simulation and, therefore, supporting the decision-making process of the fire analyst. The reinitialization approach could be applied by using the current satellite active fire data such as MODIS or VIIRS as well as Unmanned Aerial Vehicles or GPS locations from suppression resources.

The paper first reviews the mode of generation of fire whirls, their properties, and operational regimes, under well-controlled experimental conditions. The situation is different with wildfires. These are uncontrolled and less well understood. A modified analytical approach is described for these conditions. This is based on global energy levels, per unit ground area, for different fuels, and their associated rates of fire spread, under different conditions. These enable regimes of possible fire whirl generation in wildfires to be defined. The associated accuracy is not that of a laboratory flame, but it is probably practically sufficient. Only in two instances were atmospheric fires experimentally controlled. In the remainder, the rate of fire spread was a more meaningful parameter than a burning velocity, and the critical lateral velocity was seldom known accurately. Nevertheless, it was possible to relate it to the heat release rate, with both in dimensionless form.

Accurately predicting fire spread and behaviour on the fireline, in the field, is highly important in order to prevent the loss of human life, improve the success of initial attack and better understand the potential fire behaviour, minimizing many risks for firefighters. We present the Wildfire Analyst™ Pocket Edition application (WFA Pocket), a mobile tool aimed to be used by the fire fighter community. It shows punctual fire characteristics and estimated progression based on user introduced input data in an intuitive 3D map interface in real-time, allowing the user to interactively change parameters and analyze how the fire behaviour changes in relation to the inputs. The mathematical models implemented are all well-known by the scientific community and reported in this article. The application has integrated GIS capabilities, can work online and offline, and can retrieve fuel, weather and canopy data from online servers for the georeferenced ignition point. We describe the background and model foundation of WFA Pocket as well as its system design and main features. We also evaluate its robustness of results and present a case study to show the potential use of this tool in the field. Limitations and assumptions in the use of the application as well as potential improvements for the future are discussed.

Casualties and severe damages of environmental resources resulted from wildfires are to some extent caused by belated evacuating personnel and fighting fires. It is considered that if the timely detection of the high temperature signal can be achieved in the early stage of fire disaster, the duly rescue actions brought by the early fire alarming can extensively avoid casualty accidents and the detrimental fire spread. Therefore, in this work, we fabricate a cross-linked polycaprolactone (PCL) network, and based on its shape memory property and subsequent electroless deposition process, we prepare a smart conductor with ability of switching between non-conductive and conductive at low and high temperatures respectively. Outdoor experiments present that this electrically “OFF-to-ON” conductor can effectively respond to a fire and play a crucial role in early fire alarming under simulated fire scene. The finite element analysis simulation results further prove the advantages of this material over the traditional thermocouple in detecting temperature changes.

This article aims to provide a more practical forest fire spread model for predicting and managing forest fires in Heilongjiang Province, China. Heilongjiang is dominated by spatially heterogeneous combustible forests with undulating terrain and steep slopes. In this article, an artificial neural network framework is used to generate an accurate flame propagation map. Considering inherent fire propagation uncertainties, a fire propagation model containing multidimensional physical and environmental variables is established. Based on fire propagation predictions, the physical fire propagation method is also effectively understood. Additionally, the artificial neural network model can analyse spatial time series patterns and is not a traditional fire spread model. Moreover, this study established a forest fire spread prediction model combining Heilongjiang's cellular automata and Wang Zhengfei's model for comparison with the artificial neural network model. After repeated training and testing, the forest fire prediction results based on the artificial neural network, were found to have average accuracy, sensitivity, and F-measure values of 85.02%, 95.26%, and 89.85%, respectively. The proposed model is suitable for prediction of fire spread beyond large forest fires (more than 1 ha and less than 100 ha of affected forest). Therefore, the model facilitates a better understanding of fire cover propagation behaviours and quickly generates fire peak profiles. The proposed model can enable forest managers and firefighting agencies to plan better firefighting operations and improved firefighting strategy effectiveness.

In the past two decades, the interest in fire safety science of tunnels has significantly increased, mainly due to the rapidly increasing number of tunnels built and the catastrophic tunnel fire incidents occurred. This paper presents an overview of research on fire safety in underground road and railway tunnels from the perspectives of fire safety design. The main focuses are on design fires, structural protection, smoke control and use of water-based fire suppression systems. Besides, some key fire characteristics, including flame length, fire spread, heat flux and smoke stratification, are discussed.

City-scale models of urban fires were developed for countries where most construction is highly flammable, such as the US, China and Japan. Essential adjustments of existing models are required for modeling fire spread at the city scale in urban areas where construction is non-flammable and the space between buildings is filled by flammable vegetation, as in Mediterranean and Middle Eastern cities. We develop a spatially explicit city-scale model of urban fire spread for cities consisting of non-flammable buildings and apply it to different areas of the city of Haifa, Israel. We demonstrate that adequate modeling of fire spread inside non-flammable buildings demands accurate partition of the intra-building space into apartments and corridors. We present and evaluate the algorithm for establishing such partition based on standard GIS layer of the buildings footprints. Based on the model, we demonstrate that fire spread in cities consisting of non-flammable buildings is highly sensitive to the structure of urban vegetation within the immediate surroundings of each building and investigate the effects of vegetation management policies on fire spread mitigation. We discuss the use of the model for establishing the procedures of firefighters’ response during routine and multiple ignition scenarios.

We consider a wildfire spread model represented by the system (1) . We use results from the theory of Hamilton–Jacobi equations to prove that there exists a classical solution of (1) for any ( ϕ , t ) ∈ R × ( 0 , T ) and some T > 0 and satisfies particular initial conditions. We also use the method of characteristics to obtain the solution of (1) in a certain form.

The prediction of fire propagation across landscapes is necessary for safe and effective fire management. We analyzed the predictive accuracy of models currently used operationally in Australia for predicting fire spread rates in five different fuel types (grasslands, temperate and semi-arid shrublands, dry eucalypt and conifer forests) compared to their previous counterparts. We calculated error statistics and contrasted model predictions against observed spread rates of field observations of wildfires and prescribed fires. We then compared the changes in error metrics of older models to newer ones. Evaluation results show newer models to have improved prediction accuracy. Mean absolute errors were reduced by 56%, 68% and 70% in dry eucalypt forests, grasslands and crown fires in conifer forests, respectively. The most significant improvement was the reversion of under-prediction bias achieved with newer models. This study has highlighted the value of continuous improvement when it comes to developing operational wildland fire spread models.

In this paper, we report on our investigations into the behavior of successive fire spread between multiple houses in an urban area. More specifically, to acquire data necessary for the validation of our computational models, we conducted a fire spread experiment with nineteen 1/3-scale model houses aligned in a former quarry at Iwafune Mt. in Tochigi Prefecture, Japan. Most previous experiments used wood cribs or gas burners as fire sources to investigate the behavior of a fully-developed urban fire, but gave less attention to its formation due to successive occurrence of fire spread between houses. Successive fire spread between houses cannot be adequately simulated as discrete fuel elements in urban areas without replicating the exterior geometry, including openings allocated in each wall; however, this factor, which affects the intensity of heat transfer between houses, has not yet been considered in previous experiments except those that used disused houses. The experiment comprised two tests. In test 1, fire spread between model houses did not occur as was originally expected because of the short duration of the fully developed fire phase at the fire origin model house. The average mass loss rate in the fully developed fire phase was 1.33 kg/s with the maximum flame height of 7.8 m. In test 2, ceilings and roofs of model houses that were left unburnt in test 1 were reinforced so as to enhance their compartmentation, which in turn extends the duration of fire at each model house and the heating period of the adjacent model houses. As a result, fifteen out of eighteen model houses were burnt due to successive fire spread that lasted for about 50 min. The estimated maximum heat release rate of the group fire was about 100 MW with the maximum flame height of 11.0 m. The flame height after roof burn-through was modeled by introducing a conversion factor into one of the standard flame height model considering fresh air supply through openings due to the pressure difference between inside and outside of a model house. Although the quantitative agreement was not satisfactory, the overall change in flame height over time was adequately captured with the present model.

Fire spread between informal settlement dwellings (ISD) is a primary concern for large scale informal settlements conflagrations. Globally, approximately one billion people live in informal settlements and are exposed to these fires. This paper presents a fire spread experiment between two dwellings, built with ISO 9705 dimension as an approximation of an ISD and separated by 1 m. The fire development and fire spread mechanisms within and between the ISDs were investigated and benchmarked against an independent single dwelling experiment with identical boundary conditions. Parameters, such as mass loss rate of fuel, total heat release rate, gas temperatures, wall and roof temperatures, and gas velocity at the openings were measured, as well as external incident heat fluxes. A comparison between the single and double dwelling experimental results are made. It was established that the existence of the adjacent dwelling, which changes the dynamics of initial burning stage of the wood cribs in dwelling, delayed the flashover of the burning dwelling by more than 150 s (Dwelling 1). The fire spread from dwelling to dwelling that is perpendicular to the plane of the openings is hypothetically concerned with wall collapse or large flame ejections from the burning cardboard linings, rather than the radiation from the heated metal wall, with recorded fluxes of 35, 20, and 5 kW/m2, respectively. Due to the very thin-walls with high conductivity and natural leakage in ISDs, current theories for temperatures, heat release rates, flame shapes, and flashover conditions, based on thermally thick-walled dwellings, do not replicate the data well. A new fire spread model between dwellings, based on accumulated energy, is proposed in this work and conservatively under-predicts the time to ignition by 9 % for this experiment.

Balconies and horizontal projections on building facades can affect the hazard of external fire plumes. The impingement of a fire plume beneath a horizontal projection results in the radial extension of flame, which may increase the likelihood of lateral fire spread along the facade. Continuous balconies in multi-unit residential buildings (MURBs) often lack fire separation between units. Without a fire separation, an external fire plume can produce an intense heat flux on the facade. Unprotected openings in the facade can often be found in close proximity, which presents a path for exterior fire spread to adjacent compartments. Fire Dynamics Simulator (FDS) was used to predict the heat flux imposed on facades, with and without horizontal projections. Predictions achieved close agreement to experiments and empirically derived equations. Results show the presence of horizontal projections can significantly increase heat flux at greater distances along the facade. The hazard of lateral fire spread to adjacent compartments can be reduced by defining a safe separation distance between openings or the use of fire separation on balconies between compartments.

The fuel packing ratio ( β ) significantly influences the fire spread in discrete fuels; however, the underlying mechanism remains unclear. This study performed experiments using laser-cut cardboards with different packing ratios to explore the heat transfer in fire spread. We identify two distinct spread behaviors under varying packing ratios. Heat flux data indicate that radiation controls the surface heat transfer (denoting the heat transfer received by the fuel bed surface) far from the flame, while convective heating plays a considerable part surrounding the flame. The surface heat transfer is enhanced under lower packing ratios (Stage 1) and is responsible for the increase of the rate of spread (ROS) in this stage. Under higher packing ratios (Stage 2), the surface heat transfer does not vary significantly, and the surface radiation transfers more energy to fuels than surface convection. ROS reduction in Stage 2 is attributed mainly to the internal heat transfer (denoting the heat transfer received by the sides of the fuel particles) dominated by radiation. The dense fuel bed impedes the response of in-bed fuel to internal heat transfer, which, however, does not significantly influence the time integral of the internal total and radiant heat fluxes. Besides, the flame residence time almost linearly increases with the packing ratio when the flame can spread.

A self-developed laboratory-sized spilling trench is used to study the characteristics of continuously spilling fire spread over n-butanol fuel under different slope angles (0°, 1°, 2°, 3°, 4°) and discharge rates (0–500 mL/min). The hydrodynamic analysis is conducted to account for the variation of flow parameters of unburned liquid based on the theory of open-channel gradual flow. The spill flow velocity increases whereas the thickness of fuel layer decreases along the inclined spilling trench. The flame height versus discharge rate is divided into three regimes, namely the increasing regime at Q

This paper presents results from a computational and laboratory investigation of wind flow and fire spread over an isolated sloped-ridgeline laboratory-scale hill under various slopes with the wind blowing perpendicularly to the ridgeline. The results show two situations of unexpected or unusual fire behaviour; one is a lateral spread of the fire front over the windward face into a down-ridge direction resulting from a strong near-surface flow component parallel to the ridgeline. The other behaviour is a lateral enlargement of the fire front near the ridgeline over the leeward face in an up-ridge direction resulting from a flow parallel to the ridgeline. Comparison with reference fire spread rates and wind flow observations highlight the importance of the interaction between terrain-modified flow mechanisms and the fire in which they result in accelerated flows that drive the indicated unexpected behaviour. © 2021 The Author(s)

Live foliage for some tree and shrub species can support flaming fire spread at much higher moisture content than dead fuel materials. However, the role of live fuels in forest fires has been controversial in the past decades. Although ignition and spread statistical data for live and dead fuels exist in the literature, a clear understanding of the fundamental difference in the burning behavior is missing. To illuminate the role of live fuel on forest fire spreading, a laboratory ignition experiment was designed to examine the burning behavior of live Norway spruce needles. A Schlieren-Infrared combined measurement apparatus was developed with a spatial resolution of 0.75 mm and a time resolution of 0.0025 s, to visualize/measure the ignition behavior of live fuels. Schlieren and IR images revealed that the ejection of live fuel volatiles can alter the flame direction and induce previously unaccounted heating of the nearby fuel. Depending on the conditions, these interferences could heat and modify the heat flux received by the adjacent fuels. To analyze each of these outcomes, a scaling analysis using the law approach was performed. First, theoretical equations were developed and validated against a set of previously published experimental data. After the characteristic equations were verified, we used them to assess the volatile ejection phenomenon. We found that adjacent fuels were preheated by hot volatiles ejected from the heated live needle, and direct flame contact ignited the adjacent fuels. Our IR experiments confirmed the outcomes of the scaling analysis. The rapid ejection of volatiles was also found to propel burning needles far from the burning branch, resulting in micro-spotting.

Author(s): Qian, W; Ai, Y; Yu, JY; Du, J | Abstract: The consecutive occurrence of three large wildfires in 1 year is rarely seen in northern California including the deadliest case during 8–25 November 2018 in Butte County. They happened under favorable fuel and meteorological conditions including long-term warming trends, normal summer-autumn warm-dry climate, and extreme heated air masses with strong offshore wind. The former two meteorological conditions contribute a background for large wildfires but extreme heated air masses and strong offshore winds are critical potentials for a fire spread. The relationship between extreme heated/cooled air masses and the three large wildfires was carefully examined from their starts to extinguishing. An anomaly-based synoptic analysis method is used by separating atmospheric variables into climatology and anomalies. A 3-dimensional anomalous synoptic pattern of atmospheric variables is established for the three wildfire cases in 2018. The analysis showed that one anomalous warm-air mass in the mid-to-low troposphere dynamically associated with a positive center of geopotential height (GPH) anomalies at the upper troposphere (150–300 hPa) is an anomalous synoptic pattern indicating a potential large wildfire spread, and conversely by negative anomalies when the fires were extinguished. The ECMWF model seems to be capable of predicting such anomalous temperature-pressure patterns to indicate possible fire spread and extinguishing.

Wildfires are a common phenomenon on most continents. They have occurred for an estimated 60 million years and are part of a regular climatic cycle. Nevertheless, wildfires represent a real and continuing problem that can have a major impact on people, wildlife and the environment. The intensity and severity of wildfires can be reduced through fuel management activities. The most common and effective fuel management activity is prescribed burning. We propose a multi-period optimization framework based on mixed integer programming (MIP) techniques to determine the optimal spatial allocation of prescribed burning activities over a finite planning horizon. In contrast to the existing fuel management optimization literature, we model fuel accumulation with Olson’s equation. To capture potential fire spread along with irregular landscape connectivity considerations, we use a graph-theoretical approach that allows us to exploit graph connectivity measures (e.g., the number of connected components) as optimization objectives. The resulting mathematical programs can be tackled by general purpose MIP solvers, while for handling larger instances we propose a simple heuristic. Our computational experiments with test instances constructed based on real-life data reveal interesting insights and demonstrate the advantages and limitations of the proposed approaches.

This paper focuses its attention on the combustion characteristics and fire risk evaluation on the downward flame spread of polypropylene (PP) and polymethyl methacrylate (PMMA). Many characteristic parameters have been measured under different widths of samples, including flame spread rate, flame height etc. It is shown that the flame spread of PP and PMMA are diversed for different pyrolysis mechanism. The width of test sample has different impact on the fire spread rate, flame height and CO emissions during the burning period. As the width increases, the fire spread rate and flame height of PP decreases first, and then increases, while that of PPMA increases monotonically. The volume fraction of CO of PP and PPMA increases, but the effect of the width on sample PP can be neglected. Based on the Analytic Hierarchy Process (AHP), the evaluation of fire risk has been conducted. The flame height, flame spread rate and toxic gas generation rate are selected as the basic evaluation index parameters to establish a comprehensive evaluation model of fire risk. The evaluation results indicates that the fire risk of PP is greater than PMMA.

In order to study the effect of plywood’s thickness on vertical fire spread, small-sized experiment is conducted to study flame front position, pyrolysis front position and burnout front position at the thickness of 2,3,6 mm respectively. Through the effect of sample thickness on flame spread rate, flame height and pyrolysis height are analyzed, the experimental results show that the thickness has obvious influences on the process of the plywood vertical fire spread. Flame front position, pyrolysis front position and burnout front position, those three increases with the decrease on the sample thickness, which is consistent with the trend of flame spread rate with thickness. In the process of vertical combustion, flame height and pyrolysis height aren’t stable figures, but the change with time shows that the figures increase firstly and then stabilize. Flame height and pyrolysis height increase with the decrease of specimen’s thickness.

The average fire gas temperature of multiple fires in a mine drift with longitudinal ventilation is investigated. The output of a quasi-steady model is investigated and compared with experimental results from model scale fire experiments. During the analysis it was found that the calculated average fire gas temperature of the model correlates quite well with the measured temperature, except for the period when the fire closest to the measuring point reached a peak of heat release rate. This poor correlation is likely due to flame impingement as the distance to the nearest fire decreases. Uncertainty of the calculations is caused by the fire gas temperature at the site of each individual fire and further studies into the fire growth rate and maximum heat release rates of multiple fires are recommended in order to remedy this uncertainty. When calculating the average fire gas temperature, a key parameter is determined with respect to the smoke spread in a mine drift as well as the risk of fire spread. Keywords: Multiple fires, Mine drift, Average fire gas temperature

In order to study the vertical countercurrent fire spread of XPS with different widths in the space and wall adhesion conditions, the XPS vertical countercurrent fire spread experiment with different widths was carried out by self-made vertical countercurrent fire test platform. It is found that the spread rate and the average flame height of the XPS decrease first and then increase with the increasing of the width under the two working conditions. After the critical point, the countercurrent spread rate without constraint tends to be stable while the countercurrent spread with one side constraint is greatly accelerated. According to the change of the heat flux on the preheating zone, it is inferred that there are two different heat transfer modes in the two kinds of working conditions. The spread rate of XPS without constraint is mainly affected by gas-phase heat transfer. On the Contrary, The spread rate of XPS with one side constraint is affected by gas-phase heat transfer and solid-phase heat transfer. And with the increase of the width, the solid-phase heat transfer gradually replaced the gas-phase heat transfer to influence the heat-receiving area of the preheating area.

In recent years, there has been a growing number of projects on informal settlement (IS) fire research, which has been primarily focused on understanding the fire dynamics in IS through full-scale experiments. However, much less is known about real IS fire incidents. Recently, a Framework for Fire Investigations in Informal Settlements (FFIIS) was developed. However, the FFIIS has not been applied to real IS fire incidents yet. This paper seeks to conduct fire investigations by applying the FFIIS to three real fire events. One of them was recorded by a CCTV camera and was analysed in depth in previous work. The video footage was used to benchmark the findings obtain using the FFIIS. The application of the FFIIS allows one to develop hypotheses that more accurately define the area of fire origin and pattern formation sequence. This implies that the fire pattern for large post-flashover fires in ISs can be treated as wildland fires pattern, as proposed by the FFIIS. Additionally, spread rates and the impact of dwellings’ separation distances, in these incidents, are studied. Understanding the limitations and the quality of the information that can be obtained when applying the FFIIS is fundamental to improve the guidelines proposed.

This manuscript presents tools and data that serve to enable an evaluation of the risk associated with vertical fire spread on buildings. A highly detailed context to cladding fires is described to unveil the complexity and magnitude of the problem and to identify gaps of information. An engineering framework is then developed which delivers required information that fills some of those gaps and that needs to be used towards achieving quantified fire performance. The data itself has been published as a publicly available database, entitled the Cladding Materials Library (www.claddingmaterialslibrary.com.au). This data can be used to support building fire risk assessments or as the basis for more in-depth research into facade fires. This paper presents the context of the data together with the competency framework necessary for upskilling building professionals to have the capacity to implement the engineering framework.

Environmental models involve inherent uncertainties, the understanding of which is required for use by practitioners. One method of uncertainty quantification is global sensitivity analysis (GSA), which has been extensively used in environmental modeling. The suitability of GSA methods depends on the model, implementation, and computational complexity. Thus, we present a comparative analysis of different GSA methods (Morris, Sobol, FAST, and PAWN) applied to empirical fire spread models (Dry Eucalypt and Rothermel) and explain their implications. GSA methods such as PAWN, may not be able to explain all the interactions whereas methods such as Sobol can result in high computational costs for models with several parameters. We found that the Morris or the PAWN method should be prioritized over the Sobol and the FAST methods for a balanced trade-off between convergence and robustness under computational constraints. Additionally, the Sobol method should be chosen for more detailed sensitivity information.

This paper improves the existing frameworks on simulating fire following earthquake (FFE) by explicitly modeling the suppression process and the fire department response. The paper focuses on the impacts of FFE on urban areas and quantifies induced economic losses based on resources and efficiency of the fire department during post-earthquake fires. Layers of infrastructure systems, including transportation, water, and electric networks, and the building inventory are modeled and the earthquake damage to the community is characterized. The behavior of fire spread inside and between buildings is simulated based on major fire spread mechanisms. In parallel, the suppression activities are explicitly modeled and a decision-making algorithm for fire engine assignments to locations of ignition is implemented. The proposed methodology is applied to a case study. The performance of fire department response is characterized using the probability of exceedance of unsuccessful suppression scenarios, presented in the form of fragility functions. The expected direct economic losses are also presented as a function of earthquake intensity. The proposed framework can be used for planning and response applications, and to identify the tipping point of a community, above which the rate of fire spread exceeds that of suppression and the fires burn out of control.

This paper focused on analyzing the Hsuehshan Tunnel Fire in Taiwan, which occurred from a bus fire in the afternoon of May 7, 2012 and caused two death and 34 injuries. Major object damages were reviewed and CCTV records were investigated toward understanding the fire temperature, smoke layers and situations of people in the tunnel refuge area ( Fire Scenarios Analysis & Egress/Rescue Strategies of the 2012 Hsuehshan Tunnel Fire in Taiwan, MOTC, Taiwan, Jan., 2016. ). Data collected from the fire scene were fed into fire scene reconstruction using CFD method (i.e., Fire Dynamics Simulators - FDS). It reveals that the fire temperature reached 800–900 °C and HRR was around 25–30 MW, which are consistent with the reviews of the incident and experiment data. Moreover, the fire temperature obtained from the CFD method when compared with experiment data is more reasonable. It is considered lift-threatening in terms of visibility, temperature and radiant heat flux for both road users and self-defense fire/rescue team when the fire heat reaches 10 MW. It was also reasoned that the fire spread through exit holes on the bus roof and heat was carried by the ventilation flow, leading to serious damage of lighting objects and cable traps above the bus. This study also suggests that the best option for people encounter tunnel fire is to leave their vehicles immediately and evacuate toward upstream direction of the fire. For those who are in the downstream of the fire, they should use the exit doors on the connection tunnel to escape the incident.

Full-scale experiments using two 4-door sedan passenger cars, placed side by side in the reverse direction, were carried out to establish the burning behavior and describe the spread of fire to adjacent car. The temperature was measured by thermocouples. Radiant heat flux was measured with heat flux gauge placed at a distance of 5 m, at the right side of the car. Four cameras were placed inside the car and in the fire test room recording burning behavior during the test. Engine compartment was ignited by a sponge dipped with little gasoline. During the experiment, the ignition was initiated in the engine compartment of car I and approximately 20 min were enough time for fire to spread into the second car. Fully-developed burning of two cars occurred at 29 min. It was observed that the flame spread through car roof faster than through the bottom of car compartment. The fire followed a slow rate spread from engine compartment to car cab. The temperature inside the car peaked at the point of 900 °C. The peak smoke temperatures at every location were measured at the range of 89–285 °C. The smoke production at the time of 11 min to 15 min 50 s of fire was 1.76 m 3 /s, which was obtained through indirect calculation method.

Flame spread is an important parameter used in the evaluation of hazards for fire safety applications. The problem of understanding and modeling flame spread has been approached before, however new developments continue to challenge our current view of the subject, necessitating future research efforts in the field. In this review, the problem of flame spread will be revisited, with a particular emphasis on the effect of flow and geometry on concurrent flame spread over solid fuels. The majority of this research is based on that of the senior author, who has worked on wind-driven flame spread, inclined fire spread, flame spread through discrete fuels and the particular problem of wildland fires, where all of the above scenarios play an important role. Recent developments in these areas have improved our understanding of flame-spread processes and will be reviewed, and areas for future research will be highlighted.

Electrically controlled dynamic sprinkler activation is the novel technology of managing large automatic fire suppression systems that offers considerable potential advantages over conventional (thermal) sprinkler activation. It is designed to reduce the sprinkler response time, to ensure sprinkler activation in case of high ceiling clearance, and it can also be used for dynamic group activation enabling flexible response to the actual fire pattern and preventing the fire spread beyond the area protected by the group. Since the practical experience of using the new sprinkler activation algorithms is yet to be elaborated, this work attempts computational evaluation of the group enforced activation efficiency. Fire suppression dynamics is compared for a growing fire source impacted by the automatic sprinkler systems of two types: with conventional (thermal) and new (group enforced) activation algorithms. The effects of ceiling clearance, water flow rates, spray refinement, and of the horizontal airflow are examined.

Insulation panels made of organic, combustible materials are frequently used in the exterior thermal insulation systems (ETIS) for buildings. Such combustible insulation panels have been involved in several catastrophic building fires in recent years in China. One potential strategy to mitigate this fire hazard is to limit fire spread over the ETIS. The present work evaluates the effectiveness of vertical fire barriers in inhibiting fire spread over exposed insulation walls made of expanded polystyrene (EPS) panels. Reduced-scale experiments were carried out indoors using EPS panels with or without two vertical barriers made of non-combustible mineral wool, the fire started at the bottom center of the middle panel. The interval and width of the barriers were varied systematically, while the temperature distribution on the wall, the radiation heat flux from the fire, and the infra-red (IR) images were recorded. To demonstrate the validity of the concept, an outdoor, full-scale experiment was carried out using a 7-floor building. Our reduced-scale experiments showed that the installation of two vertical fire barriers successfully stopped the lateral flame spread, decreasing the peak temperatures of the two side panels by about 300 °C for all barrier configurations tested. When barrier width was fixed at 5 cm, an increase of the barrier interval from 30 to 90 cm led to increases in the peak temperatures, radiation heat flux, and the maximum rate of upward flame spread. By contrast, when barrier interval was fixed at 90 cm, an increase of the barrier width from 2 to 5 cm had little influence on the combustion dynamics of the middle panel but the peak temperature on the side panels dropped, consistent with the smaller heat transferred with wider fire barriers. In the regions of the side panels next to the barriers, pyrolysis and deformation could be observed with barrier widths of 2 and 3 cm, but not 5 cm. Finally, our outdoor, full-scale experiment demonstrated that a 30 cm wide vertical barrier made of air-filled cement successfully stopped the lateral flame spread over exposed EPS wall. The study highlights the effectiveness of vertical fire barriers in preventing the lateral flame spread over the exposed EPS insulation wall and provides another option for enhancing the fire safety of the combustible insulation systems.

This paper discusses fires in informal settlements (otherwise known as slums, ghettos, shantytowns, etc.), which are regularly ravaged by fire in South Africa. Initially an overview of the problem is presented, highlighting the factors that contribute to the frequent, large conflagrations that occur. Details have been based on research conducted in Cape Town, South Africa, although the research is applicable to settlements worldwide. Data from recent fires where up to 4500 people were left homeless is included, highlighting aspects regarding fire spread and fire dynamics. Thereafter, preliminary results from a pilot study are presented where full-scale burn tests have been carried out on informal settlement dwellings, or “shacks”. Results from (a) a smoldering fire test, (b) 25 kg/m2 wood fire load test and (c) a ‘representative’ shack fire test are presented. For flaming fires it is shown that flashover in these small dwellings can occur in as little as one minute (depending on the fuel source), which is consistent with observations from professional firefighters in the field. Photoelectric smoke detectors, ionization, and rate-of-rise heat detectors were included during fire tests, to evaluate their performance in such confined spaces, as these are currently being either used or being considered for use in settlements. Activation times are reported for the different tests conducted.

The paper proposes a probability-based Monte Carlo life-risk analysis model for fire emergencies. Based on the hazardous conditions in each compartment of a building and the evacuation path of each occupant, the model calculates the probabilities of injury and death determined by fractional effective doses due to heat and toxic gases, considers the probability of death due to fire spread, and produces the probabilities of injury and death for each occupant. Then these probabilities for all occupants are summed to give the total probabilities of injury and death in a Monte Carlo run, and statistics about the total probabilities of all Monte Carlo runs are produced for each fire scenario. According to the statistics and scenario composition, the expected risks of injury and death in the building are calculated. The model is applied to a life risk analysis of 6- and 12-storey apartment buildings. The results show that for these buildings, injuries and deaths are mainly limited to the rooms of fire origin and the effects of building area and the number of storeys on life risk are slight. The predictions for different layouts are in good agreement with the numbers of injuries and deaths given by Canadian and US statistics.

The quantitative simulation of forest fire spreading plays an essential role in designing quick risk management and implementing effective suppression policies. As a preferable modelling approach, the cellular automaton (CA) has been used to simulate the complex mechanisms of fire spreading. However, in traditional CA models, comprehensive studies on the physical principles of forest fires are needed to define the local transition rules. Instead of defining transition rules, the Extreme Learning Machine (ELM) was applied in this study. By integrating the ELM with the traditional forest fire CA framework, a new cellular automaton modelling approach was proposed. After that, its performance was validated using data collected from five fires in the west of United States. Results show that the ELM performed well in predicting each cell’s igniting probability. The impact of wind velocity on fire spreading pattern can be effectively described by the proposed modelling approach. Furthermore, the validation against actual fire behavior observations shows that its simulation performance is acceptable and in most cases is better than that of the previously reported studies.

This paper adopts a series of 1:20 scale tunnel experiments based on a series of large-scale tunnel experiments to study the influence of forced ventilation on fires. The small-scale tunnel has dimensions of 0.365 m (W)×0.26 m (H)×11.9 m (L). Cribs using a wood-based material provide the fuel source and forced ventilation velocities from 0.23 to 1.90 m/s are used. From the study of the measured heat release rate (HRR) and mass loss rate data it is found that the forced air velocity affects the fire spread rate and burning efficiency and further affects peak HRR values at different air velocities. A simple model to describe these influences is proposed. This model is used to reproduce the enhancement of peak HRR for cribs with different porosity factors noted by Ingason [1] and to assess the effects of using different length of cribs on peak HRR. The results from these analyses suggest that different porosity fuels result different involvement of burning surface area and result different changes in peak HRR. However, no significant difference to the enhancement on fire size is found when the burning surface area is similar. It is also found that the trend in the enhancement on fire size by using sufficiently long crib and available ventilation conditions matches the predictions of Carvel and Beard [2] for two-lane tunnel heavy goods vehicle fires.

Wildfire behavior predictions typically suffer from significant uncertainty. However, wildfire modeling uncertainties remain largely unquantified in the literature, mainly due to computing constraints. New multifidelity techniques provide a promising opportunity to overcome these limitations. Therefore, this paper explores the applicability of multifidelity approaches to wildland fire spread prediction problems. Using a canonical simulation scenario, we assessed the performance of control variates Monte-Carlo (MC) and multilevel MC strategies, achieving speedups of up to 100x in comparison to a standard MC method. This improvement was leveraged to quantify aleatoric uncertainties and analyze the sensitivity of the fire rate of spread (RoS) to weather and fuel parameters using a full-physics fire model, namely the Wildland-Urban Interface Fire Dynamics Simulator (WFDS), at an affordable computation cost. The proposed methodology may also be used to analyze uncertainty in other relevant fire behavior metrics such as heat transfer, fuel consumption and smoke production indicators.