Fire Propagation Research Articles

An artificial intelligence framework for predicting fire spread sustainability in semiarid shrublands

Background Fire behaviour simulation and prediction play a key role in supporting wildfire management and suppression activities. Aims Using machine-learning methods, the aim of this study was to predict the onset of fire propagation (go vs no-go) and type of fire behaviour (surface vs crown fire) in southern Australian semiarid shrublands. Methods Several machine-learning (ML) approaches were tested, including Support Vector Machine, Multinomial Naive Bayes and Multilayered Neural Networks, as was the use of augmented datasets developed with Generative Adversarial Networks (GAN) in classification of fire type. Key results Support Vector Machine was determined as the optimum machine learning classifier based on model overall accuracy against an independent evaluation dataset. This classifier correctly predicted fire spread sustainability and active crown fire propagation in 70 and 79% of the cases, respectively. The application of synthetically generated datasets in the Support Vector Machine model fitting process resulted in an improvement of model accuracy by 20% for the fire sustainability classification and 4% for the crown fire occurrence. Conclusions The selected ML modelling approach was shown to produce better results than logistic regression models when tested on independent datasets. Implications Artificial intelligence frameworks have a role in the development of predictive models of fire behaviour.

Physics-based simulations of grassfire propagation on sloped terrain at field scale: flame dynamics, mode of fire propagation and heat fluxes†

The interaction of wind and fire on a sloped terrain is always complex owing to the mechanisms of heat transfer and flame dynamics. Heating of unburned vegetation by attached flames may increase the rate of spread. The relative intensities of convective and radiative heat fluxes may change fire behaviour significantly. This paper presents a detailed analysis of flame dynamics, mode of fire propagation and surface radiative and convective heat fluxes on sloped terrain at various wind speeds using physics-based simulations. It was found that with increasing slope angles and wind velocity, the plume inclines more towards the ground and becomes elongated in upslope cases, whereas in downslope cases, the plume rises from the ground earlier. For higher wind velocities, the flame and near-surface flame dynamics appear to show rising, even though the plume is attached. The flame contour results indicate that the near-surface flame dynamics are difficult to characterise using Byram’s number. A power-law correlation was observed between the simulated flame lengths and fireline intensities. The convective heat fluxes are more relevant for wind-driven fire propagation and greater upslopes, whereas both fluxes are equally significant for lower driving wind velocities compared with higher wind velocities.

Experimental study on the flame merging and ceiling impingement behavior of transversely located double fire sources in an urban utility tunnel

The investigation of the fire characteristics and propagation behaviour in the urban utility tunnel is of great practical importance, especially for the conditions with double fire sources. In this work, a 1/8th scaled urban utility tunnel model was built to conduct the experiments to characterize the flame merging and ceiling impingement behaviour of transversely located double fire sources. Two rectangular fire sources with the same dimension were used, and their heat release rate (HRR) and fire source spacings were varied to consider the typical scenarios. Results show that for the smaller HRR, the tunnel ceiling and sidewalls have little influence on the flame merging of double fire sources. With the increase of HRR, the flame gradually impinges on the tunnel ceiling and forms a stable ceiling jet flame extension, and the ceiling and sidewalls of the tunnel can promote the merging of the flames of the double fire sources. Besides, with the increase of the fire source spacings, the flame merging probability P m can be divided into three stages, that is, (i) complete merging stage, (ii) intermittent merging stage and (iii) complete separation stage. On this basis, the predicting relation of P m was obtained by using the piecewise function.

A Neural Emulator for Uncertainty Estimation of Fire Propagation

Wildfire propagation is a highly stochastic process where small changes in environmental conditions (such as wind speed and direction) can lead to large changes in observed behaviour. A traditional approach to quantify uncertainty in fire-front progression is to generate probability maps via ensembles of simulations. However, use of ensembles is typically computationally expensive, which can limit the scope of uncertainty analysis. To address this, we explore the use of a spatio-temporal neural-based modelling approach to directly estimate the likelihood of fire propagation given uncertainty in input parameters. The uncertainty is represented by deliberately perturbing the input weather forecast during model training. The computational load is concentrated in the model training process, which allows larger probability spaces to be explored during deployment. Empirical evaluations indicate that the proposed model achieves comparable fire boundaries to those produced by the traditional SPARK simulation platform, with an overall Jaccard index (similarity score) of 67.4% on a set of 35 simulated fires. When compared to a related neural model (emulator) which was employed to generate probability maps via ensembles of emulated fires, the proposed approach produces competitive Jaccard similarity scores while being approximately an order of magnitude faster.

Coupled fire-atmosphere simulation of the 2018 Camp Fire using WRF-Fire

Background Accurate simulation of wildfires can benefit pre-ignition mitigation and preparedness, and post-ignition emergency response management. Aims We evaluated the performance of Weather Research and Forecast-Fire (WRF-Fire), a coupled fire-atmosphere wildland fire simulation platform, in simulating a large historic fire (2018 Camp Fire). Methods A baseline model based on a setup typically used for WRF-Fire operational applications is utilised to simulate Camp Fire. Simulation results are compared to high-temporal-resolution fire perimeters derived from NEXRAD observations. The sensitivity of the model to a series of modelling parameters and assumptions governing the simulated wind field are then investigated. Results of WRF-Fire for Camp Fire are compared to FARSITE. Key results Baseline case shows non-negligible discrepancies between the simulated fire and the observations on rate of spread (ROS) and spread direction. Sensitivity analysis results show that refining the atmospheric grid of Camp Fire’s complex terrain improves fire prediction capabilities. Conclusions Sensitivity studies show the importance of refined atmosphere modelling for wildland fire simulation using WRF-Fire in complex terrains. Compared to FARSITE, WRF-Fire agrees better with the observations in terms of fire propagation rate and direction. Implications The findings suggest the need for further investigation of other possible sources of wildfire modelling uncertainties and errors.

Study of the speed of fire propagation forest ground cover

Study of the speed of fire propagation forest ground cover

Zn[B3O4(OH)3] composites fabrication based on PVC pipes scrap via comparing melt mixing and casting procedures under the effect of electron beam irradiation

In several works, scientific researchers targeted the development of polymeric materials with good mechanical and thermal properties and resist heat and fire propagation. In a new approach, this article goals to the usage of waste polyvinyl chloride (WPVC) based polymer composites derived from PVC pipes scrap filled with fixed percent of zinc borate particles (ZnB), which were prepared via two different techniques named melt mixing WPVC/ZnB (M) and casting WPVC/ZnB (C). The fabricated composites by the two methods were irradiated in an electron beam accelerator (EB) at 30 kGy. A comparative study of the thermal and mechanical properties based on stress-strain curves, tensile strength (TS), elongation at break (E %), and tear strength were evaluated. Furthermore, the rate of heat burning (%) for the two methods has been performed. Moreover, differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Infrared spectroscopy analysis (FTIR), X-ray diffraction (XRD), and the activation energy (Ea) calculation of the prepared samples have been considered. The observed improvements in the mechanical, thermal, and flammability behavior of WPVC were succeeded by incorporating ZnB particles. The irradiated WPVC loaded with zinc borate presented a superior flame propagation fraction when matched with their corresponding unirradiated composites. Also, WPVC composite films prepared via the melt mixing method reveal more excellent properties than those equipped by the casting process for the most investigated factors.

Simulation of variations in the speed of fire propagation, during a prescribed burn

Fire behavior simulations are generally based on standardized models of forest fuels, which can hardly represent allpossible variations in forest ecosystems, which can result in biased estimates of fire behavior. Due to this, in the presentwork a comparative analysis of simulations of fire behavior (propagation rate [m/min]) is made, during the course of aprescribed burning in favor of the slope, in a pine-oak forest stand from the state of Chihuahua. These simulations varied inrelation to: a) fuel models; b) fuel loads; and c) wind speed. The models tested were: 1) the one that resulted from amultiple regression (considering temperature, relative humidity and slope); 2) the fuel model M-8 and its variant M-8R(includes the values of fuel charges obtained in the field); and 3) the fuel model M-9 and its variant M-9R (includes thevalues of fuel charges obtained in the field). The equations of the trends defined by the correlation between the relativehumidity (%) and the speed of fire propagation (m/min) were generated. Although neither model was found to bestatistically significant, the best fit was defined with the regression equation:, which can be used in apractical way for a rough estimation of the rate of fire spread (RP). It is concluded that, in general, the selected modelswere not appropriate for simulating fire behavior during prescribed burning. This highlights the need to generate specificfuel models for the analyzed vegetation and its variations in density, structure and composition

A Systematic Review and Bibliometric Analysis of Wildland Fire Behavior Modeling

Wildland fires have become a major research subject among the national and international research community. Different simulation models have been developed to prevent this phenomenon. Nevertheless, fire propagation models are, until now, challenging due to the complexity of physics and chemistry, high computational requirements to solve physical models, and the difficulty defining the input parameters. Nevertheless, researchers have made immense progress in understanding wildland fire spread. This work reviews the state-of-the-art and lessons learned from the relevant literature to drive further advancement and provide the scientific community with a comprehensive summary of the main developments. The major findings or general research-based trends were related to the advancement of technology and computational resources, as well as advances in the physical interpretation of the acceleration of wildfires. Although wildfires result from the interaction between fundamental processes that govern the combustion at the solid- and gas-phase, the subsequent heat transfer and ignition of adjacent fuels are still not fully resolved at a large scale. However, there are some research gaps and emerging trends within this issue that should be given more attention in future investigations. Hence, in view of further improvements in wildfire modeling, increases in computational resources will allow upscaling of physical models, and technological advancements are being developed to provide near real-time predictive fire behavior modeling. Thus, the development of two-way coupled models with weather prediction and fire propagation models is the main direction of future work.

Spark transfer in forest fires and their localization using aviation

The results of modelling of spark transfer as one of the most powerful factors influencing forest fire propagation are discussed in the paper. It is shown that this process depends on many factors such as the type and intensity of the fire, characteristics of forest vegetation, wind speed, size, mass and shape of burning particles, duration of their burning and terrain. The accuracy of the description of this process by mathematical methods depends on the degree of consideration of various factors affecting the transfer of burning particles. The developed mathematical models and the techniques created on their basis make it possible to assess the range of transport of burning particles and predict the risks of the occurrence and spread of fire including affecting settlements and objects. In particular, the obtained numerical values of the casting range of burning elements in forest fires allow correct determination of the size of the barrier strips near settlements and objects located in forests.

FDS Results for Selecting the Right Scenario in the Case of a Building Fire: A Case Study

On the evening of 5 April 2014, at a building located on 122 Tomis Boulevard, Constanta Municipality, Constanta County, Romania, a restaurant with its kitchen on the ground floor and a lounge bar located on the first floor experienced a fire, one that resulted in four victims and total building destruction. An important step in the technical-scientific expertise was the investigation of the incident based on the elaboration of two fire scenarios using the Fire Dynamic Simulator (FDS) model, which observed the fire propagation, the generation of toxic gases (carbon monoxide that disoriented and intoxicated the victims, three of whom could not save themselves) depending on the location of the plausible ignition sources, and explained the destructive effects. This paper focuses on the steps required to identify the critical conditions that led to the occurrence of the unwanted event. Based on the calculations, hypothesis, and FDS simulations, the mechanism of the event occurrence was considered to be strongly related to the onsite observations and criminal file issued by the state authorities.

High-resolution investigation of a conflagration event in the North-East Temple at Lachish via integration of forensic, stratigraphic and geoarchaeological evidence: A model for studying architectural destruction by fire

Burnt structures are well known archaeologically throughout the Near East. This study proposes an integrated interpretational framework for reconstructing fires in mud-brick structures using macro- and micro-archaeological types of evidence employing well-established tools. While previous research often utilized either macroscopic field evidence or micro-geoarchaeological data, here we present the integration of stratigraphy, architecture and location of artefacts in the framework of archaeology of crisis, spatial reconstruction of fire temperatures using micro-geoarchaeology, insights from experimental archaeology, and concepts from fire investigation. We demonstrate the utility of this integrative framework in a high-resolution reconstruction of a destructive fire event that occurred in the Late Bronze Age North-East Temple at Tel Lachish, ca. 1210–1126 BCE. We identify the area of ignition and the fire propagation path, and propose the cause of the fire in relation to the archaeology and history of the site in the 12th century BCE.

Building structures of thermal power plants: analysis of fire resistance limits

Introduction. The author analyzes real-life fire resistance limits of metal structures for one building of a thermal power plant. Experimental and computational methods were applied to identify the fire resistance limits of building structures. The temperature setting of the research, conducted to solve the problem, was the same as that of a real fire.Research goal and objectives. The purpose of the analysis is to identify the fire resistance limits of structures comprising the building of a thermal power plant using the method of heat-mass exchange analysis that takes account of conditions of a real fire. The following objectives are to be attained in compliance with the pre-set goal:to analyze the principal provisions of technical norms and regulations in terms of the fire safety of building structures of thermal power plants;to justify the principal provisions for the method of heat-mass exchange analysis, taking into account real-life fire conditions;to justify the need to improve the real-life fire resistance limits by fire-proofing agents with account taken of the most dangerous scenario of the real fire development.Methods of research. The heat-transfer equation is analyzed to identify the distribution of temperatures inside a building structure for a one-dimensional case. The field-based method of analysis is applied to solve this problem. This method is generally applied to premises having complex geometric configuration, if one geometric dimension exceeds the others.Results and their discussion. The authors have analyzed the most dangerous fire scenario characterized by the most dangerous impact on metal structures, such as the furnace oil fire spill in a boiler room.The authors also address the most dangerous fire propagation scenario in terms of the heating of bearing metal structures: the combustion of furnace oil spills in a boiler room. The computations have proven that in case of the selected fire development scenario maximal temperatures of bearing metal structures are much lower than the critical temperature of 500 °С fifteen minutes after the onset of fire.Conclusions. Having analyzed the fire resistance computations of thermal power plant structures, including their metal constructions, the have found that in case of emergency, resistance to the most dangerous manifestations of fire exceeds the required R15 value. No fireproofing of bearing metal structures in the boiler room is needed.

Generalized formulae for water cooling requirements for the fire safety of hydrocarbon storage tank farms

Cooling water application on hydrocarbon storage tank farms is used to prevent fire propagation between the tanks caused by intense incident radiation on the tanks adjacent to fires. Codes and standards recommendations regarding the spacing between tanks and the cooling water application rate are vague and contradicting. This study investigates a non-traditional technique using Non-Uniform Coolant Application Model (NUCAM) and illustrates the effect of utilizing this technique on coolant and land rationalization in comparison to the traditional uniform application technique. NUCAM investigates the effect of simultaneous fire propagation and domino effect scenarios on the dimensionless incident heat flux in large storage tanks using gasoline and ethanol fires at various Froude Numbers. The cooling water application rate required for total attenuation is investigated based on the rings distribution surrounding the target tank(s) at steady state conditions.Utilizing the non-uniform cooling water application techniques saves up to 59.1% of the cooling water consumption. While the savings in land area reaches 15.6%. NUCAM results regarding single fire scenarios are utilized to develop novel generalized formulae for the incident heat flux and the cooling water application rate taking into consideration the radiation fraction, Froude Number, the relative spacing between the fire and the target tanks and the relative elevation of the target with respect to the fire base. The formulae show flexibility and reliability when applied on large storage tanks range between 42 m and 55 m in diameter. These formulae provide simpler and faster solution approach for investigating the incident heat flux and the cooling water requirements for large atmospheric storage tanks that require complicated computational power for simulation using commercial packages.

Surviving in a hostile landscape: Nothofagus alessandrii remnant forests threatened by mega-fires and exotic pine invasion in the coastal range of central Chile

AbstractNothofagus alessandrii, categorized as Endangered on the IUCN Red List, is an endemic, deciduous tree species of the coastal range of central Chile. We assessed the effects of fire severity, invasion by the exotic fire-prone Pinus radiata, and land-cover composition and configuration of the landscape on the resilience of fragments of N. alessandrii after a mega-fire in 2017. We used remote sensing data to estimate land-use classes and cover, fire severity and invasion cover of P. radiata. We monitored forest composition and structure and post-fire responses of N. alessandrii forests in situ for 2 years after the mega-fire. In the coastal Maule region wildfires have been favoured by intense drought and widespread exotic pine plantations, increasing the ability of fire-adapted invasive species to colonize native forest remnants. Over 85% of N. alessandrii forests were moderately or severely burnt. The propagation and severity of fire was probably amplified by the exotic pines located along the edges of, or inside, the N. alessandrii fragments and the highly flammable pine plantations surrounding these fragments (> 60% of land use is pine plantations). Pinus radiata, a fire-adapted pioneer species, showed strong post-fire recruitment within the N. alessandrii fragments, especially those severely burnt. Positive feedback between climate change (i.e. droughts and heat waves), wildfires and pine invasions is driving N. alessandrii forests into an undesirable and probably irreversible state (i.e. a landscape trap). A large-scale restoration programme to design a diverse and less flammable landscape is needed to avoid the loss of these highly threatened forest ecosystems.

Experimental study on temperature characteristics in a subway train carriage with lateral openings in a longitudinally ventilated tunnel

Under the rapid development of subway systems, a fundamental understanding of subway fire safety is critically needed to benefit its designs and assessment. Previous studies on train carriage fires are limited to single-carriage fires under natural ventilation. However, it is still unclear how longitudinal ventilation affects the smoke movement in the train carriage with lateral openings. Therefore, a series of 1:3 reduced-scale experimental tests were conducted to investigate the smoke temperature characteristics in a train carriage located in a longitudinally ventilated tunnel. Under various fire sizes and ventilation rates, the ceiling gas temperature and smoke layer height were measured. Compared to the traditional fire scenario with end openings, the maximum ceiling gas temperature and the downstream temperature distribution decay factor are relatively smaller because of the lateral flame tilt and less heat loss during smoke propagation. The effects of ventilation velocity on the maximum ceiling gas temperature are significantly weakened under the blockage effect of the train carriage. The downstream temperature distribution followed a single exponential attenuation function, independent of the fire size and ventilation rate. However, the upstream temperature distribution is much more complex under the restriction of the end wall. A four-segment model was proposed to predict the upstream temperature distribution based on the relationship between the back-layering length and half the carriage length. The fire size and ventilation rate also show limited influence on the smoke stratification, with a layer height of 0.316 m in the stable region. The research outcomes offer adeeper understanding of the smoke propagation of the subway train carriage fire and a theoretical guide on the designs of future tunnels.

Assessment and Mitigation of the Fire Vulnerability and Risk in the Historic City Centre of Aveiro, Portugal

Identifying fire risk in urban centres is instrumental for supporting informed decision-making and outlining efficient vulnerability mitigation strategies. Historic centres are particularly complex in this regard due to the high density of combustible materials in these areas, the favourable fire propagation conditions between buildings, and the complex urban morphology, which makes the evacuation of inhabitants difficult in case of a fire emergency. Recent safety regulations tend not to be fully applicable to historic city centres, where the specificities of the buildings, together with the need to safeguard their heritage value, make the rules for new buildings incompatible. For that reason, an adaptation of current evaluation methods is required to assure the safety of these places. The present paper aims to contribute to this topic by presenting and discussing the results obtained from the application of a simplified fire risk assessment methodology to a representative part of the historic city centre of Aveiro, Portugal. Data were collected through fieldwork building inspections and the results were mapped using a Geographic Information System tool. The study reveals that around 63% of the assessed buildings have a level of fire risk greater than the level of risk which is acceptable for buildings with this type of use and value. Based on the work developed, different mitigation strategies are suggested and compared. Finally, the results obtained in this work are compared with results published for historic urban areas with similar characteristics.

Monitoring and Cordoning Wildfires with an Autonomous Swarm of Unmanned Aerial Vehicles

Unmanned aerial vehicles, or drones, are already an integral part of the equipment used by firefighters to monitor wildfires. They are, however, still typically used only as remotely operated, mobile sensing platforms under direct real-time control of a human pilot. Meanwhile, a substantial body of literature exists that emphasises the potential of autonomous drone swarms in various situational awareness missions, including in the context of environmental protection. In this paper, we present the results of a systematic investigation by means of numerical methods i.e., Monte Carlo simulation. We report our insights into the influence of key parameters such as fire propagation dynamics, surface area under observation and swarm size over the performance of an autonomous drone force operating without human supervision. We limit the use of drones to perform passive sensing operations with the goal to provide real-time situational awareness to the fire fighters on the ground. Therefore, the objective is defined as being able to locate, and then establish a continuous perimeter (cordon) around, a simulated fire event to provide live data feeds such as e.g., video or infra-red. Special emphasis was put on exclusively using simple, robust and realistically implementable distributed decision functions capable of supporting the self-organisation of the swarm in the pursuit of the collective goal. Our results confirm the presence of strong nonlinear effects in the interaction between the aforementioned parameters, which can be closely approximated using an empirical law. These findings could inform the mobilisation of adequate resources on a case-by-case basis, depending on known mission characteristics and acceptable odds (chances of success).

Is Portugal Starting to Burn All Year Long? The Transboundary Fire in January 2022

Changes in the large fire seasons induced by climate variability may have implications in several sectors of modern society. This communication aims to investigate possible changes in the behaviour of active fires during the wintertime and document an event that occurred in the transboundary mountainous region in the north-western Iberian Peninsula between Portugal and Spain on 28 January 2022. The VIIRS active fire data, a satellite product, were analysed for the period between December 2012 and February 2022. The Meso-NH model was used to explore the atmospheric conditions during the event that burned almost 2400 ha. It was configured in a single domain with a horizontal resolution of 1500 m (300 × 300 grid points). The study highlights an increase in fire occurrence during the winter of 2021/22 and indicates that climate variability may create atmospheric conditions propitious for fire development even during the winter. The mild temperatures, dry air, and easterly flow affecting northern Portugal played an important role in the fire that occurred on 28 January 2022. Local orographic effects associated with downslope flow favoured fire propagation. Given the lack of knowledge about large winter fires, this study can be a starting point for future research on this subject.

3D Simulation of Battery Fire on a Large Steel Frame Structure due to Depleted Battery Piles

Lithium ion batteries (LIB) can rupture and result in thermal runaway and battery fires. In the process of transporting lithium ion batteries using trains, the massive collection of batteries can cause train fire and pose significant danger to the public. This is especially critical when the fire occurs amid a heavily populated metropolitan environment. This paper reports the 3D analysis of a warehouse with possible train fire due to LIB rupture and the fire propagation at a rail yard. Six critical fire cases with the battery train in close vicinity to the warehouse were considered. The six fire cases are the worst-case scenarios of a Monte Carlo simulation of different fire cases that may occur to an actual steel storage facility at the Capital Railyard, Raleigh, North Carolina. A 3D finite element (FE) frame model was constructed for the steel warehouse and the most critical fire cases were simulated. The results indicated that several structural components of the warehouse would experience large stresses and deflections during the simulated battery fires and resulting in instability to the structure. Specifically, members of the roof frame represent the most critical elements and that the members can result in large deformations as early as 4 minutes after the fire starts. Furthermore, effective utilization of fire protection can delay somewhat the fire effects and extend time to failure to 45 minutes and in one of the simulated cases, prevent structural instability. Thus, fire from LIB waste transport using train is a very realistic problem due to the thermal runaway, and the analysis performed in current study can be used as a preventive investigation technique for buildings that may be exposed to the train fire risk.