Fire Propagation Research Articles

Planning and Evaluation of Water-Dropping Strategy for Fixed-Wing Fire Extinguisher Based on Multi-Resolution Modeling

The deployment of fixed-wing aircraft in fire-extinguishing operations represents a significant advancement in the domain of aviation emergency rescue. Addressing the challenge of enhancing firefighting efficacy, this study delves into the water-dropping strategies of fixed-wing extinguishers and provides a methodological framework for the strategic planning and assessment of water-dropping tactics, employing multi-resolution modeling. The formulation of the planning algorithm and the structure of the effectiveness evaluation index system are explained accordingly. The corresponding prototype system was designed, comprising four subsystems that utilized distinct resolution models: fire environment simulation, water-dropping point scheme planning, approaching path planning, and mission evaluation simulation. Case studies validate the system’s capability to forecast fire and smoke propagation, plan a water-dropping trajectory based on the fire line, optimize flight paths based on the trajectory, and simulate as well as evaluate the whole firefighting mission process. The above research comprehensively constructs the model, finishes the iterative optimization, and evaluates the water-dropping strategy by simulation. The technical path and methodological framework of studying water-dropping strategies are established. The outcomes of this study provide invaluable support for the parameter inversion design of the fixed-wing extinguisher, offering decision-making assistance to commanders and supplying training scenarios for new aviation crews.

Cooperative control of environmental extremes by artificial intelligent agents.

Humans have been able to tackle biosphere complexities by acting as ecosystem engineers, profoundly changing the flows of matter, energy and information. This includes major innovations that allowed to reduce and control the impact of extreme events. Modelling the evolution of such adaptive dynamics can be challenging, given the potentially large number of individual and environmental variables involved. This article shows how to address this problem by using fire as the source of extreme events. We implement a simulated environment where fire propagates on a spatial landscape, and a group of artificial agents learn how to harvest and exploit trees while avoiding the damaging effects of fire spreading. The agents need to solve a conflict to reach a group-level optimal state: while tree harvesting reduces the propagation of fires, it also reduces the availability of resources provided by trees. It is shown that the system displays two major evolutionary innovations that end up in an ecological engineering strategy that favours high biomass along with the suppression of large fires. The implications for potential artificial intelligence management of complex ecosystems are discussed.

Enhancement of an intumescent fire shield paint from the nanotube rutile mineral for the fire performance of steel structures

Building and construction fire safety is an important issue for the protection of people and property. Research investigates nano-rutile minerals' synergistic role in intumescent fire shield paint (IFSP). A synergistic ingredient was introduced to intumescent fire shield paint to evaluate its impact on char morphology, fire protection test, fire propagation test, and compare it with current market products. A hydrothermal process was used to create a rutile mineral, with various techniques used to describe its structure, size, and composition. Intumescent char was found in a furnace using FESEM and X-ray fluorescence. The results showed that rutile minerals contain a rutile phase and a nanotube structure. The surface of the sample IFSP A's char showed layer and foam structures with homogenous voids during a fire test, indicating a high porosity structure. Large holes and recurring gaps were observed in the char of the IFSP B, C, and D. Sample IFSP A took more time at the structural critical temperature (about 550 o C) than other intumescent fire shield paint samples, making it a barrier layer that effectively shields the metal substrate from heat. The intumescent char residue had the highest C/O ratio of 0.57, indicating the best char yield degree and anti-oxidation abilities. The IFSP A had a phosphorous content of 36.2%, which could combine with phosphorus and TiO2 to form a ceramic barrier. The increased TiO2 in IFSP A suggests that char layers with TiO2 may still contain strong ceramic structures and function as effective thermal protection layers.

Mefloquine-induced conformational shift in Cx36 N-terminal helix leading to channel closure mediated by lipid bilayer

Connexin 36 (Cx36) forms interneuronal gap junctions, establishing electrical synapses for rapid synaptic transmission. In disease conditions, inhibiting Cx36 gap junction channels (GJCs) is beneficial, as it prevents abnormal synchronous neuronal firing and apoptotic signal propagation, mitigating seizures and progressive cell death. Here, we present cryo-electron microscopy structures of human Cx36 GJC in complex with known channel inhibitors, such as mefloquine, arachidonic acid, and 1-hexanol. Notably, these inhibitors competitively bind to the binding pocket of the N-terminal helices (NTH), inducing a conformational shift from the pore-lining NTH (PLN) state to the flexible NTH (FN) state. This leads to the obstruction of the channel pore by flat double-layer densities of lipids. These studies elucidate the molecular mechanisms of how Cx36 GJC can be modulated by inhibitors, providing valuable insights into potential therapeutic applications.

Informal settlements ablaze: decoding the combustible nature of building materials used in Bangladesh through experiments and numerical analysis

ABSTRACT Fire outbreaks in informal settlements pose severe threats to residents and their properties. Despite the frequent occurrence of fire events in Bangladesh, detailed studies on fire propagation behaviour remain limited. This study addresses this critical issue by comprehensive investigations into the ignitability and burning behaviour of different materials such as cardboard, polyurethane foam, plastic bags, wood, and structural timber that are commonly found in informal settlements. Additionally, an advanced numerical model based on the finite volume method was developed in Fire Dynamics Simulator and then employed to accurately predict the fire-reaction properties of materials under the cone calorimeter environment. The results revealed that cardboard ignites quickly, burns moderately, and does not produce flaming droplets or ignite the filter paper. PU foam burns vigorously, with a high burning rate, and emits dense black smoke and a toxic odour. Plastic bags ignite rapidly, burn intensely, and are greatly influenced by the presence of airflow. The numerical model successfully quantified fire-reaction properties such as ignition time, heat release rate (HRR), and flame spread characteristics. Notably, wood and structural timber demonstrate a distinct combustion pattern with a sharp HRR peak, while PU foam exhibits the highest peak HRR values followed by timber masonite.

Tropical peat composition may provide a negative feedback on fire occurrence and severity

Loss of peat through increased burning will have major impacts on the global carbon cycle. In a normal hydrological state, the risk of fire propagation is largely controlled by peat bulk density and moisture content. However, where humans have interfered with the moisture status of peat either via drainage, or indirectly via climate change, we hypothesise that its botanical composition will become important to flammability, such that peats from different latitudes might have different compositionally-driven susceptibility to ignition. We use pyrolysis combustion flow calorimetry to determine the temperature of maximum thermal decomposition (Tmax) of peats from different latitudes, and couple this to a botanical composition analysis. We find that tropical peat has higher Tmax than other regions, likely on account of its higher wood content which appears to convey a greater resistance to ignition. This resistance also increases with depth, which means that loss of surface peat in tropical regions may lead to a reduction in the subsequent ignitability of deeper peat layers as they are exposed, potentially resulting in a negative feedback on increased fire occurrence and severity.

The Use of Fire Dynamics System (NIST) in Determining The Architecture of Educational Spaces for Children and Young People

Objective: This study aims to investigate the potential of the Fire Dynamics Simulator (FDS) software, developed by the National Institute of Standards and Technology (NIST), as a tool to assess and improve Fire Safety (FS) in educational environments, specifically in the classrooms of CEFET in Araxá (MG), Brazil. Theoretical Framework: The research is based on the importance of fire safety in educational environments, highlighting the vulnerability of children and young people. Concepts of fire behavior, smoke propagation, and thermal conditions in buildings are addressed. Method: The methodology adopted for this research involves detailed computer simulations using FDS to analyze different fire scenarios. The simulation results were validated with the PyroSim software. Data collection was conducted through these simulations, generating robust empirical data that support the review and development of specific regulations. Results and Discussion: The results indicate that FDS is an important ally in promoting fire safety in educational buildings. The simulations showed the effectiveness of FDS in predicting fire behavior, smoke propagation, and thermal conditions, helping to prevent and minimize potential damages. The discussion contextualizes these results, highlighting the need for accurate empirical data to strengthen Brazilian fire safety legislation. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the results can be applied to positively influence legislation, optimize architectural designs, and promote safety guidelines in educational institutions in Brazil. Originality/Value: This study significantly contributes to the advancement of knowledge and practices in FS. The originality of the research lies in the application of FDS for simulations in educational environments, offering a robust tool for evaluating and improving fire safety.

Forest Fires: Silvicultural Prevention and Mathematical Models for Predicting Fire Propagation in Southern Italy

Forest Fires: Silvicultural Prevention and Mathematical Models for Predicting Fire Propagation in Southern Italy

Characteristics of Pyrolysis Products of California Chaparral and Their Potential Effect on Wildland Fires

The aim of this study was to investigate the pyrolysis of selected California foliage and estimate the energy content of the released volatiles to show the significance of the pyrolysis of foliage and its role during wildland fires. While the majority of the volatiles released during the pyrolysis of foliage later combust and promote fire propagation, studies on the energy released from combustion of these compounds are scarce. Samples of chamise (Adenostoma fasciculatum), Eastwood’s manzanita (Arctostaphylos glandulosa), scrub oak (Quercus berberidifolia), hoaryleaf ceanothus (Ceanothus crassifolius), all native to southern California, and sparkleberry (Vaccinium arboreum), native to the southern U.S., were pyrolyzed at 725 °C with a heating rate of approximately 180 °C/s to mimic the conditions of wildland fires. Tar and light gases were collected and analyzed. Tar from chamise, scrub oak, ceanothus and sparkleberry was abundant in aromatics, especially phenol, while tar from manzanita was mainly composed of cycloalkenes. The four major components of light gases were CO, CO2, CH4 and H2. Estimated values for the high heating values (HHVs) of volatiles ranged between 18.9 and 23.2 (MJ/kg of biomass) with tar contributing to over 80% of the HHVs of the volatiles. Therefore, fire studies should consider the heat released from volatiles present in both tar and light gases during pyrolysis.

Measuring the fire growth potential of combustible solids using a cone calorimeter

The fire growth rate of interior linings, furnishings, and construction materials is measured in full-scale fire tests such as the ASTM E84 Steiner Tunnel, the ISO 9705 room fire, and a passenger aircraft fuselage as the flame-spread rate, time-to-flashover, or time to incapacitation, respectively. The results are used to indicate the level of passive fire protection afforded by the combustible material or product in the test without providing any insight into the burning process. These large-scale tests require many square meters of product, are very expensive to conduct, and can exhibit poor repeatability–making them unsuitable for product development, quality control, product surveillance, or regulatory compliance. For this reason, smaller (0.01 m2) samples are tested in bench-scale fire calorimeters under controlled conditions, and these one-dimensional burning histories are correlated with the results of the two- and three-dimensional burning histories in full-scale fire tests by a variety of empirical and semi-empirical fire propagation indices, as well as analytic and computer models specific to the full-scale fire test. The approach described here defines the potential of a material to grow a fire in terms of cone calorimeter data obtained under standard conditions. The fire growth potential, λ (m2/J), is the coupled process of surface flame spread and in-depth burning that is defined as the product of ignitability (1/ E ign) and combustibility (Δ Q/Δ E) obtained from a combustion energy diagram measured in a cone calorimeter at an external radiant energy flux [Formula: see text] (W/m2) above the critical flux for burning, [Formula: see text]. However, the potential for fire growth, λ≡ (1/ Ei gn)(Δ Q/Δ E) is only realized as a hazard when the heat of combustion of the product per unit surface area, Hc (J/m2), is sufficient to grow the fire. The dimensionless fire hazard of a combustible product of thickness b is therefore, Π = λ Hc, while the fire hazard of the component materials is an average over the product thickness, π = Π/ b. The measurement of λ, Π, and π from combustion energy diagrams of heat release Q (J/m2) versus incident energy E (J/m2) is described, as well as a physical basis for a fire growth potential that provides simple analytic forms for λ in terms of the parameters reported in cone calorimeter tests. Experimental data from the literature show that rapid fire growth in full-scale fire tests of combustible materials occurs above a value of Π determined by the severity of the fire test.

Metaheuristic algorithms for calibration of two-dimensional wildfire spread prediction model

Wildfires are complex phenomena with harmful consequences, ranging from environmental and property destruction to loss of human lives. In this sense, predicting wildfire behaviour is essential to mitigate its impacts and consequences. The Rothermel model is the most used fire rate of spread prediction model. However, input parameter uncertainty is a significant source of prediction error. In this paper, we propose the calibration of the input parameters of the fire propagation model by metaheuristic algorithms under a two-stage framework. The fire spread model consists on the Rothermel model in a two-dimensional approach for surface fires. The proposed calibration is performed in two stages iteratively repeated over time: (i) the calibration of the fire spread model’s input parameters and (ii) the wildfire spread prediction using the calibrated input parameters. The calibration was performed by the genetic algorithm, differential evolution, and simulated annealing, which calibrates the surface-area-to-volume ratio, fuel bed depth, live fuel moisture and dead fuel moisture. The symmetric difference between the real and predicted fire map shapes was defined as the fitness function of all three metaheuristic algorithms. For validation, simulations were done on two prescribed fires. The results for the real and estimated fire behaviour were then compared and revealed that all the tested metaheuristic algorithms produce a better fit to the real fire’s perimeter when compared to the uncalibrated Rothermel model. From the results, differential evolution provided the majority of best results when compared to genetic algorithm and simulated annealing algorithms in each scenario.

Simplified identification of fire spread risk in building clusters based on digital image processing technology

ABSTRACT Due to factors such as smoke, the non fire identification rate and fire identification accuracy in building fire identification are low, resulting in poor identification results. Therefore, a simplified identification method for building fire spread risk based on digital image processing technology is proposed. A fire spread model is constructed by considering both thermal radiation and thermal plumes, and based on this model, changes in smoke, temperature, and other factors during the occurrence of a fire are obtained. Using K-means to improve the dark channel defogging algorithm, the image after defogging is obtained, making the colour of the image more prominent and the feature information more abundant. Using the area threshold method to further extract the flame target contour in the defogged image, and determine whether the suspected flame area is a flame. Finally, four aspects of colour, sharp corner characteristics, area growth characteristics, and automatic estimation of propagation direction were identified to obtain simplified identification results for fire propagation risk. The experimental results show that the average non fire recognition rate of the proposed method reaches 95.8%, with good fire recognition accuracy and recognition effect, which verifies its feasibility.

An Evaluation of the Fire Safety of Waste Paper-Based Internal Finishing Materials Combined with Expandable Graphite According to Changes in Magnesium Hydroxide Content

Inflammable building finishing materials act as a major cause of fire propagation, and they, therefore, pose significant risks to life and can lead to property damage. To replace such flammable building finishing materials, many countries have established regulations limiting their use, which has led to extensive research on the development of flame-retardant building finishing materials. Such methods have included adding flame retardants to construction materials to reduce the heat release rate and total heat release. The present study aimed to enhance the fire performance of cellulose-based architectural finishing materials by creating a dual flame-retardant mixture using expandable graphite and magnesium hydroxide added to recycled paper waste. Specimen fabrication involves using a pressing method to apply uniform pressure to compress the mixture in a mold. The total heat release (THR), CO, and CO2 production of the produced specimens were measured using a cone calorimeter while varying the magnesium hydroxide additive ratio. The combustion gases were measured through NES 713 experiments to determine any changes in the Toxic Index corresponding to variations in the magnesium hydroxide content. The experiment results established a correlation between the magnesium hydroxide additive ratio and the total heat release, as well as the existence of variations in CO and CO2 production for the dual flame-retardant recycled paper material. A database for combustion gases was also obtained. It was confirmed that the fire performance was improved by confirming that the total heat release decreased by 52% from the previous one in the magnesium hydroxide content of 30 g, and it was confirmed that the inflection points of the Toxic Index value due to the change in CO and CO2 gas production occurred in the magnesium hydroxide content of 20 g due to the improvement of the fire performance. Through the ISO 5660-1 experiment data, we have secured data that can be used as foundational information for performance-oriented fire risk assessments, thereby ensuring the fire safety of cellulose materials that are vulnerable to fire.

A new-proposed triangular- prism flame radiation model of large-scale spilling fire to subsurface convection flow area

The usage of liquid fuel is commonly subjected to a spilling fire due to the accidental leakage. The flame radiation is the primary heat transfer mode in supporting the advancement of large-scale spilling fire. In this work, spilling fires are carried out based on a 6 m × 0.8 m × 0.1 m tray, and the spilling fire performance and flame radiation are examined. The instantaneous flame height and mass burning rate versus fire spread distance are examined. The radiation heat flux of large-scale spilling fire to subsurface flow area is obtained by dividing the flame configuration into a triangular-prism flame and a cuboid flame. The multi-cuboid flame equivalent-division method is proposed to estimate the radiation heat flux of leading triangular-prism flame, finding that the maximal 70 equivalent divisions are sufficiently accurate. The proportion of triangular-prism flame radiation to total heat flux reduces from 100 % to 50 % during spilling fire propagation. The triangular-prism flame radiation plays a dominant role in heat transfer to the subsurface flow area while the cuboid flame radiation plays a secondary role. The current research is of great significance for revealing heat transfer mechanism and predicting rate of spilling fire.

Synthesis and characterization of flame retardant unsaturated polyester-allyloxysilane resin for wood coatings

Fireproof coatings are the simplest, most efficient, and oldest method for protecting a wide range of flammable products, such as wood. Furthermore, surface ignition is the initial phase, so surface protection is essential to reduce fire propagation. Furthermore, delaying the spread of flames can help to save someone when a fire starts. This project synthesized flame-resistant resin starting from tetraallyloxysilane monomer as a halogen-free monomer, an intrinsic flame retardant co-curing agent. The following step synthesized polyester resin using terephthalic acid as a heat-resistant resin. Unsaturated polyester was used by bulk radical polymerization. FT-IR and 1H-NMR analysis showed the successful synthesis of the desired monomer and polymeric compound. The thermal degradation and flame retardancy of pure unsaturated polyester resin (UPE) and allyloxysilane-unsaturated polyester (AUPE) were investigated by thermogravimetric analysis (TGA/DTG/DSC). The burning test and the thermal stability of the coating layers were evaluated using standard UL 94. Physical properties of resins were evaluated using Heat Deflection Temp tests (HDT) ISO 75-A, ASTM 648, Hardness ASTM D2583, Volumetric shrinkage ASTM 3521, and Water absorption ASTM D570. The results of the tests show the successful synthesis and their flame retardant properties.

Performance-based fire assessment of a fully automated multi-storey steel parking structure: A computational approach

Conducting a structural fire analysis for automated steel parking structures present a complex challenge due to the vulnerability of steel structures to high-temperature exposure, the unpredictability of fire source locations, and the enhanced thermal loading due to high concentration of vehicles in a compact area. This study conducted a performance-based assessment (PBA) of a fully automated multi-storey steel parking structure under various fire scenarios. The assessment employed Fire Dynamic Simulator (FDS) to simulate the fire behavior in different scenarios and record the temperature developments within the structure. OpenSees was utilized to perform the subsequent thermo-mechanical analysis and obtain the fire responses of the parking structure. The fire analyses demonstrated that the ignition location and ventilation conditions within the structure considerably affects fire propagation and structural responses. Fire cases initiated on the first floor led to a slightly higher drift ratio than those initiated on the 9th floor. The PBA based on strain and drift ratio led to different results. Cases 1, 2, 4, and 6 maintained life safety based on drift ratios, and strain results indicated a collapse prevention level. For centrally located fire cases, the drift ratios were at collapse prevention level while based on strain values, the elements already exceeded the collapse prevention limit. Under all fire cases, the ultimate performance level of the structure has exceeded the collapse prevention level. The findings highlight the necessity of employing fire safety measures in multi-storey parking structures and enhancing their fire resilience.

Experimental study on the flame merging and temperature profile produced by two pool fires beneath the curved ceiling

Compared to single-source fires in tunnels, double-source fires may exhibit more intricate flame merging behavior and higher flame burning rates due to their interaction, thereby escalating the risk of fire propagation within the tunnel. In this investigation, a 1:10 scale model of a horseshoe-shaped tunnel test site was deployed to conduct experiments on lateral double-source fires, scrutinizing flame merging behavior, probability prediction models, and temperature characteristics of tunnel ceiling smoke gas by varying the oil pool size and double-source spacing. Findings from the study suggest that flame merging behavior within the tunnel is contingent upon double-source spacing and heat release rate (HRR), manifesting in three distinct forms: complete merging, intermittent merging, and complete separation. Through the introduction of non-dimensional heat release rate and non-dimensional fire source spacing, a piecewise function has been devised to forecast the probability of flame merging for both fire types. Furthermore, a predictive model for the maximum temperature rise along the longitudinal centerline of a horseshoe tunnel was formulated, drawing from established theoretical frameworks.

Thermal decomposition and combustion of interior design materials

Research findings on the patterns of thermal decomposition and combustion are reported for widely used interior design materials. The experiments were conducted using a hardware and software system including a thermogravimetric analyzer (to record the characteristics of thermal decomposition), a gas analyzer (with H2, CH4, H2S, SO2, CO and CO2 sensors) and a high-speed camera (to record the characteristics of ignition and combustion). The temperature of the oxidizing medium ranged from 500 to 900°C to investigate the conditions of thermal decomposition initiation and sustained combustion. It was established that the highest concentrations of toxic emissions were typical of the combustion of polypropylene at a maximum temperature of the oxidizing medium (900°C). Wood showed the shortest ignition delay time and the longest duration of combustion. The experimental data were used for a physical problem statement and mathematical model of heat and mass transfer to explore the thermal decomposition and combustion of interior design materials in different rooms. A comparison of the experimental findings with the mathematical modeling results validates the developed model. The growth rates of carbon monoxide and carbon dioxide concentrations were determined for construction (wooden) and interior design (polymer) materials. The maximum concentrations of CO and CO2, and the minimum times taken to reach their threshold values corresponded to wood and polyvinyl chloride panels. This research provides a deeper insight into the thermal decomposition of a wide range of fuels and the formation of gaseous pyrolysis products of these fuels. The results obtained can be used to evaluate the toxicity of construction and interior design materials during compartment fires as well as to estimate the safe egress time and risks involved in the process. They can also serve as a database for the development and testing of mathematical models describing fire outbreaks and propagation in confined spaces.

Lithium-Ion Batteries (LIBs) Immersed in Fire Prevention Material for Fire Safety and Heat Management

Lithium-ion batteries (LIBs) have emerged as the most commercialized rechargeable battery technology. However, their inherent property, called thermal runaway, poses a high risk of fire. This article introduces the “Battery Immersed in Fire Prevention Material (BIF)”, the immersion-type battery in which all of the LIB cells are surrounded by a liquid agent. This structure and the agent enable active battery fire suppression under abusive conditions while facilitating improved thermal management during normal operation. Abuse tests involving a battery revealed that the LIB module experienced fire, explosions, and burnouts with the target cell reaching temperatures of 1405 °C and the side reaching 796 °C. Conversely, the BIF module exhibited a complete lack of fire propagation, with temperatures lower than those of LIBs, particularly 285 and 17 °C, respectively. Under normal operating conditions, the BIF module exhibited an average temperature rise ~8.6 times lower than that of a normal LIB. Furthermore, it reduced the uneven thermal deviation between the cells by ~5.3 times more than LIB. This study provides a detailed exploration of the BIF and covers everything from components to practical applications. With further improvements, this technology can significantly enhance fire safety and prevent the thermal degradation of batteries in the real world.

Determining the influence of façade parameters and the width of a fire-proof eaves on preventing the spread of fire through external vertical structures of buildings

The object of this study is the process of fire propagation through the surface of external wall structures with facade thermal insulation. The paper examines the influence of facade parameters and the width of a fire-proof eaves on preventing the spread of fire by external vertical structures using the example of a residential building. With the use of FDS modeling, the relationships between the parameters of external enclosing structures and the fire-proof eaves on the processes of limiting the spread of fire were investigated. The influence of the minimum parameters of the height of the inter-floor windowsill in the absence of a fire-proof eaves on the spread of fire was determined. The dependence of temperature change near the surface of the facade on the width of the fire-proof eaves and the height of the window between floors was established. Based on a series of simulated experiments, it was established that with a height of 1.0 m between floors and the absence of a fire-proof eaves, the critical temperature value is 250 °C. This value corresponds to the destruction temperature of a standard metal-plastic window structure. For the case when the wall height is 1.0 m, and the width of the fire-proof eaves is 0.75 m, the temperature value is 180 °C. That is, the safety condition of 250 °C is met. Based on the research, a dependence was found on the criterion of not exceeding the critical temperature of 250 °C at the level of 1.4 m of the facade of the building floor located above the fire floor. The criterion holds when the width of a fire-proof eaves is at least 0.4 m and the height of the window partition is 1.0 m, as well as when the width of the eaves is 0.5 m, and the height of the window partition is 0.6 m. It was established that the height of a window interfloor partition has a smaller effect than the width of the fire-proof eaves that separates the floors that are located above