Fire Growth Research Articles

The effect of terrain-influenced winds on fire spread in QUIC-Fire

In this manuscript, we describe the implementation of the terrain-following version of QUIC-URB into QUIC-Fire and a demonstration of the impacts of terrain-influenced winds on QUIC-Fire-simulated fire spread. No changes to the underlying QUIC-Fire fire spread algorithm were made other than what was required to correctly account for the inclusion of terrain. This paper summarizes simulations used to understand how the QUIC-URB terrain-influenced winds affect upslope fire behavior without additional changes to the QUIC-Fire fire spread algorithm. Previously published FIRETEC results are compared to simulation results from the modified QUIC-Fire (incorporating terrain-influenced winds) that use the same topographies and fuels. QUIC-Fire results showed overall similar behaviors in terms of how the topographies affected fire shapes and trends in spread rates. Due to the terrain-following version of QUIC-URB being unable to generate flow separations at the crest of hills, fire spread rates in these regions across all non-flat topographies were over-predicted when compared to FIRETEC. Lateral fire growth showed similar trends with FIRETEC between topographies but did not capture the increase in spread due to a diagonal interface between grassland and forested fuel regions in the test domain. These simulations suggest possible refinements that are necessary to improve QUIC-Fire and thus guide ongoing efforts related to: how flame tilt angle is accounted for, the incorporation of non-local drag effects, and the inclusion of the wake-eddy parameterizations that are used in QUIC-URB.

ON THE RELIABILITY OF A NUMERICAL TRAVELLING FIRE MODEL

AbstractThe ongoing urbanization of our society is leading to the situation that many people live, work and gather in buildings of larger size. Open space office buildings are becoming more common, airport terminals are continuously increased in size and new larger railway stations are being built. When it comes to compartments with larger floor areas, the fire may be localized, which means that the fire does not extend on the whole floor. Yet, even when the fire load is distributed, such as in open space office buildings, the area where combustion is raging moves during the fire leading to so‐called “travelling fires”. The classical view of compartment fire with the strong assumption of uniform temperature in the compartment has been challenged, several travelling fire models have been proposed to address the phenomenon. Validation of these models is still scarce. This work is about the assessment of reliability and accuracy of a numerical travelling fire model implemented in a software called GoZone. The assessment is done mainly by comparison of relevant output in a fire compartment such as fire growth rate as well as by comparison of gas temperature, rate of heat released and resulting steel temperature. In the framework of this paper, only a part of the entire assessment focused on office building is presented.

A semi reduced-order model for multi-scale simulation of fire propagation of lithium-ion batteries in energy storage system

Thermal runaway (TR) and the resulting fire propagation are still critical issues puzzling the application of lithium-ion batteries in energy storage system (ESS). A fire propagation model including accurate TR propagating process assists in understanding the battery failure mechanism and determining the safety-optimal design of ESS, while its development is hindered by the complexity of simulating large-scale spatial system and interactions between TR and fire. In this work, a coupled semi reduced-order model (SROM) toward real-scale ESS is developed to capture battery TR and fire propagation behavior. Wherein, meshless methods are implemented for battery cluster by constructing thermal resistance network to simulate heat generation and transfer, which simultaneously couples a mass flowing network to address gas generation and subsequent jet. Full-order CFD model is adopted to simulate burning behavior in external fluid with higher precision. This model can accurately capture cross-scale parameters, including temperature evolution at cell-level and heat release rates (HRR) at system-level, as confirmed by experiments. Simulation results elucidate the failure propagation mode and mechanism from cell-to-cell to module-to-module levels. The significant impact of triggering position on fire behavior is also revealed that TR originating from the cluster center causes rapider fire growth and larger peak HRR during fire propagation. The SROM covers entire phenomena chain from cell-level to system-level, which can serve as new guidelines for designing and running safer ESS.

LOCALISED FIRE ASSESSMENT OF A STEEL STRUCTURAL SOLUTION IN A PILOT BUILDING

AbstractMany tragic fires in the past decades have highlighted the importance of fire safety engineering and its meaningful application in the engineering field. With a constant and significant growth of the research the classical approach based on prescriptive time‐temperature curve, where the gas temperature is assumed to be constant within the entire compartment and always increasing on time has been challenged by a performance‐based one. Performance‐based approach is aiming to represent the fire accounting for more physics than the prescriptive approach, considering ignition, fire growth burning and cooling phase. Nowadays practitioners facing the design stage of a project have to face the choice between designing with prescriptive or performance‐based approach. In this work a comparison between design using performance based and a prescriptive approach will be provided. In particular, the building is under development in the framework of a demonstration RFCS (Research Found for Coal and Steel) project called DREAMERS, founded by the European Commission. The chosen structure for this example is an 800 m2 steel building, which will be built in the Campus of the University of Salerno (Italy). The main peculiarity of the building is the implementation of all the most advanced technologies for the construction of a resilient structure in terms of seismic, robustness and fire safety. The building is designed in steel and steel composite solutions, following a holistic design approach and foreseeing a life time monitoring of its behavior. The flooring system is made of Asymmetric Floor Beams (AFB) and Cofradal® 260, whereas vertical elements are hot rolled HEB sections. The work here presented is showing some of the main challenges related to the fire design as well as application of next generation localised fire models.

Experimental study on the heat losses of the fuel combustion inside the compartment

This paper investigates the heat losses of the fuel combustion inside the compartment from the over-ventilated to the under-ventilated condition, which has not been quantified in the previous literature. However, these parameters are essential to estimate the heat losses ratio (fraction) and temperature. A series of experiments are performed by six cubic compartments to quantify the heat losses as well as their fractions in total heat release rate with fire growth. The temperature inside the compartment and four types of heat losses characterizing the radiation, convection, conduction and heat storage of the hot gasses are measured and quantified for various heat release rates, opening dimensions (ventilation conditions) and compartment scales. Non-dimensional correlations of the convective and conduction heat losses fractions are proposed to describe their evolutions with fire growth for various openings and compartments, which can be used to estimate the heat losses ratios. These new findings and the non-dimensional correlations provide a fundamental basis for understanding essentially these heat losses and profiles of the fuel combustion inside the compartment.

Precision of Visual Perception of Developing Fires

An aspect of human responses to fires is perceiving changes in intensity. The nature of fires can make this challenging, as flames and smoke are dynamic and change with time. For developing fires, this is in addition to growth occurring vertically and sometimes horizontally, with the footprint of the fire either remaining the same or increasing in size. The present study investigated how precisely humans could visually detect differences in the intensities and growth rates of simulated fires. Using a similar approach to research with non-symbolic visual quantities, a series of experiments compared the precision of judgments regarding which of two simulated fires was greater in intensity or growing faster in intensity when the footprint was fixed or varied. In addition, participants reported what characteristics they used to make their judgments. Precision was significantly worse when comparing the growth rates versus the intensities of fires, and it was better when the fire footprint varied. This provides initial estimates of the precision of mental representations of fire intensity and growth. In addition, participants reported using multiple characteristics, including the size of flames and smoke produced. The present study indicates that humans can precisely detect differences in the intensities of fires using visual cues, but have difficulty when comparing growth rates. We discuss how this suggests that the growth rate may not be a reliable visual cue used by occupants when responding to fires.

The Portuguese Large Wildfire Spread database (PT-FireSprd)

Abstract. Wildfire behaviour depends on complex interactions between fuels, topography, and weather over a wide range of scales, being important for fire research and management applications. To allow for significant progress towards better fire management, the operational and research communities require detailed open data on observed wildfire behaviour. Here, we present the Portuguese Large Wildfire Spread database (PT-FireSprd) that includes the reconstruction of the spread of 80 large wildfires that occurred in Portugal between 2015 and 2021. It includes a detailed set of fire behaviour descriptors, such as rate of spread (ROS), fire growth rate (FGR), and fire radiative energy (FRE). The wildfires were reconstructed by converging evidence from complementary data sources, such as satellite imagery and products, airborne and ground data collected by fire personnel, and official fire data and information in external reports. We then implemented a digraph-based algorithm to estimate the fire behaviour descriptors and combined it with the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) fire radiative power estimates. A total of 1197 ROS and FGR estimates were calculated along with 609 FRE estimates. The extreme fires of 2017 were responsible for the maximum observed values of ROS (8900 m h−1) and FGR (4400 ha h−1). Combining both descriptors, we describe the fire behaviour distribution using six percentile intervals that can be easily communicated to both research and management communities. Analysis of the database showed that burned extent is mostly determined by FGR rather than by ROS. Finally, we explored a practical example to show how the PT-FireSprd database can be used to study the dynamics of individual wildfires and to build robust case studies for training and capacity building. The PT-FireSprd is the first open-access fire progression and behaviour database in Mediterranean Europe, dramatically expanding the extant information. Updating the PT-FireSprd database will require a continuous joint effort by researchers and fire personnel. PT-FireSprd data are publicly available through https://doi.org/10.5281/zenodo.7495506 (Benali et al., 2022) and have large potential to improve current knowledge on wildfire behaviour and to support better decision making.

Effect of Salinity on Warm Season Turf Grass Species

The demand for salinity tolerant turf grasses is increasing due to augmented use of effluent or low-quality water for turf irrigation. Fresh water, along with soil Stalinization in many locations, has raised the requirement for salt-tolerant turf grass screening. Physiological responses to salinity and relative salt tolerance of Five C4 turf grasses, two variety ofCynodon dactylon(Bermuda grass), Zoysia matrella (Manilla grass), Zoysia japonica(Zoysia Grass) and Paspalum notatum(Bahia grass) were investigated during the study at Department of Horticulture Sam Higginbottom University of Agriculture Technology and Science, Prayagraj. Turf grasses were planted in plastic pots filled with sand: cocopeat: vermiculite (2:1:1) and irrigated with different concentration of salinity levels (0.6, 5.0, 10.0, 15 dS m-1). Salinity tolerance was evaluated based on leaf length leaf Wirth leaf firing, shoots and root growth reduction, proline content, total chlorophyll content RGB content and relative water content was subjected to analysis of variance. Among the four turf grass species Bahia grass found to be most salt tolerant turf grass followed by Z. matrella while Zosia japonica was least tolerant turf grass against salt stress.

Fire extinguishment tests of electric vehicles in an open sided enclosure

Electric vehicles may represent a new type of risk and require a change in fire protection and firefighting techniques in vehicle carriers and parking garages. This study presents an experimental assessment of firefighting techniques and fire dynamics of electric cars in an open-sided enclosure. The enclosure had dimensions of 12.2 m by 7.1 m, and openings of 7.1 m by 2.4 m on either end of the enclosure. A total of nine tests were performed, of which seven were conducted on the same type of car (Renault Fluence ZE). The other two electric cars tested were Tesla Model 3 and Nissan Leaf. The electric cars were surrounded by conventional internal combustion engine vehicles, and ignition was induced by short circuit of the battery. When this was not possible an external fuel load was used. The results of the tests show a significant variation in fire growth rates. Gas temperatures peaked at 1000 °C in some of the tests. The flame spread to neighboring cars occurred between 3 min and 46 min depending on the firefighting method used.

A Machine-Learning Approach to Predicting Daily Wildfire Expansion Rate

Accurate predictions of daily wildfire growth rates are crucial, as extreme wildfires have become increasingly frequent in recent years. The factors which determine wildfire growth rates are complex and depend on numerous meteorological factors, topography, and fuel loads. In this paper, we have built upon previous studies that have mapped daily burned areas at the individual fire level around the globe. We applied several Machine Learning (ML) algorithms including XGBoost, Random Forest, and Multilayer Perceptron to predict daily fire growth rate based on meteorological factors, topography, and fuel loads. Our best model on the entire dataset obtained a 1.15 km2 MAE. The ML model obtained a 90% accuracy when predicting whether a fire’s growth rate will increase or decrease the following day, compared to 61% using a logistic regression. We discuss the central factors that determine wildfire growth rate. To the best of our knowledge, this study is the first to perform such analyses on a global dataset.

Pyrolysis model parameterization and fire growth prediction: The state of the art

A failure to accurately predict fire growth on a solid object can be frequently traced to our inability to fully resolve coupling between the gas-phase processes of flaming combustion and condensed-phase processes of pyrolysis, responsible for generation of gaseous fuels. Two key quantities that define this coupling are the rate of heat flow (or heat flux) into the condensed phase and the rate of mass flow (or mass flux) of decomposition products into the gas phase. Recognizing that an improvement in our ability to compute the latter quantity may hold the key to accurate fire growth predictions, a systematic effort has been made by the fire science community to develop progressively more sophisticated models of pyrolysis. State-of-the-art pyrolysis solvers can simulate complex, multi-reaction thermal decomposition mechanisms coupled with physically diverse heat and mass transfer processes taking place in the condensed phase. However, parameterization of these models remains a non-trivial effort requiring a large number of careful measurements and inverse modeling, which is necessary because some of the processes cannot be fully decoupled through experimental design. Here we review formulation and parameterization of the state-of-the-art pyrolysis models, discuss their limitations and the impact of these limitations on fire growth predictions.

Validation of the fire dynamics simulator (FDS) model for fire scenarios with two liquid pool fires in multiple compartments

A validation study on the fire dynamics simulator (FDS) model for fire scenarios with multiple liquid pool fires occurring in multiple compartments was performed. For fire growth in the open simulation, the mass loss rate per unit area (MLRPUA) time curve obtained experimentally was used as the input. In the blind simulation, the pyrolysis model was used. For the ventilation flow rate curve, the supply/exhaust flow rate curve measured in the experiment was used as the input for the open simulation, whereas the quadratic fan curve model was used for the blind simulation. The time-averaged datasets of the output parameters from the FDS model and experiment were plotted as data points on scatter plots. In terms of bias factor and model standard deviation of output parameters, the scatter plots under the open simulation conditions were compared with those of NUREG-1824. Under blind simulation conditions, the bias factor and model standard deviation of output parameters increased significantly. A sensitivity analysis was performed on input parameters, such as the MLRPUA time curve, supply/exhaust flow time curve, compartment leak area, and maximum differential pressure in the compartment. Within the given ranges of the sensitivity input parameter values, only changing the MLRPAU time curve significantly affected the bias factor and model standard deviation of the output parameters.

In-situ synthesis of copper phytate-hierarchically porous MOF-199 hybrid in wood towards multifunctional flame-retardant wood composite

The modern society pays growing attention on global environmental issues, public safety, and individual health, which highlights the necessity of exploring sustainable, energy-saving, flame-retardant, and anti-mildew materials for building applications. Herein, by in-situ preparing copper phytate-hierarchically porous MOF-199 hybrid (PCuM) in natural wood (W) via simple phytate induced defect engineering strategy, we reported a multifunctional low fire-hazard wood composite (PCuM-W). The phytate anion not only acted as a modulator to generate hierarchical porosity in MOF-199, but also offered high flame retardancy due to its six phosphorus groups. The copper phytate anchored on the cell wall exhibited charring and graphitizing effects and enhanced the flame retardancy and smoke suppression performance of wood. By pyrolysis, a hierarchically porous MOF-199-derived carbon formed and offered a considerably enhanced catalytic activity towards the conversion of CO. With a weight percent gain of only 13.5%, the fire growth index, total smoke production, and maximum CO production rate of PCuM-W were 74.2%, 85.4%, and 33.3% lower than that of W, respectively, showing outstanding fire-hazard-reducing efficiency that surpassed most of its counterparts. Furthermore, due to the hierarchical porosity and antimicrobial property of PCuM, PCuM-W showed excellent moisture-buffering ability and mildew resistance. This work brings guidelines for fabricating hierarchically porous MOFs to realize multifunctional materials via phytate induced defect engineering.

Discussion on the Analysis of Fire Hazard in the Central Hall of a Historical Building

This study focuses on the inadequate compliance of natural smoke exhaust windows in the central hall of a historical building in Shanghai. Taking into consideration the preservation of the authenticity of the historical structure, five fire scenarios were established to evaluate the fire hazard in the central hall based on different fire heat release rates, fire growth coefficients, number of open windows and window response times. Considering the actual conditions of the historical building and its function as a medical facility, the study also analyzed the rationality of setting fire scenario parameters for evacuation time and fire safety assessment. The research findings indicate that the upper smoke temperature is significantly influenced by the values of heat release rate and the number of open windows. Increasing the number of open windows by 60% can extend the time for the upper smoke temperature to reach a dangerous state by approximately 10%.

Fire testing methodology to develop solutions for storage and ceiling heights exceeding laboratory limits

The maximum ceiling height of the FM Global laboratory is 18.3 m. Therefore, fire protection solutions for warehouses with taller ceilings cannot be directly validated through full-scale testing. This work develops a methodology to obtain the key processes of fire growth, spray-plume interaction, and fire suppression response for an 18.9 m high roll-paper storage under a 24.4 m tall ceiling. The proposed methodology uses a heptane burner assembly at the base of the commodity array to match the fire heat release and growth rate to that of a taller storage exceeding lab capability. The burner assembly included six heptane burners and two air ducts. A series of experiments was conducted to characterize the burner design, model the fire growth in the free-burn stage, and validate controlled and uncontrolled fires in terms of the number of activated sprinklers. A final large-scale fire test used a 12.8 m high storage of Kraft paper with the burner assembly under an 18.3 m tall ceiling to validate protection recommendations for Kraft paper stored 18.9 m high under a 24.4 m tall ceiling. The test demonstrated full suppression using K360 (K-factor, lpm/bar1/2), fast response, pendent sprinklers with a temperature rating of 74 °C, supplied with a water pressure of 8.3 bar.

On the Growth of Wildland Fires from a Small Ignition Source

ABSTRACT Wildland and Wildland-Urban-Interface (WUI) fires are an important problem that may have major consequences in terms of safety, air quality, and damage to buildings, infrastructure, and the ecosystem. It is expected that with climate change, the wildland fire and WUI fire problem will only intensify. Wildland fires are often initiated by small ignition sources caused either by human intervention (hot metal fragments or burning biomass) or by natural events (lighting or sun heating). Once the wildfire or structural fire has been ignited and grows, it can spread rapidly through ember spotting, where pieces of burning materials are lifted by the plume of the fire and then transported forward by the wind, landing where they can start spot fires downwind. The ignition mechanisms for all of these fires have the common characteristic of a small and localized area of origin, with the subsequent spread of the fire to wider and larger areas. Because of the three-dimensional characteristics of this type of propagating fire, its rate of spread has an initial acceleration phase leading to an equilibrium rate of spread when the fire reaches a certain size, which is referred to as a “line-fire” type of spread. Most of the studies on wildland fire propagation have been conducted with line fires and have been concerned with characterizing the equilibrium rate of spread rather than the initial spread from a small ignition source. In this paper, some of the studies conducted to date on the subject of wildland fire growth from a small ignition source, and the physics supporting the mathematical expressions that are used to describe the growth of the fire are discussed. An attempt is also made to provide support for these works through a more fundamental approach to model the problem.

Estimating the effects of meteorology and land cover on fire growth in Peru using a novel difference equation model

Abstract. Statistical analyses of wildfire growth are rarely undertaken, particularly in South America. In this study, we describe a simple and intuitive difference equation model of wildfire growth that uses a spread parameter to control the radial speed of the modeled fire and an extinguish parameter to control the rate at which the burning perimeter becomes inactive. Using data from the GlobFire project, we estimate these two parameters for 1003 large, multi-day fires in Peru between 2001 and 2020. For four fire-prone ecoregions within Peru, a set of 24 generalized linear models are fit for each parameter that use fire danger indexes and land cover covariates. Akaike weights are used to identify the best-approximating model and quantify model uncertainty. We find that, in most cases, increased spread rates and extinguish rates are positively associated with fire danger indexes. When fire danger indexes are included in the models, the spread component is usually the best choice, but we also find instances when the fire weather index and burning index are selected. We also find that grassland cover is positively associated with spread rates and extinguish rates in tropical forests, and that anthropogenic cover is negatively associated with spread rates in xeric ecoregions. We explore potential applications of this model to wildfire risk assessment and burned area forecasting.

Study on the key parameters of vehicle fires for the growth stage in road tunnels

AbstractAs the golden period for evacuation and rescue in road tunnel fires, the fire growth stage is indispensable for security. The key parameters of this stage must be clearly defined, including the maximum heat release rate (HRR), growth time, and growth coefficient. Based on the squared model, the correlations between the key parameters are investigated according to the existing fire tests of vehicle‐related materials and actual vehicles or mock‐ups. The maximum HRR and the growth coefficient of different types of vehicles are obtained. The results show that the maximum HRR is linearly related to the growth coefficient in the fire tests of vehicle‐related materials. And it is logarithmically related in the fire tests of actual vehicles or mock‐ups. The growth coefficient and growth time represent the possibility of a disaster. The larger the growth coefficient is or the shorter the growth time is, the greater the possibility is. The maximum HRR in a fire is 2 ~ 10 MW for a car, 10 ~ 50 MW for a bus, and 50 ~ 200 MW for a heavy goods vehicle. The growth coefficient in a fire is 0.003 ~ 0.013 kW/s2 for a car, 0.05 ~ 0.15 kW/s2 for a bus, and 0.2 ~ 0.3 kW/s2 for a heavy goods vehicle. The corresponding fire growth types are slow and medium, fast, fast, and ultra‐fast, respectively. This study is beneficial for the establishment of the fire growth model and the setting of emergency response time.

Fire Risk Rating Assessment for Wood Specimens Coated with Flame Retardant

Chung's equations-II, -III, and -IV were applied to evaluate the fire risk and fire risk ratings of flame retardants. As an example, a wood specimen coated with a flame retardant was selected and tested using a cone calorimeter according to the ISO 5660-1 standard. The external heat flux was fixed to 50 kW/m2. Fire performance index-III used three variables to evaluate the initial fire risk: the time to ignition, first peak heat release rate, and first peak smoke release rate. Fire growth index-III was calculated using the first peak heat release rate, peak smoke production rate, and time to reach the first peak smoke production rate. This index is a standardized fire hazard category with poly(methyl methacrylate) as the reference material. The fire risk rating index, fire risk index-IV, is expressed as the value obtained by dividing the fire growth index-III by fire performance index-III. In this study, the methodology for fire risk rating evaluation is discussed.

In-situ polymerized zinc phytate chelated Si-C-P geopolymer hybrid coating constructed by incorporating chitosan oligosaccharide and DOPO for flame-retardant plywood

Zinc phytate (ZnPA) chelated geopolymer and in-situ polymerized chitosan oligosaccharide (COS)/DOPO explored a challenging and exciting flame retardant organic–inorganic hybrid coating via sol–gel method to find halogenated high-efficiency bio-flame retardants are widely used as decorative materials for flame-retardant plywood. Herein, the results show that the appropriated ZnPA (0.5 wt%) enhances the flame retardancy of the geopolymer coating, the peak of heat release rate (p-HRR) decreases from 136.09 to 99.39 kW·m−2, the fire growth index (FGI) dropped from 0.47 to 0.28 kW m−2 s−1, the fire performance index (FPI) climbs from 1.00 to 2.52 s·m2·kW−1, and the flame retardancy index (FRI) climbs from 1.00 to 2.52. Meanwhile, through the microstructural analysis of the residual layer, a strong, compact and non-flammable resilient residues is obtained after combustion; Moreover, the pyrolysis kinetics show that the Z.-L.-T. three-dimensional diffusion reaction model governs the pyrolysis of hybrid coatings. Appropriated ZnPA increases the pyrolysis Eα from 138.95 kJ·mol−1 to 160.75 kJ·mol−1 at 741 ∼ 890 ℃ and improves the thermal stability of the coating. The Si-C-P structure improves the formaldehyde adsorption rate by 46.5%. Therefore, this study, by preparing COS-pretreated ZnPA and DOPO to co-construct alkali-excited cenospheres-based Si-C-P coating, reveals the sustainable development of modified bio-based geopolymer flame-retardant coatings in the construction industry.