Search Results (157)

Wildland–urban interface (WUI) fires expose buildings to complex thermal loads arising from radiation, convection, flame contact, and hot-gas impingement, and radiation-only assessment may be insufficient when wind-driven vegetation fires interact directly with façades. This issue is increasingly relevant in Australia, where cross-laminated timber (CLT) and other mass-timber systems are increasingly used, including in bushfire-prone regions. This study quantifies the thermal exposure of a simplified two-storey CLT building subjected to wind-driven Douglas Fir plantation fires using Fire Dynamics Simulator (FDS). A previously validated Douglas Fir vegetation-fire model was coupled with the building, and a one-factor-at-a-time parametric study varied fuel load, moisture content, building separation distance, terrain slope, wind velocity, and wind direction. The analysis considered heat release rate (HRR), gas temperature, CLT wall and glazing temperature, radiative, convective, net, and incident heat fluxes, adiabatic surface temperature, convective-to-radiative heat transfer ratio, and time-to-peak response. Fuel load and terrain slope produced the strongest increases in peak HRR, whereas moisture content reduced and delayed fire development. Increasing separation distance substantially reduced local exposure. Wind velocity and direction modified plume trajectory and façade heating, demonstrating that the highest HRR did not always correspond to the highest building temperature. Convective heating dominated over radiative heating at the monitored locations. The proposed physics-based framework integrates global fire behaviour with local thermal-response metrics and provides a basis for performance-based assessment of CLT buildings exposed to WUI fires, extending approaches that rely primarily on radiant heat exposure. Full article

This study investigates fire behavior and personnel evacuation safety in a nuclear chemical workshop based on the Fire Dynamics Simulator (FDS) and real fire experiment. The typical fire scenario caused by cable faults at middle distribution box locations was analyzed to evaluate the effects of ignition position on fire growth and smoke propagation. The FDS results show that the upper-layer temperature reaching approximately 180 °C at 173 s, while visibility at 2 m height decreases to 10 m at 176 s and CO₂ concentration rises to 1%. The CO concentration at 2 m reaches 500 ppm at around 290 s. The calculated Available Safe Egress Time (ASET) of 145 s exceeds the Required Safe Egress Time (RSET) of 117 s, indicating acceptable evacuation safety under this scenario. A full-scale real fire experiment was further conducted under a 5 MW fire. Temperature measurements showed that the thermocouple tree nearest the fire source reached a maximum temperature of approximately 620 °C, posing a severe threat to unprotected steel roof structures. The temperatures below 2 m remained relatively lower, decreasing from about 250 °C to 150 °C. These results demonstrate that the concentrated fire scenario primarily endangers roof load-bearing structures, whereas the thermal conditions in the evacuation zone are comparatively less severe. Full article

Fire-induced domino effects in tank farms can be catastrophic, particularly under wind conditions. However, due to multiple evolutionary stages, Computational Fluid Dynamics (CFD)-based modelling of wind-influenced, fire-induced domino effects and tank farm Time to Failure (TTF) calculation remain computationally expensive. This study addresses this gap by using Fire Dynamics Simulator (FDS) to model fire-induced domino effects in a tank farm and perform detailed tank farm TTF calculations across multiple wind speeds and primary pool fire scenarios. The FDS results showed that increasing wind speed from 0 to 8 m/s altered domino escalation, increasing incident heat flux on the downwind in-line tank by more than sevenfold (a 35% reduction in tank farm TTF). A new perturbation-based analytical formulation was then proposed for rapid determination of tank farm TTF under wind effects, without requiring complete CFD simulations of pool fire escalation. The formulation updates tank farm TTF under the no-wind baseline solution with wind-influenced perturbative correction terms. The proposed formulation agreed with the detailed CFD modelling-based calculation, with a mean relative error of 2.8% across all primary fire scenarios and wind conditions. This formulation provides a practical basis for rapid assessment of domino effects due to pool fire under wind conditions. However, it is calibrated for one specific six-tank configuration and crosswind directions and is not yet general. Full article

Forecasting research repeatedly finds that simple methods can match or beat complex ones out of sample. We test this in a safety-critical domain, near-real-time prediction of fire hazard state and structural damage, using a simulator-grounded benchmark: high-fidelity computational fluid dynamics (Fire Dynamics Simulator, FDS) provides reference data, an FDS-calibrated zone model (CFAST) generates a large corpus cheaply, and the temperature trajectories drive a finite-element model (OpenSees) and a HAZUS/Eurocode-informed damage rule. Under one protocol we compare simple, deep (PatchTST, TimesNet), and physics-informed (PINN, PIKAN) forecasters. Complex models do not dominate: a small corpus lets parsimonious models approach best accuracy, and physics helps mainly when data are scarce (crossover near twenty scenarios). We propose CD-PINN, which identifies a data-optimal reduced-order physics residual from the corpus by physics-guided regression over a candidate library and uses it as the physics constraint. This lifts a per-event physics model to the accuracy of corpus-trained forecasters while staying interpretable. On 26 laboratory-fire experiments, however, in-distribution rankings do not transfer: the large accuracy spread collapses to near-parity, so a leaderboard poorly predicts laboratory-fire accuracy. For downstream damage, we further show that the label definition, not the model class, sets the achievable ceiling. Full article

Indoor fire smoke degrades visible-light cameras and near-infrared Lidar through wavelength-dependent absorption and scattering, threatening robotic navigation safety. Existing path planners either ignore sensor degradation or rely on empirical penalties lacking a physical basis. To address these issues, this paper proposes Quality Cost A* (QC-A*), which maps Fire Dynamics Simulator (FDS) visibility fields to sensor perception quality via the Koschmieder and Beer–Lambert physical laws, embedding a cost function that drives paths away from high-attenuation regions. A multi-sensor fusion layer provides fault tolerance under sensor-specific failure conditions. The method is validated through FDS-based simulations across four smoke scenarios in a $20\mathrm{m}\times 6\mathrm{m}$ corridor with 21 obstacles, using 50 start–goal pairs per scenario. Perception quality derives from Beer–Lambert optical transmittance, while the hazard-zone proportion quantifies path segments with visibility below 5 m. Across the Symmetric and Asymmetric scenarios, QC-A* reduces the low-visibility hazard-zone proportion from 40.7% to 19.6% and improves worst-case perception quality from 0.067 to 0.177, with a 15.3% path length increase, while remaining close to traditional A* in light-smoke conditions. Under constructed sensor failure tests, QC-A* maintains a 96–100% planning success rate versus 48% for Camera-Only and 70% for Lidar-Only. QC-A* shifts sensor degradation modeling from empirical penalty to physical mechanism, achieving a favorable safety–efficiency balance prioritizing perceptual safety, and provides an interpretable, generalizable framework for robotic fire-environment path planning. Full article

Road tunnel fires can produce rapid heat accumulation and severe thermal loading, particularly when fixed firefighting systems are not activated during the early stages of fire development. Although previous tunnel fire studies have examined ventilation effects and individual fire scenarios, only a limited number have quantitatively evaluated the performance of water-mist fixed firefighting systems under substantially different fire intensities using identical tunnel geometry and operating conditions. This gap restricts the ability to assess suppression efficiency across both moderate and severe tunnel fire scenarios. Computational fluid dynamics modelling, particularly the FDS–LES framework, enables controlled comparison of such scenarios that would be difficult, costly, or unsafe to reproduce in full-scale tunnel experiments, while providing detailed information on temperature field development and heat propagation. This study evaluates the influence of a water-mist fixed firefighting system on temperature development and the spatial extent of high-temperature zones in a road tunnel. Numerical simulations were performed in PyroSim using the Fire Dynamics Simulator (FDS) and the Large Eddy Simulation (LES) approach. Four scenarios were analyzed under identical tunnel geometry, ventilation conditions, and operational settings, combining two heat release rates (30 MW and 200 MW) with suppressed and unsuppressed fire conditions. The 30 MW case represented a passenger vehicle or light commercial vehicle fire, whereas the 200 MW case represented a severe heavy goods vehicle fire. The results showed that, in the 200 MW scenario, activation of the fixed firefighting system reduced the maximum temperature from 950 °C to 700 °C (−26%), while in the 30 MW scenario the maximum temperature decreased from 310 °C to 160 °C (−48%). Minimum temperatures were reduced from 550 °C to 200 °C in the 200 MW scenario and from 290 °C to 110 °C in the 30 MW scenario. The water-mist system also limited the propagation of the high-temperature layer beneath the tunnel ceiling, with a more pronounced relative effect under the lower heat release rate. Although complete suppression of the 200 MW fire was not achieved, the system reduced peak temperatures and limited the extent of critical high-temperature zones. The main contribution of this study is the quantitative comparison of water-mist suppression performance under moderate and severe tunnel fire conditions using the same tunnel configuration, which provides practical evidence for assessing peak-temperature reduction, high-temperature zone limitation, and thermal loading mitigation in road tunnel fire safety design. Full article

To investigate the effects of different surface coating treatments on the fire resistance of Qing Dynasty traditional corridor-style timber structures, the Long Corridor of the Beijing Summer Palace was selected as the case study. Two representative timber species, red pine and larch, were examined under three treatment conditions, including no treatment, traditional treatment (“San-dao-hui” and “Yi-ma-wu-hui”), and composite treatment combining traditional treatment with modern flame-retardant coatings. Cone calorimeter (CC) testing and Fire Dynamics Simulator (FDS) simulation were used to systematically investigate their combustion performance and fire spread patterns. Results indicate a clear, gradual improvement in timber reaction to fire: composite treatment coating performed best, followed by plaster layer protection, and untreated wood performed the worst. Among these, the composite treatment of red pine with “Yi-ma-wu-hui” (one hemp layer and five lime plaster layers) combined with modern flame-retardant coating showed the highest overall efficacy. The time to ignition (TTI) reached 76.7 s, a 210.5% increase compared with untreated wood. Meanwhile, peak heat release rate and carbon monoxide production were both significantly reduced. Notably, the selected modern flame-retardant coating cures colorless and transparent, preserving the original appearance of the wood, and the composite treatment maintains the historical texture and color consistency required for heritage restoration. The flame-retardant efficiency of the “Yi-ma-wu-hui” plaster layer was superior to that of the “San-dao-hui” (three lime plaster layers), owing to its denser structure that provides a stronger physical barrier effect. Larch exhibited better inherent reaction to fire than red pine, and surface coating treatments effectively reduced differences between substrates. FDS simulations confirmed that the composite treatment could keep peak heat release rate below 6000 kW under the most adverse meteorological conditions, confining high temperatures and dense smoke near the ignition point and effectively restraining sequential fire spread in traditional corridor-style timber structures. These findings provide a scientific basis and practical guidance for the fire-resistant restoration of Qing Dynasty traditional corridor-style timber structures and similar heritage buildings. Full article

Fire protection remains one of the key challenges in the field of architectural heritage conservation, particularly for heritage buildings dominated by timber structures, which face greater difficulties in fire prevention and risk assessment. To systematically evaluate the fire safety performance of high-rise timber heritage buildings, this study takes the Shengjin Pagoda, a typical brick–timber pavilion-style ancient tower in Jiangxi Province, China, as the research object. A three-dimensional performance-based fire assessment framework was developed using Fire Dynamics Simulator (FDS) and PyroSim. Based on field survey data and historical documentation, the geometric characteristics, material properties, and vertical circulation system of the pagoda were reconstructed. Three representative fire scenarios, including bottom-floor ignition, simultaneous multi-level ignition, and wind-driven top-floor ignition, were established to investigate smoke propagation, thermal insulation degradation, and the thermal response of critical timber components under different fire conditions. The results show that brick walls provide effective thermal insulation during the early stages of fire, with efficiency exceeding 90%, but this decreases to approximately 55% in upper regions due to chimney-effect-driven smoke accumulation. Under wind-driven top-floor ignition, exposed dougong components can reach temperatures of 782 °C, resulting in a progressive “top-down and outside-in” failure mechanism. The study reveals the dominant smoke-driven heat transfer pathways and the failure sequence of critical load-bearing elements. Based on these findings, a performance-based fire protection strategy incorporating vertical virtual smoke control zoning and fire-resistance enhancement of key structural components is proposed to support the sustainable conservation of historic high-rise timber structures. Full article

Prescribed burning is important for reducing wildfire risk and regulating fuel loads, but its implementation in mountainous forests is strongly influenced by the coupled effects of the wind field and topography, making it difficult to control. This study focuses on Yunnan pine (Pinus yunnanensis) forests in southwestern China. A three-dimensional Fire Dynamics Simulator (FDS) combined with measured fuel characteristics was used to simulate 21 slope (0–35°) and wind speed (0–2 m s⁻¹) combinations to quantitatively analyze the fire spread, flame structure, and gaseous emission characteristics during downslope prescribed burning. The local fire spread rate (ROS), evaluated along three lateral lines (Y = 2.5, 5.0, and 7.5 m), exhibits a non-monotonic dependence on slope over the tested range, with a minimum near 30° and a modest rebound at 35°. A downslope wind of 1 m s⁻¹ promotes near-surface heating and accelerates spread, whereas a stronger wind of 2 m s⁻¹ lifts flames away from the fuel bed and suppresses combustion. Thermal field analysis reveals that peak temperature decreases with increasing slope and that a late-stage secondary heating episode occurs at 35°. CO₂ emissions are significantly positively correlated with fuel consumption, reaching a peak of 717.5 kg under a 35° slope and no-wind conditions. CO emissions, as an indicator of combustion efficiency, reach their highest value of 2.23 kg at a 35° slope and a wind speed of 1 m s⁻¹, indicating that their trend is not entirely consistent with the ROS and temperature and that there is a certain degree of decoupling. The interaction between slope and wind speed transforms fire behavior from a cooperative to a competitive mechanism, and the topography–wind field coupling provides differentiated control over the combustion intensity and completeness. This study provides a scientific basis for the safe implementation of mountain burning programs and for regional carbon emission assessments. Full article

The adoption of electric vehicles (EVs) has posed new challenges to fire safety, especially when multiple EVs are transported on electric trailers, as limited studies exist on heavy electric vehicle transportation and little research has been conducted on fire development during EV tunnel transport. The aim of this study is to investigate the temperature, smoke, and tenability conditions produced by an electric trailer transporting eight EVs, where a fire initiates and spreads to all eight EVs, under two scenarios: natural ventilation and longitudinal tunnel ventilation. The Fire Dynamics Simulator (FDS) was used, and the combined peak heat release rate (HRR) of the vehicles was found to exceed 76 MW. Air temperatures around the fire source exceeded 1100 °C, while temperatures above 950 °C were recorded at the tunnel ceiling. The simulations captured thermal behaviour, smoke propagation, and the accumulation of carbon dioxide (CO₂) and carbon monoxide (CO). Longitudinal ventilation was shown to reduce upstream smoke spread and help maintain tenable conditions for evacuation and emergency response. These findings raise critical safety concerns regarding EV transportation in tunnels and support improved decision-making for tunnel infrastructure design and emergency responders. Full article

With the widespread application of automatic fire alarm systems in various types of buildings, the problem of fire false alarms has gradually become prominent, which not only causes resource waste, but also may reduce users’ trust in the alarm system, thereby affecting the efficiency of emergency response in actual fires. According to data from a certain fire cloud platform, 99.85% of the suspected fires predicted by its system are false alarms. Although existing models can recognize most fire accidents, the accuracy of fire alarm recognition is only 0.15%, due to loose judgment logic, which still requires a large amount of manpower to verify alarms. This article analyzes a large amount of false alarm data and explores the main causes of false alarms, including environmental interference, equipment failure, and improper human operation. By using a fire dynamics simulator (FDS) to establish fire simulation models under different data settings, horizontal and vertical multi-scene fire simulation data are obtained. The study combines simulation and platform data to form a fire and false alarm dataset using a one-dimensional convolutional neural network (1D-CNN) and deep neural network (DNN) deep learning techniques to learn the deductive rules of the fire scene, establish a two-stage judgment model, and gradually, accurately, judge the results. By quantifying the precision, recall, and F1 score of the model, a deep learning model designed to accurately identify genuine fire alarms while filtering out false ones is proposed that can significantly reduce the false alarm rate. The results indicate that the model can identify 1705 false alarms out of 2255 highly suspected true alarms identified by existing systems in multiple practical scenarios and eliminate 75.61% of false positive alarms. On the premise of ensuring an authenticity recognition rate greater than 98%, the accuracy of fire alarm recognition increased from 0.15% to 28.85%, which will significantly reduce the workload of staff verifying alerts, and has good practical value. Full article

Carbon fiber-reinforced polymer (CFRP) has been widely used in various fields due to its significant advantages. However, research on their pyrolysis and combustion behavior under fire conditions, which directly affects structural integrity and safety, remains insufficient. To challenge this issue, thermogravimetric analysis was employed to investigate the pyrolysis characteristics of the CFRP in both air and nitrogen atmospheres at heating rates of 20–40 °C/min with relevant pyrolysis kinetic parameters calculated using the Kissinger method. Fourier-transform infrared (FTIR) spectrometer was utilized to analyze pyrolytic gas species and concentrations at 40 °C/min in nitrogen atmosphere. Cone calorimeter tests at 50 kW/m² were conducted to obtain combustion characteristic parameters. Based on atomic conservation and oxygen-consumption principles, the equivalent molecular formula (CH_5.787O_0.541) of the epoxy resin pyrolysis gas and its combustion reaction equation were derived through reverse deduction. The heating, pyrolysis, and combustion processes of the CFRP (cone calorimetry specimen) were numerically simulated using Fire Dynamics Simulator (FDS). The predicted heat release rate, mass loss rate, and gas production rate showed good agreement with experimental results. Full article

Recently, numerous countries have experienced devastating wildfires, leading to significant destruction and loss of life. These catastrophic events highlight the shortcomings in current building regulations and testing methods. There is a pressing need for a more profound understanding of the characteristics and behaviour of large outdoor fires to address these inadequacies effectively. Wildfires can spread to structures located at the wildland–urban interface, leading to further fire propagation from one building to another. In this study, the Fire Dynamics Simulator (FDS) model was validated using experimental data from the National Institute of Standards and Technology (NIST). The experiment consisted of a target wall and a small wooden shed containing six wooden cribs as fuel, with a separation distance of 3 m. Both FDS and the experiment proved that 3 m is the safe separation distance. Different shed materials, such as steel, were used, which reduced the total heat release rate by 40% and the flame height by 20%. The effects of wind speed and direction were investigated using two wooden sheds in FDS to observe fire spread between them. The safe separation distance was 3 m for both wind speeds (2 and 5 m/s) in all directions, where the critical temperature was not reached to cause self-ignition of the second shed, except in the north direction (inward) at a speed of 5 m/s. When the separation distance increased to 3.5 m, the average heat flux at the other shed reduced to 3.18 kW/m², which did not cause self-ignition. Therefore, the safe separation distance between two structures for a wind speed of 5 m/s should be 3.5 m to mitigate the spread of fire based on the shed dimensions and the fire source load. Full article

Wildland fires, including surface and crown fires, present significant challenges for ecosystems and forest management. Accurate fire modelling is crucial for risk assessment and mitigation strategies. The Fire Dynamics Simulator (FDS) v6.8.0, developed by the National Institute of Standards and Technology (NIST), is a physics-based model that simulates fire behaviour by incorporating advanced physics and chemistry. However, its reliability requires thorough validation. This study validates FDS 6.8.0’s performance in modelling both surface fires and single tree burning. Two separate simulation sets were conducted. For surface fires, pine needle fuel beds were used at a laboratory scale to examine fire behaviour on slopes of 0°, 10°, and 20°. The results were validated against experimental data. A burning Douglas fir tree was simulated, and the results were compared with experimental measurements. The surface fire simulations at 0° and 10° slopes showed strong agreement with experimental data. In single-tree burning, both experimental and simulated results exhibited similar trends, with a rapid increase to a peak mass-loss rate (MLR) followed by a gradual decline. Validating FDS 6.8.0 forms an essential first step toward supporting the investigation of complex wildland fire behaviour, such as surface-to-crown fire transition, canyon fire, and dynamic escalation, using the same FDS version. Full article

The paper presents computational fluid dynamics (CFD) simulations of a propane-fueled and under-ventilated fire in a reduced-scale corridor-like enclosure. The fire source is positioned at the closed end of the corridor. Due to the restricted inflow of oxygen, the flame lifts off from the gaseous burner and travels—along with unburned fuel—all the way to the open doorway at the opposite end of the corridor. Oxygen calorimetry shows that a quasi-steady state plateau is established, during which the heat release rate (HRR) within the enclosure is equal to the theoretical value ${\dot{Q}}_{in}=1500 A_o\sqrt{H_o}$ where $A_o\sqrt{H_o}$ is the ventilation factor. Then, external flaming occurs. CFD simulations with the Fire Dynamics Simulator (FDS) captured well the overall flame dynamics. More specifically, the HRR plateau is well predicted, provided that the actual autoignition temperature of propane, AIT = 450 °C, is prescribed instead of the default AIT = −273 °C. However, the occurrence time of external flaming remains significantly underestimated and is better predicted by setting AIT = 600 °C. This aspect of the modelling, linked to extinction and (re-)ignition, remains to be further investigated in the future. Full article