Research

22 pages, 5533 KiB

Open AccessArticle

A Fireline Displacement Model to Predict Fire Spread

by Domingos X. Viegas, Carlos Ribeiro, Thiago Fernandes Barbosa, Tiago Rodrigues and Luís M. Ribeiro

Fire 2024, 7(4), 121; https://doi.org/10.3390/fire7040121 - 06 Apr 2024

Viewed by 677

Abstract

Most current surface fire simulators rely upon Rothermel’s model, which considers the local properties of fuel, topography, and meteorology to estimate the rate of spread, and utilises the concept of elliptical growth to predict the evolution of the fire perimeter throughout time. However, [...] Read more.

Most current surface fire simulators rely upon Rothermel’s model, which considers the local properties of fuel, topography, and meteorology to estimate the rate of spread, and utilises the concept of elliptical growth to predict the evolution of the fire perimeter throughout time. However, the effects of convective processes near the fireline, which modify fire spread conditions along the fire perimeter, are not considered in this model. An innovative fire prediction simulator based on the concept of fireline element displacement, which is composed of translation, rotation, and extension, rather than a point-by-point displacement, is proposed in this article. Based on the laws of convective heat fluxes across and along the fireline and on laboratory experiments, models to estimate the angular rotation velocity and the extension of the fireline during its displacement are proposed. These models are applied to a set of laboratory experiments of point ignition fires on slopes of 30° and 40° and, given the fact that the rate of spread of the head, back, and flank fire are known, the evolution of the fire perimeter can be predicted. The fire spread model can be applied to other situations of varying boundary conditions provided that the parameters required by the model are known. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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15 pages, 3246 KiB

Open AccessArticle

Numerical Simulation of the Smoke Distribution Characteristics in a T-Shaped Roadway

by Cui Ding, Dou Chang, Diange Sun and Songling Zou

Fire 2024, 7(3), 80; https://doi.org/10.3390/fire7030080 - 03 Mar 2024

Viewed by 829

Abstract

This paper numerically analyzes the influence of heat release rate (HRR) and longitudinal ventilation velocity on smoke distribution characteristics in a T-shaped roadway when the fire source was located upstream of the T-junction. The back-layering length, critical ventilation velocity, smoke temperature, and CO [...] Read more.

This paper numerically analyzes the influence of heat release rate (HRR) and longitudinal ventilation velocity on smoke distribution characteristics in a T-shaped roadway when the fire source was located upstream of the T-junction. The back-layering length, critical ventilation velocity, smoke temperature, and CO concentration in the main and branched roadway were investigated and analyzed. The results showed that the ventilation velocity is the key factor influencing back-layering length, while the effect of HRR on back-layering length is gradually weakened as HRR increases. The critical ventilation velocity in the T-shaped roadway is higher than in a single-tube roadway, and the predicted model of dimensional critical ventilation velocity in a T-shaped bifurcated roadway is proposed. The correlation between average temperature (Z = 1.6 m) (both in the main roadway I and the branched roadway) and ventilation velocity fits the power function, and the variation in average temperature (Z = 1.6 m) according to HRR fits the linear formula. The relation between average concentration of CO (Z = 1.6 m) (both inside the main roadway I and the branched roadway) and longitudinal ventilation velocity follows the power relation, and the variation in average concentration of CO (Z = 1.6 m) according to HRR follows the linear function. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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14 pages, 3090 KiB

Open AccessArticle

Thermal Decomposition Process of Fireproof Sealant Measured with Thermogravimetric and Fourier Transform Infrared Spectroscopy Analysis and Estimated Using Shuffled Complex Evolution

by Wei Liu, Xinrong Xu, Jiaqing Zhang, Yu Zhong, Xiang Li and Yanming Ding

Fire 2024, 7(1), 25; https://doi.org/10.3390/fire7010025 - 12 Jan 2024

Viewed by 1329

Abstract

Fireproof sealing technology is widely used in industrial, commercial, and other public buildings, so the performance of fireproof sealing materials in high temperatures or fire environments must be taken into account as an important factor. Fireproof sealant is considered to be a highly [...] Read more.

Fireproof sealing technology is widely used in industrial, commercial, and other public buildings, so the performance of fireproof sealing materials in high temperatures or fire environments must be taken into account as an important factor. Fireproof sealant is considered to be a highly effective adhesive for sealing and fireproofing purposes. To explore its thermal decomposition mechanism and estimate its pyrolysis behaviors, a series of thermogravimetric experiments from 10 K/min to 60 K/min coupled with Fourier transform infrared spectroscopy analysis technology were performed. The results indicated that the thermal decomposition of the fireproof sealant could be divided into three reactions: the degradation of ammonium polyphosphate, melamine, and acrylic acid. In addition, the pyrolysis behavior of the fireproof sealant was compared under two kinds of atmosphere (nitrogen and air). Furthermore, the initial kinetic parameters in the nitrogen atmosphere were calculated based on model-free methods including the Friedman, KAS, and Starink methods. The average activation energy of three reactions obtained by the three methods was 108.32 kJ/mol, 200.46 kJ/mol, and 177.10 kJ/mol, respectively, while these obtained parameters were hard to regenerate, the thermogravimetric curves were accurately based on the established pyrolysis reaction scheme, with the existence of clear deviations. Therefore, a global heuristic optimization algorithm, Shuffled Complex Evolution (SCE), was selected to optimize 14 parameters (including activation energies and the pre-exponential factors) and the optimized pyrolysis results agreed well with the experimental data, even at the extra heating rate, with the correlation coefficient for the mass loss and mass loss rate being reaching up to 0.9943 and 0.9019, respectively. The study indicated that the SCE algorithm showed an appropriate potential to estimate the pyrolysis behavior of an unknown thermogravimetric experiment group. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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15 pages, 3373 KiB

Open AccessArticle

Sensitivity Analysis of Influencing Factors of Fire Smoke Transport on Subway Station Platforms

by Huaitao Song, Qianlong Chen, Zeqi Wu, Haowei Yao, Zhen Lou, Zhenpeng Bai, Jingfen Li and Yueyang Yu

Fire 2023, 6(12), 448; https://doi.org/10.3390/fire6120448 - 23 Nov 2023

Viewed by 1428

Abstract

This paper investigates the sensitivity of factors influencing the transport of smoke in subway station fires by developing a three-dimensional physical model of a subway station using Building Information Modeling (BIM) technology and importing it into Fire Dynamics Simulator (FDS) software for numerical [...] Read more.

This paper investigates the sensitivity of factors influencing the transport of smoke in subway station fires by developing a three-dimensional physical model of a subway station using Building Information Modeling (BIM) technology and importing it into Fire Dynamics Simulator (FDS) software for numerical simulation. The orthogonal test method analyzes the effects of four common factors on temperature, CO concentration, and visibility. These factors are the mode of opening the screen door, the number of smoke vents opened, the number of smoke barriers, and the wind speed of the smoke vents. The results show that the smoke control system and the building structure influence smoke transport in subway stations, while the temperature and CO concentration gradually decrease as the distance from the fire source increases. In addition, the mode of opening the screen door is the most significant factor influencing temperature, CO concentration, and visibility using range and variance analysis. Moreover, the sensitivity analysis indicates that the optimal combination of all factors can significantly enhance the smoke exhaust efficiency. Compared with the average, the temperature optimal combination increases the smoke exhaust efficiency by 20.8%, CO concentration by 56.59%, and visibility by about 13.41%. This study provides a foundation for optimizing smoke control systems and formulating personnel evacuation strategies in subway stations. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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22 pages, 22943 KiB

Open AccessArticle

An FDS Simulation to Predict the Kerosene Pool Fire Results at Rocket Launchpad Basement Facilities in the Republic of Korea

by Hee Jin Kim, Kyeong Min Jang, In Seok Yeo, Hwa Young Oh, Sun Il Kang and Eun Sang Jung

Fire 2023, 6(10), 385; https://doi.org/10.3390/fire6100385 - 08 Oct 2023

Viewed by 1460

Abstract

In the Republic of Korea, a new rocket launchpad was constructed to launch the KSLV-II on an island, and all the launchpad facilities are located in basement. Because of the complex and diverse facilities, fire accidents have increased. Using the FDS (Fire Dynamics [...] Read more.

In the Republic of Korea, a new rocket launchpad was constructed to launch the KSLV-II on an island, and all the launchpad facilities are located in basement. Because of the complex and diverse facilities, fire accidents have increased. Using the FDS (Fire Dynamics Simulator) to predict the damage from kerosene storage and drain tank pool fires is garnering more attention as a tool of choice. The FDS supports a sprinkler model, which is needed to analyze fire extinguishing by water sprinkling. To predict and estimate the resistance of the building and thermal damage, the main analysis factors for a kerosene tank pool fire accident are temperature and HRR (heat release rate per unit volume). In 3

m^{3}

release cases, the maximum temperature decreased by 33% from 900 K to 600 K by sprinkled water, and the maximum HRR decreased by 70% from 20,000 kW/

m^{3}

to 6000 kW/

m^{3}

. In 10

m^{3}

release cases, the temperature and HRR decreased by 44%, from 800 K to 450 K and 68% from 25,000 kW/

m^{3}

to 8000 kW/

m^{3}

, respectively. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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14 pages, 4387 KiB

Open AccessArticle

Numerical Simulation of Downward Flame Propagation in Discontinuous Region of Solid Fuel

by Yeming Zhu, Shengfeng Luo, Yanli Zhao, Yiping Zeng, Guohua Wu, Ruichao Wei and Shutang Sun

Fire 2023, 6(5), 207; https://doi.org/10.3390/fire6050207 - 17 May 2023

Viewed by 1076

Abstract

This paper presents a numerical model that investigates the characteristics of flow, heat, and mass transfer on downward flame propagation in the discontinuous region of solid fuel. Simulations were carried out for various discontinuous distances to analyze the morphology of the flame front [...] Read more.

This paper presents a numerical model that investigates the characteristics of flow, heat, and mass transfer on downward flame propagation in the discontinuous region of solid fuel. Simulations were carried out for various discontinuous distances to analyze the morphology of the flame front and the competition between the “jump” of flame spread and heat transfer from the flame to the unburned area. The results demonstrate that there is a “jump” in the flame propagation in the discontinuous zone, with the flame front exhibiting a defined “acute angle” that undergoes a process from large to small during the flame spreading in the discontinuous area and deflects towards the discontinuous area of the material. The temperature in the discontinuous zone reaches a peak, and the average flame spread rate initially increases and then decreases with the increase of discontinuity distance until the flame spread stops. The study provides valuable insights into the growth and development of fires involving discretely distributed combustible materials. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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18 pages, 8279 KiB

Open AccessArticle

Numerical Simulation on the Smoke Prevention Performance of Air Curtains in an Island-Type Subway Station

by Xu Yan, Hongyun Yang, Huiqiang Mo, Ye Xie, Zhongfu Jin and Yang Zhou

Fire 2023, 6(5), 177; https://doi.org/10.3390/fire6050177 - 26 Apr 2023

Cited by 4 | Viewed by 1046 | Correction

Abstract

Subway fires are a major threat to the safe and smooth operation of subway stations. In this paper, an island-type subway station was taken as an example to conduct a series of numerical simulations using Fire Dynamics Simulator (FDS). The temperature, visibility, and [...] Read more.

Subway fires are a major threat to the safe and smooth operation of subway stations. In this paper, an island-type subway station was taken as an example to conduct a series of numerical simulations using Fire Dynamics Simulator (FDS). The temperature, visibility, and CO concentration in the subway station were analysed under different thicknesses and jet velocities of the air curtains. The smoke-prevention performance of the air curtains in the subway station was investigated. As the thickness and jet velocity increase, the flame tilts significantly, which greatly hinders the spread of smoke toward the stairs. The smoke temperature and CO concentration on the left side of the air curtains gradually decrease, while the visibility increases significantly. For a 3 MW fire scenario, to satisfy the evaluation criteria, the results show that the thickness of the air curtains needs to be at least 0.3 m, and the jet velocity needs to be at least 2 m/s. The sealing effectiveness (E_sealing) tends to increase and then remains constant with increasing momentum, and the maximum is obtained when the momentum of the air curtains (I_a) is 12.5 kg·m/s². Meanwhile, it is found that an energy-saving efficiency of 85.2% can be achieved by replacing positive pressure ventilation with air curtains. The results of this work can provide a significant reference for the design of smoke protection in subway stations. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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14 pages, 5780 KiB

Open AccessArticle

Numerical Study of the Effects of Surface Tension and Initial Volume Fraction on Gas-Liquid-Foam Three-Phase Flow Separation Process

by TianTian Tan, Jiaqing Zhang, Junjie Hu, Jianghong Zhang, Gang Sun, Bo Li and Yi Guo

Fire 2023, 6(3), 117; https://doi.org/10.3390/fire6030117 - 13 Mar 2023

Viewed by 1083

Abstract

Since it is low in cost and low in toxicity and has good biodegradability, gas-liquid-foam three-phase flow has been widely used in industrial fire protection. Due to the different characteristics of gas, liquid, and foam, liquid precipitation is liable to occur under static [...] Read more.

Since it is low in cost and low in toxicity and has good biodegradability, gas-liquid-foam three-phase flow has been widely used in industrial fire protection. Due to the different characteristics of gas, liquid, and foam, liquid precipitation is liable to occur under static conditions, resulting in unstable performance of the mixture. To improve fire extinguishing efficiency, it is of great significance to study the separation process of gas-liquid-foam. In the present study, the effects of the surface tension (range from 0.04 to 0.07) and initial liquid volume fraction (range from 0.2 to 0.5) on the gas-liquid-foam separation process are investigated with the numerical tool Fluent. The liquid volume fraction is mainly influenced by two inverse effects: (a) the transformation of liquid into foam, and (b) the liquid drainage and bursting of foam. In the separation process, the volume fraction of small foam decreases monotonically while the volume fraction of medium and large foam increases slightly. Since the volume fraction of small foam is much greater than medium and large foam and its bursting process is dominant, the liquid volume fraction presents a monotonic increasing trend. The volume of the separated liquid increases almost linearly with time at various surface tensions and initial volume fractions, and the increase rate is about 0.004. In the range of the surface tension examined, the separation process is insensitive to the surface tension, resulting in almost the same drainage time. On the other hand, the separation process depends on the initial liquid volume fraction non-monotonically; namely, when the initial volume fraction is small, with the increase of the initial volume fraction, the liquid is more easily separated from the mixture, and when the initial volume fraction is over a critical value (about 0.4), the separation process is decelerated. Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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14 pages, 4881 KiB

Open AccessArticle

Simulation of RC Beams during Fire Events Using a Nonlinear Numerical Fully Coupled Thermal-Stress Analysis

by Mohamed Elshorbagi and Mohammad AlHamaydeh

Fire 2023, 6(2), 57; https://doi.org/10.3390/fire6020057 - 07 Feb 2023

Cited by 3 | Viewed by 1494

Abstract

The collapse and deterioration of infrastructures due to fire events are documented annually. These fire incidents result in multiple deaths and property loss. In this paper, a reliable and practical numerical methodology was introduced to facilitate the whole process of fire simulations and [...] Read more.

The collapse and deterioration of infrastructures due to fire events are documented annually. These fire incidents result in multiple deaths and property loss. In this paper, a reliable and practical numerical methodology was introduced to facilitate the whole process of fire simulations and increase the practicality of performing comprehensive parametric studies in the future. These parametric studies are crucial for understanding the factors that affect thermal–structural responses and avoiding the high cost of destructive tests. The proposed algorithm comprises a fully nonlinear coupled thermal-stress analysis involving thermal and structural material nonlinearity and the thermal–structural response during a fire. A detailed numerical modeling analysis was performed with ABAQUS to achieve the proposed algorithm. The results of the proposed numerical methodology were validated against published experimental work. The experimental work includes a full-scale RC beam loaded with working loads and standard heating conditions to simulate real-life scenarios. The tested beam failed during the fire, and its fire resistance was recorded. The results demonstrated a good correlation with the experimental results in thermal and structural responses. Moreover, this paper presents the direct coupling technique (DCT) and the advantages of using DCT over the traditional sequential coupling technique (SCT). Full article

(This article belongs to the Special Issue Fire Numerical Simulation)

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