Armando La Scala, Pierpaolo Loprieno, S. Ivorra, Dora Foti, Massimo La Scala
This study analyzes the thermo-mechanical behavior of a brick vault and the effect of a fire on its dynamic characteristics. Based on the results of an experimental test of a real barrel vault with a net span of 161 cm and a net rise of 46.5 cm, an accurate numerical model to simulate the behavior of the brick-and-mortar structure under thermo-mechanical stresses has been implemented. The comparison of the evolution of the displacement in the keystone and the temperatures at various points of the vault allows us to affirm that the adopted micro-modeling approach presents a good accuracy and a feasible computational effort. Finally, this study shows, from a numerical point of view, how the variation in the structure’s eigenfrequencies can be predicted for extreme situations, such as fire damage. This aspect can be critical to develop effective intervention and prevention strategies, which can be useful for the preservation of our valuable cultural and historic resources.
{"title":"Modal Analysis of a Fire-Damaged Masonry Vault","authors":"Armando La Scala, Pierpaolo Loprieno, S. Ivorra, Dora Foti, Massimo La Scala","doi":"10.3390/fire7060194","DOIUrl":"https://doi.org/10.3390/fire7060194","url":null,"abstract":"This study analyzes the thermo-mechanical behavior of a brick vault and the effect of a fire on its dynamic characteristics. Based on the results of an experimental test of a real barrel vault with a net span of 161 cm and a net rise of 46.5 cm, an accurate numerical model to simulate the behavior of the brick-and-mortar structure under thermo-mechanical stresses has been implemented. The comparison of the evolution of the displacement in the keystone and the temperatures at various points of the vault allows us to affirm that the adopted micro-modeling approach presents a good accuracy and a feasible computational effort. Finally, this study shows, from a numerical point of view, how the variation in the structure’s eigenfrequencies can be predicted for extreme situations, such as fire damage. This aspect can be critical to develop effective intervention and prevention strategies, which can be useful for the preservation of our valuable cultural and historic resources.","PeriodicalId":12279,"journal":{"name":"Fire","volume":" 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141368353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Berta Elena Ferrandez-Garcia, Teresa Garcia-Ortuño, M. Ferrández-Villena, M. Ferrandez-García
Repurposing agricultural and forestry by-products not only is beneficial for the environment but also follows the principles of the circular economy. In southeastern Spain, the Canary Island palm tree (Phoenix canariensis W.) is widely used in urban landscapes. Plantations affected by the red weevil, a pest, generate an abundance of plant waste that must be crushed and transferred to authorized landfills. The aim of this study was to manufacture boards using particles from trunks of the Canary Island palm tree without adding any binders in order to obtain an ecological and fire-resistant product. In order to manufacture the boards, three particle sizes (<0.25, 0.25–1, and 1–2 mm), a temperature of 110 °C, a pressure of 2.6 MPa, and a pressing time of 7 min were used. The boards were pressed in a hot plate press for 7 min up to four times (7 min, 7 + 7 min, 7 + 7 + 7 min, and 7 + 7 + 7 + 7 min). The resulting boards showed good thermal performance, and the board´s reaction-to-fire performance was classified as Bd0 (an Fs value of 70.3 mm). This study also showed that boards with a particle size smaller than 0.25 mm that underwent four pressing cycles of 7 min each in the press can be categorized as grade P2 according to the European Standards (MOR of 20 N/mm2, MOE of 2589.8 N/mm2, and IB of 0.74 N/mm2). Therefore, these manufactured particleboards could be used as a flame-retardant material for the interior enclosures of buildings (vertical and horizontal) without the need for coatings.
{"title":"Evaluation of the Properties and Reaction-to-Fire Performance of Binderless Particleboards Made from Canary Island Palm Trunks","authors":"Berta Elena Ferrandez-Garcia, Teresa Garcia-Ortuño, M. Ferrández-Villena, M. Ferrandez-García","doi":"10.3390/fire7060193","DOIUrl":"https://doi.org/10.3390/fire7060193","url":null,"abstract":"Repurposing agricultural and forestry by-products not only is beneficial for the environment but also follows the principles of the circular economy. In southeastern Spain, the Canary Island palm tree (Phoenix canariensis W.) is widely used in urban landscapes. Plantations affected by the red weevil, a pest, generate an abundance of plant waste that must be crushed and transferred to authorized landfills. The aim of this study was to manufacture boards using particles from trunks of the Canary Island palm tree without adding any binders in order to obtain an ecological and fire-resistant product. In order to manufacture the boards, three particle sizes (<0.25, 0.25–1, and 1–2 mm), a temperature of 110 °C, a pressure of 2.6 MPa, and a pressing time of 7 min were used. The boards were pressed in a hot plate press for 7 min up to four times (7 min, 7 + 7 min, 7 + 7 + 7 min, and 7 + 7 + 7 + 7 min). The resulting boards showed good thermal performance, and the board´s reaction-to-fire performance was classified as Bd0 (an Fs value of 70.3 mm). This study also showed that boards with a particle size smaller than 0.25 mm that underwent four pressing cycles of 7 min each in the press can be categorized as grade P2 according to the European Standards (MOR of 20 N/mm2, MOE of 2589.8 N/mm2, and IB of 0.74 N/mm2). Therefore, these manufactured particleboards could be used as a flame-retardant material for the interior enclosures of buildings (vertical and horizontal) without the need for coatings.","PeriodicalId":12279,"journal":{"name":"Fire","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141369883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huaizhou Li, Shuaijun Wang, Sen Li, Hong Wang, Shupei Wen, Fengyu Li
Obtaining thermal infrared images with prominent details, high contrast, and minimal background noise has always been a focal point of infrared technology research. To address issues such as the blurriness of details and low contrast in thermal infrared images, an enhancement algorithm for thermal infrared images based on multi-scale guided filtering is proposed. This algorithm fully leverages the excellent edge-preserving characteristics of guided filtering and the multi-scale nature of the edge details in thermal infrared images. It uses multi-scale guided filtering to decompose each thermal infrared image into multiple scales of detail layers and a base layer. Then, CLAHE is employed to compress the grayscale and enhance the contrast of the base layer image. Then, detail-enhancement processing of the multi-scale detail layers is performed. Finally, the base layer and the multi-scale detail layers are linearly fused to obtain an enhanced thermal infrared image. Our experimental results indicate that, compared to other methods, the proposed method can effectively enhance image contrast and enrich image details, and has higher image quality and stronger scene adaptability.
{"title":"Thermal Infrared-Image-Enhancement Algorithm Based on Multi-Scale Guided Filtering","authors":"Huaizhou Li, Shuaijun Wang, Sen Li, Hong Wang, Shupei Wen, Fengyu Li","doi":"10.3390/fire7060192","DOIUrl":"https://doi.org/10.3390/fire7060192","url":null,"abstract":"Obtaining thermal infrared images with prominent details, high contrast, and minimal background noise has always been a focal point of infrared technology research. To address issues such as the blurriness of details and low contrast in thermal infrared images, an enhancement algorithm for thermal infrared images based on multi-scale guided filtering is proposed. This algorithm fully leverages the excellent edge-preserving characteristics of guided filtering and the multi-scale nature of the edge details in thermal infrared images. It uses multi-scale guided filtering to decompose each thermal infrared image into multiple scales of detail layers and a base layer. Then, CLAHE is employed to compress the grayscale and enhance the contrast of the base layer image. Then, detail-enhancement processing of the multi-scale detail layers is performed. Finally, the base layer and the multi-scale detail layers are linearly fused to obtain an enhanced thermal infrared image. Our experimental results indicate that, compared to other methods, the proposed method can effectively enhance image contrast and enrich image details, and has higher image quality and stronger scene adaptability.","PeriodicalId":12279,"journal":{"name":"Fire","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141369805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wen-xiong Xi, Peng Liu, Rongdi Zhang, Tianyang Dong, Jian Liu
This work primarily focuses on a three-dimensional model of flame propagation and stable combustion in a scramjet chamber. The one-equation LES turbulence model is adopted to close the sub-grid-scale turbulent viscosity terms. The finite-rate combustion model, along with the Jachimowski detailed hydrogen reaction mechanism with eight components and nineteen steps, is used to analyze the flame propagation characteristics of hydrogen combustion in the scramjet combustion chamber. Initially, based on the combustion chamber model, the effect of different injection locations and equivalence ratios on flame kernel formation and the flame propagation process is analyzed. The relationship between different fuel injection conditions and the oxygen consumption rate of the combustion chamber, as well as the total pressure recovery coefficient changes, is investigated. The research focuses on changes in equivalence ratios and injection hole distributions, with injection holes arranged upstream, downstream, and inside of the cavity. The result indicated that when the injection holes were arranged downstream of the cavity, there was a phenomenon of flame backflow into the cavity, which was related to the size of the injection pressure. For this work, the pressure causing flame backflow was approximately 2 MPa. When the injection hole was arranged inside the cavity, the relative distance difference between the injection hole and the upper wall of the cavity led to the formation of two reaction zones in the combustion chamber. When the injection hole was arranged upstream of the cavity, different injection equivalence ratios affected the final stable position and structure of the flame. Therefore, the injection position, injection pressure, and injection equivalence ratio all had a certain impact on the flame kernel formation and flame propagation process.
这项研究主要侧重于火焰在喷气燃烧室中传播和稳定燃烧的三维模型。采用一方程 LES 湍流模型来关闭子网格尺度湍流粘度项。有限速率燃烧模型与包含八个组成部分和十九个步骤的 Jachimowski 详细氢气反应机理一起用于分析氢气在scramjet 燃烧室中燃烧的火焰传播特性。首先，基于燃烧室模型，分析了不同喷射位置和当量比对火焰内核形成和火焰传播过程的影响。研究了不同燃料喷射条件与燃烧室耗氧率之间的关系，以及总压恢复系数的变化。研究重点是等效比和喷射孔分布的变化，喷射孔分别布置在腔体的上游、下游和内部。结果表明，当喷射孔布置在空腔下游时，会出现火焰倒流进入空腔的现象，这与喷射压力的大小有关。在这项工作中，导致火焰倒流的压力约为 2 兆帕。当喷射孔布置在空腔内部时，喷射孔与空腔上壁之间的相对距离差导致燃烧室内形成两个反应区。当喷射孔布置在空腔上游时，不同的喷射当量比会影响火焰的最终稳定位置和结构。因此，喷射位置、喷射压力和喷射当量比都对焰核的形成和火焰的传播过程有一定的影响。
{"title":"Numerical Investigation of Flow Structures and Combustion Mechanisms with Different Injection Locations in a Hydrogen-Fueled Scramjet Combustor","authors":"Wen-xiong Xi, Peng Liu, Rongdi Zhang, Tianyang Dong, Jian Liu","doi":"10.3390/fire7060191","DOIUrl":"https://doi.org/10.3390/fire7060191","url":null,"abstract":"This work primarily focuses on a three-dimensional model of flame propagation and stable combustion in a scramjet chamber. The one-equation LES turbulence model is adopted to close the sub-grid-scale turbulent viscosity terms. The finite-rate combustion model, along with the Jachimowski detailed hydrogen reaction mechanism with eight components and nineteen steps, is used to analyze the flame propagation characteristics of hydrogen combustion in the scramjet combustion chamber. Initially, based on the combustion chamber model, the effect of different injection locations and equivalence ratios on flame kernel formation and the flame propagation process is analyzed. The relationship between different fuel injection conditions and the oxygen consumption rate of the combustion chamber, as well as the total pressure recovery coefficient changes, is investigated. The research focuses on changes in equivalence ratios and injection hole distributions, with injection holes arranged upstream, downstream, and inside of the cavity. The result indicated that when the injection holes were arranged downstream of the cavity, there was a phenomenon of flame backflow into the cavity, which was related to the size of the injection pressure. For this work, the pressure causing flame backflow was approximately 2 MPa. When the injection hole was arranged inside the cavity, the relative distance difference between the injection hole and the upper wall of the cavity led to the formation of two reaction zones in the combustion chamber. When the injection hole was arranged upstream of the cavity, different injection equivalence ratios affected the final stable position and structure of the flame. Therefore, the injection position, injection pressure, and injection equivalence ratio all had a certain impact on the flame kernel formation and flame propagation process.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"206 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141375876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Majdalani, Ignacio Calderón, Wolfram Jahn, J. Torero
The traditional concept of compartmentation guaranteed by fire resistance is mainly concerned with the problem of destructive internal spread potential. External convective spread potential pertains to the loss of compartmentation associated with windows and facade systems. As such, it is assumed that internal fire spread occurs following mechanisms of excessive heat conduction and/or successive failure of the compartment boundaries, which can be, in most cases, conservatively characterised using traditional methods of performance assessment such as fire resistance. Nevertheless, external fire spread represents a potentially more effective route by which fire can spread through the convective advancement of flames and hot gases. This is particularly important in cases such as timber construction, where the presence of exposed timber can result in increased convective spread potential and where loss of compartmentation can result in disproportionate consequences. A simplified compartment fire model is proposed with the objective of quantifying the fuel contribution of exposed timber elements to the compartment fire and determining the impact of variable percentages of exposed timber on the convective spread potential. The overall results show that the convective fire spread potential increases with the increasing percentage of available timber.
{"title":"Understanding Compartmentation Failure for High-Rise Timber Buildings","authors":"A. Majdalani, Ignacio Calderón, Wolfram Jahn, J. Torero","doi":"10.3390/fire7060190","DOIUrl":"https://doi.org/10.3390/fire7060190","url":null,"abstract":"The traditional concept of compartmentation guaranteed by fire resistance is mainly concerned with the problem of destructive internal spread potential. External convective spread potential pertains to the loss of compartmentation associated with windows and facade systems. As such, it is assumed that internal fire spread occurs following mechanisms of excessive heat conduction and/or successive failure of the compartment boundaries, which can be, in most cases, conservatively characterised using traditional methods of performance assessment such as fire resistance. Nevertheless, external fire spread represents a potentially more effective route by which fire can spread through the convective advancement of flames and hot gases. This is particularly important in cases such as timber construction, where the presence of exposed timber can result in increased convective spread potential and where loss of compartmentation can result in disproportionate consequences. A simplified compartment fire model is proposed with the objective of quantifying the fuel contribution of exposed timber elements to the compartment fire and determining the impact of variable percentages of exposed timber on the convective spread potential. The overall results show that the convective fire spread potential increases with the increasing percentage of available timber.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"314 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141386181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qing Nian Chan, Dongli Gao, Yu Zhou, S. Xing, Guanxiong Zhai, Cheng Wang, Wei Wang, S. H. Lim, Eric Wai Ming Lee, Guan Heng Yeoh
Developing mmWave radar sensors for indoor crowd motion sensing and tracking faces a critical challenge: the scarcity of large-scale, high-quality training data. Traditional human experiments encounter logistical complexities, ethical considerations, and safety issues. Replicating precise human movements across trials introduces noise and inconsistency into the data. To address this, this study proposes a novel solution: a movable platform equipped with a life-size mannequin to generate realistic and diverse data points for mmWave radar training and testing. Unlike human subjects, the platform allows precise control over movements, optimising sensor placement relative to the target object. Preliminary optimisation results reveal that sensor height impacts tracking performance, with an optimal sensor placement above the test subject yields the best results. The results also reveal that the 3D data format outperforms 2D data in accuracy despite having fewer frames. Additionally, analysing height distribution using 3D data highlights the importance of the sensor angle—15° downwards from the horizontal plane.
{"title":"A Novel Movable Mannequin Platform for Evaluating and Optimising mmWave Radar Sensor for Indoor Crowd Evacuation Monitoring Applications","authors":"Qing Nian Chan, Dongli Gao, Yu Zhou, S. Xing, Guanxiong Zhai, Cheng Wang, Wei Wang, S. H. Lim, Eric Wai Ming Lee, Guan Heng Yeoh","doi":"10.3390/fire7060181","DOIUrl":"https://doi.org/10.3390/fire7060181","url":null,"abstract":"Developing mmWave radar sensors for indoor crowd motion sensing and tracking faces a critical challenge: the scarcity of large-scale, high-quality training data. Traditional human experiments encounter logistical complexities, ethical considerations, and safety issues. Replicating precise human movements across trials introduces noise and inconsistency into the data. To address this, this study proposes a novel solution: a movable platform equipped with a life-size mannequin to generate realistic and diverse data points for mmWave radar training and testing. Unlike human subjects, the platform allows precise control over movements, optimising sensor placement relative to the target object. Preliminary optimisation results reveal that sensor height impacts tracking performance, with an optimal sensor placement above the test subject yields the best results. The results also reveal that the 3D data format outperforms 2D data in accuracy despite having fewer frames. Additionally, analysing height distribution using 3D data highlights the importance of the sensor angle—15° downwards from the horizontal plane.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"9 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141101354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Meng Li, Zhenhua Wang, Juncheng Jiang, Wanbing Lin, Lei Ni, Yong Pan, Guanghu Wang
The use of existing natural gas pipelines for the transport of hydrogen/natural gas mixtures can achieve large-scale, long-distance and low-cost hydrogen transportation. A jet fire induced by the leakage of high-pressure pure hydrogen and hydrogen-blended natural gas pipelines may pose a severe threat to life and property. Based on the Abel–Nobel equation of state and a notional nozzle model, an equivalent pipe leakage model is established to simulate high-pressure pipeline gas leakage jet fire accidents. Large-scale high-pressure hydrogen and natural gas/hydrogen mixture jet fires are simulated, showing the jet impingement process and obtaining an accurate and effective simulation framework. This framework is validated by comparing the simulated and experimental measured results of flame height, flame appearance and thermal radiation. Several combustion models are compared, and the simulated data show that the non-premixed chemical equilibrium combustion model is superior to other combustion models. The influence of the pipe pressure and the hydrogen blending ratio on the consequences of natural gas/hydrogen mixture pipeline leakage jet fire accidents is explored. It is found that when the hydrogen blending ratio is lower than 22%, the increase in the hydrogen blending ratio has little effect on the decrease in the thermal radiation hazard distance.
{"title":"Numerical Simulation and Consequence Analysis of Full-Scale Jet Fires for Pipelines Transporting Pure Hydrogen or Hydrogen Blended with Natural Gas","authors":"Meng Li, Zhenhua Wang, Juncheng Jiang, Wanbing Lin, Lei Ni, Yong Pan, Guanghu Wang","doi":"10.3390/fire7060180","DOIUrl":"https://doi.org/10.3390/fire7060180","url":null,"abstract":"The use of existing natural gas pipelines for the transport of hydrogen/natural gas mixtures can achieve large-scale, long-distance and low-cost hydrogen transportation. A jet fire induced by the leakage of high-pressure pure hydrogen and hydrogen-blended natural gas pipelines may pose a severe threat to life and property. Based on the Abel–Nobel equation of state and a notional nozzle model, an equivalent pipe leakage model is established to simulate high-pressure pipeline gas leakage jet fire accidents. Large-scale high-pressure hydrogen and natural gas/hydrogen mixture jet fires are simulated, showing the jet impingement process and obtaining an accurate and effective simulation framework. This framework is validated by comparing the simulated and experimental measured results of flame height, flame appearance and thermal radiation. Several combustion models are compared, and the simulated data show that the non-premixed chemical equilibrium combustion model is superior to other combustion models. The influence of the pipe pressure and the hydrogen blending ratio on the consequences of natural gas/hydrogen mixture pipeline leakage jet fire accidents is explored. It is found that when the hydrogen blending ratio is lower than 22%, the increase in the hydrogen blending ratio has little effect on the decrease in the thermal radiation hazard distance.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"6 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141100856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoliang Zhang, Shibing Kuang, Yanli Zhao, Jun Zhang, Shengfeng Luo
Flame spread over discrete fuels is a typical phenomenon in fire scenes. Experimental and theoretical research on flame spread over discrete thermally thin fuels separated by air gaps with different inclination angles was conducted in the present study. Experiments with six inclination angles ranging from 0° to 85° and various fuel coverage rates from 0.421 to 1 were designed. The flame spread behavior, the characteristic flame size, and the flame spread rate were analyzed. The results show that the flow pattern, stability, and flame size exhibit different characteristics with different inclination angles and gap sizes. As the inclination angle increases, particularly with smaller gaps, turbulent and oscillating flames are observed, while larger gap sizes promote flame stability. The mechanism of flame propagation across the gap depends on the interplay between the flame jump effect and heat transfer, which evolves with gap size. Average flame height, average flame width, and flame spread rate initially increase and then decline with the increase in fuel coverage, peaking at fuel coverage rates between 0.93 and 0.571 for different inclination angles. A theoretical model is proposed to predict the flame spread rate and the variation in the flame spread rate with inclination angle and fuel coverage. Furthermore, the map determined by inclination angle and fuel coverage is partitioned into distinct regions, comprising the accelerated flame spread region, the flame spread weakening region, and the failed flame spread region. These findings provide valuable insights into flame spread dynamics over discrete thermally thin fuels under diverse conditions.
{"title":"Experimental Investigation and Theoretical Analysis of Flame Spread Dynamics over Discrete Thermally Thin Fuels with Various Inclination Angles and Gap Sizes","authors":"Xiaoliang Zhang, Shibing Kuang, Yanli Zhao, Jun Zhang, Shengfeng Luo","doi":"10.3390/fire7060177","DOIUrl":"https://doi.org/10.3390/fire7060177","url":null,"abstract":"Flame spread over discrete fuels is a typical phenomenon in fire scenes. Experimental and theoretical research on flame spread over discrete thermally thin fuels separated by air gaps with different inclination angles was conducted in the present study. Experiments with six inclination angles ranging from 0° to 85° and various fuel coverage rates from 0.421 to 1 were designed. The flame spread behavior, the characteristic flame size, and the flame spread rate were analyzed. The results show that the flow pattern, stability, and flame size exhibit different characteristics with different inclination angles and gap sizes. As the inclination angle increases, particularly with smaller gaps, turbulent and oscillating flames are observed, while larger gap sizes promote flame stability. The mechanism of flame propagation across the gap depends on the interplay between the flame jump effect and heat transfer, which evolves with gap size. Average flame height, average flame width, and flame spread rate initially increase and then decline with the increase in fuel coverage, peaking at fuel coverage rates between 0.93 and 0.571 for different inclination angles. A theoretical model is proposed to predict the flame spread rate and the variation in the flame spread rate with inclination angle and fuel coverage. Furthermore, the map determined by inclination angle and fuel coverage is partitioned into distinct regions, comprising the accelerated flame spread region, the flame spread weakening region, and the failed flame spread region. These findings provide valuable insights into flame spread dynamics over discrete thermally thin fuels under diverse conditions.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"12 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141106742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adéla Snohová, Petr Kučera, Jiri Pokorny, A. Bernatik
This paper addresses the evacuation of people from multipurpose halls and introduces an innovative approach that uses a probabilistic model, specifically the Monte Carlo method, to analyse iterative evacuation processes. The aim is to explore how this modern technology can contribute to the development of effective and safe evacuation plans for mass events. The Monte Carlo method was applied to a specific example of a multipurpose hall that offers different configurations for events such as sports matches, concerts, or performances. The evacuation of people was analysed for two configurations: a hockey match with a capacity of 9500 people and a concert with a capacity of 11,000 people. In both cases, the total evacuation of people from the hall was analysed, and the evacuation time was evaluated when two parameters were changed: speed of movement and preference for door selection. The results of the simulations can provide valuable information for the design of effective safety measures in multipurpose halls and other similar multipurpose venues. This innovative approach to evacuation analysis allows for a comprehensive assessment of the evacuation process, identification of critical areas, and verification of the layout of the space.
{"title":"Monte Carlo Analysis for Evacuation in Multipurpose Event Spaces","authors":"Adéla Snohová, Petr Kučera, Jiri Pokorny, A. Bernatik","doi":"10.3390/fire7060178","DOIUrl":"https://doi.org/10.3390/fire7060178","url":null,"abstract":"This paper addresses the evacuation of people from multipurpose halls and introduces an innovative approach that uses a probabilistic model, specifically the Monte Carlo method, to analyse iterative evacuation processes. The aim is to explore how this modern technology can contribute to the development of effective and safe evacuation plans for mass events. The Monte Carlo method was applied to a specific example of a multipurpose hall that offers different configurations for events such as sports matches, concerts, or performances. The evacuation of people was analysed for two configurations: a hockey match with a capacity of 9500 people and a concert with a capacity of 11,000 people. In both cases, the total evacuation of people from the hall was analysed, and the evacuation time was evaluated when two parameters were changed: speed of movement and preference for door selection. The results of the simulations can provide valuable information for the design of effective safety measures in multipurpose halls and other similar multipurpose venues. This innovative approach to evacuation analysis allows for a comprehensive assessment of the evacuation process, identification of critical areas, and verification of the layout of the space.","PeriodicalId":12279,"journal":{"name":"Fire","volume":"29 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141104802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander J. McFadden, D. Stow, P. Riggan, R. Tissell, John O’Leary, Henry Scharf
Studies on estimating cumulative fire intensity from spreading wildland fires based on fire radiative energy density (FRED) have primarily been conducted through controlled experiments. The objective of this study was to assess the potential for estimating FRED for freely-burning wildfires at landscape scales. Airborne thermal infrared image sequences collected 8 and 9 December 2017 during the Thomas Fire were used for surface temperature derivation and FRED estimation. Sensitivity of varying ambient temperatures, and a newly developed method that adjusts for ash radiances on fire radiative flux density (FRFD) and FRED estimates were tested. Pixel-level image classification was run to identify FRFD time sequences that were complete or incomplete because of cloud obscuration and provided the basis for an obscuration gap filling technique. Variations in estimated ambient temperature used to estimate FRFD had little impact on FRED estimates, while our ash adjustment led to notable differences. An exponential decay model characterized FRFD time sequences well, providing a basis for gap filling irregular sequences caused by atmospheric obscuration. FRED estimates were regressed on rate of spread (ROS) magnitudes and found to be positively and significantly correlated. FRED magnitudes were higher on 9 December when the Thomas Fire burned under higher wind speeds and lower relative humidity levels (Santa Ana weather conditions) than on 8 December.
基于火灾辐射能量密度（FRED）估算蔓延野火的累积火灾强度的研究主要是通过受控实验进行的。本研究的目的是评估在地貌尺度上估算自由燃烧野火的 FRED 的潜力。在 2017 年 12 月 8 日和 9 日托马斯大火期间采集的机载热红外图像序列被用于地表温度推导和 FRED 估算。测试了不同环境温度的敏感性，以及新开发的方法，该方法可调整灰烬辐射对火灾辐射通量密度（FRFD）和 FRED 估计值的影响。进行了像素级图像分类，以确定因云层遮挡而完整或不完整的 FRFD 时间序列，并为遮挡间隙填充技术提供依据。用于估算 FRFD 的估计环境温度的变化对 FRED 估计值影响不大，而我们的灰分调整则导致了明显的差异。指数衰减模型很好地描述了 FRFD 时间序列，为填补大气遮蔽造成的不规则序列提供了依据。对 FRED 估计值与扩散率（ROS）大小进行了回归分析，发现两者之间存在显著的正相关关系。与 12 月 8 日相比，托马斯大火在风速更高、相对湿度更低（圣安娜天气条件）的情况下于 12 月 9 日燃烧时的 FRED 幅值更高。
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