Numerical Simulations of Dynamics of a Tunnel Fire

2004 ◽  
Author(s):  
Kedar Pathak ◽  
Kendrick Aung
Keyword(s):  
Fire Hazard ◽  
Radiation Heat Transfer ◽  
Fire Behavior ◽  
Radiant Heat ◽  
Temperature Fields ◽  
Smoke Movement ◽  
Transit Systems ◽  
Tunnel Fire ◽  
Computational Fluid Dynamics Cfd ◽  
Turbulent Models

Study of fire in a tunnel is very important for fire safety. Increasing concerns over terrorism put a lot of focus on the fires in tunnels as they are used extensively in mass transit systems all over the world. A lot of experiments have been carried out to study the fire hazard, smoke movement, and the effects of ventilation on fire behavior. In this paper, dynamics of a ventilated tunnel fire have been simulated using Computational Fluid Dynamics (CFD) Software, CFX 5.6, from Ansys Inc. Simulations considers different models of turbulence and radiation heat transfer. Combustion of methane is modeled using the chemical reaction schemes available in the CFX software. Two turbulent models, k–ε and Shear Stress Transport, are considered. Radiant heat exchange between the species is modeled using P1 model available in CFX 5.6. The results of the simulation have highlighted the effects of ventilation on the fire and movement of harmful gases such as carbon monoxide and nitrogen oxide. Comparison of simulated temperature fields and flame shape with the experimental data has shown good agreement.

scholarly journals AEGIS: a wildfire prevention and management information system

2016 ◽  
Vol 16 (3) ◽  
pp. 643-661 ◽  
Author(s):  
Kostas Kalabokidis ◽  
Alan Ager ◽  
Mark Finney ◽  
Nikos Athanasis ◽  
Palaiologos Palaiologou ◽  
...  
Keyword(s):  
Fire Hazard ◽  
Fire Behavior ◽  
End Users ◽  
Burned Area ◽  
Fire Control ◽  
Web Based ◽  
Ignition Point ◽  
Weather Information ◽  
Management Platform ◽  
Burn Probability

Abstract. We describe a Web-GIS wildfire prevention and management platform (AEGIS) developed as an integrated and easy-to-use decision support tool to manage wildland fire hazards in Greece (http://aegis.aegean.gr). The AEGIS platform assists with early fire warning, fire planning, fire control and coordination of firefighting forces by providing online access to information that is essential for wildfire management. The system uses a number of spatial and non-spatial data sources to support key system functionalities. Land use/land cover maps were produced by combining field inventory data with high-resolution multispectral satellite images (RapidEye). These data support wildfire simulation tools that allow the users to examine potential fire behavior and hazard with the Minimum Travel Time fire spread algorithm. End-users provide a minimum number of inputs such as fire duration, ignition point and weather information to conduct a fire simulation. AEGIS offers three types of simulations, i.e., single-fire propagation, point-scale calculation of potential fire behavior, and burn probability analysis, similar to the FlamMap fire behavior modeling software. Artificial neural networks (ANNs) were utilized for wildfire ignition risk assessment based on various parameters, training methods, activation functions, pre-processing methods and network structures. The combination of ANNs and expected burned area maps are used to generate integrated output map of fire hazard prediction. The system also incorporates weather information obtained from remote automatic weather stations and weather forecast maps. The system and associated computation algorithms leverage parallel processing techniques (i.e., High Performance Computing and Cloud Computing) that ensure computational power required for real-time application. All AEGIS functionalities are accessible to authorized end-users through a web-based graphical user interface. An innovative smartphone application, AEGIS App, also provides mobile access to the web-based version of the system.

scholarly journals Risk Analysis of Road Tunnels: A Computational Fluid Dynamic Model for Assessing the Effects of Natural Ventilation

2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Ciro Caliendo ◽  
Gianluca Genovese ◽  
Isidoro Russo
Keyword(s):  
Natural Ventilation ◽  
Fluid Dynamic ◽  
Movement Time ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Maximum Heat ◽  
Road Tunnels ◽  
Maximum Heat Release ◽  
Computational Fluid Dynamics Cfd ◽  
Time Required

We have developed an appropriate Computational Fluid Dynamics (CFD) model for assessing the exposure to risk of tunnel users during their evacuation process in the event of fire. The effects on escaping users, which can be caused by fire from different types of vehicles located in various longitudinal positions within a one-way tunnel with natural ventilation only and length less than 1 km are shown. Simulated fires, in terms of maximum Heat Release Rate (HRR) are: 8, 30, 50, and 100 MW for two cars, a bus, and two types of Heavy Goods Vehicles (HGVs), respectively. With reference to environmental conditions (i.e., temperatures, radiant heat fluxes, visibility distances, and CO and CO2 concentrations) along the evacuation path, the results prove that these are always within the limits acceptable for user safety. The exposure to toxic gases and heat also confirms that the tunnel users can safely evacuate. The evacuation time was found to be higher when fire was related to the bus, which is due to a major pre-movement time required for leaving the vehicle. The findings show that mechanical ventilation is not necessary in the case of the tunnel investigated. It is to be emphasized that our modeling might represent a reference in investigating the effects of natural ventilation in tunnels.

Experimental study on temperature profile and smoke movement in a model-branched tunnel fire under longitudinal ventilation

2022 ◽  
Vol 121 ◽  
pp. 104324
Author(s):  
Dongyue Zhao ◽  
Changkun Chen ◽  
Peng Lei ◽  
Tong Xu ◽  
Weibing Jiao ◽  
...  
Keyword(s):  
Experimental Study ◽  
Temperature Profile ◽  
Smoke Movement ◽  
Tunnel Fire ◽  
Longitudinal Ventilation

An Experimental Study of Smoke Movement in Tunnel Fire with Natural and Forced Ventilations

2005 ◽  
Vol 29 (6) ◽  
pp. 711-721 ◽  
Author(s):  
Cheol-Hong Hwang ◽  
Byung-Hun Yoo ◽  
Sung-Min Kum ◽  
Jung-Yup Kim ◽  
Hyun-Joon Shin ◽  
...  
Keyword(s):  
Experimental Study ◽  
Smoke Movement ◽  
Tunnel Fire

scholarly journals The Survival of Pinus ponderosa Saplings Subjected to Increasing Levels of Fire Behavior and Impacts on Post-Fire Growth

Fire ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 23 ◽  
Author(s):  
Wade D. Steady ◽  
Raquel Partelli Feltrin ◽  
Daniel M. Johnson ◽  
Aaron M. Sparks ◽  
Crystal A. Kolden ◽  
...  
Keyword(s):  
Dose Response ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Forest Growth ◽  
Growth And Yield ◽  
Radiative Energy ◽  
Fire Growth ◽  
Growth Metrics

Improved predictions of tree species mortality and growth metrics following fires are important to assess fire impacts on forest succession, and ultimately forest growth and yield. Recent studies have shown that North American conifers exhibit a ‘toxicological dose-response’ relationship between fire behavior and the resultant mortality or recovery of the trees. Prior studies have not been conclusive due to potential pseudo-replication in the experimental design and time-limited observations. We explored whether dose-response relationships are observed in ponderosa pine (Pinus ponderosa) saplings exposed to surface fires of increasing fire behavior (as quantified by Fire Radiative Energy—FRE). We confirmed equivalent dose-response relationships to the prior studies that were focused on other conifer species. The post-fire growth in the saplings that survived the fires decreased with increasing FRE dosages, while the percentage mortality in the sapling dosage groups increased with the amount of FRE applied. Furthermore, as with lodgepole pine (Pinus contorta), a low FRE dosage could be applied that did not yield mortality in any of the replicates (r = 10). These results suggest that land management agencies could use planned burns to reduce fire hazard while still maintaining a crop of young saplings. Incorporation of these results into earth-system models and growth and yield models could help reduce uncertainties associated with the impacts of fire on timber growth, forest resilience, carbon dynamics, and ecosystem economics.

scholarly journals No evidence of increased fire risk due to agricultural land abandonment in Sardinia (Italy)

2012 ◽  
Vol 12 (5) ◽  
pp. 1333-1336 ◽  
Author(s):  
C. Ricotta ◽  
D. Guglietta ◽  
A. Migliozzi
Keyword(s):  
Rural Areas ◽  
Agricultural Land ◽  
Plant Biomass ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Land Abandonment ◽  
Fuel Load ◽  
Short Paper ◽  
Ignition Probability ◽  
Fire Ignition

Abstract. Different land cover types are related to different levels of fire hazard through their vegetation structure and fuel load composition. Therefore, understanding the relationships between landscape changes and fire behavior is of crucial importance for developing adequate fire fighting and fire prevention strategies for a changing world. In the last decades the abandonment of agricultural lands and pastoral activities has been the major driver of landscape transformations in Mediterranean Europe. As agricultural land abandonment typically promotes an increase in plant biomass (fuel load), a number of authors argue that vegetation succession in abandoned fields and pastures is expected to increase fire hazard. In this short paper, based on 28 493 fires in Sardinia (Italy) in the period 2001–2010, we show that there is no evidence of increased probability of fire ignition in abandoned rural areas. To the contrary, in Sardinia the decreased human impact associated with agricultural land abandonment leads to a statistically significant decrease of fire ignition probability.

scholarly journals Estimating Fuel Loads and Structural Characteristics of Shrub Communities by Using Terrestrial Laser Scanning

2020 ◽  
Vol 12 (22) ◽  
pp. 3704
Author(s):  
Cecilia Alonso-Rego ◽  
Stéfano Arellano-Pérez ◽  
Carlos Cabo ◽  
Celestino Ordoñez ◽  
Juan Gabriel Álvarez-González ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Goodness Of Fit ◽  
Fire Hazard ◽  
Structural Characteristics ◽  
Fire Behavior ◽  
Terrestrial Laser Scanning ◽  
Fuel Load ◽  
Fuel Loads ◽  
Litter Depth ◽  
Species Specific

Forest fuel loads and structural characteristics strongly affect fire behavior, regulating the rate of spread, fireline intensity, and flame length. Accurate fuel characterization, including disaggregation of the fuel load by size classes, is therefore essential to obtain reliable predictions from fire behavior simulators and to support decision-making in fuel management and fire hazard prediction. A total of 55 sample plots of four of the main non-tree covered shrub communities in NW Spain were non-destructively sampled to estimate litter depth and shrub cover and height for species. Fuel loads were estimated from species-specific equations. Moreover, a single terrestrial laser scanning (TLS) scan was collected in each sample plot and features related to the vertical and horizontal distribution of the cloud points were calculated. Two alternative approaches for estimating size-disaggregated fuel loads and live/dead fractions from TLS data were compared: (i) a two-steps indirect estimation approach (IE) based on fitting three equations to estimate shrub height and cover and litter depth from TLS data and then use those estimates as inputs of the existing species-specific fuel load equations by size fractions based on these three variables; and (ii) a direct estimation approach (DE), consisting of fitting seven equations, one for each fuel fraction, to relate the fuel load estimates to TLS data. Overall, the direct approach produced more balanced goodness-of-fit statistics for the seven fractions considered jointly, suggesting that it performed better than the indirect approach, with equations explaining more than 80% of the observed variability for all species and fractions, except the litter loads.

CFD Analysis of Batch-Type Reheating Furnace

2007 ◽  
Author(s):  
Bin Wu ◽  
Andrew M. Arnold ◽  
Eugene Arnold ◽  
George Downey ◽  
Chenn Q. Zhou
Keyword(s):  
Three Dimensional ◽  
Furnace Operation ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Cfd Analysis ◽  
Reheating Furnace ◽  
Batch Type ◽  
Billet Quality ◽  
Actual Operating ◽  
Computational Fluid Dynamics Cfd

In the steelmaking industry, reheating furnaces are used to heat the billets or blooms to the rolling temperature; the uniformity of the temperature in the furnace determines billet quality. In order to obtain a better understanding of the furnace operation, which influences the temperature distribution; Computational Fluid Dynamics (CFD) analysis is conducted to examine the transient and three dimensional temperature fields in a reheating furnace using the commercial software Fluent®. A number of actual operating conditions, based on the ArcelorMittal Steelton No.3 reheating furnace, are computed. The numerical results are used to optimize the operating parameters and thus help to improve the steel quality.

Numerical Simulation Flow and Temperature Fields of Fiber Air Dispersion System

2015 ◽  
Vol 671 ◽  
pp. 242-247
Author(s):  
Meng Zhang ◽  
Xiao Hong Zhou
Keyword(s):  
Fluid Dynamics ◽  
Indoor Air ◽  
Low Cost ◽  
Temperature Fields ◽  
Experiment Data ◽  
Evaluation Standard ◽  
Dispersion System ◽  
Air Dispersion ◽  
Computational Fluid Dynamics Cfd ◽  
Air Diffusion

Fiber air dispersion system (FADS) is an advanced flexible ventilation terminal in ventilated areas. Its benefits are numerous, which are air diffusion without feeling, anti-condensation, easy cleaning and low cost etc. The technology of computational fluid dynamics (CFD) was used in this paper. At first, a physical model of the environment conditioned by FADS was built. Then, the both field of temperature and flow in the environment was simulated. The boundary conditions and parameters was measured and calculated. Finally, the numerical results were verified by comparing with the experiment data to confirm the reliability of the model. Meanwhile, by using the indoor air evaluation standard, FADS was confirmed to provide a more comfortable environment and better air quality.

Simulating fuel treatment effects in dry forests of the western United States: testing the principles of a fire-safe forest

2011 ◽  
Vol 41 (5) ◽  
pp. 1018-1030 ◽  
Author(s):  
Morris C. Johnson ◽  
Maureen C. Kennedy ◽  
David L. Peterson
Keyword(s):  
United States ◽  
Treatment Effects ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Post Treatment ◽  
Western United States ◽  
Crown Fire ◽  
Fuel Treatments ◽  
Dry Forests ◽  
Fuel Treatment

We used the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) to simulate fuel treatment effects on 45 162 stands in low- to midelevation dry forests (e.g., ponderosa pine ( Pinus ponderosa Dougl. ex. P. & C. Laws.) and Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) of the western United States. We evaluated treatment effects on predicted post-treatment fire behavior (fire type) and fire hazard (torching index). FFE-FVS predicts that thinning and surface fuel treatments reduced crown fire behavior relative to no treatment; a large proportion of stands were predicted to transition from active crown fire pre-treatment to surface fire post-treatment. Intense thinning treatments (125 and 250 residual trees·ha–1) were predicted to be more effective than light thinning treatments (500 and 750 residual trees·ha–1). Prescribed fire was predicted to be the most effective surface fuel treatment, whereas FFE-FVS predicted no difference between no surface fuel treatment and extraction of fuels. This inability to discriminate the effects of certain fuel treatments illuminates the consequence of a documented limitation in how FFE-FVS incorporates fuel models and we suggest improvements. The concurrence of results from modeling and empirical studies provides quantitative support for “fire-safe” principles of forest fuel reduction (sensu Agee and Skinner 2005. For. Ecol. Manag. 211: 83–96).

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