Justification of Fire Field Models by Atrium Hot Smoke Tests

2009 ◽  
Author(s):  
W. K. Chow ◽  
S. S. Li ◽  
C. L. Chow
Keyword(s):  
Field Model ◽  
Field Tests ◽  
Design Tool ◽  
Fire Dynamics ◽  
Design Fire ◽  
Air Temperatures ◽  
Fire Environment ◽  
Measurement Results ◽  
Smoke Layer ◽  
Computational Fluid Dynamics Cfd

Computer thermal fire models are used in hazard assessment for performance-based fire design. Fire field model using Computational Fluid Dynamics (CFD) is now a popular design tool. The thermal fire environment can be predicted in a ‘microscopic’ picture with air flow pattern, pressure and temperature contours. However, most of the field models are only validated by some experiments not specially designed for such purpose. Whether those models are suitable for use is queried, leading to challenges. In this paper, prediction on smoke filling in a big atrium by the CFD tool Fire Dynamics Simulator developed at the National Institute of Standards and Technology in USA was justified by field tests. Smoke layer interface height and air temperatures inside the atrium were taken as the parameters. CFD results predicted were compared with the field measurement results.

scholarly journals Sustainable Smoke Extraction System for Atrium: A Numerical Study

2021 ◽  
Vol 13 (13) ◽  
pp. 7406
Author(s):  
Martin Lyubomirov Ivanov ◽  
Wei Peng ◽  
Qi Wang ◽  
Wan Ki Chow
Keyword(s):  
Mechanical Ventilation ◽  
Natural Ventilation ◽  
Numerical Study ◽  
Ventilation System ◽  
High Heat ◽  
Fire Dynamics ◽  
Sustainable Environment ◽  
Design Fire ◽  
Smoke Layer ◽  
Computational Fluid Dynamics Cfd

Smoke extraction systems, either static with natural ventilation, or dynamic with mechanical ventilation are required to keep smoke layer at high levels in many tall atria. It is observed that a design fire with high heat release rate (HRR) is commonly used for designing natural vents, but a low HRR is used for mechanical ventilation system. This will not produce a sustainable environment. There are no internationally agreed on design guides to determine the HRR in the design fire for different extraction systems and scenarios. This issue will be studied using a Computational Fluid Dynamics (CFD)-based software, the Fire Dynamics Simulator (FDS) version 6.7.1. Simulations on natural smoke filling, static and dynamic smoke extractions were carried out in a big example atrium. CFD-FDS predictions were compared with previous full-scale burning tests. Results confirmed that static smoke extraction is a good option for big fires, and a dynamic system is best for small fires. A sustainable new hybrid design combining the advantages of static and dynamic systems is proposed, which could result in a lower smoke temperature and higher smoke layer interface height, indicating a better extraction design.

Justification of a Fire Model on Predicting Fire in Large Room

2012 ◽  
Vol 193-194 ◽  
pp. 1103-1108
Author(s):  
Shu Sheng Li ◽  
Ye Gao ◽  
Gao Wan Zou ◽  
Yan Huo
Keyword(s):  
Fire Test ◽  
Cfd Model ◽  
Layer Height ◽  
Fire Model ◽  
Fire Models ◽  
Air Temperatures ◽  
Fire Environment ◽  
Smoke Layer ◽  
Computational Fluid Dynamics Cfd ◽  
Microscopic Picture

Fire models using Computational Fluid Dynamics (CFD) are now popular design or evaluation tools as the computer’s development sharply. By those tools the thermal fire environment can be predicted in a ‘microscopic’ picture with air flow pattern, pressure and temperature contours. However, most of the fire models are only validated by some experiments not specially designed for such purpose, especially for large rooms. In this paper, an existing fire test was used to justify a fire model - FDS4.07 on predicting fires in large room. Smoke layer height and air temperatures inside the room were taken as the parameters. Functional analysis was applied to justify the predictions by the CFD model.

Points to Note in Modeling Fire With Computational Fluid Dynamics

2012 ◽  
Author(s):  
L. Qu ◽  
W. K. Chow
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Design Tool ◽  
Performance Based Design ◽  
Cfd Model ◽  
Fire Dynamics ◽  
Design Fire ◽  
Computational Fluid Dynamics Cfd ◽  
Three Dimensional Simulations

Computational Fluid Dynamics (CFD) is a popular design tool in many projects for ensuring fire safety through performance-based design. However, there are always challenges on the quality and uncertainties of the CFD simulated results. Two points raised are on the grid size and free boundary conditions. A simple corridor fire with a small design fire is taken as an example to address these two points in this paper. The CFD model Fire Dynamics Simulator (FDS) version 5 was taken as the simulation tool Two-dimensional and three-dimensional simulations are compared. The geometry is proposed to outside for better description on minimizing opening boundary.

scholarly journals Numerical Investigations on the Propagation of Fire in a Railway Carriage

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4999
Author(s):  
Matthew Craig ◽  
Taimoor Asim
Keyword(s):  
Fire Spread ◽  
Ignition Energy ◽  
Fire Dynamics ◽  
Fire Propagation ◽  
Average Temperature ◽  
Smoke Density ◽  
Smoke Layer ◽  
Most Significant Change ◽  
Computational Fluid Dynamics Cfd ◽  
Safety Guidelines

In this study, advanced Computational Fluid Dynamics (CFD)-based numerical simulations have been performed in order to analyse fire propagation in a standard railway compartment. A Fire Dynamics Simulator (FDS) has been employed to mimic real world scenarios associated with fire propagation within railway carriages in order to develop safety guidelines for railway passengers. Comprehensive parametric investigations on the effects of ignition location, intensity and cabin upholstery have been carried out. It has been observed that a fire occurring near the exits of the carriage results in a lower smoke layer height, due to the local carriage geometry, than an identical fire igniting at the center of the carriage. This in turn causes the smoke density along the aisleway to vary by around 30%. Reducing the ignition energy by half has been found to restrict combustion, thus reducing smoke density and carbon exhaust gases, reducing the average temperature from 170 °C to 110 °C. Changing the material lining of the seating has been found to cause the most significant change in output parameters, despite its relative insignificance in bulk mass. A polyester sample produces a peak carbon monoxide concentration of 7500 ppm, which is 27× greater compared with nylon. This difference has been found to be due to the fire spread and propagation between fuels, signifying the polyester’s unsuitability for use in railway carriages.

scholarly journals AN ANALYTICAL MODEL ON STATIC SMOKE EXHAUST IN ATRIA

2010 ◽  
Vol 16 (3) ◽  
pp. 372-381 ◽  
Author(s):  
Cheuk Lun Chow ◽  
Junmei Li
Keyword(s):  
Fluid Dynamics ◽  
Driving Force ◽  
Natural Ventilation ◽  
Flow Model ◽  
Far East ◽  
Field Tests ◽  
The Far East ◽  
Smoke Layer ◽  
Simple Flow ◽  
Exhaust Systems

Static smoke exhaust systems with natural vents are starting to be installed in big shopping complexes, ware‐houses and cargo terminals in the Far East. These systems are used for natural ventilation as well as for letting out smoke. This paper responds to concerns over the performance of static smoke exhaust systems, which remain less popular than dynamic smoke exhaust systems with mechanical fans. We propose a modification of a simple flow model found in the literature, adapting this to study smoke layer interface height with natural vents opened. We compare and justify our results, as generated by both Computational Fluid Dynamics and zone models, alongside reports of historical field tests. The model of smoke exhaust is applied in an illustrative example of a large hall, leading to the suggestion that a flow model could be used for designing natural vents. As the key driving force in removing smoke through natural vents is smoke's own buoyancy, the system might only be effective for bigger fires. Santrauka Tolimuosiuose Rytuose statines dūmu šalinimo sistemos su natūralios ventiliacijos angomis pradedamos irengti dideliuose prekybos kompleksuose, sandeliuose ir kroviniu terminaluose. Tokios sistemos naudojamos ir natūraliai ventiliacijai, ir dūmams šalinti. Šis straipsnis parengtas susirūpinus, kad statines dūmu išmetimo sistemos yra ne tokios populiarios nei dinamines dūmu išmetimo sistemos su mechaniniais ventiliatoriais. Autoriai siūlo literatūroje aprašomo paprasto srauto modelio modifikacija, pritaikant ši modeli dūmu sluoksnio salyčio su natūralios ventiliacijos angomis aukščiui tirti. Straipsnyje palyginti ir pagristi rezultatai, gauti taikant tiek skaičiuojamosios skysčiu dinamikos, tiek zonavimo modelius kartu su eksperimentiniais tyrimais vietoveje. Pateiktas dūmu šalinimo modelio taikymo pavyzdys dideleje saleje ir padaryta išvada, kad srauto modelis galetu būti taikomas irengiant natūralia ventiliacija. Kadangi pagrindine varomoji jega šalinant dūmus per natūralias ventiliacijos angas yra dūmu plūdrumas, sistema gali būti veiksminga tik esant didesniems gaisrams.

scholarly journals Computational Fluid Dynamics (CFD) as a tool for the analysis of ventilation and indoor microclimate in agricultural buildings

1997 ◽  
Vol 45 (1) ◽  
pp. 81-96 ◽  
Author(s):  
A. Mistriotis ◽  
T. De Jong ◽  
M.J.M. Wagemans ◽  
G.P.A. Bot
Keyword(s):  
Fluid Dynamics ◽  
Laboratory Experiments ◽  
Numerical Technique ◽  
Design Tool ◽  
Indoor Climate ◽  
Pressure Coefficients ◽  
Computational Fluid Dynamics Cfd ◽  
Basic Concepts ◽  
Experimental Values ◽  
Broiler House

The basic concepts of CFD are presented in relation to applications in modelling the ventilation process and the resulting indoor climate of agricultural buildings. The validity and the advantages of this numerical technique are presented using 3 examples. Firstly the pressure coefficients along the roof of a 7-span Venlo-type greenhouse were calculated and compared with the corresponding experimental values. Next, the ventilation process in a single-span greenhouse was investigated and the results were compared to laboratory experiments. Finally, the use of CFD as a design tool for more efficient ventilation systems was demonstrated for the case of a broiler house.

Reduction of ground-borne vibrations from rail lines on viaducts by means of elastic anti-vibration mats

2018 ◽  
Vol 233 (5) ◽  
pp. 550-565
Author(s):  
Caiyou Zhao ◽  
Wang Ping ◽  
Mengting Xing ◽  
Qiang Yi ◽  
Liuchong Wang
Keyword(s):  
High Speed ◽  
Reaction Force ◽  
Field Tests ◽  
Ground Vibration ◽  
Coupling System ◽  
Step Procedure ◽  
Measurement Results ◽  
Track Bridge ◽  
Bridge Bearing ◽  
The Impact

In this paper, the effectiveness of elastic anti-vibration mats in reducing ground-borne vibrations from rail viaducts is investigated by means of theoretical analysis and is validated by the results of field tests. A two-step procedure is adopted for analyzing the vehicle-track-bridge-soil coupling system. In the first step, the train-track-bridge-pier subsystem is considered, and the bridge-bearing reaction force is solved. In the second step, the pier-pile-soil subsystem is considered, and the ground vibration solution is obtained by applying the negative bridge-bearing reaction force to the pier top on a pier-pile-soil model. The accuracy of the presented model is then verified in comparison with in-situ measurement results. On the basis of this comparison, a parametric study on the impact of anti-vibration mats on ground-borne vibrations was investigated theoretically, and the effectiveness of elastic anti-vibration mats with the suggested optimal parameters was further validated by field tests. The results show that when the stiffness of the elastic anti-vibration mats is 1.5 MPa/m, ground vibration decreases significantly and the vertical rail displacement agrees with high-speed railway regulations.

Mountain Ash

2015 ◽  
Author(s):  
David Lindenmayer ◽  
David Blair ◽  
Lachlan McBurney ◽  
Sam Banks
Keyword(s):  
Forest Ecosystems ◽  
Fire Severity ◽  
Fire Dynamics ◽  
High Severity ◽  
Fire Environment ◽  
Arboreal Marsupials ◽  
New Findings ◽  
Mountain Ash ◽  
Old Trees ◽  
Very High

Mountain Ash draws together exciting new findings on the effects of fire and on post-fire ecological dynamics following the 2009 wildfires in the Mountain Ash forests of the Central Highlands of Victoria. The book integrates data on forests, carbon, fire dynamics and other factors, building on 6 years of high-quality, multi-faceted research coupled with 25 years of pre-fire insights. Topics include: the unexpected effects of fires of varying severity on populations of large old trees and their implications for the dynamics of forest ecosystems; relationships between forest structure, condition and age and their impacts on fire severity; relationships between logging and fire severity; the unexpectedly low level of carbon stock losses from burned forests, including those burned at very high severity; impacts of fire at the site and landscape levels on arboreal marsupials; persistence of small mammals and birds on burned sites, including areas subject to high-severity fire, and its implications for understanding how species in this group exhibit post-fire recovery patterns. With spectacular images of the post-fire environment, Mountain Ash will be an important reference for scientists and students with interests in biodiversity, forests and fire.

scholarly journals A Numerical Analysis of the Fire Characteristics after Sprinkler Activation in the Compartment Fire

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3099 ◽  
Author(s):  
Ho Trong Khoat ◽  
Ji Tea Kim ◽  
Tran Dang Quoc ◽  
Ji Hyun Kwark ◽  
Hong Sun Ryou
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Fire Suppression ◽  
Compartment Fire ◽  
Fire Dynamics ◽  
Fire Dynamics Simulator ◽  
Safety Design ◽  
Smoke Layer ◽  
Fire Characteristics ◽  
Sprinkler Spray

Understanding fire characteristics under sprinkler spray is valuable for performance-based safety design. However, fire characteristics during fire suppression by sprinkler spray has seldom been studied in detail. In order to present a fire suppression model by sprinkler spray and determine the fire characteristics after sprinkler activation in a compartment, a numerical analysis was conducted using a fire dynamics simulator (FDS). A simple fire suppression model by sprinkler spray was calibrated by comparing ceiling temperatures from experimental data. An extinguishing coefficient of 3.0 was shown to be suitable for the fire suppression model. The effect of sprinkler spray on the smoke layer during fire suppression was explained, revealing a smoke logging phenomenon. In addition, the smoke, which spread under the influence of the sprinkler spray, was also investigated. The temperature, velocity, and mass flow rate of the smoke layer through the doorway was significantly reduced during fire suppression compared to a free burn case.

Deterministic–stochastic approach to compartment fire modelling

2008 ◽  
Vol 465 (2104) ◽  
pp. 1029-1041 ◽  
Author(s):  
V Bertola ◽  
E Cafaro
Keyword(s):  
Deterministic Model ◽  
Random Noise ◽  
Stochastic Approach ◽  
Fire Dynamics ◽  
Arbitrary Degree ◽  
Compartment Fires ◽  
External Perturbations ◽  
Fire Modelling ◽  
Smoke Layer ◽  
Suitable Potential

A generalized Semenov model is proposed to describe the dynamics of compartment fires. It is shown that the transitions to flashover or to extinction can be described in the context of the catastrophe theory (or the theory of dynamical systems) by introducing a suitable potential function of the smoke layer temperature. The effect on the fire dynamics of random perturbations is then studied by introducing a random noise term accounting for internal and external perturbations with an arbitrary degree of correlation. While purely Gaussian perturbations (white noise) do not change the behaviour of the fire with respect to the deterministic model, perturbations depending on the model variable (‘coloured’ noise) may drive the system to different states. This suggests that the compartment fires can be controlled or driven to extinction by introducing appropriate external perturbations.

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