Fire Dynamics Simulator Model Research Articles

Wind Effect on External Fire Spread through Openings under the Protection of Horizontal Projections or Vertical Spandrels—A Numerical Study

A numerical investigation has been conducted to analyse the effect of wind on the vertical spread of fire through a front opening in a building’s external walls. The study utilises a building geometry established from previous experimental work conducted by the National Research Council of Canada (NRCC). A horizontal projection or a vertical spandrel is introduced above the opening of the compartment of fire origin. The purpose of the projection or spandrel is to inhibit the vertical spread of the fire, following the relevant requirements in the Australian National Construction Code (NCC). A computational fluid dynamics (CFD) package for fire-driven fluid flow, namely the Fire Dynamics Simulator (FDS), is employed to simulate the fire behaviour. The FDS model is validated against the NRCC’s experimental results, and a good agreement is achieved. Winds from three horizontal directions (front wind is normal to the opening, side wind is parallel to the opening, and back wind is from behind the building) have been investigated, with speeds ranging up to 10 m/s for each wind direction. Front wind speeds below 1 m/s are found to slightly enhance the vertical spread of the fire, while speeds exceeding 1 m/s are inclined to promote horizontal spread. The impact of side wind on the vertical fire spread was also found to vary with wind speed. The increase in the speed of back wind influences flame buoyancy, resulting in an augmented vertical fire spread. Furthermore, the numerical results reveal that a vertical spandrel of 1100 mm height is less effective in preventing vertical fire spread through openings, compared to a 1100 mm deep horizontal projection. The study suggests that the fire safety design in reducing the hazard of vertical fire spread through openings in buildings’ external walls could be further improved if the effect of wind is considered.

Simulation of fire dynamics in parking lot taking into account the analysis of spatial heat flux distribution

The article considers static data on car fires, including those in closed parking lots. Using the Fire Dynamics Simulator model in the Fenix + 3 program, the dynamics of heat flow in space and time was simulated to determine the possible situation at such facilities. Keywords closed parking lot, automobile fires, modeling, heat flow

Analyzing the gas temperature of a hydrogen jet fire in a compartment with the Fire Dynamics Simulator

This study presents a method to simulate hydrogen jet fire using the Fire Dynamics Simulator (FDS). To avoid modeling an actual nozzle, high-speed Lagrangian particles released from a virtual nozzle are introduced to simulate released hydrogen. The capability of this FDS model to predict gas temperature is validated by comparing simulation results with five existing experiments in a rectangular steel compartment with an open end. The effects of relevant parameters prescribed in the FDS model on the gas temperature are also analyzed, including numerical parameters (auto-ignition exclusion zone, offset, particle count, and grid) and physical parameters (particle velocity, spray angle, and auto-ignition temperature). The results show that gas temperatures near the nozzle are sensitive to these parameters. Based on the grey relational analysis, the auto-ignition temperature is the least important parameter to predict gas temperatures, while the grid is the most significant parameter for gas temperatures near the ceiling.

Thermal Hydraulics Simulation of a Water Spray System for a Cooling Fluid Catalytic Cracking (FCC) Regenerator

Olefins are crucial building blocks for petrochemical industry, serving as raw materials for the production of various products such as plastics, synthetic fibers, detergents, solvents, and other chemicals. In FCC, heavy petroleum feedstocks are injected into a catalytic cracking unit, where they are mixed with a catalyst. The catalyst aids in breaking down the large hydrocarbon molecules into smaller fragments, including olefins like Propylene and Ethylene. These polymerization reactions occur at high temperatures. They demand that heat removal occurs as quickly as possible in order to control the reactor temperature and to avoid “hot spots” in the Regenerator or localized oxidation reactions (and to avoid creep rupture of the regenerator steel cladding). The cooling of the regenerator cladding surface can be achieved by impinging water droplets (spray), ejected from a spray nozzle. Spray cooling can provide uniform cooling and handle high heat fluxes in both a single phase and two phases. This research provides a thermal hydraulic design of regenerator spray cooling systems. In the framework of this research, Fire Dynamics Simulator (FDS) software was applied in order to simulate the temperature field and the water vapor mass fraction. A COMSOL Multiphysics finite element code was used in order to calculate the temperature field inside the regenerator cladding. The calculated surface temperatures and heat transfer convective coefficient, obtained using FDS software, were validated successfully against COMSOL numerical results and previous results in the literature. The numerical simulations were carried out for two cases. The first case was carried out at a distance of 0.5 m, and the second case was carried out at a distance of 0.2 m. A grid sensitivity study was carried out on the FDS model. Numerical integrations were carried out over time in order to calculate the average temperatures. The difference between these four average temperatures, calculated by applying different grids, is less than 7.4%. The calculated surface temperatures and heat transfer convective coefficient were validated successfully against COMSOL numerical results and previous research. It was shown that the calculated temperatures decrease in the second case. The water spray system managed to cool the steel wall more effectively as the water spray system approaches the steel cladding.

Validation of the fire dynamics simulator (FDS) model for fire scenarios with two liquid pool fires in multiple compartments

A validation study on the fire dynamics simulator (FDS) model for fire scenarios with multiple liquid pool fires occurring in multiple compartments was performed. For fire growth in the open simulation, the mass loss rate per unit area (MLRPUA) time curve obtained experimentally was used as the input. In the blind simulation, the pyrolysis model was used. For the ventilation flow rate curve, the supply/exhaust flow rate curve measured in the experiment was used as the input for the open simulation, whereas the quadratic fan curve model was used for the blind simulation. The time-averaged datasets of the output parameters from the FDS model and experiment were plotted as data points on scatter plots. In terms of bias factor and model standard deviation of output parameters, the scatter plots under the open simulation conditions were compared with those of NUREG-1824. Under blind simulation conditions, the bias factor and model standard deviation of output parameters increased significantly. A sensitivity analysis was performed on input parameters, such as the MLRPUA time curve, supply/exhaust flow time curve, compartment leak area, and maximum differential pressure in the compartment. Within the given ranges of the sensitivity input parameter values, only changing the MLRPAU time curve significantly affected the bias factor and model standard deviation of the output parameters.

Investigation of Fires in Natural Ecosystems of the Ukrainian Roztochchiya by Wildland Fire Dynamics Simulator Model

Investigation of Fires in Natural Ecosystems of the Ukrainian Roztochchiya by Wildland Fire Dynamics Simulator Model

Fire Models as a Tool for Evaluation of Energy Balance in Burning Space Relating to Building Structures

Fire is defined as an extremely hazardous event, causing a threat to life and health of persons, but also damage to the economic sphere. It has been shown many times that fire can occur anywhere and at any time. In order to minimize the risk of fire manifestations, it is necessary to understand its course. In technical practice, computational models are used to determine the partial manifestations of fire, such as fire spread rate, smoke generation rate in the burning area, formation of toxic burning products, flame height, and others. One of the important characteristics is also the energy balance in the burning area relating to the character of burning material, access of oxygen necessary for exothermic reaction of burning, and reaction of the installed safety devices. In this paper we will point out the fire safety of the building. The FDS (Fire Dynamics Simulator) model is recently used in practice, and its advantage is the possibility to model fire even in large and atypical spaces. The contribution of this paper is the practical application of fire safety of construction using the FDS Model, to reduce the cost of fire safety for the structure being constructed. Attention was paid to evaluating how the heat energy that is released during a fire can be influenced by the installed stable fire-extinguishing equipment, taking into consideration the fire resistance of the building structures.

Advanced dynamic modeling study of fire and smoke of crude oil storage tanks

The combustion properties of large-scale crude oil pool fire have great significance for security design and firefighting of current crude oil reserves. Burning rate, flame shape and radiation intensity are the most important parameters for fire properties. The novelty of this study is that the Fire Dynamics Simulator (FDS) is adopted to simulate pool fires in a tank farm. It does not only investigate and analyze heat radiation flux, but also the temperature difference rise and flame/smoke temperature contours behavior. This simulation is performed in order to predict the potentials of a large crude oil storage tank fire outbreak and the smoke temperature distribution that counters in and around the tank. These data are used in designing tank farms and applying the firefighting strategy. A super CPU with large RAM is used to operate the simulation program, to simulate one of the largest crude oil farms in the world. The model will be investigated for identifying the worst-case scenarios that might occur in a large crude oil tank. One of these scenarios might be fire outbreak in rim seal in one of the four storage tanks, where the fire is transferred to full surface fire. The model predicts the potential of tank fire outbreak, smoke tracing and both smoke/flame temperature that spreads at wind speed of 3 m/s, 9 m/s, 18 m/s in south-west direction. FDS model provides qualitative data that increase the level of safety, such as the minimum safe separation distances and the location of firefighters during the firefighting process. It also determines the most critical area, which is needed for water-cooling system. This study also tackles the duration after which human beings feel pain after being exposed to heat radiation.

Timber beam in virtual furnace

Purpose This paper aims to present a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. Temperatures calculated inside the timber beam are compared to measured values from the fire test. Design/methodology/approach The paper presents a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. The presented part lies in a virtual furnace which simulates temperature environment around tested elements in the furnace. Comparison of results show good agreement in the case when burning of timber is included in the numerical model. Findings The virtual furnace presented in this paper allows to calculate temperature environment around three timber beams. After validation of the fire dynamics simulator (FDS) model, the temperature conditions are passed to the FE model which solves heat transfer to the tested element. Temperatures inside the timber beam which are solved in software Atena Science are compared to measured temperatures from the fire test. The comparison of temperatures in three control points shows good accuracy of the calculation in the point closer to the heated edge. An inaccuracy is shown in points located deeper in the beam cross-section – below the char layer. Research limitations/implications In conclusion, the virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by object-oriented finite element model (OOFEM). The interconnection of both software is made owing to MuPIF python library. Practical implications The virtual furnace takes advantage of great possibilities of computational fluid dynamics code FDS. The model is based on an accurate representation of a real fire furnace of fire laboratory PAVUS a.s. located in the Czech Republic. It includes geometry of the real furnace, material properties of the furnace linings, burners, ventilation conditions and tested elements. Gas temperature calculated in the virtual furnace is validated to temperatures measured during a fire test. Social implications The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. Originality/value The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by OOFEM. The interconnection of both software is made thanks to MuPIF python library.

Towards a simplified fire dynamic simulator model to analyse fire spread between multiple informal settlement dwellings based on full‐scale experiments

SummaryThis paper develops a Fire Dynamics Simulator (FDS) model to analyse fire spread for informal settlements, based upon full‐scale experiments. Informal settlements are frequently ravaged by fires, leaving thousands of people homeless, and with more than 1 billion people residing in informal settlements, there is a significant need to understand and improve the fire safety in such areas. Due to high levels of uncertainty inherent with input parameters regarding informal settlements, this work also investigates the sensitivity of fire behaviour to the input parameters used in numerical simulations. It is shown that spread times between two dwellings can vary from 1 minute after flashover to no spread at all, depending on the simulation input parameters selected. This paper highlights the importance of such input parameters when trying to model fire spread between dwellings. The simulations indicate that a simplified fire spread model for informal settlements is possible, especially for steel clad dwellings, however it showed that significant work is required for timber clad dwellings, that is, because the rate at which additional ventilation forms in the simulation for the timber clad dwellings is significantly slower than reality, which is as a result of the simplifications made. The simplification of using heating, ventilation, and air conditioning (HVAC) systems to model leakages, resulting from the corrugated flutes, showed good enclosure fire dynamics behaviour compared to the experiments, but created new challenges with regards to the spread mechanism, since HVAC systems do not allow electromagnetic waves to penetrate in the same manner as an opening.

Smoke Hazard Assessment Model Based on Fire Dynamics Simulator and FED Model

Smoke is the main cause of fire death. In order to minimize the potential danger of smoke hazard, a rational VR based fire training simulator should fully consider all aspects of smoke hazard. In the simulator, the visualization of data based on FDS (Fire Dynamics Simulator) and FED fire dynamic data and volume rendering is further optimized, which can be effectively and quickly applied to virtual fire protection. In addition, a comprehensive smoke hazard assessment model based on FED and FED is established to assess the IHD value of different paths, which represents the safety of different paths, and can be used for evacuation or rescue in virtual training. Taking the case of campus fire drill as an experiment, the research shows the accuracy and effectiveness of smoke assessment based on FDS and FED model. The road force with the highest safety can be selected through the comprehensive model. So the assessment model is proved to be valuable.

Measurements and predictions of thermophoretic soot deposition

A thin laminar flow channel with a transverse temperature gradient was used to examine thermophoretic deposition of soot aerosol particles in experiments and modeled in Fire Dynamics Simulator (FDS) simulations. Conditions investigated included three flowrates, with nominal Reynolds number based on the hydraulic diameter of 55, 115 and 230, and two applied temperature gradients, nominally 10 °C/mm and 20 °C/mm, with repeats. Soot was generated from a propene diffusion flame. The burner exhaust was mixed with dilution air, and most large agglomerates greater than 1 μm aerodynamic diameter were removed prior to the channel inlet. The expected thermophoretic velocity of the aerosol was calculated from the applied temperature gradient. A calculated deposition velocity was determined from the mass of deposition, the channel inlet soot concentration, and the exposure time. Uniform soot deposition allowed targets to be used to measure the mass of deposition on the cold side of the channel. The mass of deposition was also determined by subtracting the mass of soot exiting the channel from the mass of soot entering the channel during the exposure time. The deposition velocities from these two methods generally agreed with the thermophoretic velocity and with each other. The deposition mass predicted by the FDS model also compared well with the experiments in most cases. The disagreements for the lowest flow rate cases are attributed to buoyant flow effects adding uncertainty to the actual temperature gradients present in the channel. (The opinions, findings, and conclusions expressed in this paper are the authors’ and do not represent the views or policies of NIST or the United States Government.)

Modeling carbon monoxide spread in underground mine fires

Carbon monoxide (CO) poisoning is a leading cause of mine fire fatalities in underground mines. To reduce the hazard of CO poisoning in underground mines, it is important to accurately predict the spread of CO in underground mine entries when a fire occurs. This paper presents a study on modeling CO spread in underground mine fires using both the Fire Dynamics Simulator (FDS) and the MFIRE programs. The FDS model simulating part of the mine ventilation network was calibrated using CO concentration data from full-scale mine fire tests. The model was then used to investigate the effect of airflow leakage on CO concentration reduction in the mine entries. The inflow of fresh air at the leakage location was found to cause significant CO reduction. MFIRE simulation was conducted to predict the CO spread in the entire mine ventilation network using both a constant heat release rate and a dynamic fire source created from FDS. The results from both FDS and MFIRE simulations are compared and the implications of the improved MFIRE capability are discussed.

Utilization of Fire Dynamics Simulator Model to Study Rice Husk Gasification in Fixed-bed Gasifier

Computational Fluid Dynamic (CFD) modeling applications of the biomass gasification process help to optimize the gasifier. This study aims to investigate the impact of several physical parameters on the behavior of gasification in a fixed-bed downdraft gasifier. To that end, the study presents a comparison of the results computed using the Fire Dynamics Simulator (FDS) model with experimental results of biomass gasification. Therefore, different sets of simulations and experiments have been performed to examine the effects of initial moisture content, equivalence ratio, high heating value (HHV), and cold gas efficiency (CGE). At the optimum operation, the equivalence rate is 0.3, the HHV can reach 5.71 MJ/m3, and the produced hydrogen concentration is 26.53 vol%. For an initial moisture content of 11.18%, the measured CGE is 66.85%, which is within the range of 65.07% to 70.44%. In general, the initial moisture content of the rice husks is suggested to be below 18%. The overall results indicate that the FDS model can effectively simulate and analyze gasification performance inside the gasifier, and the performance of an improved downdraft gasifier system (IDGS) is improved by higher cold gas efficiency.

Detailing the effects of geometry approximation and grid simplification on the capability of a CFD model to address the benchmark test case for flow around a computer simulated person

This paper details the use of a simplified CFD model to predict the flow patterns around a computer simulated person in a displacement ventilated room. The use of CFD is a valuable tool for indoor airflow analysis and the level of complexity of the model being investigated is often critical to the accuracy of predictions. The closer the computational geometry is to the real geometry of interest, the more accurate the corresponding results are expected to be. High complexity meshes enable elaborated geometries to be resolved. The drawback is, however, their increased computational cost. The Fire Dynamics Simulator (FDS) model (Version 5) enabled to investigate the effects of geometry and computational grid simplification on the accuracy of numerical predictions. The FDS model is based on a three-dimensional Cartesian coordinate system and all solid obstructions are forced to conform to the underlying numerical grid which is a potential limitation when dealing with complex geometries such as those of a human body. Nevertheless, the developed computational model was based exclusively on a three-dimensional rectangular geometry. At the same time, in order to limit the total number of grid cells, a relatively coarser grid than those used for similar simulations was adopted in the investigation. The developed model was then assessed in terms of its capability of reproducing benchmark temperature and air velocity distributions. The extent to which numerical results depend on different simulation settings was detailed and different boundary conditions are discussed in order to provide some guidance on the parameters that resulted to affect the accuracy of the predicted results. The comparison between numerical results and measurements showed that a simplified CFD model can be used to capture the airflow characteristics of the investigated scenario with predictions showing a favourable agreement with experimental data at least in the qualitative features of the flow (the detailed investigation of the local airflow field near the occupant can not be probably conducted apart from considering the real human geometry). Significant influence of simulator geometry and of boundary conditions was found.

스프링클러 분무가 화재유동특성에 미치는 영향에 관한 수치해석 연구

The present study investigates the effects of sprinkler spray on fire driven flow characteristics in a compartment based on numerical approach. The FDS (Fire Dynamics Simulator), a widely used fire field model, was used to simulate the fire induced flow and sprinkler spray and a series of grid independence tests have been performed to obtain the optimal grid size. In order to validate the result predicted by FDS model, the calculated results were compared with experimental results of Magnone et al.. The FDS model matches quite well to experiments in temperature profile and mass flux through doorway, however, the discrepancy between the FDS model and experiments increases with increasing water discharge rate. As with previous study, the FDS calculation also shows a decrease of mass flow rate of combustion products through doorway due to the sprinkler spray. This study can contribute to optimize the sprinkler system design and verify the validity of the fire field model with sprinkler spray.

Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment

Adiabatic surface temperature is an efficient way of expressing thermal exposure. It can be used for bridging the gap between fire models and temperature models, as well as between fire testing and temperature models. In this study, a full-scale compartment fire experiment with wood crib fuel was carried out in a concrete building. Temperatures were measured with plate thermometers and ordinary thermocouples. Five plate thermometers and five thermocouples with a diameter of 0.25 mm were installed at different positions. These two different temperature devices recorded different temperatures, especially near the floor surface. The adiabatic surface temperature was derived by a heat balance analysis from the plate thermometer measurements. The thermal inertia of the plate thermometer was taken into account to correct the measured results. In addition, the fire experiment scenario was also simulated with fire dynamics simulator. The fire source was specified as a given heat release rate, which was calculated from the measured mass loss rate of the wood fuel. The adiabatic surface temperatures at these measuring positions were simulated by the fire dynamics simulator model and compared with the experimental adiabatic surface temperatures. The comparative results showed that fire dynamics simulator predicted the adiabatic surface temperature accurately during the steady-state period.

Effectiveness of downward evacuation in a large-scale subway fire using Fire Dynamics Simulator

Effective evacuation routes in the case of a large-scale subway fire were studied. A serious problem in the subway fire is that the directions of smoke flow are coincident with those of evacuation toward the surface. Hence, it is necessary to design an evacuation route without interference from smoke. A disastrous fire broke out in the Jungangno subway station in Daegu, South Korea in 2003. Based on this case, the Jungangno subway station with three basement levels was used in Fire Dynamics Simulator model in this study. The influences of smoke, temperature, and toxic gases (carbon monoxide [CO] and carbon dioxide [CO 2]) were computed at the evacuation staircases in the subway station with a fire source in the third basement floor (B3). The calculations showed that the evacuation staircases had high smoke density, temperature, and concentrations of CO and CO 2 in the subway fire. Hence, these factors greatly affected all of the upward evacuation staircases due to the coincidence of the smoke flow and the evacuation routes. Therefore, our paper proposes a new subway station with a fourth basement floor (B4) having downward evacuation routes which are in the opposite direction to the smoke flow. The results of analysis show that these factors hardly affected the staircases from B3 to B4. We conclude that downward evacuation can be more effective than upward evacuation for a large-scale subway fire.

Assessment of the Use of Fire Dynamics Simulator in Performance-Based Design

This paper discusses a procedure for the use of fire modelling in the performance-based design environment to quantify design fires for commercial buildings. This procedure includes building surveys, medium-and full-scale experiments and computer modelling. In this study, a survey of commercial premises was conducted to determine fire loads and types of combustibles present in these buildings. Statistical data from the literature were analysed to determine the frequency of fires, ignition sources, and locations relevant to these premises. Based on the results of the survey and the statistical analyses a number of fuel packages were designed that represent fire loads and combustible materials in commercial buildings. The fuel packages were used to perform medium- and full-scale, post-flashover fire tests to collect data on heat release rates, compartment temperatures and production and concentration of toxic gases. Based on the experimental results, input data files for the computational model, Fire Dynamics Simulator (FDS), were developed to simulate the burning characteristics of the fuel packages observed in the experiments. Comparative analysis between FDS model predictions and experimental data of HRR, carbon monoxide (CO), and carbon dioxide (CO2), indicated that FDS model was able to predict the HRR, temperature profile in the burn room, and the total production of CO and CO2 for medium- and large-scale experiments as well as real size stores.

Comparison of FDS Prediction of Smoke Movement in a 10-Storey Building with Experimental Data

In this study, the Fire Dynamics Simulator (FDS), a computational fluid dynamics (CFD) model developed by National Institute of Standards and Technology (NIST) is used to simulate fire tests conducted at the National Research Council of Canada (CNRC). These tests were conducted in an experimental 10-storey tower to generate realistic smoke movement data. A full size FDS model of the tower was developed to predict smoke movement from fires that originate on the second floor. Three propane fire tests were modelled, and predictions of O2, CO2 concentrations and temperature on each floor are compared with the experimental data. This paper provides details of the tests, and the numerical modelling, and discusses the comparisons between the model results and the experiments. The 10-storey experimental tower was designed to simulate the centre core of high-rise buildings. It includes a compartment and corridor on each floor, a stair shaft, elevator shaft and service shafts. Three propane fire tests were conducted in 2006 and 2007 to study smoke movement through the stair shaft to the upper floors of the building. The fire was set in the compartment of the 2nd floor. Thermocouples and gas analyzers were placed on each floor to measure temperature and O2, CO2 and CO concentrations. Comparisons in the fire compartment and floor of fire show that the FDS model gives a good prediction of temperature and O2 and CO2 concentrations. In the stair shaft and upper floors there are some small differences which are due to the effect of heat transfer to the stairs that was not considered in the model. Overall the study demonstrates that FDS is capable of modelling fire development and smoke movement in a high rise building for well ventilated fires.