Numerical Simulation Of Fire Research Articles

Numerical simulation of high-pressure jet fire in on-board hydrogen storage cylinders under fire conditions

Hydrogen fuel cell vehicles (HFCVs) may cause fires in the event of an accident. When the high-pressure hydrogen storage cylinders are exposed to fire for a long time, there will be a risk of catastrophic consequences such as leakage, jet fire and explosion. Fire test is the main method to study the safety performance of hydrogen storage cylinders. During the firing process, the wall and internal temperature of the hydrogen storage cylinder rise gradually, and the thermally activated pressure relief device (TPRD) of the cylinder reaches a certain temperature and then releases high-pressure hydrogen to prevent the cylinder from bursting. As the hydrogen storage cylinder is in the fire environment, the release of high-pressure hydrogen will be ignited to form a jet fire and cause damage to personnel and equipment. In this paper, CFD software Fluent was used to numerically simulate the local fire test of the hydrogen storage cylinder with high-temperature air as the fire source. The variation law of cylinder wall temperature, gas temperature and pressure inside the cylinder, and the activation of TPRD were analyzed. At the same time, on the basis of the fire test simulation, a high-pressure hydrogen jet fire simulation numerical model caused by the TPRD action was established. The velocity field, temperature field and hydrogen concentration distribution of the jet fire were obtained, and the overpressure generated by the jet fire and the flame length size were analyzed. The results show that the high-pressure hydrogen released by TPRD was ignited under the fire condition to produce a jet flame and generated an overpressure in the jet direction, and the influence range of the overpressure was smaller than the influence range of the jet flame.

Numerical simulation and safety assessment of fires in historic timber structures based on fire load investigation

Historic timber structures face substantial fire loads and complex fire risks. Subsequent renovations and utilization may influence their fire safety performance. Therefore, accurately predicting indoor fire development in historic buildings and assessing their fire safety performance is crucial. Numerical fire simulation is currently at the forefront of analyzing and assessing fire risks in historic buildings. However, there is a shortage of globally accessible historic building fire data. This paper proposes a method to determine fire scenarios, peak heat release rates, and development curves of indoor fires in wooden historic buildings through a fire load investigation. Using the Guangzhou ancestral hall as an example, PyroSim fire dynamics simulation software is employed to calculate fire development and assess the available safe evacuation time. The simulation results are subsequently input into the Pathfinder evacuation simulation software to ascertain the required safe evacuation time for indoor occupants. A comparative assessment is conducted to evaluate the fire safety performance before and after the renovation of historic buildings. The research findings indicate that installing closed glass curtain walls in the courtyards of ancestral hall buildings in Guangzhou accelerates the infiltration of smoke during fires, leading to rapid fire spread and long-distance ignition, significantly reducing the time available for safe evacuation. Therefore, when renovating and utilizing the ancestral hall buildings in Guangzhou, the installation of ventilation and smoke extraction systems should be prioritized to slow down fire development. Additionally, controlling the number of indoor occupants is an effective management measure to mitigate fire damage in historic buildings.

Dynamic design of hazardous chemical storage in high-rise R&D building based on numerical simulation

With the increasing demand for research on hazardous chemicals in high-rise research and development (R&D) buildings, the use of a large number of flammable chemicals increases the fire risk significantly. Therefore, the research on the storage of hazardous chemicals in high-rise R&D buildings becomes more and more important. This paper presents a maximum dynamic design method for hazardous chemical storage. A set of fire risk indicators has been established in the research, including temperature, carbon monoxide concentration, and visibility. The representative hazardous chemicals are selected through the investigation of the distribution and quantity of hazardous chemicals. Through numerical simulation of high-rise building fire with different stocks of dangerous chemicals and evacuation simulation of different fire floors, the time when the risk factors of fire occurrence reach the critical threshold of human body (ASET) and the necessary time for human evacuation (RSET) are obtained. By adjusting the amount of hazardous chemicals stored, the time to reach the hazardous critical threshold (RSET) and the time to evacuate (ASET) are changed accordingly. When RSET < ASET, the storage capacity of hazardous chemicals in the high-rise R&D building meets the target requirements. In the case study, ethanol was selected as the representative substance, and numerical simulation and example calculation were carried out on a 16-story R&D building. The amount of ethanol stored on each floor was calculated. Among them, the eighth layer has the largest ethanol storage capacity (1.81 L/m2) and the ninth layer has the smallest ethanol storage capacity (0.89 L/m2).

Numerical Simulation of Fire in Library Atrium Based on FDS

In order to prevent the fire accident in the comprehensive library, using the fire dynamic simulation software (FDS), taking a comprehensive library of a university as the research object, and taking the atrium self-study area on the second floor with the fastest smoke diffusion as the fire point, the temperature, smoke flow, visibility The distribution characteristics of CO and CO2 volume fraction are analyzed by numerical simulation, and the variation characteristics of each parameter are obtained. The simulation results show that the temperature, visibility and smoke layer height near the fire source have a great impact on the safe evacuation in the process of fire development. Among them, temperature has a decisive impact on personnel safety in the range of about 1m from the fire source. In the range of 5-10 m, visibility has the greatest impact on safe evacuation. The closer to the fire source, the faster the height of smoke layer decreases.

Numerical Fire Simulation: Key Tools in Fire Safety for Modern Engineering

Numerical Fire Simulation: Key Tools in Fire Safety for Modern Engineering

Modelling flame-to-fuel heat transfer by deep learning and fire images

In numerical fire simulations, the calculation of thermal feedback from the flame to the solid and liquid fuel surface plays a critical role as it connects the fundamental gas-phase flame burning and condensed-phase fuel gasification. However, it is a computationally intensive task in CFD fire modelling methods because of the requirement of a high-resolution grid for calculating the interface heat transfer. This paper proposed a real-time prediction of the flame-to-fuel heat transfer by using simulated flame images and a computer-vision deep learning method. Different methanol pool fires were selected to produce the image database for training the model. As the pool diameters increase from 20 to 40 cm, the dominant flame-to-fuel heat transfer shifts from convection to radiation. Results show that the proposed AI algorithm trained by flame images can predict both the convective and radiative heat flux distributions on the condensed fuel surface with a relative error below 20%, based on the input of real-time flame morphology that can be captured by a larger grid size. Regardless of growing or decaying fires or puffing flames induced by buoyancy, this method can further predict the non-uniform distribution of heat transfer coefficient on the interface rather than using empirical correlations. This work demonstrates the use of AI and computer vision in accelerating numerical fire simulation, which helps simulate complex fire behaviours with simpler models and smaller computational costs. Highlights A total framework between AI model and fire simulation software is designed to further enhance the reliability of AI-based fire simulations. A standard pool fire simulation database is built using numerical model recommend by the IAFSS Computation Group. A deep learning model is developed to predict both the convective and radiative heat flux distributions on the condensed fuel surface using numerical images database. The demonstration showcases the application of AI and computer vision to accelerate numerical fire simulation.

Estimating longitudinal maximum smoke temperature attenuation due to large-angle bifurcation in UTLT-like tunnels under longitudinal ventilation condition

Extensive studies have focused on single-straight tunnels or subway bifurcation tunnel fire. However, the effect of large angle bifurcation on longitudinal maximum temperature rise attenuation in Urban Traffic Link Tunnel（UTLT）needs to be further studied. In this study, based on the theoretical analysis, a double exponential prediction model for longitudinal temperature rise attenuation in bifurcation tunnels is established. To obtain the correlation coefficients, a series of full-scale numerical fire simulation experiments were carried out in an UTLT-like tunnels using Fire Dynamics Simulator. The results revealed that the bifurcation structure of the large-angle bifurcation angle tunnels impeded the longitudinal movement of the fire smoke and hot smoke diversion. Without longitudinal ventilation conditions, the longitudinal decay of the temperature rise in each region can be expressed as the sum of double exponential expressions with different coefficients. The law governing the effect of the bifurcation angle on the longitudinal decay of the temperature rise is the quadratic equation of the angle sin α. A prediction model for the longitudinal decay of the temperature rise in the tunnel downstream of the fire source under longitudinal ventilation is proposed. The findings of the numerical simulation corresponded to those of the model prediction.

Simulation Study on Fire Product Movement Law and Evacuation in a University High-Rise Teaching Building

High-rise teaching buildings are complex public buildings that combine the evacuation risks of school buildings and high-rise buildings. In this regard, studying fire product transport patterns and personnel evacuation characteristics of high-rise school buildings is crucial for safe and rapid evacuation. In this paper, we applied Pyrosim2018 software to build a model of a teaching building and performed numerical fire simulation to analyze temperature, CO gas, and visibility to determine the available evacuation time ASET; meanwhile, we performed evacuation simulation by Pathfinder 2019 to determine the required evacuation time and analyze the congestion problem during evacuation. By improving the evacuation route, secondary simulations were conducted and compared with the previous results. The results show that visibility is the main factor affecting evacuation in of the event of a fire in this school building. Based on the visibility analysis, it is recommended that personnel evacuate from floors four and above within 709.2 S when the fire location is at a specific position on the third floor. While the original safety exits of the school building can avoid a large number of casualties, they cannot guarantee the safe evacuation of all people, and planning a reasonable evacuation route can obviously relieve the evacuation pressure in the high-rise corridor.

Numerical Simulation of 35kV Oil-Immersed Transformer Fire and Extinguishing Effects of High-Pressure Fine Water Mist

Numerical Simulation of 35kV Oil-Immersed Transformer Fire and Extinguishing Effects of High-Pressure Fine Water Mist

Fire spread along vertical greenery systems from window ejected flame: A study based on a fire dynamic simulator model

Recent studies have shown that, poorly maintained vertical greenery systems (VGS) have a high fire risk and a tendency to cause very high heat release rates (HRR) in a case of fire. High HRR in materials often results in rapid fire spread in upward orientation. This study used numerical fire simulations with computational fluid dynamics (CFD) to investigate the fire spread along a VGS. The fire simulations were conducted in fire dynamic simulator (FDS) using the pyrolysis model that was specifically developed for vegetation. In FDS, the fire was initiated as a room fire of 1 MW followed by a window ejected flame, which ignited a 12 m tall and 9 m wide VGS. Fire spread along a VGS was modelled with four different moisture contents (MC) and four different packing ratios (PR) of the vegetation fuel bed. The different MCs represented regularly and scarcely watered vegetation, while different PRs represented different bulk densities of the vegetation in the VGSs. The fire spread rate was increased when both the MC and PR were decreased. The rate of fire spread in the upward orientation, which is the most hazardous mode of fire spread, was found to increase by 469.8% when the MC was decreased from 80% to 10%, and by 207.1% when the PR was decreased from 0.5 to 0.1. The results are helpful in understanding the design of a VGS with an optimum level of vegetation density and maintaining the vegetation fresh and alive to minimise the fire hazard. • Numerical simulations are conducted with a fire dynamic simulator model. • Moisture content (MC) and packing ratio (PR) of vegetation were varied. • Lower MC and PR of vegetation increase the fire spread rate. • Fire spread is notably faster in the upward direction over green wall. • Keeping vegetation fresh and lush is vital to reduce the fire risk.

Numerical Simulation of Gas-solid Jet Fire in Natural Gas Pipeline Leakage

Aiming at the problem that gas-solid two-phase jet flame formed by jet fire entrained by natural gas pipeline leakage is less studied, the gas-solid two-phase jet and pure gas-phase jet flame models formed by natural gas pipeline leakage are established by FLUENT software. The differences between the gas-solid two-phase jet and the pure gas-phase jet flame were comparatively studied, and the effect of different particle size on flame height, temperature and radiation of gas-solid jet was analyzed. The results indicate that the solid particles entering the flame will lead to a lower temperature compared to a gas-jet-only flame. The larger the mass flow of solid particles is, the lower the flame temperature of the gas-solid jet will be, and the corresponding flame height and radiation hazards are also reduced. The present study findings can be used for the purpose of studying gas-solid two-phase jet flame in leakage of natural gas pipelines.

Full scale experimental and numerical simulation of outside transformer fire

To study the real scale transformer fire and fire control process, this paper uses FDS to simulate the transformer fire combustion process and analyzes the data of transformer fire temperature and flow field. Through data analysis, this paper establishes a fire visualization system based on the unity3d engine and uses modeling software to complete the Substation Scene Modeling, the visualization process of fire particles and fire water jet in the whole process of transformer fire occurrence and fighting is realized. The research results are of great significance for substation fire construction and emergency rescue.

Introducing the “Mathematical Modelling and Numerical Simulation of Combustion and Fire” Section of the Journal Fire

It is my immense pleasure to assume the role of Editor-in-Chief for the “Mathematical Modelling and Numerical Simulation of Combustion and Fire” Section of Fire, which is intended to take a leading role in the dissemination of high-quality research in this area [...]

Numerical Simulation of Fire in Underground Commercial Street.

In this study, while aiming at the prevention of fire accidents in underground commercial streets, an underground commercial street is selected as a research object, and the building fire is numerically simulated using the PyroSim software. Fire simulation scenarios are divided according to different fire zones by analyzing the temperature, carbon monoxide (CO) concentration, and visibility in the smoke layer inside a building. The available safe evacuation time is calculated according to the critical fire hazard judgment conditions. We found that the time when the flue gas temperature and CO concentration reached the critical value in the fire site was longer than the time when the visibility reached the critical value reducing or even avoiding the spread of smoke from the fire area to the evacuation stairs can provide effective help for crowd evacuation. Finally, the safety of the building is evaluated, and fire prevention countermeasures are defined based on the actual situation and fire numerical simulation results to reduce fire incidence, casualties, and economic losses.

Effect of tunnel slope on the critical velocity of densimetric plumes and fire plumes in ventilated tunnels

To control the harmful releases in a tunnel, a longitudinal ventilation flow has to be imposed. The concept of critical velocity has been the focus of numerous tunnel fire studies, with researches focus on horizontal tunnels and tunnels with inclination have received much less attention. Due to the stack effect, smoke movement in inclined tunnels (with inclination angle θ) is different from that in horizontal tunnels and the critical velocity can be affected. In this study, we tackle the problem of critical velocity theoretically, experimentally and numerically. The theoretical model relies on a top-hat plume impinging on the ceiling, and predicts a dependence, in case of buoyancy-driven releases, of the form Vc/Vc0=1+Cksinθ. Experiments are performed in a reduced scale tunnel, inclined from -5° to +5°, and using light gas mixture (air/helium) to simulate the presence of light smokes. Numerical simulations are performed using FDS (Fire Dynamics Simulator) with hot-air plume and propane fire. Experimental results show that the dynamical condition at the source affects the critical velocity: when the buoyant plume is momentum-driven, the influence of slope is small; when the buoyant plume is buoyancy-driven, the influence of slope is large. This feature is conveniently reproduced by the analytical model adopting Ck=2.1. Similar influence of Γi has been observed in the hot-air plume simulation with that in the experiment. Finally, in the numerical simulation of propane fire, results show that the influence of the slope on the ratio Vc/Vc0 is not affected by the heat release rate.

Extended CFD models for numerical simulation of tunnel fire under natural ventilation: Comparative analysis and experimental verification

This paper proposed Air Entrainment Model (AEM) and Mass Transfer-Volumetric Heating Source model (MT-VHS). Then different physical models of tunnel, gas description models and combustion models were used. CFD results were compared with reduced scale experiments and previous theories. The results show that traditional numerical simulation on tunnel model may cause asymmetrical temperature profile, because the pressure of tunnel portal is always set to be constant. Expanded computational domain can avoid this unreasonable setting. Boussinesq approximation underestimates temperature profile under ceiling because it ignores the variation of air property with temperature. Fitting parameters of air properties are more reasonable. In terms of combustion model, Volumetric Heating Source (VHS) neglects the plume generation. Heat release rate by Eddy Dissipation (ED) is not stable because it is affected by turbulent mixing. The mass sink of AEM entrains not only fresh air but also hot smoke. So the temperature profile by AEM deviates from experimental data much. Maximum temperature, temperature profile under ceiling and smoke layer height predicted by MT-VHS is close to experimental data and theoretical predictions, especially when the heat convection between wall and hot smoke is considered.

Some aspects of design ventilation system in road tunnels

In the base, working of ventilation system can be analyzed in regular and incidental modes of operation. This paper concerns the specification of the longitudinal ventilation necessary to prevent upstream movement of combustion products in a tunnel fire. In this work the objective of the study is to analyze the road way tunnel ventilation system using CFD software to create comfort ventilation system in the tunnel. The comfort ventilation concept refers to the situation when air quality within the tunnel is reduced due to presence of polluted air in the tunnel. This paper is focused on ventilation system in a road traffic tunnel in moment of accident situation as fire. In this investigation numerical simulation of fire was carried out and determination of a critical air velocity depending on the power of the fire was conducted. The output results of the software developed for this purpose, which is also used in the realization of practical projects, are shown.

Heat transfer model for calculation of the temperature field inside thin-walled sections in fire

This paper introduces the heat transfer model for simple calculation of the temperature field inside thin-walled sections in fire. It is dedicated for various shapes of a cross-section of structural elements made of metal. It utilizes the concept of an adiabatic surface temperature (AST) for determination of thermal boundary conditions. Due to the non-uniform heat exposure and arbitrary shape of the cross-section, the resulted temperature field is non-uniform. The given solution is valid for a transient heat transfer problem. The heat transfer model takes into account the practical abilities for measuring heat exposures both in experiments and numerical fire simulations and takes into account the inherent features of beam finite elements with stiffness integration at each step of an analysis, which is important for analyses of skeletal structures in fire. Finally, the heat transfer model is verified by comparison of results to the 2D finite element method solution and validated using data obtained from experiments.

Fire Emergency Evacuation for Large-Scale Public Buildings In 3d Gis

High temperature and smoke poisoning during indoor fires can be fatal, yet traditional evacuation methods fail to account for the high temperature distribution and smoke flow. In this paper, we proposed a fire emergency crowd evacuation model for large-scale public building. Our model integrates fire numerical simulations, individual behavior, and a model to search for the shortest path. Navigation meshes for each floor are connected to form complex 3D multi-meshes for complex architectural interior spaces. The fire numerical simulation provides smoke diffusion flows and the temperature field distribution. The A* algorithm, with its heuristic social force model function for individual behavior, is applied to determine the safest and shortest evacuation route, avoiding risk hazard zones across different floors.

Peculiarities of hazardous chemical fire in high-rise R&D buildings based on numerical simulation

There are lots of chemical laboratories in high-rise R&D buildings. Large amounts of hazardous chemicals were stored in them. Once a fire breaks out in high-rise R&D buildings, its severity will be much greater than that of high-rise residential building fire. Inflammable chemicals, explosive chemicals, toxic chemicals are usually get involved in hazardous chemical fire. FDS software is usually used for numerical simulation of hazardous chemical fire. Then, the impact of hazardous chemicals fire in high-rise R&D buildings can be analyzed under different fire conditions. This paper collected the hazardous chemicals stocks of 69 companies in the R&D buildings and screened the storage data of hazardous chemicals. Typical hazardous chemicals were selected as fire simulation objects. The consequences of hazardous chemical fires can be analyzed by simulation results. The difference between hazardous chemical fire in R&D high-rise buildings and residential building fire can be found out. At the same time, relevant performance indexes will be proposed for the evacuation of high-rise R&D hazardous chemical fire.