Methanol Pool Fires Research Articles

Detailed radiation modeling of two flames relevant to fire simulation using Photon Monte Carlo — Line by Line radiation model

This work reports benchmark data sets for radiative heat transfer in two distinct fire configurations obtained from the Measurement and Computation of Fire Phenomena (MaCFP) working group database. The cases include a 19.2 kW non-sooting turbulent methanol pool fire and a 15 kW sooting ethylene flame (referred to as the FM burner). The base configurations were simulated with large eddy simulation (LES) approaches using two different codes, namely FireFOAM and Fire Dynamics Simulator, respectively. Multiple frozen snapshots from these LES runs were radiatively evaluated using a photon Monte Carlo radiation solver and a line-by-line spectral model. The results were presented at three levels: Firstly, the radiative fields, including radiative emission, reabsorption, and heat flux contours, were shown. Secondly, the global radiative contributions from molecular gas species, soot, and wall boundaries were compared. Thirdly, a detailed spectral analysis of radiative fields for different components within five distinct spectral bands was presented. In the case of the non-sooting methanol pool fire, the radiative emission from CO2 predominates. However, for the radiation reaching the boundaries, both CO2 and H2O contribute almost equally. Conversely, for the sooty FM burner configuration, radiative emission from soot, CO2, and H2O all contribute similarly. In terms of radiation reaching the boundary, soot is the primary contributor in FM Burner. In the methanol pool fire, the pool surface receives a comparable contribution from CO2, H2O, and burner rim radiation, whereas, for the FM burner, the burner inlet surface primarily receives radiation from soot.

Validation Assessment of Turbulent Reacting Flow Model Using the Area-Validation Metric on Medium-Scale Methanol Pool Fire Results

Abstract Accident analysis and ensuring power plant safety are pivotal in the nuclear energy sector. Significant strides have been achieved over the past few decades regarding fire protection and safety, primarily centered on design and regulatory compliance. Yet, after the Fukushima accident a decade ago, the imperative to enhance measures against fire, internal flooding, and power loss has intensified. Hence, a comprehensive, multilayered protection strategy against severe accidents is needed. Consequently, gaining a deeper insight into pool fires and their behavior through extensive validated data can greatly aid in improving these measures using advanced validation techniques. A model validation study was performed at Sandia National Laboratories (SNL) in which a 30-cm diameter methanol pool fire was modeled using the SIERRA/Fuego turbulent reacting flow code. This validation study used a standard validation experiment to compare model results against, and conclusions have been published. The fire was modeled with a large eddy simulation (LES) turbulence model with subgrid turbulent kinetic energy closure. Combustion was modeled using a strained laminar flamelet library approach. Radiative heat transfer was accounted for with a model utilizing the gray-gas approximation. In this study, additional validation analysis is performed using the area validation metric (AVM). These activities are done on multiple datasets involving different variables and temporal/spatial ranges and intervals. The results provide insight into the use of the area validation metric on such temporally varying datasets and the importance of physics-aware use of the metric for proper analysis.

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.

Developing an enhanced thermal radiation model through a Semi-A priori approach

The accurate prediction of thermal radiation is crucial for effective fire safety assessment and the development of proactive prevention strategies. This article presents an innovative approach to thermal radiation modelling through the integration of a semi-a priori methodology. The proposed model combines the strengths of a priori modelling and data-driven approaches, utilising the well-established single point source model as a foundation. The proposed model undergoes refinement and development using experimental data involving propane gas fires, ethanol pool fires, and isopropyl alcohol pool fires. These datasets serve as fitting data, enabling the model to improve its accuracy and performance. The refined model's performance is further assessed through the validation process using experimental data and simulation data. Experimental data from different fire scenarios, i.e., acetone and methanol pool fires, are utilised for the validation. Additionally, the estimated heat flux values generated by the proposed model and the single point source model are also compared with simulation results obtained from Fire Dynamics Simulator (FDS), specifically for heptane and methane pool fires. The findings of this research highlighted the enhanced accuracy and reliability of the proposed model in predicting thermal radiation behaviour. This research offers insights into thermal radiation modelling, providing valuable information for fire safety practitioners and researchers in enhancing fire risk assessment and mitigation strategies. By combining physical principles with empirical data, the proposed approach offers an alternative method for thermal radiation prediction in diverse fire scenarios.

Modelling and effects of fuel radiation in methanol pool fires

This article proposes a computationally affordable radiative heat transfer model to predict accurately the feedback toward the fuel surface. It combines the multi-scale full-spectrum k (MSFSK) approach to model accurately the radiative interaction between CO2/H2O and the fuel and the rank correlated (RCFSK) scheme. The model achieves the narrow band correlated-k model accuracy with only five quadrature points for each of the two scales. The predictions are also weakly dependent on the Planck temperature which allows to store efficiently the MSRCFSK parameters in a flamelet library. The model is implemented in a well-validated numerical model to provide large eddy simulations of 30 cm and 1 m diameter methanol pool fires. The heat feedback predictions are improved when methanol radiation is considered. The overall radiative contribution of methanol results from two competitive mechanisms: an increase in emission in the hot part of the fuel dome and an increase in absorption close to the pool surface. For both pool fires, the enhancement in emission overall dominates, leading to higher radiative loss and heat feedback. The contribution of absorption increases with the pool size and, as a result, the effects of methanol radiation are more pronounced for the 30 cm pool than for the 1 m one.

On the use of natural and forced convection correlations in predictive CFD simulations of liquid pool fires

This paper presents a detailed analysis of predictive numerical simulations of liquid pool fires, i.e., a 1 m – diameter methanol pool, a 0.7 m × 0.8 m ethanol pool, and a 0.18 m – diameter heptane pool. The burning rate is predicted using the ‘film’ model, including empirical correlations for heat and mass transfer. Although the forced convection approach (used in Fire Dynamics Simulator, FDS 6.7.5) yields relatively good results in fuel evaporation rate, it is somewhat questionable from a fundamental standpoint for quiescent burning conditions. Therefore, the natural convection approach is implemented in FDS 6.7.5. The predicted burning rates are similar to the forced convection approach, but the fuel surface temperature is closer to the boiling point by the natural convection approach. Based on the extensive analysis for the methanol pool fire, a modified natural convection correlation is proposed. The latter is tested for the ethanol test with satisfactory results for the peak Heat Release Rate (HRR), burning time, and surface temperature (closer to the boiling point). The modified natural convection approach is further tested for the heptane pool fire. Improved predictions are obtained for the peak burning rate, the transient stage, and the surface temperature.

Assessment study of different radiation models in the simulation of 1 m methanol pool fire

Pool fires are one of the most commonly encountered flame types in fire disasters, and the accurate and detailed modeling of pool fires is beneficial for the hazard analysis and assessment of liquid-related fire accidents. The radiation model is known to be the critical component in the accurate simulation of various fire scenarios. Therefore, to develop a proper radiation model, an LES study of a large-scale methanol pool fire was performed in this work by coupling four different radiation models into the open-source fire simulation code FDS and solving the radiation intensity transport equation using the discrete ordinates method. The impact characteristics of different radiation models are evaluated in detail with the NIST experiments, where the comparative analysis was carried out. Regarding the temperature calculations, the WSGG (weighted-sum-of-gray-gases)-based radiation model and Cassol’s model performed better. In addition, all models predict pulsation frequencies well. However, regarding the prediction of the radiative heat fluxes, Cassol’s two models and the FDS default model outperformed the other models, which indicates that the database for obtaining the spectral information of each species and the method to determine the WSGG coefficient of mixed gases are significant factors for the successful prediction of flame radiation.

Experimental Research on the Effectiveness of Different Types of Foam of Extinguishing Methanol / Diesel Pool Fires

ABSTRACT Storage tank fire can pose great threats to life and environment as it can cause strong radiant heat, fast-spreading flame, and destructive explosion. In this research, a 1.5 m-diameter circular steel pan is used to simulate the full surface fire of a storage tank in an industrial park. A self-built fire-extinguishing system gently releasing foam at the rate of 11.4 L/min was applied for the evaluation of the effectiveness of different types of foam of extinguishing diesel/methanol pool fires. Experiments were conducted to analyze the temperature increases of fires after releasing different types of foam. In this research, the nondimensional average temperature 0.85 and 0.71 regard as the fire extinguishing temperatures of methanol and diesel fuel, respectively. Over the spreading process, the increase in foam spreading length over time still follows the power law. The fastest flow velocity of 6% FP/AR in methanol pool fire and 6% Synthetic foams in diesel pool fire was 0.0136 m s −1and 0.044 m s −1, respectively, with a foam application rate of 11.4 L/min. The results show that, in the methanol pool fire, the cooling effect of the foam is ranked as FP/AR > AFFF > AFFF/AR > S > FP > S/AR. And the cooling effect of foam for diesel is ranked as S > S/AR > AFFF > AFFF/AR > FP > FP/AR. Foam’s cooling impact is especially notable in diesel pool fires. As for methanol pool fires, the foam extinguishing mechanism is mainly based on the “anti-soluble film” effect, which quickly forms a covering layer on the surface of the flammable liquid, seperating the flame from heat feedback and inhibiting the generation of flammable vapors, insulating itself against the air and ultimately asphyxiating the fire.

Study of radiative heat transfer and flow physics from medium-scale methanol pool fire simulations

A medium-scale (30 cm diameter) methanol pool fire was simulated using Sandia National Laboratories’ Sierra/Fuego low-Mach number multi-physics turbulent reacting flow code. Large Eddy Simulation (LES) with subgrid turbulent kinetic energy closure was used as the turbulence model. Combustion was modeled using a strained laminar flamelet library approach. Radiative heat transfer was modeled using the gray-gas approximation. This paper details analysis done to support a validation study for the fire model. In this analysis, integral quantities were primarily examined. The radiant fraction was computed and used as a model calibration parameter. Integrated buoyancy flux was calculated and compared to an engineering correlation. Entrainment rate was computed with and without a mixture fraction threshold filter and compared to engineering correlations. Turbulent kinetic energy was computed and the effect of mesh size on the subgrid and total turbulent kinetic energy was examined. Flame height was calculated using an intermittency definition with two input parameters. A sensitivity study was then conducted to determine the sensitivity of the estimated flame height to the input parameters. This analysis aided in achieving the primary validation study objectives by providing model calibration and expanding the scope of the validation effort. In addition, the range of physics examined was increased, enhancing the understanding of the model's overall performance and of the relationship between phenomena.

Flow and thermal radiation characteristics of a turbulent flame by large eddy simulation

Liquid fuel pool fire flame is a common combustion problem for liquid oil in many practical applications. Thermal radiation has considerable effect on its combustion process and fire spread. Based on the large eddy simulation method of the fireFOAM framework, the flame properties and thermal radiation characteristics of a 1 m diameter methanol pool fire are investigated. The flame structure features frequent buoyance-driven upward movement and air entrainment from surrounding environment due to turbulent mixing and combustion. The radiative heat feedback shows strong temporal and spatial variations, which is caused by the fluctuating behaviors of the temperature and species fields. The radiation transfer models have significant discrepancies in predicting the radiative heat feedback for all the surfaces with the weighted-sum-of-gray gases model producing better results. Ray effects of the solvers lead to unphysical non-uniform distributions of radiative heat flux on the bottom and side walls.

Numerical Simulations of a Postulated Methanol Pool Fire Scenario in a Ventilated Enclosure Using a Coupled FVM-FEM Approach

Numerical investigations have been carried out for a postulated enclosure fire scenario instigated due to methanol pool ignition in a chemical cleaning facility. The pool fire under consideration is radiation-dominated and poses a risk to the nearby objects if appropriate safety requirements are not met. The objective of the current study was to numerically evaluate the postulated fire scenario and provide safety recommendations to prevent/minimize the hazard. To do this, the fire scenario was first modeled using the finite volume method (FVM) based solver to predict the fire characteristics and the resulting changes inside the enclosure. The FDS predicted temperatures were then used as input boundary conditions to conduct a three-dimensional heat transfer analysis using the finite element method (FEM). The coupled FVM–FEM simulation approach enabled detailed three-dimensional conjugate heat transfer analysis. The proposed FVM–FEM coupled approach to analyze the fire dynamics and heat transfer will be helpful to safety engineers in carrying out a more robust and reliable fire risk assessment.

Medium-Scale Methanol Pool Fire Model Validation

Abstract Medium scale (30 cm diameter) methanol pool fires were simulated using the latest fire modeling suite implemented in Sierra/Fuego, a low Mach number multiphysics reacting flow code. The sensitivity of model outputs to various model parameters was studied with the objective of providing model validation. This work also assesses model performance relative to other recently published large eddy simulations (LES) of the same validation case. Two pool surface boundary conditions were simulated. The first was a prescribed fuel mass flux and the second used an algorithm to predict mass flux based on a mass and energy balance at the fuel surface. Gray gas radiation model parameters (absorption coefficients and gas radiation sources) were varied to assess radiant heat losses to the surroundings and pool surface. The radiation model was calibrated by comparing the simulated radiant fraction of the plume to experimental data. The effects of mesh resolution were also quantified starting with a grid resolution representative of engineering type fire calculations and then uniformly refining that mesh in the plume region. Simulation data were compared to experimental data collected at the University of Waterloo and the National Institute of Standards and Technology (NIST). Validation data included plume temperature, radial and axial velocities, velocity temperature turbulent correlations, velocity velocity turbulent correlations, radiant and convective heat fluxes to the pool surface, and plume radiant fraction. Additional analyses were performed in the pool boundary layer to assess simulated flame anchoring and the effect on convective heat fluxes. This work assesses the capability of the latest Fuego physics and chemistry model suite and provides additional insight into pool fire modeling for nonluminous, nonsooting flames.

Local contributions of resolved and subgrid turbulence-radiation interaction in LES/presumed FDF modelling of large-scale methanol pool fires

The present study aims to quantify individual contributions to turbulence-radiation interaction (TRI) in LES of large methanol pool fires with diameters ranging from 1m to 4m. These simulations feature a steady laminar flamelet (SLF)/presumed Filtered Density Function (FDF) combustion model and the Rank Correlated Full Spectrum k-distribution (RC FSK) for spectral gas radiation. This quantification has a fundamental interest to, on the one hand, understand how these contributions affect the radiative heat transfer from the flame to the surroundings that controls fire growth in industrial fires and, on the other hand, to provide guidance for the development of simplified models for TRI. This analysis is accomplished by exercising a well-validated fire model and using a scaling strategy that preserves the relative contributions of resolved-scale and subgrid-scale (SGS) scalar fluctuations. Large-scale non-luminous pool fires feature large optical thicknesses that increase significantly with the pool diameter. As a result, applying the optically-thin fluctuation approximation (OTFA) leads to a noticeable overestimation of the global radiative loss. The fire plume dynamics is governed by the puffing process whose frequency decreases with the pool size, and, in turn, affects the levels of turbulent intensity. As a result, emission TRI increases in the continuous flame and decreases in the high intermittent flame regions. The contribution of SGS emission TRI to global emission TRI becomes progressively dominant as the pool size increases. The largest contributions to both resolved-scale and SGS emission TRI are the temperature self-correlation and the absorption coefficient-temperature cross correlation, although this latter becomes negligible at the subgrid scale for pool diameters larger than 1m. In addition, the SGS absorption-coefficient self-correlation is also found to be negligible.

The Evolving Temperature Field in a 1 m Methanol Pool Fire.

Thin filament pyrometry is used to measure the time-varying temperature field in a 1 m methanol pool fire. A digital camera with optical filters and zoom lens recorded the emission intensity of an array of 12 μm Silicon-Carbide filaments oriented horizontally at various heights across the steadily burning pool fire. A 50 μm diameter thermocouple measured the temperature at locations corresponding to the filament positions. A correlation was developed between the local probability density functions of the thermocouple time series measurements corrected for radiation and thermal inertia effects and the camera grayscale pixel intensity of the filaments. A regression analysis yields the local mean temperature and its variance. The time series of the temperature field is transformed into average values during consecutive phases of the fire's puffing cycle, providing quantitative insight into the complex and dynamic structure of a turbulent fire.

Experimental Thermal Performance of Unloaded Spiral Strand and Locked Coil Cables Subject to Pool Fires

There are no contemporary code requirements for the fire resistance of bridge infrastructure, nor is there guidance available for practitioners who wish to design cable-supported structures for the fire. This research seeks to develop an understanding of the thermal response of steel stay-cables under exposure to a pool fire. Multiple varieties of locked coil and spiral strand stay-cables are instrumented with thermocouples and heated by a methanol pool fire. Novel imaging techniques observe the cables’ surface during heating and cooling and enable the calculation of thermal strains and deformations. Results herein illustrate a normalisation of cross-sectional temperatures outside of the localised heating region for cable diameters up to 140 mm, provide comparisons of heat transfer behaviours for different cable sizes and configurations, present novel thermal rotational effects, and calculation of cable thermal expansion values. Predictive thermal expansion values provided by the Eurocode are shown to underpredict cable thermal expansion in most cases.

The effect of convective motion within liquid fuel on the mass burning rates of pool fires – A numerical study

To improve numerical simulation of liquid pool fires and remove the need for experimentally measured or empirically calculated mass burning rates as boundary conditions, a fully coupled three-dimensional (3-D) numerical formulation, which directly solves convective motion in the fuel region by incorporating inhomogeneous heat feedback, is formulated. The fire dynamics is modelled using the large eddy simulation (LES) approach. Incompressible laminar flow formation is applied to the liquid fuel region, assuming constant thermo-physical properties except for the density which follows the Boussinesq approximation. The numerical formulation of the two phases is solved using a fully coupled conjugate heat transfer approach at the pool surface. The coupled model is validated against published measurements for a thin-layer heptane pool fire and a deep methanol pool fire. The convective motion within the liquid phase is found to have important effects on the pool fire mass burning rate and its neglection would result in a fast rise and over-prediction of the mass burning rate.

Large Eddy Simulation of medium-scale methanol pool fires - effects of pool boundary conditions

This article reports Large Eddy Simulation (LES) of 30 cm diameter methanol pool fires in order to investigate the effects of the burner boundary conditions on the pool dynamics. The numerical model involves state-of-the-art subgrid scale (SGS) sub-models for mixing, combustion and turbulence-radiation interaction with all the model constants computed dynamically. The non-adiabatic steady laminar flamelet (SLF)/presumed filtered density function (FDF) combustion model is used whereas the radiation model combines the Rank Correlated Full Spectrum k-distribution (RCFSK) for spectral radiation with the finite volume method (FVM) as radiative transfer equation (RTE) solver. The baseline case considers a burner located one-pool diameter above the floor and a fuel lip height of 1 cm as specified in the experiments used for model validation. Model predictions for puffing frequency, mean and rms temperature and velocity, mean molar fractions of major species, radiative loss to the surrounding and radiative and total heat feedback to the fuel surface are in good agreement with the available experimental data. Two other burner boundary conditions are designed. The first disregards the fuel lip height while keeping the burner located one-pool diameter above the floor. The second modifies the first configuration by assuming that the burner rim is floor flush. Model results show that the burner boundary conditions affect significantly the flow structure and the pool fire dynamics by altering the flame base instability near the edge of the pan. A non-zero fuel lip height produces significantly wider and shorter flames which affect the heat feedback toward the fuel surface whereas altering the air entrainment at the pool basis enhances substantially the puffing frequency. This shows that the experimental burner boundary conditions have to be reproduced scrupulously for relevant model validations.

Deep-Learning Emulators of Transient Compartment Fire Simulations for Inverse Problems and Room-Scale Calorimetry

This work describes a deep learning methodology for “emulating” temperature outputs produced by the Fire Dynamics Simulator (FDS), a CFD software. An array of artificial neural networks (ANNs) is trained to predict transient temperatures at specified locations for a transient heat release rate (HRR) input. These locations correspond to the locations of thermocouples used in an experimental burn structure. In order to build the training set, A Gaussian process (GP) framework is used to develop a generative model that produces random viable HRR ramps. Although this procedure may require thousands of FDS runs to build a sufficient training set, the application of transfer learning can reduce the required number of runs by nearly an order of magnitude. This refers to the process of initially training an ANN to predict the output of the Consolidated Model of Fire and Smoke Transport (CFAST) and then transferring its knowledge to an ANN that learns to predict FDS outputs. CFAST is a much faster model than FDS, so a large training set can be generated quickly. The final state of the ANN trained to emulate CFAST is used as the initial state of an ANN that learns to emulate FDS. The result is a model that produces FDS temperature predictions with a mean absolute error (MAE) of less than 2°C and runs over five orders of magnitude faster than FDS. The emulators are also capable of learning inverse mappings; i.e. for a given temperature output, they can predict the HRR ramp that would cause FDS to produce the temperature response. This ability to invert for the HRR profile is exercised on data collected from eight fire experiments with peak HRRs up to 200 kW, including four propane burner fires, two methanol pool fires, and two n-Hexane pool fires. The model inverts for the experimental HRR with a MAE of 5.8 kW-15.4 kW (11.3%–16.7%) for the burner tests and 5.0 kW–25.5 kW (12.1%–28.6%) for the pool fire tests, with a tendency to underestimate the HRR of the pool fires. Finally, the computational speed of the emulators allows for the incorporation of CFD physics in Bayesian parameter inversion. As an example, this is demonstrated to infer the radiative fraction from experimental and synthetic data in conjunction with reported uncertainties from the FDS Validation Guide.

Influence of gas radiative property models on Large Eddy Simulation of 1 m methanol pool fires

The main objective of this work is to analyze the effects of gas radiative property models on the radiative outputs and flame structure in a 1 m diameter methanol pool fire. Large Eddy Simulation (LES) are run with the non-adiabatic steady laminar flamelet (SLF)/presumed filtered density function (FDF) model to close subgrid-scale (SGS) turbulence-chemistry and turbulence-radiation emission interactions. The radiative transfer equation (RTE) is solved using the Finite Volume Method (FVM) with different angular meshes, including uniform angular dicretizations comprising 16 (polar angle) × 24 (azimuthal angle) and 48 × 96 control angles and the FTn scheme with n up to 48. Four gas radiative property models, namely the Rank Correlated Full Spectrum k-distribution (RCFSK), the non-grey Weighted-Sum-of-Grey-Gases (WSGG), and two versions of the grey WSGG based on different evaluations of the mean path length are assessed. Model predictions with the RCFSK reproduce with fidelity the available experimental data in terms of flame structure and radiative loss to the surrounding. The radiative heat transfer within the flame, where radiation is isotropic, is adequately resolved with the FT12 angular resolution whereas finer angular meshes with at least 32 segments to discretize the polar angle are required to predict accurately the vertical distributions of radiative flux outside the flame. The grey models fail to reproduce the radiative structure of the flame, predicting an optically thin flame instead of an optically intermediate medium. In an opposite way, although the non-grey WSGG overestimates both emission and absorption, it provides predictions in overall reasonable agreement with the RCSFK.

Experimental and numerical study of pool fire dynamics in an air-tight compartment focusing on pressure variation

The present paper studies the fire-induced pressure evolution in an air-tight compartment. Two cases with different sizes (i.e., 0.3 m × 0.3 m and 0.5 m × 0.5 m) of square methanol pool fire are considered. Repeated tests were performed for each case, leading to a total of four fire experiments. The leakage of the compartment is measured under different pressure conditions in order to obtain the relationship between the leakage and the pressure increase. The pressure inside the compartment reaches peak values of 133 Pa and 697 Pa for the small and the large pool fire, respectively. Simulation results using the Fire Dynamics Simulator (FDS) 6.5.3 match well with experiments. The simulated leakage flow rates, which reach values up to 65 m3/h and 200 m3/h, respectively, depend on the pressure variation and leakage settings. The pressure rises strongly in the growth phase of the fire, in line with a rapid increase in fire heat release rate. The gradually increasing heat losses subsequently lead to a decrease in pressure.