Large-scale Pool Fires Research Articles

Effects of a Full Scale Aircraft Immersed within a Large Aviation-Fuel Fire in Crosswind on the Flame Shape - A Numerical Study

Large Eddy Simulation combined with an Eddy Dissipation Concept (EDC) combustion model shows the feasibility for simulations of a full scale aircraft immersed within a large aviation-fuel fire in a moving fluid medium. Coupling between the condensed fuel and gas phases allows investigating the roles of the wind speed on the burning rate of condensed fuel, and consequently, the heat release rate. The predicted combustion efficiency of a large scale liquid pool fire remains approximately constant with a value of 85%. The predicted burning rate of a liquid pool fire increases with wind speed up to critical value of about 3-4 m/s, then decrease strongly with a further increase in the wind speed. It appears that the primary flame zone is not significant affected by the presence of an aircraft for the wind speed below 2 m/s. The prediction indicates that interaction between the aircraft and fire environment combined with the influence of medium wind speed of 5 m/s affects dramatically the flame shape. Presence of an aircraft leads to a factor of about 1.8 increases in the elongation of turbulent boundary layer diffusion flame for the wind speed beyond 5 m/s. globally, the flame height in large-scale pool fire is mainly associated with the fire dynamics at low source Froude number and the flame length with the wind speed.

Experimental and numerical study on attenuation of thermal radiation from large-scale pool fires by water mist curtain

Full-scale experiments and numerical simulations were conducted to study the thermal radiation attenuation from large fires by water mist curtain with low and intermediate pressures. Fire dynamics simulator (version 6) was used for numerical simulations. A novel multi-injector nozzle was designed to generate a homogeneous water mist curtain with low water consumption. Water mist characteristics of one of the injectors were measured by Shadowgraphy technology. A 1 × 1 m diesel pool fire was considered as the fire source. The experimental results show that the water mist curtain has high thermal radiation attenuation efficiency, for example, about 82.7% radiant heat flux could be attenuated by the water mist curtain with 2 MPa working pressure and flow rate of 13.3 L/min. Comparisons with the experimental results show that the calculated radiant heat flux and temperature are slightly underestimated.

Assessment of four turbulence models in simulation of large-scale pool fires in the presence of wind using computational fluid dynamics (CFD)

Pool fires are the most common of all process industry accidents. Pool fires often trigger explosions which may result in more fires, causing huge losses of life and property. Since both the risk and the frequency of occurrence of pool fires are high, it is necessary to model the risks associated with pool fires so as to correctly predict the behavior of such fires.Among the parameters which determine the overall structure of a pool fire, the most important is turbulence. It determines the extent of interaction of various parameters, including combustion, wind velocity, and entrainment of the ambient air. Of the various approaches capable of modeling the turbulence associated with pool fires, computational fluid dynamics (CFD) has emerged as the most preferred due to its ability to enable closer approximation of the underlying physical phenomena.A review of the state of the art reveals that although various turbulence models exist for the simulation of pool fire no single study has compared the performance of various turbulence models in modeling pool fires. To cover this knowledge-gap an attempt has been made to employ CFD in the assessment of pool fires and find the turbulence model which is able to simulate pool fires most faithfully. The performance of the standard k–ɛ model, renormalization group (RNG) k–ɛ model, realizable k–ɛ model and standard k–ω model were studied for simulating the experiments conducted earlier by Chatris et al. (2001) and Casal (2013). The results reveal that the standard k–ɛ model enabled the closest CFD simulation of the experimental results.

Periodic puffing instabilities of buoyant large-scale pool fires in a confined compartment

This article presents an experimental study of the pulsating period of pool fires in a confined and ventilated compartment. Based on large-scale pool fire experiments, two modes of flame pulsation are identified. The first one is the common mode of flame puffing observed in an open atmosphere, and the second one is a perturbed pulsation mode induced by a hot vitiated environment. A description of these modes and their spectral analysis based on image processing are described. The second new mode differs from the common mode by a lower puffing frequency of the reacting gas phase. The effect of the pool diameter is analysed for the two modes.

Large-scale pool fires

A review of research into the burning behavior of large pool fires and fuel spill fires is presented. The features which distinguish such fires from smaller pool fires are mainly associated with the fire dynamics at low source Froude numbers and the radiative interaction with the fire source. In hydrocarbon fires, higher soot levels at increased diameters result in radiation blockage effects around the perimeter of large fire plumes; this yields lower emissive powers and a drastic reduction in the radiative loss fraction; whilst there are simplifying factors with these phenomena, arising from the fact that soot yield can saturate, there are other complications deriving from the intermittency of the behavior, with luminous regions of efficient combustion appearing randomly in the outer surface of the fire according the turbulent fluctuations in the fire plume. Knowledge of the fluid flow instabilities, which lead to the formation of large eddies, is also key to understanding the behavior of large-scale fires. Here modeling tools can be effectively exploited in order to investigate the fluid flow phenomena, including RANS- and LES-based computational fluid dynamics codes. The latter are well-suited to representation of the turbulent motions, but a number of challenges remain with their practical application. Massively-parallel computational resources are likely to be necessary in order to be able to adequately address the complex coupled phenomena to the level of detail that is necessary.

Hazards of Large Scale Pool Fire of Dimethyl Ether

Hazards of Large Scale Pool Fire of Dimethyl Ether

Experimental study of thin-layer boilover in large-scale pool fires

By performing a series of pool fire experiments, the authors attempt to apply knowledge of thin-layer boilover to the large scale (pool diameter from 1.5 to 6 m). Two commercial hydrocarbons were used: gasoline and diesel. As expected, only in the case of diesel did the phenomenon of thin-layer boilover occur. Data were used to analyze various features of thin-layer boilover in fires, particularly its intensity and onset time. A comparison with results published in the literature shows the importance of this study.

Model of large pool fires

A two zone entrainment model of pool fires is proposed to depict the fluid flow and flame properties of the fire. Consisting of combustion and plume zones, it provides a consistent scheme for developing non-dimensional scaling parameters for correlating and extrapolating pool fire visible flame length, flame tilt, surface emissive power, and fuel evaporation rate. The model is extended to include grey gas thermal radiation from soot particles in the flame zone, accounting for emission and absorption in both optically thin and thick regions. A model of convective heat transfer from the combustion zone to the liquid fuel pool, and from a water substrate to cryogenic fuel pools spreading on water, provides evaporation rates for both adiabatic and non-adiabatic fires. The model is tested against field measurements of large scale pool fires, principally of LNG, and is generally in agreement with experimental values of all variables.

Modelling of the thermal radiation of pool fires

Since the thermal radiation of large-scale fires can be a hazard to surrounding buildings, there is a need for suitable models to describe the thermal radiation of these fires. With the presented radiation model OSRAMO II, which is experimentally validated, it is possible to calculate the mean surface emissive power of pool fires with pool diameters 8 m ≤ d ≤ 25 m. Direct numerical simulations of a small-scale ethylene pool fire show that the periodical rise of vortex structures like soot parcels and hot spots has a major influence on the temporal variation of flame temperature, soot volume fraction and volume emissive power. Furthermore, the modelling of a large-scale kerosene pool fire shows a time depending temperature field due to the periodical rise of vortices.

CFD Modeling of Large-Scale Pool Fires

Chemie Ingenieur TechnikVolume 73, Issue 6 p. 638-639 Article CFD Modeling of Large-Scale Pool Fires C. Kuhr, C. Kuhr Gerhard-Mercator-Universität Duisburg, FB 6 Technische Chemie, Lotharstr. 1, 47057 Duisburg, Germany, Tel.: +49 (0)203 3792714Search for more papers by this authorA. Schönbucher, A. Schönbucher Gerhard-Mercator-Universität Duisburg, FB 6 Technische Chemie, Lotharstr. 1, 47057 Duisburg, Germany, Tel.: +49 (0)203 3792714Search for more papers by this author C. Kuhr, C. Kuhr Gerhard-Mercator-Universität Duisburg, FB 6 Technische Chemie, Lotharstr. 1, 47057 Duisburg, Germany, Tel.: +49 (0)203 3792714Search for more papers by this authorA. Schönbucher, A. Schönbucher Gerhard-Mercator-Universität Duisburg, FB 6 Technische Chemie, Lotharstr. 1, 47057 Duisburg, Germany, Tel.: +49 (0)203 3792714Search for more papers by this author First published: 12 July 2001 https://doi.org/10.1002/1522-2640(200106)73:6<638::AID-CITE6383333>3.0.CO;2-0AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume73, Issue6Juni 2001Pages 638-639 RelatedInformation

Behavior of luminous zones appearing on plumes of large-scale pool fires of kerosene

Abstract In order to understand characteristics of large pool fires, behavior of intermittent luminous zones appearing on the smoky plumes has been analyzed using a recently developed image processing technique. The images of large pool fires analyzed in this study are of 30 and 50-m diameter pool fires of kerosene recorded on videotapes at the large-scale experiments performed in Japan, 1981. The results indicate that the probability of a luminous zone appearing is the maximum on the central point of the average plume width and at a distance from its base, and decreases with the distance from the maximum point. It can be inferred that the luminous zone on the smoky plume of a pool fire likely appears at its concave boundary (in a side view). It ascends at an almost constant velocity while changing it's area at the same frequency as that of the “breathing”.

Temporal and Spatial Characteristics of Radiation from Large Scale Pool Fires

Temporal and Spatial Characteristics of Radiation from Large Scale Pool Fires

A Study of Boilover in Liquid Pool Fires Supported on Water Part I: Effects of a Water Sublayer on Pool Fires

Abstract Under certain circumstances, the water on which a burning pool of liquid fuel is supported may begin to boil. The water vapor that is released and escapes through the fuel surface tends to atomize the oil, which results in an emulsive-droplet flame above the fuel surface. This phenomenon, called boilover, has been observed for large scale pool fires, but the mechanism causing it to occur has not been fully investigated yet. This paper describes fundamental aspects of the effect of a boiling water sublayer on the behavior of pool fires. A burner system in which the burning surface of the fuel can be fed into the flame so that the fuel/water interface with respect to the edge of the container remains fixed was used. Ten different single-component and six different multicomponent fuels were tested. Conventional flow visualization techniques were applied to study the liquid motion, and results for an ethylbcnzene pool in a 4.8cm diameter pan are presented. Data obtained include temperatures and mass ...

Buoyant plumes of large-scale pool fires

A series of large-scale pool fire tests were conducted to investigate the variation of plume gas temperature and velocity. Three pool diameters: 1.219 m, 1.737 m and 2.438 m, were selected; four fuels with drastically different heat release rates were employed. In each test, measurements were made of plume gas temperatures and velocities and weight loss of the fuel pool. The measured plume temperature profiles at several elevations were fitted with Gaussian distributions in order to determine plume centerline position and centerline values of gas temperatures and velocities. The plume convective heat flux was then determined from the fitted profiles of plume temperatures and velocities. The plume centerline temperature followed the 2/3 power of the convective heat flux, Q c , and the −5/3 power of the pulme height with respect to the virtual source location, z-z o , down to the level where intermittent flames were found; the centerline gas velocity varied as the 1/3 power of Q c and −1/3 power of z-z o . The virtual source locations were found to be related to the flame heights. For large values of the ratio of flame height versus pool diameter, the distance from the flame tip to the virtual source is proportional to the 2/5 power of the convective heat flux and the virtual source location correlates well with a parameter 10 sed for flame correlation. For small flame-height to pool-diameter ratios, in several tests, the virtual source locations were below the pool surface; however, the virtual source moved upward as the pool diameter increased or the convective heat flux per unit pool surface increased.