Experimental study of fire containment using water mist curtains in a reduced-scale deck of a ro-ro ship

Experiments have been conducted to evaluate the containment of smoke and heat using water mist curtains in a model setup of a ro-ro ship's cargo deck with a scale of 1:13, providing practical insights into the application of such fire protection systems in the cargo deck as well as valuable data for future numerical simulations. In this regard, the requirements of the international convention of Safety of Life at Sea (SOLAS) are studied for the side openings of so-called ‘open decks’ in comparison with ‘closed decks’, especially to examine the feasibility of using water mist curtains for creating isolated subdivisions in the ro-ro space as a fire management strategy. The water mist curtains are created with one or two rows of water mist nozzles at pressures ranging from 3 to 8 bar, while the source of smoke and heat is a liquid pool fire, and inert cargo items are used in some experiments. Correspondingly, the interaction between the water mist curtain(s) and the fire is evaluated in terms of its heat release rate, and the containment effect is quantified via measurements of smoke flow through the deck and through the windows, concentrations of gaseous species, as well as gas temperatures at various key locations. The study shows that water mist curtains have a strong effect on fire dynamics and smoke propagation, but containment is dependent on the configuration of side openings and the location of fire, among other important factors

Vegetation fire spread database: 85 wood wool shaving experiments at laboratory scale

International audienc

Use of a water mist for smoke confinement and radiation shielding in case of fire during tunnel construction

International audienc

Radiation emission from a heating coil or a halogen lamp on a semitransparent sample

The radiation emission of the heating coil of a Cone Calorimeter and the one of the halogen lamp of a Fire Propagation Apparatus have been studied experimentally for varying power settings. These are two standard apparatuses used for fire calorimetry. The objective is to characterize and compare the radiative flux spectrum received by a fuel sample during pyrolysis experiments. The deviation from the standard assumption of black or gray emission is discussed. It is observed that the emission of the heating coil can be approximated well to an ideal blackbody, especially in the infrared range. On the contrary, the halogen lamp emission is more complex, non gray, with an important contribution in the visible and in the near infrared ranges. The flux received by a sample exposed to these emitters is predicted using ray tracing simulations. This shows that the irradiation flux and spectrum from the cone can be accurately calculated if the coil temperature is known. The non Lambertian irradiation flux from the lamp is modeled with a combination of diffuse and collimated intensities, representing the direct emission from the lamp itself and the reflection by the mirror at the rear side. For both emitters, the irradiation is confirmed to be approximately uniform over the surface of a sample 5 cm large (maximum deviation of ±2% on the incident flux). The uniformity decreases for larger samples, but the ratio of the flux at the center to average flux is still 1.04 for standard 10 cm × 10 cm samples under the cone. For illustration purposes, the influence of the spectral characteristics of the emitter is studied in the case of a sample of PMMA, a non gray translucent medium. Using recently published measurements of PMMA absorptivity, the absorbed flux by a 3 cm thick sample is predicted. In the case of an incident flux of 20 kW/m2, the calculated average absorptivity of the sample is 0.91 under the cone, while it is 0.32 under the FPA lamp. These calculations involve absorption data of a virgin sample at room temperature and consequently the numerical results only hold for the initial instants of irradiation. However, the very large differences in radiative behavior show that important discrepancies in the pyrolysis behavior are expected between the two emitters. This might have consequences for fire testing and inter comparisons of flammability results worth further investigation

Experimental Investigation of Radiation Emitted by Optically Thin to Optically Thick Wildland Flames

International audienceA series of outdoor experiments were conducted in a fire tunnel to measure the emission of infrared radiation from wildland flames, using a FTIR spectrometer combined with a multispectral camera. Flames of different sizes were produced by the combustion of vegetation sets close to wildland fuel beds, using wood shavings and kermes oak shrubs as fuels. The nongray radiation of the gas-soot mixture was clearly observed from the infrared emitted intensities. It was found that the flame resulting from the combustion of the 0.50 m long fuel bed, with a near-zero soot emission, may be considered as optically thin and that the increase in bed length, from 1 to 4 m, led to an increase in flame thickness, and therefore, in flame emission with contributions from both soot and gases. A further analysis of the emission was conducted in order to evaluate effective flame properties (i.e., emissivity, extinction coefficient, and temperature). The observation of emission spectra suggests thermal nonequilibrium between soot particles and gas species that can be attributed to the presence of relatively cold soot and hot gases within the flame

Spectral emission of flames from laboratory-scale vegetation fires

International audienceOutdoor experiments were conducted on a laboratory scale to study the infrared radiation emission of vegetation flames. Measurements were made in the spectral range 1000–4500 cm–1, using a compact and portable Fourier-transform infrared spectrometer including an HgCdTe/InSb dual detector. Flame emission was compared with the reference signal emitted by a blackbody surface at 1000 K. We carried out two different series of fire experiments: a series of fires in a 0.45 m-diameter steel tray and a series of wind-tunnel fires. Various types of wildland fuels were used: wood wool, vine branches, dry wood, and Kermes oak branches. From a qualitative observation of emission spectra, it appears that the main contribution comes from the hot gaseous combustion products, with a low-intensity background radiation from soot, as the small-scale flames in these experiments were optically thin. It was also found that, in the flaming combustion zone of the fuel bed, both phases contribute to infrared emission. Our results, in combination with existing data on the absorptivity of vegetation, give a better understanding of radiative transfer in vegetation fires and show how total radiative properties could be deduced from spectral measurements. We believe that this preliminary study provides pilot data for future studies in this area

Radiative flux emitted by a burning PMMA slab

International audienc

Study of a V-shape flame based on IR spectroscopy and IR imaging

International audienc

A hybrid small-world network/semi-physical model for predicting wildfire spread in heterogeneous landscapes

International audienc