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International audience; A better understanding of the formation of soot particles is essential to improve combustion-related processes. For this purpose, this work reports for the first time the measurement of the size of soot particles under formation in a turbulent atmospheric flame in a planar configuration. This is ensured by the detection of the elastic scattering of a laser sheet thanks to two cameras positioned at different scattering angles (45° and 135°). The size information is then used to interpret the scattering signal collected by an additional camera positioned at 90° in order to evaluate the soot number concentration. This last step relies on a calibration ensured by soot volume fraction and primary particle size previously determined by autocompensating laser-induced incandescence in the same flame.Moreover, the use of a 1kHz repetition rate nanosecond laser and three high speed CMOS cameras enables the access to these physical parameters with a high temporal resolution. The 2D and time-resolved soot characterization is of interest because it enables the observation of the temporal and spatial modifications of soot structures when propagating in such turbulent flames. In particular, in this flame, the transport and mixing of soot pockets are clearly observed and the impact of these processes on the size and number concentration is quantified.

Combustion and other high-temperature processes frequently result in the emission of aerosols in the form of polydisperse fractal-like aggregates made of condensed-phase nanoparticles (soot for instance). If certain conditions are met, the emitted aerosol particles are known to evolve into important cloud condensation nuclei (CCN) in the atmosphere. In this work, the hygroscopic parameter κ of complex morphology aggregates is calculated from the supersaturation-dependent activated fraction Fa=Fa(SS) in the frame of κ-Köhler theory. The particle size distribution is approximated with the morphology-corrected volume equivalent diameter calculated from the electrical mobility diameter by taking into account the diameter of the primary particle and the fractal dimension of the aggregate experimentally obtained from transmission electron microscopy measurements. Activation experiments are performed in water supersaturation conditions using a commercial CCN-100 condensation nuclei counter. The model is tested in close-to-ideal conditions of size-selected, isolated spherical particles (ammonium sulfate nanoparticles dispersed in nitrogen), then with complex polydisperse fractal-like aggregates (soot particles activated by exposure to ozone with κ as low as 5×10-5) that represent realistic anthropogenic emissions in the atmosphere.

International audience; Gasoline emissions contain high levels of pollutants, including particulate matter (PM), which are associated with several health outcomes. Moreover, due to the depletion of fossil fuels, biofuels represent an attractive alternative, particularly second-generation biofuels (B2G) derived from lignocellulosic biomass. Unfortunately, compared to the abundant literature on diesel and gasoline emissions, relatively few studies are devoted to alternative fuels and their health effects. This study aimed to compare the adverse effects of gasoline and B2G emissions on human bronchial epithelial cells. We characterized the emissions generated by propane combustion (CAST1), gasoline Surrogate, and B2G consisting of Surrogate blended with anisole (10%) (S+10A) or ethanol (10%) (S+10E). To study the cellular effects, BEAS-2B cells were cultured at air-liquid interface for seven days and exposed to different emissions. Cell viability, oxidative stress, inflammation, and xenobiotic metabolism were measured. mRNA expression analysis was significantly modified by the Surrogate S+10A and S+10E emissions, especially CYP1A1 and CYP1B1. Inflammation markers, IL-6 and IL-8, were mainly downregulated doubtless due to the PAHs content on PM. Overall, these results demonstrated that ultrafine particles generated from biofuels Surrogates had a toxic effect at least similar to that observed with a gasoline substitute (Surrogate), involving probably different toxicity pathways.

Black carbon aerosol emissions are recognized as contributors to global warming and air pollution. There remains, however, a lack of in-situ techniques to remotely quantify black carbon aerosol particles with high range and time resolution. This article presents for the first time, to our knowledge, a direct and contact-free remote measurement of black carbon aerosol number and mass concentration less than ten of meters from the emission source. This is done with a novel picosecond short-range elastic backscatter lidar (PSR-EBL) technique. To address the complexity of retrieving lidar products at short measurement ranges, we apply a forward inversion method featuring radiometric lidar calibration. Our method is based on an extension of a well-established light-scattering model, the Rayleigh-Debye-Gans for Fractal-Aggregates (RDG-FA) theory, which computes an analytical expression for lidar parameters. These parameters are the backscattering cross-sections and the lidar ratio for black carbon fractal aggregates. Using a small-scale Jet A-1 kerosene pool fire, it is shown that our technique can quantify the aerosol number and mass concentration with centimetre range-resolution and millisecond time-resolution.; Les émissions d'aérosols de carbone noir sont reconnues comme contribuant au réchauffement climatique et à la pollution de l'air. Il reste cependant un manque de techniques pour quantifier à distance les particules d'aérosol de noir de carbone avec une plage et une résolution temporelle élevées. Cet article présente une technique à distance directe et sans contact pour quantifier le nombre d'aérosols de carbone noir et la concentration massique à quelques mètres de la source d'émission. Cela se fait à l'aide de l'instrument Colibri basé sur une nouvelle technique, appelée ici Picosecond Short-Range Elastic Backscatter Lidar (PSR-EBL). Pour faire face à la complexité de la récupération des produits lidar à de courtes plages de mesure, nous appliquons une méthode d'inversion directe avec étalonnage radiométrique du lidar. Notre méthode est basée sur une extension d'un modèle de diffusion de la lumière bien établi, la théorie Rayleigh-Debye-Gans for Fractal-Aggregates (RDG-FA), qui calcule une expression analytique des paramètres lidar. Ces paramètres sont les sections efficaces de rétrodiffusion et le rapport lidar pour les agrégats fractals de carbone noir. À l'aide d'un feu de nappe de kérosène Jet A-1 à petite échelle, nous démontrons la capacité de la technique à quantifier le nombre d'aérosols et la concentration en masse avec une résolution centimétrique et une résolution temporelle en millisecondes.

International audience; Knowledge of the optical properties of soot black carbon (BC) is required for the prediction of the radiative effects of freshly-emitted and aged BC particles. Here we review BC mass absorption cross section (MAC) and absorption function E(m) measurements, focusing on freshly-emitted BC. First, we review recently reported MACs at 550 nm wavelength as obtained from direct measurements of particulate absorption and mass concentration; we find an average of 8.0 ± 0.7 m2/g from ten measurements, not significantly higher (p > 0.26) than the widely used MAC of 7.5 ± 1.2 m2/g recommended by Bond and Bergstrom [Bond, T. C., and R. W. Bergstrom. 2006. Light absorption by carbonaceous particles: An investigative review. Aerosol Sci. Technol. 40(1):27–67]. Second, we review recently reported E(m), whose retrieval is more complex due to the need to combine measurements with numerical models to estimate the contribution of scattering to extinction. Third, we review recent numerical studies that have aimed to predict the BC MAC using various complex refractive indices (m = n + ik). Most of these studies have used m = 1.95 + 0.79i recommended by Bond and Bergstrom (2006), yet failed to predict a MAC as high as 7.5 or 8.0 m2/g at 550 nm wavelength. Fourth, we summarize a selected range of alternative values of m that has been reported by recent studies and place them in the context of measurements using a contour plot of E(m) on the n–k plane. We show that the widely used m = 1.95 + 0.79i corresponds to an E(m) that is too low to be consistent with the measured MAC values. We conclude that the E(m) of BC in the visible and near infrared should be greater than 0.32, and that the commonly used BC models or the refractive index, or both, are still in need of improvement.

The present study demonstrates the exploitation of the spectral elastic light scattering technique. Additional information provided by the spectral response of the light scattering signals enables the measurement of the soot size distribution with only two scattering angles. It also provides quantitative data on the spectral dependence of the soot optical index, which is related to the soot chemical composition. The measurement principle consists in dividing the scattered spectra collected at two scattering angles and processing this ratio using the Rayleigh–Debye–Gans theory for Fractal Aggregates (RDG-FA). It is shown that the median diameter of gyration and geometric standard deviation of a lognormal soot size distribution can be determined without any prior information on key parameters such as the fractal prefactor, particle primary diameter, aggregate number density and soot optical properties. A proof of concept was performed on soot particles produced by a miniCAST generator by comparing the optical results with the soot size distributions measured by SMPS. A statistical Bayesian inversion approach was used to determine posterior distributions with a particular emphasis on their uncertainty quantification.

Combustion generated soot appears as fractal aggregates formed by polydisperse nearly spherical primary particles. Knowledge of their radiative properties is a prerequisite for laser based diagnostics of soot. In this parametric study, the effect of primary particle polydispersity on soot aggregate absorption and scattering properties is investigated numerically. Two series of fractal aggregates formed by normal and lognormal distributed primary particles of different levels of standard deviation were numerically generated for typical flame soot with a fractal dimension and prefactor fixed to D f = 1.73 and kf ≈ 1.5, respectively. Three aggregate sizes consisting of N p = 15 , 50 and 150 monomers per aggregate were investigated. Due to the uncertainty in soot refractive index, radiative properties were calculated by considering two different refractive indices at λ ≈ 532 nm recommended in the literature using the Discrete Dipoles Approximation and the Generalized Multiparticle Mie method. The results are interpreted in terms of correction factors to the Rayleigh–Debye–Gans theory for fractal aggregates (RDG-FA) for the forward scattering cross section A and for the absorption cross section h. It is shown that differential cross section for vertically polarized incident light, total scattering and absorption cross sections are well predicted by the RDG-FA theory for all considered aggregates formed by normally ( σ / d p ¯ ≤ 30%) and lognormally (σgeo ≤ 1.6) distributed primary particles. The refractive index is found to be of greater impact than primary particle polydispersity on the importance of multiple scattering. The radiative force per unit laser power experienced by the soot aggregates was found primarily determined by the aggregate volume, regardless of the level of primary particle polydispersity.

The influence of the fire exposure on the degradation mechanism of thin carbon/epoxy and carbon/polyphenylene sulphide (PPS) laminates has been investigated using a propane burner. The burner used in this work is able to provide a controlled and repeatable heating condition, with the test condition of 106 kW/m2 representative of a severe fire condition. Mass loss and temperature measurements made during the fire aggression coupled with post-fire microscopic analysis aim at providing a better understanding of the physical and mechanical changes on laminates depending on matrix nature and different fire-exposure times. For a high heat flux, a 300s fire exposure is more detrimental for the carbon/epoxy sample (22% mass loss) than for the carbon/PPS (6% mass loss) although ATG results show a similar char yield of around 75% under nitrogen for both materials. Observation and analysis of microscopic images after different fire-exposure times fire suggest that the thermal behaviour of the 2 mm thin laminates is driven by the formation of major delamination and macroscopic pores forming a thermal barrier as the analysis of the images indicates a void content 2 to 5 times higher for the carbon/PPS sample than for the carbon/epoxy specimens. On the one hand, the degradation of the thermoplastic PPS matrix into a viscous product seems to trap pyrolysis gases into macroscopic gaseous cells. These porosities provide an efficient thermal barrier protecting the back surface from the flame high thermal flux. On the other hand the degradation of the thermosetting epoxy matrix forms a dry network of carbon fibres and porous char.

International audience; Experimental studies of soot morphology based on analysis of transmission electron microscopy (TEM) images usually neglect the potential effects of primary particle polydispersity and overlapping. In this study, fractal aggregates of different sizes consisting of polydisperse and overlapping primary particles were numerically generated using typical fractal dimension and prefactor relevant to soot. A total of 3600 simulated two-dimensional projections for each primary particle size distribution and level of overlapping considered was produced and analyzed using two TEM image analysis methods commonly used in the literature to evaluate the effects of primary particle polydispersity and overlapping on the recovered morphological parameters of soot. Fairly large deviations in the recovered number of primary particles in aggregates were obtained by both methods considered using the procedure commonly used in the literature. A recommendation was proposed to improve the accuracy of the retrieved number of polydisperse primary particles in an aggregate. We show that the results obtained by using both the Tian et al. (2006) and Brasil et al. (1999) methods can be significantly improved by using the recommended modification for primary particle polydispersity levels commonly encountered in flame soot. Finally, we recommend to use the modified Tian et al. 2006 method for recovering the number of primary particles of aggregates consisting of both polydisperse and overlapped primary particles.

The fractal-like black carbon particles emitted from combustion systems and biomass burning are short-lived pollutants that contribute significantly to climate forcing. To accurately quantify the forcing and interpret optical measurements of uncoated and coated black carbon (BC) particles, it is indispensable to know the refractive index m = n + ki of BC in the visible and near infrared. In this study the effects of various morphological parameters and structure defects of black carbon particles on their mass absorption cross section (MAC) were first investigated using the generalized Mie-solution method (GMM) and discrete dipole approximation (DDA). The accuracy of the Rayleigh-Debye-Gans (RDG) approximation is also evaluated. Based on recent measurements of the soot absorption function E(m) and freshly emitted BC MAC in the visible and near-infrared, the most probable range of E(m) was recommended. A criterion was proposed to determine the valid range of refractive index of freshly emitted BC based on the contour plot of E(m) on the n-k plane., The 9th International Symposium on Radiative Transfer, RAD-19, June 3-7, 2019, Athens, Greece

International audience; The morphological description of fractal agglomerates is generally reduced to only two parameters,namely the mass fractal dimension and its prefactor. In the most evolved approaches, a stretching exponent is also introduced, while a packing factor is preferred to the fractal prefactor. In any case, the current analytical description of agglomerates morphology is accurate only for sufficiently large agglomerates, which is due to the limited spatial extension of the clusters that are actually quasi-fractal. In the present study, a cutoff function of the pair correlation function is considered for both larger and smaller scales. This enables a more accurate morphological description valid for any cluster size is to be given taking into account the polydispersity of the primary spheres. This new analytical morphological description relying on 5 parameters, is presented here for the first time. The physical range covered by these morphological parameters is determined based on virtually generated Diffusion Limited Cluster Agglomeration. Finally, the model is used to express the fractal prefactor and structure factors and their dependence on agglomerate size and morphological parameters is investigated.

WOS:000373250400012; International audience; The effects of weakly absorbing material coating on soot have attracted considerable research attention in recent years due to the significant influence of such coating on soot radiative properties and the large differences predicted by different numerical models. Soot aggregates were first numerically generated using the diffusion limited cluster aggregation algorithm to produce fractal aggregates formed by log-normally distributed polydisperse spherical primary particles in point-touch. These aggregates were then processed by adding a certain amount of primary particle overlapping and necking to simulate the soot morphology observed from transmission electron microscopy images. After this process, a layer of WAM coating of different thicknesses was added to these more realistic soot aggregates. The radiative properties of these coated soot aggregates over the spectral range of 266-1064 nm were calculated by the discrete dipole approximation (DDA) using the spectrally dependent refractive index of soot for four aggregates containing N-p =1, 20, 51 and 96 primary particles. The considered coating thicknesses range from 0% (no coating) up to 100% coating in terms of the primary particle diameter. Coating enhances both the particle absorption and scattering cross sections, with much stronger enhancement to the scattering one, as well as the asymmetry factor and the single scattering albedo. The absorption enhancement is stronger in the UV than in the visible and the near infrared. The simple corrections to the Rayleigh-Debye-Gans fractal aggregates theory for uncoated soot aggregates are found not working for coated soot aggregates. The core-shell model significantly overestimates the absorption enhancement by coating in the visible and the near infrared compared to the DDA results of the coated soot particle. Treating an externally coated soot aggregate as an aggregate formed by individually coated primary particles significantly underestimates the absorption enhancement by coating in the visible and the near infrared. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

WOS:000358626000003; International audience; Effective density measurements are used extensively to convert submicron particle sizes based on a particle's mobility diameter into mass. Measurements of the effective density also provide information concerning the particle morphology. For example, the effective density curves of fractal aggregates reveal a scaling factor that seems to correlate with the fractal dimension of the particles. The present paper proposes a simple semi-empirical model that permits the quantitative interpretation of these measurements to determine parameters such as the fractal dimension, the primary particle size, and the bulk density of an aggregate particle. The proposed model is based on the assumption that the hydrodynamic drag force of an aggregate is proportional to the drag force applied to isolated primary spheres and to the number of primary spheres in the aggregate at power a. The model was applied to soot particles produced by either a spark discharge (PALAS GFG1000) or by combustion (miniCAST 5206)-both mechanisms enable the generation of aggregates or agglomerates with very different primary sphere diameters. The proposed model showed a good fit for all of the effective density measurements obtained in this study; the a parameter was driven by the aggregate fractal dimension and by the Knudsen number that was determined based on the primary particle diameter. Finally, for a known primary particle diameter, the fractal dimension and the bulk density were determined successfully with the proposed model. (C) 2015 Elsevier Ltd. All rights reserved.

WOS:000357543800021; International audience; There is a strong interest in accurately modelling the radiative properties of soot aggregates (also known as black carbon particles) emitted from combustion systems and fires to gain improved understanding of the role of black carbon to global warming. This study conducted a systematic investigation of the effects of overlapping and necking between neighbouring primary particles on the radiative properties of soot aggregates using the discrete dipole approximation. The degrees of overlapping and necking are quantified by the overlapping and necking parameters. Realistic soot aggregates were generated numerically by constructing overlapping and necking to fractal aggregates formed by point-touch primary particles simulated using a diffusion-limited cluster aggregation algorithm. Radiative properties (differential scattering, absorption, total scattering, specific extinction, asymmetry factor and single scattering albedo) were calculated using the experimentally measured soot refractive index over the spectral range of 266-1064 nm for 9 combinations of the overlapping and necking parameters. Overlapping and necking affect significantly the absorption and scattering properties of soot aggregates, especially in the near UV spectrum due to the enhanced multiple scattering effects within an aggregate. By using correctly modified aggregate properties (fractal dimension, prefactor, primary particle radius, and the number of primary particle) and by accounting for the effects of multiple scattering, the simple Rayleigh-Debye-Gans theory for fractal aggregates can reproduce reasonably accurate radiative properties of realistic soot aggregates. (C) 2015 Elsevier Ltd. All rights reserved.

The Institute of Radioprotection and Nuclear Safety (IRSN in French) is conducting research on the impact of a fire on the behaviour of containment devices such as high efficiency particulate air (HEPA) pleated filters for radioactive materials. This work aims to study the clogging of HEPA filters in case of fire involving realistic materials (polymers making up gloves boxes, waste treatment solvent, hydraulic oil, solid material mixtures making up a trash bin, electrical cables, and cabinets) used in nuclear facilities, from the medium to large scale. The clogging kinetics of industrial pleated HEPA filters is monitored by measuring the pressure drop of the filters and the filtered air temperature at a given filtration velocity (from 0.23 to 2.1 cm/s). Upstream HEPA filters, combustion aerosols are characterized in terms of size distribution, mass concentration, composition, and particle morphology using, respectively, a DMS500 (CambustionLTD), glass fiber filter sampling, and transmission electron micro...

Specific surface areas of particles produced at small-scale diffusion flame burners and also in pilot and large-scale fires involving complex fuels are reported and compared. Specific surface area SBET is determined by BET (Brunauer-Emmett-Teller) analysis and also according to previously developed approach STEM relying on the primary sphere based on TEM (Tansmission Electron Microscopy) images analysis. True density is also determined and the respective influences of primary particle diameter (Dpp) and organic carbon to total carbon ratio (OC/TC) are discussed. The present study is the first to propose a careful comparison between TEM and BET specific surface areas of 20 different samples of carbonaceous particles emitted under realistic fire conditions and to bring validity range for such TEM based approach. For samples containing low and moderate OC content (less than 20%), a good agreement between STEM and SBET is reported (within ± 20% for a confidence interval of 95%), confirming the significant influence of primary particle diameter and the relevance of a purely geometrical description of the surface specific area of soot particles. For larger OC/TC, such approach fails to predict the particles specific surface area within a reasonable confidence interval.

International audience; We investigate two main methods for detecting correlations between the size and fractal dimension of small particle aggregates from two-dimension Transmission Electron Microscopy (TEM) images. The first method is based on a multi-scale analysis of an entire aggregate sample, whereas the second method (modified Box-Counting algorithm, MBC) is based on the analysis the self-similarity properties of each aggregate within a sample. Both methods were tested on a sample of soot aggregates as well as synthetic TEM images produced with a tuneable Diffusion Limited Aggregation code. We have found that the MBC method provides a less noisy estimation for the evolution of the fractal dimension with the size of aggregates, giving at the same time a criterion to reject the aggregates with insufficient self-similarity properties. So that with this method, the mean fractal dimension of the soot sample was found to be much lower (1.66 +/- 0.02) than that derived with the classical multi-scale analysis (1.88 +/- 0.02). Published by Elsevier Ltd.

The refractive index of soot is an essential parameter for its optical diagnostics. It is necessary for quantitative interpretation of LII (Laser Induced Incandescence) signals, light scattering or extinction measurements as well as for emissivity calculations. The most cited values have been determined by intrusive methods or without taking into account the soot size distribution and its specific morphology. In the present study, soot generated by the combustion of diesel and diesel/rapeseed methyl ester (RME) mixture (70% diesel and 30% RME) are extensively characterized by taking into account the morphology, the aggregate size distribution, the mass fraction and the spectral dispersion of light. The refractive index m for wavelengths λ between 300 and 1000 nm is determined for diesel and diester fuels by both in-situ and ex-situ methods. The ex-situ method is based on the interpretation of extinction spectra by taking into account soot sizes and fractal morphology with the RDG-FA (Rayleigh–Debye–Gans for Fractal Aggregate) theory. The in-situ approach is based on the comparison of the LII signals obtained with two different excitation wavelengths. The absorption function E(m) and the scattering function F(m) are examined. This study reveals similar optical properties of soot particles generated by both studied fuels even at ambient and flame temperatures. The function E(m) is shown to reach a maximum for λ=250 nm and to tend toward a plateau-like behavior close to E(m)=0.3 for higher wavelength (600

International audience; The aim of this work was to compare the fractal characteristics, Df and kf, the primary particle diameter, Dpp, the gyration diameter of aggregates, Dg, and the overlap coefficient, Cov, of carbon nanoparticle aggregates produced by an ethylene diffusion flame and sampled by means of four commonly used techniques. The first method involves a thermophoretic piston probe (TPP) which inserts a TEM grid into the flame. Three other methods were applied at the outlet of a dilution device, also inserted in the flame. The first of these used a nuclepore filtration sampler (NFS), and is based on filtration of particles onto a polycarbonate membrane. The second, post dilution method, the insertion particle sampler (IPS), inserts a TEM grid, perpendicular to the aerosol flow. Similar to TPP, the last method is a thermophoretic particle sampler (TPS) sampling directly onto a TEM grid. After collection, the samples are stored in the dark either, (1) in a nitrogen filled cell at low humidity or, (2) in ambient air for studying atmospheric ageing. Good agreement was observed between TPP, TPS, and IPS indicating that the dilution induced for TPS and IPS does not significantly change the morphology of soot. On the other hand, the NFS protocol tended to overestimate the overlap coefficient and the size of primary particles and aggregates. Finally, with regard to the aging effect, we found that kf and Dpp evolve slowly during storage in the atmosphere while Df, was insensitive to the storage conditions. However, the overlap coefficient increased and the gyration diameter decreased as a function of storage duration, while storage under nitrogen tended to reduce these changes.

Fire is one of the greatest industrial risks. In nuclear facilities this is complicated by the need to ensure the containment of airborne contamination at all times, in both normal and accidental situations. In the event of a fire, the soot particles emitted in the smoke may have a double impact, first on containment (clogging of filtration barriers in the ventilation network) and secondly on fire propagation, through the radiative properties of these particles. Consequently, a better understanding of their properties is needed, not only in the fire zones, but also in the smoke of diffusion flames encountered during a fire. Here, we present a study of the physical and optical parameters of soot particles sampled in the plumes of over-ventilated diffusion flames of acetylene, toluene and polymethyl methacrylate. For these three fuels, and relative to several global equivalence ratios, we have established the size distribution for the primary particles and soot aggregates, along with morphological parameter...

Experimental results are reported on the resuspension of particles deposited on polymer samples representative of glove boxes used in the nuclear industry, under thermal degradation. A parametric study was carried out on the effects of heat flux, air flow rate, fuel type and particle size distribution. Small-scale experiments were conducted on 10 cm × 10 cm PolyMethyl MethAcrylate (PMMA) and PolyCarbonate (PC) samples covered with aluminium oxide particles with physical geometric diameters of 0.7 and 3.6 μm. It was observed for both polymer (fuel) samples that heat flux has no effect on the airborne release fraction (ARF), whereas particle size is a significant parameter. In the case of the PMMA sample, ARF values for 0.7 and 3.6 μm diameter particles range from 12.2% (± 6.2%) to 2.1% (± 0.6%), respectively, whereas the respective values for the PC sample range from 3.2% (± 0.8%) to 6.9% (± 3.9%). As the particle diameter increases, a significant decrease in particle release is observed for the PMMA sample, whereas an increase is observed for the PC sample. Furthermore, a peak airborne release rate is observed during the first instants of PMMA exposure to thermal stress. An empirical relationship has been proposed between the duration of this peak release and the external heat flux.

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Delcour S., Herbert D., Ouf, F., Coppalle, A., Azema N., Ferry L., Lopez-Cuesta Jose-Marie, Salm F., Talbaut M. and Yon, J., 2014. Feasibility of Particle Imaging Velocimetry in Cone Calorimeter experiments. Fire Safety Science 11: 152-164. 10.3801/IAFSS.FSS.11-152; International audience; Experimental results are reported on the feasibility of particle imaging velocimetry in a cone calorimeter. PolyMethyl MethAcrylAte (PMMA) plates have been contaminated at their surface by alumina particles (Dev=4.4 ?m) as seeding particles allowing PIV analysis. Particles are released by bubble bursting during the thermal degradation of the PMMA for each heat flux investigated (25, 35 and 45 kW/m2). A “layer” of particles could be noticed for the highest heat flux (35 and 45 kW/m2) while for the smallest flux (25 kW/m2), the release is confined and more erratic. Velocity increases as a function of the height above the polymer surface from 0.03 m/s at the PMMA surface to 0.3 m/s at the bottom of the conical heater and these results are in good agreement with previous experiments and numerical simulations. As an overall conclusion, this first attempt demonstrates the huge potential of PIV analysis, associated to our deposition set-up, for investigating flow field during cone calorimeter experiments involving bubbling polymers.