Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model In Physical Modelling the conservation equations (mass, momentum, energy) are solved Observations, experiments, and modelling show that there is gas flow ahead of the flame near the fuel bed and inside the porous fuel bed Bellemare, 2000 Obviously, there is also flow inside shrubs and inside foliage

Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model Several sub-models are used to deal with a number of phenomena The temperatures of fuel bed, shrubs, foliage, and of the gas that flows inside them are not necessarely the same  heat transfer between the gas and these fuel matrixes occurs This energy exchange plays an important role in the decrease of fuel moisture content and in the fuel pyrolysis The flow inside the fuel matrices is subjected to aerodynamic drag  sub-models for heat transfer and aerodynamic drag are, therefore, necessary

Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model There is no data on porous beds similar to forest fire fuel matrices Data on packed beds from chemical engineering have been used But chemical packed beds are very different from the forest fuel matrices Objective : - to measure the heat transfer coefficient h and pressure drop through matrices of forest fuels

Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model Existing wind tunel (used for aerodynamic studies  very good performance) Section 1 : electric resistances (5 kW) to heat the flow Section 2 : working section packed with pine needles 1000 x 160 x 240 mm (l x h x w) 6 thermocouples and pressure taps insulated walls + 1 honeycomb 2 + heating elements 3 + working section honeycomb pine needles heating elements or twigs and leaves or just twigs 4 + oooooo working section honeycomb pine needles thermocouple heating elements pressure tap

Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model 125  m K type thermocouple “inserted” at the fuel particle’s surface 125  m K type thermocouple in the air at the vicinity of the fuel particle Thicker wire (250  m) to which the thin wire is attached Thin thermocouples had to be “inserted” at the fuel surfaces

Fire Star conclusive symposium: Marseille March 18th Physical sub-models to be included in the main model Examples of the curves obtained for h and for pressure drop Pressure drop per unit length for Quercus coccifera Influence of the strata location and existence (or not) of leaves Nu as a function of Re for Pinus pinaster and Quercus coccifera h = Nu = Nu D 4 / SVR k

Fire Star conclusive symposium: Marseille March 18th Experimental fires in the INIA wind tunnel Experimental fires in the wind tunnel were devoted to: Validate the behaviour model of wildland fire Analyse effects of Wind speed Shrub moisture content Width of a discontinuity on the fire behaviour in a fuel complex of Pinus pinaster litter and Chamaespartium tridentatum shrubs General view of INIA wind tunnel

Fire Star conclusive symposium: Marseille March 18th Experimental fires in the INIA wind tunnel Example of test : Wind speed = 1 m/s Shrub m.c.: 40 % Width of discontinuity = 0 m P. pinaster litter C. tridentatum shrubs

Fire Star conclusive symposium: Marseille March 18th Example of Test on discontinuous fuel: Wind speed = 0 m/s Shrub m.c.: 40 % Width of discontinuity = 2 m Experimental fires in the INIA wind tunnel

Fire Star conclusive symposium: Marseille March 18th Variation of Rate of Spread with Wind Speed Similar set of results are available for: * Flame height * Byram´s fireline intensity Examples of results obtained at INIA wind tunnel Experimental fires in the INIA wind tunnel Variation of Maximum Temperatures with Height Width of discontinuity = 0 m

Fire Star conclusive symposium: Marseille March 18th LIR-UC3M Fire parameters obtained by IR Spectral Imaging 1.Equipment set up and Images Acquisition Tunnel and lab meas.: 2 cameras one for each band (MIR &TIR). Field measurements: 1 camera: up to 4 MIR sub-bands Infrared images are simultaneous, co-registered and calibrated (brightness temperatures) Multi- spectral TIR MIR Visible Bi-spectral images (MIR & TIR bands) Multispectral images (4 MIR bands) TIR (8-12  m) MIR (3-5  m )

Fire Star conclusive symposium: Marseille March 18th IR image: Physical parameters measured T (K) Class map MIR TIR Bi-spectral image (For multispectral images is analogous) Brigthness temperatures Scene classification Rate of spread IR flame height Instantaneous Radiated power Estimation of: Total released power (roughly, 17% of the power released is radiated) Fire front intensity Heat released per unit area LIR-UC3M Fire parameters obtained by IR Spectral Imaging 2. Pixel Classification and image processing In collaboration with INIA and CIF-Lourizan

Fire Star conclusive symposium: Marseille March 18th spectral absorbance  Objective: to gain knowledge on the pyrolysis chemistry  FTIR spectrometry: a) identification of gases by the spectral location of absorbance bands b) determination of gas concentration from the band depth c) acquires simultaneously information on the whole spectral range (2-16  m)  Gases under study: CO 2, CO, CH 4, NH 3 CO 2 CO CH 4 LIR-UC3M Fuel Pyrolysis Studies based on FTIRS- Fourier Transform IR Spectrometry: 1. Schematics and aims FTIR IR emitter Fuel sample Heater gases In collaboration with INIA

Fire Star conclusive symposium: Marseille March 18th combustion efficiency - clear correlation of NH 3 with CO emissions -data dispersion - low rate of CH 4 emission LIR-UC3M Fuel Pyrolysis Studies based on FTIRS 2. Some remarkable results In collaboration with INIA

Fire Star conclusive symposium: Marseille March 18th Sketch of the experiment 5 thermocouples onto a vertical DESIRE plate median axis of DESIRE infrared camera UP VIEW SIDE VIEW camera field of view INRA DESIRE bench

Fire Star conclusive symposium: Marseille March 18th Comparison of infrared signal and thermocouple temperature near fire front thermocouple at 5 cm high  gas temperature thermocouple à 5 cm de haut  température du gaz 1 pixel of the infrared image  solid fuel temperature comparison of time signals position of the cotton thread position du fil de coton INRA DESIRE bench

Fire Star conclusive symposium: Marseille March 18th Time evolutions of solid fuel and gas temperature – Slope 0° Breaking of the cotton thread Coupure du fil de coton the thermocouple ‘enters’ the flame le thermocouple ‘entre’ dans la flamme Pre-heating of the litter Préchauffage de la litière solid fuel temperature  gas temperature INRA DESIRE bench Slope 0° Pente 0° Moyenne mobile des données de température

Fire Star conclusive symposium: Marseille March 18th Breaking of the cotton thread Coupure du fil de coton the thermocouple ‘enters’ the flame le thermocouple ‘entre’ dans la flamme Pre-heating of the litter Préchauffage de la litière solid fuel temperature  gas temperature INRA DESIRE bench Time evolutions of solid fuel and gas temperature – Slope 30° Slope 30° Pente 30°