Apparatus designed to replicate the spontaneous ignition of a forest fuel bed. Nowadays the experiments have been made with ¨Pine Needles¨ specifically from the Pinus Radiata, which is representative of the forest across Chile

To measure the temperature, fifteen thermocouples have been installed, plugged into a DAQ, ableto recall the info from all of them, also it ́s been necessary to include a load cell for the mass loss,meanwhile, to replicate the radiation conditions, a cylindrical heater has been used, regulating theradiation with the power source, in this case a VARIAC; also to obtain a more stable measurement,a Kanthal has been include


The burner consisting of a vertical tube (diameter of 10.9 mm inner) for the fuel stream and a co-annular concentric tube (diameter of 100 mm) for the oxidizer flow [doi:10.1364/AO.38.002478]. Constant stream of fuels andoxidants are injected using digital thermal mass flow controllers (MFC) of low uncertainties. This burner allows us to stabilized axisymmetric diffusion flames under controlled condition. The fuel tube and outer surface of theburner are heated with silicon heater bands and insulated by a Ertalon cover [doi: 10.1016/j.fuel.2020.117030], in order to avoid condensation of fuels when vaporized liquid fuelsare used. Three motorized translation stages are used to position the burner with micrometric resolution (~10 um).


The soot concentration and soot temperature in flames are measured by line-of-sight attenuation (LOSA) and flame emission techniques (10.1016/j.fuel.2016.06.126, 10.1016/j.combustflame.2020.12.049). Figure 3 shows a schematic of the experimental setup for the absorption/emission measurements. Pulsed LEDs coupled to an integrating sphere provide a uniform diffused beam source that passing through the flame. Extinction (LED on) and emission (LED off) measurements are taking with spatial and spectral resolution using an Electron-multiplying CCD camera and a motorized filter wheel with band-pass filters, respectively. After performing a spatial deconvolution(10.1016/j.fuel.2020.119011), the ratio between the images of the attenuated beam and the incident beam allows us to determine the radial distribution of the soot volume fraction. 

The soot temperature is obtained by deconvolving the flame images (LED off) and solving the radiative transfer equation(10.1080/00102202.2020.1825401, 10.1364/OL.424529). A radiometric calibration of detection system is carried out using a traceable NIST light source and a spectrometer.

Schematic of the optical rig: (1) burner, (2) translation stage, (3) LED driver, (4) LED source, (5) spectrometer, (6) calibrated light source, (7) stabilized broadband light source, (8) integrating sphere, (9) achromatic lens, (10) neutral density filters, (11) spectral filter wheel, (12) camera lens, (13) Andor CCD camera, (14) mass flow readout module, (15) mass flow controllers, and (16) pulse generator.