Firebrand generation from burning vegetation

Abstract

A series of real-scale fire experiments were performed to determine the size and mass distribution of firebrands generated from Douglas-fir (Pseudotsuga menziesii) trees. The experiments were performed in the Large Fire Laboratory at the National Institute of Standards and Technology. The Douglas-fir trees used for the experiments ranged in total height from 2.6 to 5.2 m and the tree moisture content was varied. An array of pans filled with water was used to collect the firebrands that were generated from the burning trees. This ensured that firebrands would be quenched as soon as they made contact with the pans. The firebrands were subsequently dried and the sizes were measured using callipers and the dry mass was determined using a precision balance. For all experiments performed, the firebrands were cylindrical in shape. The average firebrand size measured from the 2.6-m Douglas-fir trees was 3 mm in diameter, 40 mm in length. The average firebrand size measured for the 5.2-m Douglas-fir trees was 4 mm in diameter with a length of 53 mm. The mass distribution of firebrands produced from two different tree sizes under similar tree moisture levels was similar. The only noticeable difference occurred in the largest mass class. Firebrands with masses up to 3.5 g to 3.7 g were observed for the larger tree height used (5.2 m). The surface area of the firebrands scaled with firebrand weight.

Assessing the flammability of surface fuels beneath ornamental vegetation in wildland–urban interfaces in Provence (south-eastern France)

“…Regarding ornamental vegetation, Long et al (2006a) provided flammability data for horticultural beds by evaluating the effect of the type of mulch, planting composition and drought conditions on fire spread and heat release in both field and controlledenvironment conditions. Several experiments were carried out on firebrands but very few used surface fuels (Manzello et al 2006a(Manzello et al , 2006b(Manzello et al , 2007(Manzello et al , 2008(Manzello et al , 2009Ganteaume et al 2011b). …”

The Performance of Concrete Tile and Terracotta Tile Roofing Assemblies Exposed to Wind-Driven Firebrand Showers

“…Manzello et al [5] have shown that the firebrands produced using these filtering and ignition procedures generate firebrands with mass up to 0.2 g and surface area up to 1000 mm 2 . This is within the range of firebrands generated from burning conifer species (Douglas-Fir and Korean Pine Trees) [8][9].…”

Physical parametrisation of fire-spotting for operational fire spread models: response analysis with a model based on the Level Set Method

“…Researchers have tried to understand the phenomenology of fire-spotting through both experimental and theoretical aspects to update the existing wildfire management decision support systems. Most of the experimental procedures for studying the fire-spotting phenomenon focus on characterization of the gen-5 eration of firebrands (Manzello et al, 2007;El Houssami et al, 2016;Thomas et al, 2017), shape and size of the firebrands (Manzello et al, 2009;Tohidi et al, 2015), drag forces and ignition processes (Manzello et al, 2008). The short temporal and spatial scales of the experiments limit a detailed description of the landing distributions and the flight paths of the firebrands.…”