Piloted ignition of live forest fuels

McAllister, Sara; Grenfell, Isaac C.; Hadlow, Ann M.; Jolly, W. Matt; Finney, Mark A.; Cohen, Jonathan

doi:10.1016/j.firesaf.2012.04.001

Cited by 93 publications

(68 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Introductionmentioning

confidence: 99%

“…Works by various authors [1][2][3][4][5][6][7] focus on the flammability characterization of vegetation fuel, in various apparatuses. Samples used in these studies are single layer [2][3][4] or thicker fuel beds [5][6][7]. Various tests conditions such as airflow, bulk properties, fuel moisture content (FMC) were considered and the analysis focuses mainly on evaluating ignition delay time (also referred to as time to ignition), heat release rates and critical mass loss and ignition temperature data.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Experimental Study Evaluating the Burning Dynamics of Pitch Pine Needle Beds Using the FPA

Thomas¹,

Simeoni²,

Gallagher³

et al. 2014

Fire Saf. Sci.

View full text Add to dashboard Cite

Pine needle litters, a key fuel in coniferous forest systems, are highly porous fuel beds. They provide a source of continuous fuel medium that can be easily ignited and will sustain flame spread on the ground during forest fires. This work represents an experimental study that is focused on the influence of the fuel moisture content on the burning dynamics and the flammability characteristics of forest fuel beds. The FM Global Fire Propagation Apparatus was utilized to obtain time to ignition, heat release rate, total heat released and CO/CO 2 concentration data. The methodologies applied in previous studies were improved with new modifications. The results were analyzed with respect to the sample's fuel moisture content as well as other test conditions, such as airflow condition (wind), sample holder openness and external heat flux. The importance of the fuel moisture content is critical to understand as the majority of fuels present in the natural environment have elevated moisture content compared to dead dry fuel. Samples studied are representative of wet ground fuels as well as live fuels which do burn when crowning conditions develop. The results presented here are a building block for developing an experimental database that can be used to understand the influence of environmental conditions on the flammability of porous forest fuels and assess the risks that comes with a wildfire. Furthermore, the data can also be used for fire behavior model validation.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Experimental Study Evaluating the Burning Dynamics of Pitch Pine Needle Beds Using the FPA

Thomas¹,

Simeoni²,

Gallagher³

et al. 2014

Fire Saf. Sci.

View full text Add to dashboard Cite

show abstract

“…The study of ignition and subsequent flame spread of forest fuels has largely been performed using dried and dead fuels and only a few works were found that examined live fuels [12,13,14,15,16]. Dimitrakopoulos and Papaioannou [12], Jervis et al [13], McAllister et al [14], all studied ignition due to radiative heating.…”

Section: Introductionmentioning

confidence: 99%

“…Dimitrakopoulos and Papaioannou [12], Jervis et al [13], McAllister et al [14], all studied ignition due to radiative heating. Xanthopoulos and Wakimoto [16] and Fletcher and coworkers ( [15, 17, and 18]) were the only studies found that convectively heated live fuels to ignition.…”

Section: Introductionmentioning

confidence: 99%

“…Fletcher and coworkers ( [15, 17, and 18) attempted to correlate the ignition time with leaf thickness and moisture content, however, almost no correlation with moisture content and only a slight correlation with leaf thickness were found. Though the heating mechanism was radiation, both Jervis et al [13] and McAllister et al [14] also noted a difference in the ignition behavior of live fuels than cannot be solely explained by moisture content. Jervis et al [13] suggested that volatiles were lost in drying the fuels which contributed to the very different ignition behavior seen between live and dried.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Convection Ignition of Live Forest Fuels

McAllister¹,

Finney²

2014

Fire Saf. Sci.

Self Cite

View full text Add to dashboard Cite

Wildland fires are an extremely costly and deadly problem. Crown fires, where live foliage ignites and burns, are particularly unpredictable -in part because live fuel ignition and combustion is poorly understood. Many wildland fire models assume radiation is the controlling heat transfer mechanism. However, there is a growing indication that radiation is insufficient to ignite the small, thin fuel particles that carry a wildland fire and that convective heating and flame bathing is a critical component. Unfortunately, ignition by convection heating of any fuel is poorly understood. Ignition of live forest fuels by any means is also completely unknown due to complicated moisture content and fuel chemistry considerations. To gain some insight into the wildland fire problem, an apparatus was built using two 6.5 kW electrical heaters to heat gas (air, nitrogen, etc.) over a range of temperatures from ambient up to 1200°C. The flow rate of these "airtorches" is adjustable. This apparatus was used to convectively ignite a range of both live and dead forest fuels. Fuels from all over the United States where used including Southern California, Utah, Florida, and Montana. To examine ignition threshold conditions and to have distinguishable differences in ignition times, air temperatures of 500°C and 600°C were used. The airflow rate varied slightly from 1.3 m/s to 1.4 m/s due to the density difference. Because live forest fuels contain large amounts of water, the evolution of both water and carbon dioxide was measured with time using a differential gas analyzer. Flaming ignition was seen for all dead fuels at 500°C, but the live fuels mostly showed glowing ignition. At 600°C, all fuels showed flaming ignition within 1-26 sec. Interestingly, all live fuels were still actively releasing water at ignition, implying there are steep temperature gradients within these physically thin fuels (i.e. not thermally thin). Simple heat transfer analysis in conjunction with the water evolution information was used to help explain the differences in ignition times due to fuel geometry.

show abstract

Experimental study on the burning behaviour of Pinus halepensis needles using small‐scale fire calorimetry of live, aged and dead samples

Jervis

Rein

2015

Fire and Materials

View full text Add to dashboard Cite

SUMMARYLimited research has been conducted on the burning characteristics of live fuels, which are commonly assumed to behave like moist dead fuels. We use small-scale laboratory calorimetric experiments to investigate the differences in fire dynamics between live and dead Pinus halepensis needles. The study includes laboratory-aged samples and different moisture conditions (fresh or oven dry). A series of ten fire behaviour parameters are extracted from the measurements to identify and quantify differences. The main parameters are the following: time to ignition; flaming time; mass loss pre-ignition, during flaming, and during smouldering; peak power; effective heat of combustion; mean and peak CO/CO 2 ; and radiative fraction. Using these parameters, we show that the most flammable samples are fresh dead and aged needles, followed by dry dead and dry live needles. The least flammable is fresh live needles. Live needles ignite about four times slower, and burn with~60% lower power and~50% lower heat of combustion than dead needles. Aged needles resemble most closely the behaviour of dead needles, but many fire behaviour parameters were significantly different. The results confirm the importance of moisture content in the burning behaviour of pine needles, but the differences between live and dead samples cannot be explained solely in terms of moisture but require consideration of plant chemistry and sample drying.

show abstract

Piloted ignition of live forest fuels

Cited by 93 publications

References 23 publications

An Experimental Study Evaluating the Burning Dynamics of Pitch Pine Needle Beds Using the FPA

An Experimental Study Evaluating the Burning Dynamics of Pitch Pine Needle Beds Using the FPA

Convection Ignition of Live Forest Fuels

Experimental study on the burning behaviour of Pinus halepensis needles using small‐scale fire calorimetry of live, aged and dead samples

Contact Info

Product

Resources

About