Changes in fire behavior caused by fire exclusion and fuel build-up vary with topography in California montane forests, USA

2022 ◽  
Vol 304 ◽  
pp. 114255
Author(s):  
Catherine Airey-Lauvaux ◽  
Andrew D. Pierce ◽  
Carl N. Skinner ◽  
Alan H. Taylor
Keyword(s):  
Fire Behavior ◽  
Montane Forests ◽  
Fire Exclusion ◽  
In Fire

Flashover and instabilities in fire behavior

1980 ◽  
Vol 38 ◽  
pp. 159-171 ◽  
Author(s):  
P.H. Thomas ◽  
M.L. Bullen ◽  
J.G. Quintiere ◽  
B.J. McCaffrey
Keyword(s):  
Fire Behavior ◽  
In Fire

Numerical Analysis of Fire Behavior of a Large Space Pre-Stressed Steel Structure under Fire

2011 ◽  
Vol 71-78 ◽  
pp. 3729-3732
Author(s):  
Ming Zhou ◽  
Zhi Guo Xie ◽  
Xin Tang Wang
Keyword(s):  
Numerical Analysis ◽  
Fire Behavior ◽  
Thermal Response ◽  
Structural Response ◽  
Steel Structure ◽  
Large Space ◽  
Fire Source ◽  
Lattice Shell ◽  
In Fire ◽  
Influence Degree

The computational model of numerical analysis of a suspended pre-stressed steel reticulated shell subjected to fire load is established with using the software Marc. Based on the model presented here, numerical analysis of thermal response and structural response of the pre-stressed steel structure are computed. The different space height and different rise-span ratio are considered for analysis of response temperature, displacements and stresses of the pre-stressed lattice shell under fire for one fire source. It is also shown that displacement of the node right above the inner cable is the maximum among the four nodes presented here as the fire source is located at the position right below the second-ring cable of the structure. It is concluded that the influence degree of space height of the structure on the fire response of the structure is not great, but rise-span ratio has obvious and great effect on displacements and stresses of the pre-stressed steel structure with large span in fire.

scholarly journals Thermodynamics of Pyrocumulus: A Conceptual Study

2018 ◽  
Vol 146 (8) ◽  
pp. 2579-2598 ◽  
Author(s):  
Kevin J. Tory ◽  
William Thurston ◽  
Jeffrey D. Kepert
Keyword(s):  
Full Range ◽  
Fire Behavior ◽  
Atmospheric Conditions ◽  
Neutral Buoyancy ◽  
Lightning Strikes ◽  
Plume Temperature ◽  
Conceptual Study ◽  
Lifting Condensation Level ◽  
In Fire ◽  
Insight Into

Abstract In favorable atmospheric conditions, fires can produce pyrocumulonimbus cloud (pyroCb) in the form of deep convective columns resembling conventional thunderstorms, which may be accompanied by strong inflow, dangerous downbursts, and lightning strikes that can produce dangerous changes in fire behavior. PyroCb formation conditions are not well understood and are difficult to forecast. This paper presents a theoretical study of the thermodynamics of fire plumes to better understand the influence of a range of factors on plume condensation. Plume gases are considered to be undiluted at the fire source and approach 100% dilution at the plume top (neutral buoyancy). Plume condensation height changes are considered for this full range of dilution and for a given set of factors that include environmental temperature and humidity, fire temperature, and fire-moisture-to-heat ratios. The condensation heights are calculated and plotted as saturation point (SP) curves on thermodynamic diagrams. The position and slope of the SP curves provide insight into how plume condensation is affected by the environment thermodynamics and ratios of fire heat to moisture production. Plume temperature traces from large-eddy model simulations added to the diagrams provide additional insight into plume condensation heights and plume buoyancy at condensation. SP curves added to a mixed layer lifting condensation level on standard thermodynamic diagrams can be used to identify the minimum plume condensation height and buoyancy required for deep, moist, free convection to develop, which will aid pyroCb prediction.

scholarly journals The Impact of Fuel Treatments on Wildfire Behavior in North American Boreal Fuels: A Simulation Study Using FIRETEC

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 18 ◽  
Author(s):  
Ginny Marshall ◽  
Dan Thompson ◽  
Kerry Anderson ◽  
Brian Simpson ◽  
Rodman Linn ◽  
...  
Keyword(s):  
Black Spruce ◽  
Treatment Options ◽  
Fire Behavior ◽  
Fire Spread ◽  
Natural Forests ◽  
Spread Rate ◽  
Multiple Components ◽  
In Fire ◽  
The Impact ◽  
Common Tree

Current methods of predicting fire spread in Canadian forests are suited to large wildfires that spread through natural forests. Recently, the use of mechanical and thinning treatments of forests in the wildland-urban interface of Canada has increased. To assist in community wildfire protection planning in forests not covered by existing operational fire spread models, we use FIRETEC to simulate fire spread in lowland black spruce fuel structures, the most common tree stand in Canada. The simulated treatments included the mechanical mulching of strips, and larger, irregularly shaped areas. In all cases, the removal of fuel by mulch strips broke up the fuels, but also caused wind speed increases, so little decrease in fire spread rate was modelled. For large irregular clearings, the fire spread slowly through the mulched wood chips, and large decreases in fire spread and intensity were simulated. Furthermore, some treatments in the black spruce forest were found to be effective in decreasing the distance and/or density of firebrands. The simulations conducted can be used alongside experimental fires and documented wildfires to examine the effectiveness of differing fuel treatment options to alter multiple components of fire behavior.

Fire Protection of High-Performance Concrete Using Protective Lining

2011 ◽  
Vol 82 ◽  
pp. 758-763
Author(s):  
Eike Wolfram Klingsch ◽  
Andrea Frangi ◽  
Mario Fontana
Keyword(s):  
High Performance ◽  
Input Data ◽  
High Performance Concrete ◽  
Fire Behavior ◽  
Explosive Spalling ◽  
Protective Lining ◽  
In Fire ◽  
Concrete Elements ◽  
Basic Input ◽  
Fire Design

The paper presents results of experimental and numerical analyses on the fire behavior of concrete elements protected by sprayed protective linings. Particular attention is given to high- (HPC) and ultrahigh performance concrete (UHPC), as HPC and UHPC tend to exhibit explosive spalling in fire due to low porosity. The results provide basic input data for the development of simplified rules for the fire design of concrete structures protected by sprayed protective linings.

Fire history and age structure in red fir forests of Sequoia National Park, California

1987 ◽  
Vol 17 (7) ◽  
pp. 582-587 ◽  
Author(s):  
Donald C. Pitcher
Keyword(s):  
Age Structure ◽  
National Park ◽  
Fire History ◽  
Fire Behavior ◽  
White Pine ◽  
Sequoia National Park ◽  
Fire Scar ◽  
Forest Age Structure ◽  
Negative Exponential ◽  
In Fire

The relationship between historical fires and age structure was examined on three plots in red fir (Abiesmagnifica var. shastensis Lemm.) forests within Sequoia National Park, California, U.S.A. All trees greater than 0.1 m in height were mapped and aged. Fire history was determined from 16 fire-scar sections. Red fir trees are more shade tolerant, longer lived, larger, and slower growing than western white pine (Pinusmonticola Dougl.) on the plots. No fires have occurred since 1886, but prior to that time the average fire-free interval was 65 years. Most of the trees on two of the plots originated after fires, but on the third plot red fir regeneration was delayed for at least 60 years following the last fire. Structural differences between the plots were linked to variations in fire behavior. The decrease in fire frequencies in this century may have led to a decrease in red fir establishment. Excluding the most recent period, the forest age structure is in something of a steady state that approximates a negative exponential age-class distribution.

scholarly journals Warning signals for eruptive events in spreading fires

2015 ◽  
Vol 112 (8) ◽  
pp. 2378-2383 ◽  
Author(s):  
Jerome M. Fox ◽  
George M. Whitesides
Keyword(s):  
Forest Fires ◽  
Chaotic Systems ◽  
Fire Suppression ◽  
Fire Behavior ◽  
Feedback Loops ◽  
Heterogeneous Environments ◽  
Combustion Instabilities ◽  
Experimental Examination ◽  
Slowing Down ◽  
In Fire

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires propagate. Such transitions are rarely captured by predictive models of fire behavior and, thus, complicate efforts in fire suppression. This paper describes a simple, remarkably instructive physical model for examining the eruption of small flames into intense, rapidly moving flames stabilized by feedback between wind and fire (i.e., “wind–fire coupling”—a mechanism of feedback particularly relevant to forest fires), and it presents evidence that characteristic patterns in the dynamics of spreading flames indicate when such transitions are likely to occur. In this model system, flames propagate along strips of nitrocellulose with one of two possible modes of propagation: a slow, structured mode, and a fast, unstructured mode sustained by wind–fire coupling. Experimental examination of patterns in dynamics that emerge near bifurcation points suggests that symptoms of critical slowing down (i.e., the slowed recovery of the system from perturbations as it approaches tipping points) warn of impending transitions to the unstructured mode. Findings suggest that slowing responses of spreading flames to sudden changes in environment (e.g., wind, terrain, temperature) may anticipate the onset of intense, feedback-stabilized modes of propagation (e.g., “blowup fires” in forests).

scholarly journals A Numerical Approach of the Influence of Water Temperature in the Extinction of Fire Developed in Closed Spaces

2022 ◽  
Vol 960 (1) ◽  
pp. 012006
Author(s):  
P Cozma ◽  
D Pavel ◽  
C A Safta ◽  
A Chisacof
Keyword(s):  
Numerical Simulation ◽  
Fire Behavior ◽  
Numerical Approach ◽  
Water Mist ◽  
Simulation Approach ◽  
Influence Of Water ◽  
Different Temperatures ◽  
Fire Extinguish ◽  
Different Diameters ◽  
In Fire

Abstract The aim of this work is to make a visual investigation of the fire behavior during the extinguish process with water mist at different temperatures, different diameters of the nozzle and different angles of diffusion jet, too. It was used a numerical simulation approach to analyze 24 scenarios regarding the influence of mist water in fire extinguish process. The main test was focused on a given enclosure with dimensions of 1.0 × 1.0 × 3.0 m and the fire source placed inside, in the middle. The enclosure is considered opened on the upper part. From the numerical simulation values, we concluded the best scenario in fire extinguish process using water mist.

scholarly journals Effects of canopy midstory management and fuel moisture on wildfire behavior

2019 ◽  
Author(s):  
Tirtha Banerjee ◽  
Warren Heilman ◽  
Scott Goodrick ◽  
Kevin Hiers ◽  
Rodman Linn
Keyword(s):  
Fire Behavior ◽  
Fire Risk ◽  
Fire Intensity ◽  
Fuel Moisture ◽  
Fine Scale ◽  
Mean Flow ◽  
Prescribed Burns ◽  
Fuel Heterogeneity ◽  
Fire Exclusion ◽  
Intensity Spread

Wildfires burning more and more areas in North America can partly be attributed to fire exclusion activities in the past few decades which led to higher fuel accumulation. Mechanical thinning and prescribed burns are effective techniques to manage fuel loads and to establish a higher degree of control over future fire risk as well as to restore fire prone landscapes to their natural states of succession. However, given the complexity of interactions between fine scale fuel heterogeneity and wind, it is difficult to assess the success of thinning operations and prescribed burns. The present work addresses this issue systematically by simulating a fire starting from a simple fire line and moving through a vegetative environment where the midstory has been cleared in different degrees, leading to a canopy with almost no midstory, another with a sparse midstory and another with a thick midstory. The simulations are conducted for these three canopies under two different conditions, where the fuel moisture is high and where it is low. These six sets of simulations show widely different fire behavior, in terms of fire intensity, spread rate and consumption. To understand the physical mechanisms that lead to these differences, detailed analyses are conducted to look at wind patterns, mean flow and turbulent fluxes of momentum and energy. The analyses also lead to improved understanding of processes leading to high intensity crowning behavior in presence of a dense midstory. Moreover, this work highlights the importance of considering fine scale fuel heterogeneity, seasonality, wind effects and the associated fire-canopy-atmosphere interactions while considering prescribed burns and forest management operations.

scholarly journals Grass Species Flammability, Not Biomass, Drives Changes in Fire Behavior at Tropical Forest-Savanna Transitions

2018 ◽  
Vol 1 ◽  
Author(s):  
Anabelle W. Cardoso ◽  
Imma Oliveras ◽  
Katharine A. Abernethy ◽  
Kathryn J. Jeffery ◽  
David Lehmann ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Fire Behavior ◽  
Grass Species ◽  
In Fire
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