scholarly journals Fire Behavior under a Ceiling in Growing Fire Part 2 Ceiling Jet Velocity and Flame Length

2007 ◽  
Vol 26 (4) ◽  
pp. 479-483
Author(s):  
Takahiro Ishihara ◽  
Hiroyuki Sunahara ◽  
Akimitsu Kikkawa ◽  
Masayuki Mizuno ◽  
Yoshifumi Ohmiya ◽  
...  
Keyword(s):  
Fire Behavior ◽  
Flame Length ◽  
Jet Velocity

Effects of wind velocity and slope on flame properties

1996 ◽  
Vol 26 (10) ◽  
pp. 1849-1858 ◽  
Author(s):  
David R. Weise ◽  
Gregory S. Biging
Keyword(s):  
Froude Number ◽  
Wind Velocity ◽  
Fire Behavior ◽  
Flame Length ◽  
Parameter Estimates ◽  
Combined Effects ◽  
Field Scale ◽  
Support Theory ◽  
Length Data ◽  
Flame Angle

The combined effects of wind velocity and percent slope on flame length and angle were measured in an open-topped, tilting wind tunnel by burning fuel beds composed of vertical birch sticks and aspen excelsior. Mean flame length ranged from 0.08 to 1.69 m; 0.25 m was the maximum observed flame length for most backing fires. Flame angle ranged from −46° to 50°. Observed flame angle and length data were compared with predictions from several models applicable to fires on a horizontal surface. Two equations based on the Froude number underestimated flame angle for most wind and slope combinations; however, the data support theory that flame angle is a function of the square root of the Froude number. Discrepancies between data and predictions were attributed to measurement difficulties and slope effects. An equation based on Byram's convection number accounted for nearly half of the observed variation in flame angle (R2 = 0.46). Byram's original equation relating fireline intensity to flame length overestimated flame length. New parameter estimates were derived from the data. Testing of observed fire behavior under a wider range of conditions and at field scale is recommended.

Fuel treatment effects on modeled landscape-level fire behavior in the northern Sierra Nevada

2010 ◽  
Vol 40 (9) ◽  
pp. 1751-1765 ◽  
Author(s):  
Jason J. Moghaddas ◽  
Brandon M. Collins ◽  
Kurt Menning ◽  
Emily E.Y. Moghaddas ◽  
Scott L. Stephens
Keyword(s):  
Sierra Nevada ◽  
Fire Behavior ◽  
Treatment Strategies ◽  
Weather Conditions ◽  
Fire Regimes ◽  
Flame Length ◽  
Fuel Treatment ◽  
Burn Probability ◽  
Pre Treatment ◽  
Landscape Level

Across the western United States, decades of fire exclusion combined with past management history have contributed to the current condition of extensive areas of high-density, shade-tolerant coniferous stands that are increasingly prone to high-severity fires. Here, we report the modeled effects of constructed defensible fuel profile zones and group selection treatments on crown fire potential, flame length, and conditional burn probabilities across 11 land allocation types for an 18 600 ha study area within the northern Sierra Nevada, California. Fire modeling was completed using FlamMap and FARSITE based on landscape files developed with high-resolution aerial (IKONOS) imagery, ground-based plot data, and integrated data from ARCFUELS and the Forest Vegetation Simulator. Under modeled 97th percentile weather conditions, average conditional burn probability was reduced between pre- and post-treatment landscapes. A more detailed simulation of a hypothetical fire burning under fairly severe fire weather, or “problem fire”, revealed a 39% reduction in final fire size for the treated landscape relative to the pre-treatment condition. To modify fire behavior at a landscape level, a combination of fuel treatment strategies that address topographic location, land use allocations, vegetation types, and fire regimes is needed.

Flame characteristics of wind-driven surface fires

1986 ◽  
Vol 16 (6) ◽  
pp. 1293-1300 ◽  
Author(s):  
Ralph M. Nelson Jr. ◽  
Carl W. Adkins
Keyword(s):  
Boundary Layer ◽  
Tilt Angle ◽  
Fire Behavior ◽  
Flame Length ◽  
Fire Intensity ◽  
Square Root ◽  
Pine Needle ◽  
Weather Variables ◽  
Practical Applications ◽  
Surface Fires

Twenty-two fires in a laboratory wind tunnel and 8 field fires were studied with video techniques to determine relationships between their flame characteristics and fire behavior. The laboratory fires were in pine needle fuel beds with and without an overlying stratum of live vegetation. These fuels simulated 2-year roughs in southeastern fuel types. The field bums were in 1- and 2-year roughs in similar fuels. Byram's fire intensity ranged from 98 to 590 kW/m in the laboratory, and from 355 to 2755 kW/m in the field. Flame lengths were proportional to the square root of fire intensity when fuel consumption exceeded 0.5 kg/m2, in agreement with predictions from buoyant flame theory. However, for burns in the needle layer (consumption approximately 0.5 kg/m2), flame lengths were constant at about 0.5 m, regardless of intensity. Similar values were observed on two of the field fires. It is speculated that flame length is limited by a boundary layer pattern for the overall flow, even though the flames themselves did not exhibit boundary layer characteristics. Also, laboratory correlations of flame tilt angle and fire intensity with other fire and weather variables depart from buoyant flame theory. Further study under field conditions is needed before relationships involving flame tilt angle, fire intensity, and wind speed should be used in practical applications.

Examining fire behavior in mesquite - acacia shrublands

2005 ◽  
Vol 14 (2) ◽  
pp. 131 ◽  
Author(s):  
Tamara J. Streeks ◽  
M. Keith Owens ◽  
Steve G. Whisenant
Keyword(s):  
Flame Temperature ◽  
Fire Behavior ◽  
Fire Spread ◽  
Flame Length ◽  
South Texas ◽  
Fire Intensity ◽  
Rate Of Spread ◽  
Vegetation Shift ◽  
Naturally Occurring ◽  
Behavior Systems

The vegetation of South Texas has changed from mesquite savanna to mixed mesquite–acacia (Prosopis–Acacia) shrubland over the last 150 years. Fire reduction, due to lack of fine fuel and suppression of naturally occurring fires, is cited as one of the primary causes for this vegetation shift. Fire behavior, primarily rate of spread and fire intensity, is poorly understood in these communities, so fire prescriptions have not been developed. We evaluated two current fire behavior systems (BEHAVE and the CSIRO fire spread and fire danger calculator) and three models developed for shrublands to determine how well they predicted rate of spread and flame length during three summer fires within mesquite–acacia shrublands. We also used geostatistical analyses to examine the spatial pattern of net heat, flame temperature and fuel characteristics. The CSIRO forest model under-predicted the rate of fire spread by an average of 5.43 m min−1 and over-predicted flame lengths by 0.2 m while the BEHAVE brush model under-predicted rate of spread by an average of 6.57 m min−1 and flame lengths by an average of 0.33 m. The three shrubland models did not consistently predict the rate of spread in these plant communities. Net heat and flame temperature were related to the amount of 10-h fuel on the site, but were not related to the cover of grasses, forbs, shrubs, or apparent continuity of fine fuel. Fuel loads were typical of South Texas shrublands, in that they were uneven and spatially inconsistent, which resulted in an unpredictable fire pattern.

Behavior of experimental grass fires vs. predictions based on Rothermel's fire model

1977 ◽  
Vol 7 (2) ◽  
pp. 357-367 ◽  
Author(s):  
Richard J. Sneeuwjagt ◽  
William H. Frandsen
Keyword(s):  
Combustion Zone ◽  
Fire Behavior ◽  
Fire Spread ◽  
Flame Length ◽  
Fuel Load ◽  
Physical Parameters ◽  
Rate Of Spread ◽  
Least Squares Fit ◽  
Zone Depth ◽  
Positive Agreement

Fire behavior observations with rates of spread up to 20 m/min (66 ft/min) have been recorded on 40 prescribed grass fires in central Washington and northern California. Physical parameters were also recorded describing the grass fuel array (fuel load, moisture content (≤ 15%), etc.), along with the wind speed (up to 8 km/h) and slope (near zero). These data were sufficient to allow a prediction of the fire spread rate, combustion zone depth, and flame length using the Rothermel fire spread model.A least squares fit of the observed versus the predicted results shows that positive agreement (slope = 1, intercept = 0) is supported for rate of spread. Flame length shows positive agreement for the intercept but not for slope. Combustion zone depth does not show positive agreement for either intercept or slope. The authors attribute the lack of positive agreement to less accurate measurements (ocular estimates) of the flame length and combustion zone depth.

Exploratory analysis of the variables affecting initial attack hot-spotting containment rate

1991 ◽  
Vol 21 (4) ◽  
pp. 540-544 ◽  
Author(s):  
Peter J. Murphy ◽  
Paul M. Woodard ◽  
Dennis Quintilio ◽  
Stephen J. Titus
Keyword(s):  
Forest Cover ◽  
Black Spruce ◽  
Fire Behavior ◽  
Correlation Coefficients ◽  
Flame Length ◽  
Weather Variables ◽  
Weather Index ◽  
Fire Weather Index ◽  
Rate Of Spread ◽  
Forest Cover Types

Hot-spotting containment rates were determined for 18 fires of various intensities in two common boreal forest cover types: 8 in jack pine (Pinusbanksiana Lamb.) and 10 in black spruce (Piceamariana (Mill.) B.S.P.). Hot-spotting containment rates did not differ significantly between the two cover types. Correlation coefficients showed that hot-spotting containment rates were more closely related to fire behavior than to weather variables measured as part of the Canadian Forest Fire Weather Index System. Hot-spotting containment rate (HCR; m/man-hour) may be predicted based on rate of spread (ROS; m/min) and flame length (FL; m) using the following model: HCR = exp(6.0140 – 0.1830ROS – 0.1201FL). This model was fitted using weighted nonlinear regression; the R2-value was 0.76.

Microplot Sampling of Fire Behavior on Populus tremuloides Stands in North-Central Colorado

1993 ◽  
Vol 3 (2) ◽  
pp. 85 ◽  
Author(s):  
JK Smith ◽  
RD Laven ◽  
PN Omi
Keyword(s):  
Populus Tremuloides ◽  
Fire Behavior ◽  
Fire Effects ◽  
Flame Length ◽  
Fire Intensity ◽  
Total Heat Release ◽  
Spread Rate ◽  
North Central ◽  
Area Burned ◽  
In Fire

Fire behavior research has traditionally used whole burns as sampling units. Numerous burns were required to quantify relationships between pre-burn descriptors, fire behavior, and fire effects. Recent studies have used small plots within burns (called microplots) as the sampling units. This study measured pre-burn descriptors and fire behavior on 0.75-m2 microplots in two Populus tremuloides Michx. burns in north-central Colorado. Microplot estimates of woody fuels, spread rate, and area burned were comparable with measurements from whole burns. Two methods of estimating fire intensity on microplots produced inconsistent results. Juniperus communis L. patches burned more intensely and released more heat than herbaceous areas. Duff characteristics were the most useful pre-burn descriptors for predicting area burned, spread rate, flame length, and total heat release. Microplot sampling on two bums enabled us to relate variability in fire behavior to pre-burn characteristics and to obtain replicate estimates of these relationships.

scholarly journals FIRE BEHAVIOR PREDICTING MODELS EFFICIENCY IN BRAZILIAN COMMERCIAL EUCALYPT PLANTATIONS

CERNE ◽  
2016 ◽  
Vol 22 (4) ◽  
pp. 389-396 ◽  
Author(s):  
Benjamin Leonardo Alves White ◽  
Larissa Alves Secundo White ◽  
Genésio Tâmara Ribeiro ◽  
Rosemeri Melo Souza
Keyword(s):  
Fire Suppression ◽  
Fire Behavior ◽  
Fire Spread ◽  
Flame Length ◽  
Eucalypt Plantations ◽  
Spread Model ◽  
Experimental Laboratory ◽  
Predicted Values ◽  
In Fire ◽  
Better Than

ABSTRACT Knowing how a wildfire will behave is extremely important in order to assist in fire suppression and prevention operations. Since the 1940’s mathematical models to estimate how the fire will behave have been developed worldwide, however, none of them, until now, had their efficiency tested in Brazilian commercial eucalypt plantations nor in other vegetation types in the country. This study aims to verify the accuracy of the Rothermel (1972) fire spread model, the Byram (1959) flame length model, and the fire spread and length equations derived from the McArthur (1962) control burn meters. To meet these objectives, 105 experimental laboratory fires were done and their results compared with the predicted values from the models tested. The Rothermel and Byram models predicted better than McArthur’s, nevertheless, all of them underestimated the fire behavior aspects evaluated and were statistically different from the experimental data.

scholarly journals Potential Effects of Climate Change on Fire Behavior, Economic Susceptibility and Suppression Costs in Mediterranean Ecosystems: Córdoba Province, Spain

Forests ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 679 ◽  
Author(s):  
Juan Ramón Molina ◽  
Armando González-Cabán ◽  
Francisco Rodríguez y Silva
Keyword(s):  
Climate Change ◽  
New Technologies ◽  
Economic Valuation ◽  
Fire Behavior ◽  
Flame Length ◽  
Fire Intensity ◽  
Climate Change Scenarios ◽  
Adaptation Measures ◽  
Digital Version ◽  
Mitigation And Adaptation

The potentially large ecological, economic, and societal impacts of climate change makes it a significant problem of the 21st century. These consequences have led to tremendous development in climate change scenarios and new technologies to increase knowledge on the effect and efficiency of mitigation and adaptation measures. Large fires will occur at a higher rate than currently because of lower fuel moisture content resulting in a lower resistance to burning. This is also evidenced by more extreme fire behavior that contributes to higher economic impacts, suppression difficulties and suppression costs. The economic susceptibility concept integrates a set of economic valuation approaches for valuing timber and non-timber resources, considering the fire behavior, and as a consequence, the net value changes for each resource. Flame length increased by 4.6% to 15.69%, according to the different future climate scenarios. Climate change is expected to cause widespread changes to economic susceptibility and suppression costs because of higher flame length and fire intensity. Therefore, our outcomes show an increase in the economic susceptibility of Córdoba Province in the medium and long term (2041–2070) between 6.05% and 25.99%, respectively. In addition, we have found an increase between 65.67% and 86.73% in suppression costs in the last decade. The digital version of the economic susceptibility model using Geographic Information Systems improves its operational capabilities enhancing also its dynamism and simplicity to accept modifications and predictions revisions.

scholarly journals A Study of the Flow Field Surrounding Interacting Line Fires

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Trevor Maynard ◽  
Marko Princevac ◽  
David R. Weise
Keyword(s):  
Flow Field ◽  
Cross Correlation ◽  
Fire Behavior ◽  
Flame Length ◽  
Adjacent Line ◽  
Momentum Imbalance ◽  
Predicted Values ◽  
Simple Potential ◽  
In Fire ◽  
Potential Flow Model

The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which results from a momentum imbalance triggered by fire geometry. The model was validated by measuring the velocity field surrounding stationary alcohol pool fires. The flow field was seeded with high-contrast colored smoke, and the motion of smoke structures was analyzed using a cross-correlation optical flow technique. The measured velocities and flame angles are found to compare reasonably with the predicted values, and an analogy between merging fires and wind-blown flames is proposed.

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