Flame characteristics, temperature - time curves, and rate of spread in fires propagating in a bed of Pinus pinaster needles

2003 ◽  
Vol 12 (1) ◽  
pp. 67 ◽  
Author(s):  
José M. C. Mendes-Lopes ◽  
João M. P. Ventura ◽  
José M. P. Amaral
Keyword(s):  
Wind Speed ◽  
Moisture Content ◽  
Pinus Pinaster ◽  
Flame Height ◽  
Fuel Moisture ◽  
Propagation Models ◽  
Fire Propagation ◽  
Rate Of Spread ◽  
Fuel Moisture Content ◽  
Flame Angle

An extensive set of experiments was carried out in order to collect data to validate fire propagation models being developed in the context of an European research project. The experiments were performed in a dedicated burning tray (2.0 m × 0.70 m working section), where wind velocity, fuel moisture content and slope were varied to study fire propagation in beds of Pinus pinaster needles. All the runs were videotaped and, from the recordings, information on flame geometry (i.e. flame height, flame length and flame angle) and rate of spread was obtained. Temperature measurements were also carried out by a small tower of six thermocouples at different heights above the fuel bed. Results show that headfire rate of spread increases steeply with wind speed for wind-driven fires but does not depend on wind speed for backing fire spread rates. Rate of spread increases slightly with slope for up-hill propagation, and is not slope dependent for down-hill cases. Rate of spread decreases when fuel moisture content increases. Flame angle and flame height are also dependent on wind velocity, slope, and fuel moisture content. The importance of temperature for fire propagation is discussed, emphasizing the role of radiation heat transfer in the process. Correlations between temperature and other indicators of fire behaviour (namely the rate of spread) are presented. Results are discussed and compared. The results obtained provide a good database for the assessment of fire propagation models.

Empirical modelling of surface fire behaviour in maritime pine stands

2009 ◽  
Vol 18 (6) ◽  
pp. 698 ◽  
Author(s):  
Paulo M. Fernandes ◽  
Hermínio S. Botelho ◽  
Francisco C. Rego ◽  
Carlos Loureiro
Keyword(s):  
Wind Speed ◽  
Moisture Content ◽  
Fire Spread ◽  
Fire Intensity ◽  
Fuel Moisture ◽  
Fire Behaviour ◽  
Spread Rate ◽  
Surface Fire ◽  
Rate Of Spread ◽  
Fuel Moisture Content

An experimental burning program took place in maritime pine (Pinus pinaster Ait.) stands in Portugal to increase the understanding of surface fire behaviour under mild weather. The spread rate and flame geometry of the forward and backward sections of a line-ignited fire front were measured in 94 plots 10–15 m wide. Measured head fire rate of spread, flame length and Byram’s fire intensity varied respectively in the intervals of 0.3–13.9 m min–1, 0.1–4.2 m and 30–3527 kW m–1. Fire behaviour was modelled through an empirical approach. Rate of forward fire spread was described as a function of surface wind speed, terrain slope, moisture content of fine dead surface fuel, and fuel height, while back fire spread rate was correlated with fuel moisture content and cover of understorey vegetation. Flame dimensions were related to Byram’s fire intensity but relationships with rate of spread and fine dead surface fuel load and moisture are preferred, particularly for the head fire. The equations are expected to be more reliable when wind speed and slope are less than 8 km h–1 and 15°, and when fuel moisture content is higher than 12%. The results offer a quantitative basis for prescribed fire management.

Convective heat transfer in fire spread through fine fuel beds

2010 ◽  
Vol 19 (3) ◽  
pp. 284 ◽  
Author(s):  
W. R. Anderson ◽  
E. A. Catchpole ◽  
B. W. Butler
Keyword(s):  
Heat Transfer ◽  
Wind Speed ◽  
Moisture Content ◽  
Flame Front ◽  
Free Stream ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Fuel Moisture ◽  
Fire Front ◽  
Fuel Moisture Content

An extensive set of wind-tunnel fires was burned to investigate convective heat transfer ahead of a steadily progressing fire front moving across a porous fuel bed. The effects of fuel and environmental variables on the gas temperature profile and the ‘surface wind speed’ (gas velocity at the fuel bed surface) are reported. In non-zero winds, the temperature of the air near the fuel bed surface decays exponentially with distance from the fire front. In zero winds, the temperature decreases rapidly within a very short distance of the flame front, then decays slowly thereafter. The maximum air temperature decreases as the free stream wind speed, packing ratio and fuel moisture content increase. The characteristic distance of the exponential decay increases strongly with the free stream wind speed and decreases with the packing ratio and surface area-to-volume ratio of the fuel. The surface wind speed depends strongly on the free stream wind speed, and to a lesser extent on packing ratio, fuel bed depth and fuel moisture content. There are three general regimes for the surface flow: (1) a constant velocity flow of approximately half the free stream flow, far from the flame front; (2) an intermediate zone of minimum flow characterised by low or reversed flow; and (3) a region near the flame front where the velocity rises rapidly almost to the free stream velocity. The boundaries between the three regions move further from the flame front with increasing wind speed, in a way which is only slightly affected by fuel geometry.

A cellular automata model to link surface fires to firebrand lift-off and dispersal

2013 ◽  
Vol 22 (4) ◽  
pp. 428 ◽  
Author(s):  
Holly A. Perryman ◽  
Christopher J. Dugaw ◽  
J. Morgan Varner ◽  
Diane L. Johnson
Keyword(s):  
Wind Speed ◽  
Wildland Fire ◽  
Fire Spread ◽  
Fuel Moisture ◽  
Fuel Loading ◽  
Cellular Automata Model ◽  
Rate Of Spread ◽  
Lift Off ◽  
Fuel Moisture Content ◽  
Spot Fires

In spite of considerable effort to predict wildland fire behaviour, the effects of firebrand lift-off, the ignition of resulting spot fires and their effects on fire spread, remain poorly understood. We developed a cellular automata model integrating key mathematical models governing current fire spread models with a recently developed model that estimates firebrand landing patterns. Using our model we simulated a wildfire in an idealised Pinus ponderosa ecosystem. Varying values of wind speed, surface fuel loading, surface fuel moisture content and canopy base height, we investigated two scenarios: (i) the probability of a spot fire igniting beyond fuelbreaks of various widths and (ii) how spot fires directly affect the overall surface fire’s rate of spread. Results were averages across 2500 stochastic simulations. In both scenarios, canopy base height and surface fuel loading had a greater influence than wind speed and surface fuel moisture content. The expected rate of spread with spot fires occurring approached a constant value over time, which ranged between 6 and 931% higher than the predicted surface fire rate of spread. Incorporation of the role of spot fires in wildland fire spread should be an important thrust of future decision-support technologies.

scholarly journals Useful Life of Prescribed Fires in a Southern Mediterranean Basin: An Application to Pinus pinaster Stands in the Sierra Morena Range

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 486
Author(s):  
Juan Ramón Molina ◽  
Macarena Ortega ◽  
Francisco Rodríguez y Silva
Keyword(s):  
Moisture Content ◽  
Prescribed Fire ◽  
Pinus Pinaster ◽  
Prescribed Fires ◽  
Fuel Moisture ◽  
Fuel Treatment ◽  
Fuel Dynamics ◽  
Useful Life ◽  
Fuel Moisture Content ◽  
Stand Characteristics

Prescribed fire is a globally relevant fuel treatment for surface fuel management and wildfire hazard reduction. However, Mediterranean ecosystems are adapted to low and moderate fires; hence, the useful life of prescribed fires is limited. Useful life is defined as the effective rotation length of prescribed fires to mitigate fire spread based on critical surface intensity for crown combustion. In this sense, the useful life of a prescribed fire focuses on surface fuel dynamics and its potential fire behavior. In Pinus pinaster stands, the useful life can be established between 0 and 4 years. Canopy base height, time elapsed from the burning, postfire precipitation, and fine fuel moisture content during the burning were identified as the most important variables in postburn fuel dynamics. Other stand characteristics and postfire precipitation can improve the fine fuel and live fuel dynamics models. Our findings support prescribed fires as an effective fuel treatment in the medium term for forest fire prevention, according to stand characteristics and burning implementation conditions. In this sense, forest managers can use the proposed decision tree to identify the useful life of each prescribed fire based on fine fuel moisture content during burning implementation.

Conversion of fuel moisture content values to ignition potential for integrated fire danger assessment

2004 ◽  
Vol 34 (11) ◽  
pp. 2284-2293 ◽  
Author(s):  
Emilio Chuvieco ◽  
Inmaculada Aguado ◽  
Alexandros P Dimitrakopoulos
Keyword(s):  
Moisture Content ◽  
Fire Danger ◽  
Assessment System ◽  
Fuel Moisture ◽  
Fire Propagation ◽  
Web Mapping ◽  
Danger Assessment ◽  
Fuel Moisture Content ◽  
In Fire ◽  
Fire Ignition

Fuel moisture content (FMC) estimation is a critical part of any fire danger rating system, since fuel water status is determinant in fire ignition and fire propagation. However, FMC alone does not provide a comprehensive assessment of fire danger, since other factors related to fire ignition (lightning, human factors) or propagation (wind, slope) also need to be taken into account. The problem in integrating all these factors is finding a common scale of danger rating that will make it possible to derive synthetic indices. This paper reviews the importance of FMC in fire ignition and fire propagation, as well as the most common methods of estimating FMC values. A simple method to convert FMC values to danger ratings is proposed, based on computing ignition potential from thresholds of moisture of extinction adapted to each fuel. The method has been tested for the Madrid region (central Spain), where a fire danger assessment system has been built. All the variables related to fire danger were integrated into a dedicated geographic information system and information provided to fire managers through a web mapping server.

scholarly journals PROPAGATOR: An Operational Cellular-Automata Based Wildfire Simulator

Fire ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 26
Author(s):  
Andrea Trucchia ◽  
Mirko D’Andrea ◽  
Francesco Baghino ◽  
Paolo Fiorucci ◽  
Luca Ferraris ◽  
...  
Keyword(s):  
Moisture Content ◽  
Fire Spread ◽  
Fire Fighting ◽  
Fuel Moisture ◽  
Time Step ◽  
Ignition Point ◽  
The Real ◽  
Fire Propagation ◽  
Spread Model ◽  
Fuel Moisture Content

PROPAGATOR is a stochastic cellular automaton model for forest fire spread simulation, conceived as a rapid method for fire risk assessment. The model uses high-resolution information such as topography and vegetation cover considering different types of vegetation. Input parameters are wind speed and direction and the ignition point. Dead fine fuel moisture content and firebreaks—fire fighting strategies can also be considered. The fire spread probability depends on vegetation type, slope, wind direction and speed, and fuel moisture content. The fire-propagation speed is determined through the adoption of a Rate of Spread model. PROPAGATOR simulates independent realizations of one stochastic fire propagation process, and at each time-step gives as output a map representing the probability of each cell of the domain to be affected by the fire. These probabilities are obtained computing the relative frequency of ignition of each cell. The model capabilities are assessed by reproducing a set of past Mediterranean fires occurred in different countries (Italy and Spain), using when available the real fire fighting patterns. PROPAGATOR simulated such scenarios with affordable computational resources and with short CPU-times. The outputs show a good agreement with the real burned areas, demonstrating that the PROPAGATOR can be useful for supporting decisions in Civil Protection and fire management activities.

Combustibility of a mixture of live and dead fuel components

2013 ◽  
Vol 22 (7) ◽  
pp. 992 ◽  
Author(s):  
D. X. Viegas ◽  
J. Soares ◽  
M. Almeida
Keyword(s):  
Moisture Content ◽  
Mass Fraction ◽  
Linear Models ◽  
Fuel Moisture ◽  
Fuel Component ◽  
Rate Of Spread ◽  
Fire Front ◽  
Composite Fuel ◽  
The Dead ◽  
Fuel Moisture Content

The problem of predicting the rate of spread of a linear fire front in a fuel bed composed of one live and one dead fuel component in no-slope and no-wind conditions is addressed. Two linear models based on the mass fraction of each fuel component are proposed to predict the rate of spread of a fire front as a function of the mass fraction of the dead or dry fuel component. Experimental results obtained with two different mixtures show that for each fuel mixture there is a threshold value of mass concentration of the dead fuel below which the fire front does not spread. The rate of spread results compare favourably with the proposed models. A composite fuel moisture content of the fuel bed is shown to be a good descriptor of the rate of spread of the mixture. An exponential model using composite fuel moisture content of the fuel bed is proposed to estimate the rate of spread of the mixture and a comparison is made with the concept of fuel curing that is used to characterise live fuels.

scholarly journals A generic fuel moisture content attenuation factor for fire spread rate empirical models

2018 ◽  
Vol 27 (2) ◽  
pp. e009 ◽  
Author(s):  
Carlos G. Rossa
Keyword(s):  
Moisture Content ◽  
Attenuation Factor ◽  
A Priori ◽  
Fire Spread ◽  
Fuel Moisture ◽  
Ignition Energy ◽  
Spread Rate ◽  
Fire Propagation ◽  
Damping Effect ◽  
Fuel Moisture Content

Aim of study: To develop a fuel moisture content (FMC) attenuation factor for empirical forest fire spread rate (ROS) models in general fire propagation conditions.Methods: The development builds on the assumption that the main FMC-damping effect is a function of fuel ignition energy needs.Main results: The generic FMC attenuation factor was successfully used to derive ROS models from laboratory tests (n = 282) of fire spread in no-wind and no-slope, slope-, and wind-aided conditions. The ability to incorporate the FMC attenuation factor in existing field-based ROS models for shrubland fires and grassland wildfires (n = 123) was also positively assessed.Research highlights: Establishing a priori the FMC-effect in field fires benefits the proper assessment of the remaining variables influence, which is normally eluded by heterogeneity in fuel bed properties and correlated fuel descriptors.

Assessing the probability of sustained flaming in masticated fuel beds

2015 ◽  
Vol 45 (1) ◽  
pp. 68-77 ◽  
Author(s):  
T.J. Schiks ◽  
B.M. Wotton
Keyword(s):  
Wind Speed ◽  
Moisture Content ◽  
Fire Behavior ◽  
Fire Risk ◽  
Field Testing ◽  
Behavior Modeling ◽  
Fuel Moisture ◽  
Fire Behaviour ◽  
Fire Weather Index ◽  
Fuel Moisture Content

Mechanical mastication is increasingly used as a fuel management treatment to reduce fire risk at the wildland–urban interface, although ignition and fire behaviour in these novel fuel beds are poorly understood. We investigated the influence of observed fuel moisture content, wind speed, and firebrand size on the probability of sustained flaming of masticated fuel beds under both laboratory and field settings. Logistic regression techniques were applied to assess the probability of sustained flaming in both datasets. Models for the field were also developed using estimated moisture from three sets of weather-based models: (i) the hourly Fine Fuel Moisture Code (FFMC) from the Canadian Forest Fire Weather Index System, (ii) the National Fire Danger Rating System (NFDRS) moisture estimates for 1 h and 10 h fuels, and (iii) a masticated surface fuel moisture model (MAST). In both laboratory and field testing, the likelihood of a successful ignition increased with decreasing moisture content and increasing wind speed; the effect of firebrand size was only apparent in laboratory testing. The FFMC, NFDRS, and MAST predictions had somewhat reduced discriminative power relative to direct moisture in predicting the probability of sustained flaming based on our field observations. Our results speak to the disparity between the fire behaviour modeling that occurs in the laboratory and the fire behavior modeling that occurs in the field, as the methodology permitted comparison of predictions from sustained flaming models that were developed for one experimental setting and applied to the other.

A generic, empirical-based model for predicting rate of fire spread in shrublands

2015 ◽  
Vol 24 (4) ◽  
pp. 443 ◽  
Author(s):  
Wendy R. Anderson ◽  
Miguel G. Cruz ◽  
Paulo M. Fernandes ◽  
Lachlan McCaw ◽  
Jose Antonio Vega ◽  
...  
Keyword(s):  
Moisture Content ◽  
Experimental Studies ◽  
Fire Spread ◽  
Fuel Moisture ◽  
Fire Behaviour ◽  
Weather Factors ◽  
Vegetation Height ◽  
Rate Of Spread ◽  
Wide Range ◽  
Fuel Moisture Content

A shrubland fire behaviour dataset was assembled using data from experimental studies in Australia, New Zealand, Europe and South Africa. The dataset covers a wide range of heathlands and shrubland species associations and vegetation structures. Three models for rate of spread are developed using 2-m wind speed, a wind reduction factor, elevated dead fuel moisture content and either vegetation height (with or without live fuel moisture content) or bulk density. The models are tested against independent data from prescribed fires and wildfires and found to predict fire spread rate within acceptable limits (mean absolute errors varying between 3.5 and 9.1 m min–1). A simple model to predict dead fuel moisture content is evaluated, and an ignition line length correction is proposed. Although the model can be expected to provide robust predictions of rate of spread in a broad range of shrublands, the effects of slope steepness and variation in fuel quantity and composition are yet to be quantified. The model does not predict threshold conditions for continuous fire spread, and future work should focus on identifying fuel and weather factors that control transitions in fire behaviour.

Sign in / Sign up

Export Citation Format

Share Document