Fire Front Width Effects on Fire Spread Across a Laboratory Scale Sloping Fuel Bed

2001 ◽  
Vol 166 (1) ◽  
pp. 67-90 ◽  
Author(s):  
F. MORANDINI ◽  
P.A. SANTONI ◽  
J.H. BALBI
Keyword(s):  
Fire Spread ◽  
Laboratory Scale ◽  
Front Width ◽  
Fire Front

The effect of fire front width on surface fire behaviour

1999 ◽  
Vol 9 (4) ◽  
pp. 247 ◽  
Author(s):  
B.M. Wotton ◽  
R.S. McAlpine ◽  
M.W. Hobbs
Keyword(s):  
Forest Litter ◽  
Fire Spread ◽  
Fire Behaviour ◽  
Pine Plantation ◽  
Spread Rate ◽  
Surface Fire ◽  
Flame Radiation ◽  
Surface Fires ◽  
Front Width ◽  
Fire Front

To determine the effect of fire front width on surface fire spread rates, a series of simultaneously ignited experimental fires was carried out in a pine plantation. Fires were ignited in plots with widths ranging from 0.5 m to 10 m and were burned in low wind conditions. Flame lengths were small in all fires, ranging from 20 cm to 60 cm. Since pre-heating of the forest litter from flame radiation is assumed to be an important mechanism in the spread of low intensity, low wind surface fires, it then follows that the width of a flaming front should effect on the heating of the fuel to ignition temperatures. Total flame radiation was also measured at a point 50 cm ahead of the advancing flame front for a number of the fires. Experimental results indicate that a flame radiation measured ahead of the fire stays fairly constant once the flame width is between 2 and 5 m. Theoretical flame radiation calculations confirm this trend. Rates of spread between the 5 and 10 metre width fires also appear to be similar; this indicates that, for the type of fires studied, once flame width is greater than about 2 m, radiation from any extra width of fire front has little effect on spread rate.

Fire line rotation as a mechanism for fire spread on a uniform slope

2002 ◽  
Vol 11 (1) ◽  
pp. 11 ◽  
Author(s):  
Domingos Xavier Viegas
Keyword(s):  
Natural Convection ◽  
Flame Front ◽  
Fire Spread ◽  
Laboratory Scale ◽  
Initial Orientation ◽  
Experimental Results ◽  
Slope Gradient ◽  
Gradient Direction ◽  
Fire Front

The evolution of a linear flame front in a homogeneous fuel bed in a slope, for arbitrary values of the initial orientation of the fire front is studied. It is shown that, with the exception of initially horizontal or down-slope propagating fire lines, the propagation is not stationary. In its movement the fire front rotates, tending to become parallel to the slope gradient direction. The concept of fire line rotation as a tool to interpret and describe the evolution of a fire front is presented. Experimental results developed at a laboratory scale in a 30˚ slope are presented to support it. Some insight about the role played by natural convection induced by the fire is provided. A model using the concept of fire line rotation is proposed to predict the evolution of a fire front. Its application to the case of a point ignition fire in a slope is presented.

scholarly journals Ignition Vulnerabilities of Combustibles around Houses to Firebrand Showers: Further Comparison of Experiments

2021 ◽  
Vol 13 (4) ◽  
pp. 2136
Author(s):  
Sayaka Suzuki ◽  
Samuel L. Manzello
Keyword(s):  
Experimental Data ◽  
Thermal Radiation ◽  
Driving Force ◽  
Fire Spread ◽  
Significant Problem ◽  
Next Generation ◽  
Similar Time ◽  
Comparison Of Experiments ◽  
Fire Front ◽  
Wui Fires

Wildland fires and wildland urban-interface (WUI) fires have become a significant problem in recent years. The mechanisms of home ignition in WUI fires are direct flame contact, thermal radiation, and firebrand attack. Out of these three fire spread factors, firebrands are considered to be a main driving force for rapid fire spread as firebrands can fly far from the fire front and ignite structures. The limited experimental data on firebrand showers limits the ability to design the next generation of communities to resist WUI fires to these types of exposures. The objective of this paper is to summarize, compare, and reconsider the results from previous experiments, to provide new data and insights to prevent home losses from firebrands in WUI fires. Comparison of different combustible materials around homes revealed that wood decking assemblies may be ignited within similar time to mulch under certain conditions.

Fine-Scale Fire Spread in Pine Straw

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 69
Author(s):  
Daryn Sagel ◽  
Kevin Speer ◽  
Scott Pokswinski ◽  
Bryan Quaife
Keyword(s):  
Fire Spread ◽  
Small Scale ◽  
Natural Setting ◽  
Fine Scale ◽  
Prescribed Burn ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
Scale Models ◽  
Fire Front ◽  
Visible Images

Most wildland and prescribed fire spread occurs through ground fuels, and the rate of spread (RoS) in such environments is often summarized with empirical models that assume uniform environmental conditions and produce a unique RoS. On the other hand, representing the effects of local, small-scale variations of fuel and wind experienced in the field is challenging and, for landscape-scale models, impractical. Moreover, the level of uncertainty associated with characterizing RoS and flame dynamics in the presence of turbulent flow demonstrates the need for further understanding of fire dynamics at small scales in realistic settings. This work describes adapted computer vision techniques used to form fine-scale measurements of the spatially and temporally varying RoS in a natural setting. These algorithms are applied to infrared and visible images of a small-scale prescribed burn of a quasi-homogeneous pine needle bed under stationary wind conditions. A large number of distinct fire front displacements are then used statistically to analyze the fire spread. We find that the fine-scale forward RoS is characterized by an exponential distribution, suggesting a model for fire spread as a random process at this scale.

Laboratory fire spread analysis using visual and infrared images

2006 ◽  
Vol 15 (2) ◽  
pp. 179 ◽  
Author(s):  
J. Ramiro Martínez-de Dios ◽  
Jorge C. André ◽  
João C. Gonçalves ◽  
Begoña Ch. Arrue ◽  
Aníbal Ollero ◽  
...  
Keyword(s):  
Graphical Model ◽  
Fire Spread ◽  
Rate Of Spread ◽  
Virtual View ◽  
Fire Front ◽  
Computer Based ◽  
Front Shape ◽  
Processing Techniques ◽  
Spread Analysis ◽  
Base Width

This paper presents an experimental method using computer-based image processing techniques of visual and infrared movies of a propagating fire front, taken from one or more cameras, to supply the time evolutions of the fire front shape and position, flame inclination angle, height, and base width. As secondary outputs, it also provides the fire front rate of spread and a 3D graphical model of the fire front that can be rendered from any virtual view. The method is automatic and non-intrusive, has space–time resolution close to continuum and can be run in real-time or deferred modes. It is demonstrated in simple laboratory experiments in beds of pine needles set upon an inclinable burn table, with point and linear ignitions, but can be extended to open field situations.

The FireFlux II experiment: a model-guided field experiment to improve understanding of fire–atmosphere interactions and fire spread

2019 ◽  
Vol 28 (4) ◽  
pp. 308 ◽  
Author(s):  
Craig B. Clements ◽  
Adam K. Kochanski ◽  
Daisuke Seto ◽  
Braniff Davis ◽  
Christopher Camacho ◽  
...  
Keyword(s):  
Fire Spread ◽  
Model Systems ◽  
Large Set ◽  
Tall Grass ◽  
Combustion Gases ◽  
Tall Grass Prairie ◽  
Fire Front ◽  
Air Chemistry ◽  
Atmosphere Model ◽  
Behaviour Data

The FireFlux II experiment was conducted in a tall grass prairie located in south-east Texas on 30 January 2013 under a regional burn ban and high fire danger conditions. The goal of the experiment was to better understand micrometeorological aspects of fire spread. The experimental design was guided by the use of a coupled fire–atmosphere model that predicted the fire spread in advance. Preliminary results show that after ignition, a surface pressure perturbation formed and strengthened as the fire front and plume developed, causing an increase in wind velocity at the fire front. The fire-induced winds advected hot combustion gases forward and downwind of the fire front that resulted in acceleration of air through the flame front. Overall, the experiment collected a large set of micrometeorological, air chemistry and fire behaviour data that may provide a comprehensive dataset for evaluating and testing coupled fire–atmosphere model systems.

The contribution of turbulent plume dynamics to long-range spotting

2017 ◽  
Vol 26 (4) ◽  
pp. 317 ◽  
Author(s):  
William Thurston ◽  
Jeffrey D. Kepert ◽  
Kevin J. Tory ◽  
Robert J. B. Fawcett
Keyword(s):  
Transport Model ◽  
Fire Spread ◽  
Substantial Impact ◽  
Landing Position ◽  
Plume Dynamics ◽  
Large Eddy ◽  
Rapid Spread ◽  
Fire Front ◽  
Turbulent Plume ◽  
Physical Realism

Spotting can start fires up to tens of kilometres ahead of the primary fire front, causing rapid spread and placing immense pressure on suppression resources. Here, we investigate the dynamics of the buoyant plume generated by the fire and its ability to transport firebrands. We couple large-eddy simulations of bushfire plumes with a firebrand transport model to assess the effects of turbulent plume dynamics on firebrand trajectories. We show that plume dynamics have a marked effect on the maximum spotting distance and determine the amount of lateral and longitudinal spread in firebrand landing position. In-plume turbulence causes much of this spread and can increase the maximum spotting distance by a factor of more than 2 over that in a plume without turbulence in our experiments. The substantial impact of plume dynamics on the spotting process implies that fire spread models should include parametrisations of turbulent plume dynamics to improve their accuracy and physical realism.

Physical modelling of forest fire spreading through heterogeneous fuel beds

2011 ◽  
Vol 20 (5) ◽  
pp. 625 ◽  
Author(s):  
Albert Simeoni ◽  
Pierre Salinesi ◽  
Frédéric Morandini
Keyword(s):  
Field Experiments ◽  
Heterogeneous Medium ◽  
Reaction Diffusion ◽  
Physical Modelling ◽  
Fire Spread ◽  
Physical Models ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Fire Front ◽  
Fire Spreading

Vegetation cover is a heterogeneous medium composed of different kinds of fuels and non-combustible parts. Some properties of real fires arise from this heterogeneity. Creating heterogeneous fuel areas may be useful both in land management and in firefighting by reducing fire intensity and fire rate of spread. The spreading of a fire through a heterogeneous medium was studied with a two-dimensional reaction–diffusion physical model of fire spread. Randomly distributed combustible and non-combustible square elements constituted the heterogeneous fuel. Two main characteristics of the fire were directly computed by the model: the size of the zone influenced by the heat transferred from the fire front and the ignition condition of vegetation. The model was able to provide rate of fire spread, temperature distribution and energy transfers. The influence on the fire properties of the ratio between the amount of combustible elements and the total amount of elements was studied. The results provided the same critical fire behaviour as described in both percolation theory and laboratory experiments but the results were quantitatively different because the neighbourhood computed by the model varied in time and space with the geometry of the fire front. The simulations also qualitatively reproduced fire behaviour for heterogeneous fuel layers as observed in field experiments. This study shows that physical models can be used to study fire spreading through heterogeneous fuels, and some potential applications are proposed about the use of heterogeneity as a complementary tool for fuel management and firefighting.

scholarly journals Georeferencing Oblique Aerial Wildfire Photographs: An Untapped Source of Fire Behaviour Data

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 81
Author(s):  
Henry Hart ◽  
Daniel D. B. Perrakis ◽  
Stephen W. Taylor ◽  
Christopher Bone ◽  
Claudio Bozzini
Keyword(s):  
Fire Behavior ◽  
Fire Spread ◽  
Behavior Prediction ◽  
Empirical Relationships ◽  
Rate Of Spread ◽  
Front Position ◽  
Fire Front ◽  
Initial Work ◽  
The Mean ◽  
Behaviour Data

In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31–118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from −19 to −50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.

scholarly journals Towards predictive data-driven simulations of wildfire spread – Part I: Reduced-cost Ensemble Kalman Filter based on a Polynomial Chaos surrogate model for parameter estimation

2014 ◽  
Vol 14 (11) ◽  
pp. 2951-2973 ◽  
Author(s):  
M. C. Rochoux ◽  
S. Ricci ◽  
D. Lucor ◽  
B. Cuenot ◽  
A. Trouvé
Keyword(s):  
Parameter Estimation ◽  
Kalman Filter ◽  
Ensemble Kalman Filter ◽  
Surrogate Model ◽  
Polynomial Chaos ◽  
Computational Cost ◽  
Fire Spread ◽  
Data Driven ◽  
Fire Front ◽  
Wildfire Spread

Abstract. This paper is the first part in a series of two articles and presents a data-driven wildfire simulator for forecasting wildfire spread scenarios, at a reduced computational cost that is consistent with operational systems. The prototype simulator features the following components: an Eulerian front propagation solver FIREFLY that adopts a regional-scale modeling viewpoint, treats wildfires as surface propagating fronts, and uses a description of the local rate of fire spread (ROS) as a function of environmental conditions based on Rothermel's model; a series of airborne-like observations of the fire front positions; and a data assimilation (DA) algorithm based on an ensemble Kalman filter (EnKF) for parameter estimation. This stochastic algorithm partly accounts for the nonlinearities between the input parameters of the semi-empirical ROS model and the fire front position, and is sequentially applied to provide a spatially uniform correction to wind and biomass fuel parameters as observations become available. A wildfire spread simulator combined with an ensemble-based DA algorithm is therefore a promising approach to reduce uncertainties in the forecast position of the fire front and to introduce a paradigm-shift in the wildfire emergency response. In order to reduce the computational cost of the EnKF algorithm, a surrogate model based on a polynomial chaos (PC) expansion is used in place of the forward model FIREFLY in the resulting hybrid PC-EnKF algorithm. The performance of EnKF and PC-EnKF is assessed on synthetically generated simple configurations of fire spread to provide valuable information and insight on the benefits of the PC-EnKF approach, as well as on a controlled grassland fire experiment. The results indicate that the proposed PC-EnKF algorithm features similar performance to the standard EnKF algorithm, but at a much reduced computational cost. In particular, the re-analysis and forecast skills of DA strongly relate to the spatial and temporal variability of the errors in the ROS model parameters.

Sign in / Sign up

Export Citation Format

Share Document