Calibration and Field Testing of Passive Flame Height Sensors

1992 ◽  
Vol 2 (3) ◽  
pp. 115 ◽  
Author(s):  
MA Finney ◽  
RE Martin
Keyword(s):  
Experimental Test ◽  
Prescribed Burning ◽  
Fire Retardant ◽  
Field Testing ◽  
Flame Length ◽  
Flame Height ◽  
Video Tape ◽  
Fire Damage ◽  
String Type

The concept of a passive flame height sensor involves thin strings permeated with fire retardant or solder which record heights of flame contact. Both types of sensors were calibrated during 12 experimental test fires with respect to flame heights measured on video tape. Three thresholds of fire damage to string-type sensors were identified: singeing of fine string fibers, complete blackening of the string, and thorough charring or consumption. These damage thresholds were found to exceed95%, 71% and48% of all flame heights measured from video tape, respectively. 18-gauge solder melted to a height exceeding 86% of measured flame heights. Field testing of 512 sensors during prescribed burning affirmed the potential practicality of this technique for estimating flame length.

The effects of wind on the flame characteristics of individual leaves

2011 ◽  
Vol 20 (5) ◽  
pp. 657 ◽  
Author(s):  
Wesley J. Cole ◽  
McKaye H. Dennis ◽  
Thomas H. Fletcher ◽  
David R. Weise
Keyword(s):  
Froude Number ◽  
Flame Length ◽  
Flame Height ◽  
Combustion Model ◽  
Small Scale ◽  
Single Leaf ◽  
Small Branch ◽  
Flame Burner ◽  
Broadleaf Species ◽  
Semi Empirical

Individual cuttings from five shrub species were burned over a flat-flame burner under wind conditions of 0.75–2.80 m s–1. Both live and dead cuttings were used. These included single leaves from broadleaf species as well as 3 to 5 cm-long branches from coniferous and small broadleaf species. Flame angles and flame lengths were determined by semi-automated measurements of video images. Additional data, such as times and temperatures corresponding to ignition, maximum flame height and burnout were determined using video and infrared images. Flame angles correlated linearly with wind velocity. They also correlated with the Froude number when either the flame length or flame height was used. Flame angles in individual leaf experiments were generally 50 to 70% less than flame angles derived from Froude number correlations reported in the literature for fuel-bed experiments. Although flame angles increased with fuel mass and moisture content, they were unaffected by fuel species. Flame lengths and flame heights decreased with moisture contents and wind speed but increased with mass. In most cases, samples burned with wind conditions ignited less quickly and at lower temperatures than samples burned without wind. Most samples contained moisture at the time of ignition. Results of this small-scale approach (e.g. using individual cuttings) apply to ignition of shrubs and to flame propagation in shrubs of low bulk density. This research is one of the few attempts to characterise single-leaf and small-branch combustion behaviour in wind and is crucial to the continued development of a semi-empirical shrub combustion model.

scholarly journals Antelope Bitterbrush and Scouler's Willow Response to a Shelterwood Harvest and Prescribed Burn in Western Montana

1999 ◽  
Vol 14 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Dayna M. Ayers ◽  
Donald J. Bedunah ◽  
Michael G. Harrington
Keyword(s):  
Fuel Consumption ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Prescribed Burning ◽  
Selective Logging ◽  
Western Montana ◽  
Fire Damage ◽  
Prescribed Burn ◽  
Large Trees ◽  
Shelterwood Cut

Abstract In many western Montana ponderosa pine (Pinus ponderosa) stands, fire suppression and past selective logging of large trees have resulted in conditions favoring succession to dense stands of shade-tolerant, but insect- and disease-prone Douglas-fir (Pseudotsuga menziesii). Stand thinning and understory prescribed burning have been proposed as surrogates for pre-Euro-American settlement ecological processes and as potential treatments to improve declining forest condition and reduce the probability of severe wildfire. To test the effectiveness of these silvicultural techniques on overstory and understory conditions, research is ongoing in the Lick Creek Demonstration Site in the Bitterroot National Forest, Montana. Our research examined the response (mortality and vigor) of the dominant browse species, antelope bitterbrush (Purshia tridentata) and Scouler's willow (Salix scouleriana), to a ponderosa pine stand restoration project utilizing four treatments: (1) a shelterwood cut that removed 53% of the tree basal area; (2) a shelterwood cut with a low fuel consumption burn; (3) a shelterwood cut with a high fuel consumption burn; and (4) a control. Prior to the application of treatments, 1,856 bitterbrush and 871 willow were located, and their survival and vigor subsequently monitored for 2 yr posttreatment. The cut and burn treatments resulted in the greatest reduction in antelope bitterbrush and Scouler's willow density averaging 66% and 24% of pretreatment density, respectively. The shelterwood cut reduced bitterbrush and Scouler's willow density by 35% and 14%, respectively. On treatments receiving a shelterwood cut (all treatments but the control), but where antelope bitterbrush and Scouler's willow did not have fire damage, mortality was 45% for bitterbrush and 20% for willow, respectively. For bitterbrush and Scouler's willow plants that received fire damage, mortality was 72% for bitterbrush and 19% for willow. Although the burn and shelterwood harvest treatments resulted in reduced density of antelope bitterbrush and Scouler's willow 2 yr posttreatment, these treatments increased vigor of both species and created mineral seedbeds that may be necessary for establishment of seedlings. West. J. Appl. For. 14(3):137-143.

Interdependencies between flame length and fireline intensity in predicting crown fire initiation and crown scorch height

2012 ◽  
Vol 21 (2) ◽  
pp. 95 ◽  
Author(s):  
Martin E. Alexander ◽  
Miguel G. Cruz
Keyword(s):  
Wildland Fire ◽  
Stem Bark ◽  
Flame Length ◽  
Flame Height ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Surface Fire ◽  
Crown Scorch ◽  
Fire Initiation ◽  
Bark Char

This state-of-knowledge review examines some of the underlying assumptions and limitations associated with the inter-relationships among four widely used descriptors of surface fire behaviour and post-fire impacts in wildland fire science and management, namely Byram’s fireline intensity, flame length, stem-bark char height and crown scorch height. More specifically, the following topical areas are critically examined based on a comprehensive review of the pertinent literature: (i) estimating fireline intensity from flame length; (ii) substituting flame length for fireline intensity in Van Wagner’s crown fire initiation model; (iii) the validity of linkages between the Rothermel surface fire behaviour and Van Wagner’s crown scorch height models; (iv) estimating flame height from post-fire observations of stem-bark char height; and (v) estimating fireline intensity from post-fire observations of crown scorch height. There has been an overwhelming tendency within the wildland fire community to regard Byram’s flame length–fireline intensity and Van Wagner’s crown scorch height–fireline intensity models as universal in nature. However, research has subsequently shown that such linkages among fire behaviour and post-fire impact characteristics are in fact strongly influenced by fuelbed structure, thereby necessitating consideration of fuel complex specific-type models of such relationships.

Fire behaviour in masticated forest fuels: lab and prescribed fire experiments

2018 ◽  
Vol 27 (4) ◽  
pp. 280 ◽  
Author(s):  
Zachary D. Lyon ◽  
Penelope Morgan ◽  
Camille S. Stevens-Rumann ◽  
Aaron M. Sparks ◽  
Robert F. Keefe ◽  
...  
Keyword(s):  
Pinus Ponderosa ◽  
Prescribed Fire ◽  
Laboratory Experiments ◽  
Prescribed Burning ◽  
Cost Effective ◽  
Flame Length ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Forest Fuels ◽  
Fire Experiments

Managers masticate fuels to reduce extreme fire hazards, but the effect on fire behaviour within the resulting compact fuelbeds is poorly understood. We burned 54 masticated fuelbeds in laboratory experiments one and two growing seasons after mastication and 75 masticated fuelbeds in prescribed fire experiments one growing season after treatment in three replicate Pinus ponderosa stands. Mastication treatments reduced density of trees >5 cm diameter by 30–72% resulting in total fuel depth of 6.9–13.7 cm and surface woody fuel loading of 1.0–16.0 kg m−2. Flame length and rate of spread were low and similar for coarse and fine mastication treatments and controls. Smouldering combustion lasted 6–22 h in prescribed fire experiments where fuelbeds included duff and were well mixed by machinery, compared with <2 h in the laboratory where fuelbeds did not include duff and had varying fuel moisture. Fuel consumption in the prescribed fires was highly variable, ranging from 0 to 20 cm in depth and was less from 2-year-old fuelbeds than 1-year-old fuelbeds in laboratory burns. Compared with fine mastication treatments, coarse treatments took less time to implement and were more cost-effective. Although laboratory experiments expand our understanding of burning masticated fuels under controlled conditions, they did not readily translate to prescribed burning conditions where fuels, weather and ignition patterns were more variable. This highlights the need for more laboratory experiments and in situ research that together can be used to develop much-needed, scalable predictive models of mastication combustion.

Corrigendum to: Interdependencies between flame length and fireline intensity in predicting crown fire initiation and crown scorch height

2017 ◽  
Vol 26 (4) ◽  
pp. 345 ◽  
Author(s):  
Martin E. Alexander ◽  
Miguel G. Cruz
Keyword(s):  
Wildland Fire ◽  
Stem Bark ◽  
Flame Length ◽  
Flame Height ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Surface Fire ◽  
Crown Scorch ◽  
Fire Initiation ◽  
Bark Char

This state-of-knowledge review examines some of the underlying assumptions and limitations associated with the inter-relationships among four widely used descriptors of surface fire behaviour and post-fire impacts in wildland fire science and management, namely Byram's fireline intensity, flame length, stem-bark char height and crown scorch height. More specifically, the following topical areas are critically examined based on a comprehensive review of the pertinent literature: (i) estimating fireline intensity from flame length; (ii) substituting flame length for fireline intensity in Van Wagner's crown fire initiation model; (iii) the validity of linkages between the Rothermel surface fire behaviour and Van Wagner's crown scorch height models; (iv) estimating flame height from post-fire observations of stem-bark char height; and (v) estimating fireline intensity from post-fire observations of crown scorch height. There has been an overwhelming tendency within the wildland fire community to regard Byram's flame length–fireline intensity and Van Wagner's crown scorch height–fireline intensity models as universal in nature. However, research has subsequently shown that such linkages among fire behaviour and post-fire impact characteristics are in fact strongly influenced by fuelbed structure, thereby necessitating consideration of fuel complex specific-type models of such relationships.

Spatiotemporal flame mapping in a large-bore marine diesel engine using multiple high-speed cameras

2019 ◽  
Vol 21 (4) ◽  
pp. 622-631 ◽  
Author(s):  
Johan Hult ◽  
Alexios Matamis ◽  
Eric Baudoin ◽  
Stefan Mayer ◽  
Mattias Richter
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Flame Length ◽  
Flame Height ◽  
Quantitative Studies ◽  
Flame Emission ◽  
Space Carving ◽  
Engine Cylinder ◽  
Flame Development ◽  
Marine Diesel

A calibrated multiple high-speed camera arrangement recording the flame emission from three different directions has been demonstrated on an engine. From the multiple views, the flame position inside the engine cylinder can be spatially mapped, allowing quantitative studies of the dynamics of ignition, flame development and propagation. Through space carving, the three-dimensional flame contour can be estimated. From this contour, properties like flame length, flame height, ignition locations and flame directions can be extracted. The technique is demonstrated by measurements on diesel flames inside a marine two-stroke engine with a bore diameter of 500 mm. It is found to be a valuable tool for spatiotemporal flame mapping in this asymmetric industrial combustion system.

Experimental study of the width effects on self-induced buoyant blow off in upward flame spread over thin fabric fuels

2019 ◽  
Vol 90 (11-12) ◽  
pp. 1404-1413 ◽  
Author(s):  
Guoqing Zhu ◽  
Yunji Gao ◽  
Guoqiang Chai ◽  
Jinju Zhou ◽  
Shuai Gao
Keyword(s):  
Flame Spread ◽  
Flame Length ◽  
Flame Height ◽  
Spread Rate ◽  
Fire Control ◽  
Constant Length ◽  
Flame Spreading ◽  
Upward Flame Spread ◽  
Flame Thickness ◽  
Induced Velocity

In this paper, a series of upward flame spreading experiments were conducted on thin flax fabric with various widths ranging from 3.0 to 8.0 cm and length of 1.6 m. Symmetric ignition at the entire bottom edge of samples led to two-sided upward flame growth initially. A very interesting behavior of flame blown off was observed in upward flame spreading and an explanation was provided based on the increased buoyancy-induced velocity at the flame base. When the sample width is 6 cm or less, the flame length increases to a critical value and, correspondingly, the buoyancy-induced velocity reaches the blow off velocity, which results in a flame being blown off on one side. The remaining flame on the other side would shrink in length and propagate to the end of the sample with an asymptotically constant length and steady spread rate. For samples wider than 6 cm, the two-sided flame continues to spread to the end of samples and the self-induced blow off phenomenon is not observed. Moreover, the width effects on the flame height, flame thickness and flame spread rate are analyzed and explained in this paper. The results of this study may help advance better understanding of flame blow off behaviors over solid surfaces and have implications concerning fire control of flame spread over solid fuels.

Ignition and flame spread over thermal aging electrical wires in subatmospheric pressure

2019 ◽  
pp. 089270571986686 ◽  
Author(s):  
Yue Zhang ◽  
Jun Fang ◽  
Jingwu Wang ◽  
Luyao Zhao ◽  
Yongming Zhang
Keyword(s):  
Chemical Kinetics ◽  
Flame Spread ◽  
Thermal Aging ◽  
Ignition Delay ◽  
Pyrolysis Temperature ◽  
Flame Length ◽  
Heating Time ◽  
Flame Height ◽  
Scanning Calorimetry ◽  
Pressure Region

Thermal aging affects polymer ignition and flame spread process by changing the polymer kinetic parameters. Polyethylene (PE) with 0.15 mm thickness insulated by copper core of 0.5 mm diameter was used in this experiment. The PE was preheated under different temperature and heating time. Wires which have experienced thermal aging at 130°C for 30 and 200 h display higher crystallinity and pyrolysis temperature. However, the crystallinity and pyrolysis temperature decrease of wires, which experienced thermal aging at 150°C for 30 and 200 h by the results of thermogravimetric analysis and differential scanning calorimetry tests. The ignition experiment results highlight the ignition delay exhibiting “U” type with pressure. Chemical kinetics controls the ignition delay in lower pressure region, and the heat transfer controls the ignition delay in higher pressure region. The region controlled by chemical kinetics is larger for the wire with higher crystallinity and pyrolysis temperature. The flame spread experiment results show that the flame area relays more on flame length for the wires with lower crystallinity and pyrolysis temperatures, while wires with greater crystallinity and higher pyrolysis temperature depend more on flame height.

Radiation Model of Horizontal Jet Flame Governed by Buoyancy and Momentum

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Liu Changchun ◽  
Deng Tiandiao ◽  
Zhou Shasha ◽  
Liu Xinlei ◽  
Deng Jun ◽  
...  
Keyword(s):  
Predictive Accuracy ◽  
Flame Length ◽  
Length Ratio ◽  
Flame Height ◽  
Laptop Computer ◽  
Jet Flame ◽  
New Model ◽  
Trajectory Model ◽  
Data Points ◽  
Lift Off

AbstractBuoyancy causes a horizontal jet flame to bend upward when it loses sufficient initial momentum. Therefore, the variation in flame trajectory must be considered to accurately predict the thermal radiant flux of a horizontal jet flame governed by buoyancy and momentum. We introduce the flame trajectory equation into the linear source equation of radiation to establish a new model. The flame length ratio is calculated by flame trajectory length, horizontal projected flame length, and vertical projected flame height in the new model. This paper also presents a formula for flame lift-off distance and flame radiant fraction. We further list the geometric parameters of the horizontal-kite shape, tile-kite shape, and flame trajectory models. Comparing the experimental data and model predictions shows that the flame trajectory model is more accurate than the horizontal-kite and tile-kite models, especially when the Froude number is low. We also study the effects of flame lift-off distance and flame length ratio on predictive accuracy. The flame trajectory model computes quickly, and a normal laptop computer needs only 1.08 s to get a picture with 24,000 data points.

Experimental study of welding region effects on upward flame spread over textile membranes

2018 ◽  
Vol 89 (10) ◽  
pp. 2041-2053 ◽  
Author(s):  
Yunji Gao ◽  
Guoqing Zhu ◽  
Mengwei Yu ◽  
Feng Guo ◽  
Yu Xia ◽  
...  
Keyword(s):  
Flame Spread ◽  
Ignition Time ◽  
Flame Temperature ◽  
Air Entrainment ◽  
Flame Length ◽  
Flame Height ◽  
Spread Rate ◽  
Pyrolysis Gas ◽  
Upward Flame Spread ◽  
Pyrolysis Spread Rate

Textile membranes are used widely as a main architectural material in membrane structure buildings. However, very few studies have been conducted to investigate the flame spread characteristics of textile membranes, especially in the case of upward flame spread. In this paper, the effects of welding region on upward flame spread were investigated experimentally using sample sheets of textile membranes 60 cm tall and 6 cm wide with and without welding region. The corresponding observations are as follows: the width of flame with welding region is narrower than that without welding region; flame height, pyrolysis height, preheating length, flame length, and pyrolysis spread rate decrease significantly in the presence of a welding region, while ignition time increases; flame temperature decreases in the presence of a welding region, and temperature along the welding region is higher than that near the edge. The welding region effects are as follows: in presence of a welding region, the thickness of welding region increases and, accordingly, ignition time shows an increase, leading to relatively low pyrolysis gas generated per unit time and relatively less heat released; in addition, a relatively larger pyrolysis gas concentration gradient over the width for welding membranes results in a relatively stronger air entrainment occurring at the sample sides, taking away part of the heat flux and narrowing the flame width. Thus, the presence of a welding region has negative effects of increasing ignition time and reducing preheating length on upward flame spread over textile membranes, eventually decreasing the pyrolysis spread rate.

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