The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Michael J Gollner - One of the best experts on this subject based on the ideXlab platform.
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Lateral Flame Spread over PMMA Under Forced Air Flow
Fire Technology, 2019Co-Authors: Kun Zhao, Michael J Gollner, Junhui Gong, Lizhong YangAbstract:In wildland and other Flame Spread scenarios a Spreading fire front often forms an elliptical shape, incorporating both forward and lateral Spread. While lateral Flame Spread is much slower than forward rates of Spread, it still contributes to the growth of the overall fire front. In this work, a small-scale experiment is performed to investigate the mechanisms causing this lateral Spread in a simple, small-scale configuration. PMMA strips with thicknesses ranging from 1 mm to 3.1 mm and widths of 5 cm and 10 cm were ignited under forced flow in a laminar wind tunnel. Unlike traditional concurrent or opposed Flame Spread experiments, Flames were allowed to progress from one side of the sample to the other, perpendicular to the wind direction. An infrared camera was used to track the progression of the pyrolysis front by estimating the surface temperature of the PMMA. The Flame Spread rate, depth of the burning region, thermal diffusion length, and radiant heat flux were determined and analyzed. Based on a theory of heat and mass transfer for a laminar diffusion Flame, a thermal heat transfer model was developed for the preheating region to predict the lateral Flame Spread rate. Results show that the thermal diffusion length decreases with wind velocity, ranging from 4.5 mm to 3 mm. Convection dominates the Flame-Spread rate, accounting for more than 80% of the total heat flux. The theoretical Flame Spread rate agrees well with experimental data from all but the thinnest samples tested, overpredicting the lateral Flame Spread rate for 1 mm thick samples. The resulting model for lateral Flame Spread under concurrent flow works for forced-flow dominated Flame Spread over thermally-thin fuels and helps provide physical insight into the problem, aiding in future development of two-dimensional, elliptical fire Spread models.
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Flame Spread and burning rates through vertical arrays of wooden dowels
Proceedings of the Combustion Institute, 2019Co-Authors: Lin Jiang, Colin Miller, Zhao Zhao, Wei Tang, Michael J GollnerAbstract:Abstract Fuel loads in real-world fire scenarios often feature discrete elements, discontinuities, or inhomogeneities; however, most models for Flame Spread only assume a continuous, homogeneous fuel. Because discrete fuels represent a realistic scenario not yet well-modeled, it is of interest to find simple methods to model fire growth first in simple, laboratory-scale configurations. A detailed experimental and theoretical study was therefore performed to investigate the controlling mechanisms of Flame Spread through arrays of wooden dowels, with dowel spacings of 0.75, 0.875, and 1.5 cm. Flames were found to Spread vertically for all spacings; however, for the 1.5 cm spacing, the gap was too large for horizontal Flame Spread to occur. A radiation-controlled model for horizontal Flame Spread was developed that predicted the horizontal Flame Spread rate through various arrays of dowels. Combined with an existing convection-based model for vertical Flame Spread, both horizontal and vertical Flame Spread was modeled to predict the number of burning wooden dowels as a function of time. Using models for the burning rate of wooden dowels and boundary-layer theory, a global burning rate model was developed that provided reasonable agreement with experimental results.
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the effect of flow and geometry on concurrent Flame Spread
Fire Safety Journal, 2017Co-Authors: Michael J Gollner, Colin Miller, Wei Tang, Ajay V SinghAbstract:Abstract Flame Spread is an important parameter used in the evaluation of hazards for fire safety applications. The problem of understanding and modeling Flame Spread has been approached before, however new developments continue to challenge our current view of the subject, necessitating future research efforts in the field. In this review, the problem of Flame Spread will be revisited, with a particular emphasis on the effect of flow and geometry on concurrent Flame Spread over solid fuels. The majority of this research is based on that of the senior author, who has worked on wind-driven Flame Spread, inclined fire Spread, Flame Spread through discrete fuels and the particular problem of wildland fires, where all of the above scenarios play an important role. Recent developments in these areas have improved our understanding of Flame-Spread processes and will be reviewed, and areas for future research will be highlighted.
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upward Flame Spread over discrete fuels
Fire Safety Journal, 2015Co-Authors: Colin Miller, Michael J GollnerAbstract:Abstract Upward Flame Spread over discrete fuels has been analyzed through experiments on vertical arrays of alternating lengths of PMMA and inert insulation board. By manipulating the lengths of the PMMA fuel and the insulation, trends relating Flame Spread to fuel loading were assessed. The peak upward Flame Spread rate was observed in non-homogeneous fuel arrays where the fraction of exposed area consisting of fuel (i.e., the fuel coverage f) was below unity. A maximum Flame Spread rate was observed for f=0.67, possibly due to a delayed thickening of the boundary layer or increased air entrainment. In arrays with f ≤ 0.5 , the Flame Spread rate decreased; in fact, deceleration of the pyrolysis front was observed. This behavior indicates that a homogeneous fuel bed approximation, which might be applicable when f is near unity, would be highly unsuitable for arrays with low fuel coverage. Trends for the mass fluxes and Flame heights were also assessed, and it was noted that the mass loss rate per burning area was negatively correlated with f. This provides further support to the hypothesis that decreased thickening of the boundary layer, which would lower the Flame standoff distance, plays a causal role. A method for approximation of the fuel Spread rate was also proposed. This estimate requires reasonable estimates for the homogeneous Flame Spread rate and the lowest fuel coverage value that sustains Spread.
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Studies on upward Flame Spread
2013Co-Authors: Michael J GollnerAbstract:Experimental techniques have been used to investigate three upward Flame Spread phenomena of particular importance for fire safety applications. First, rates of upward Flame Spread during early-stage burning were observed during experiments on wide samples of corrugated cardboard. Results indicated a slower acceleration than was obtained in previous measurements and theories. It is hypothesized that the non-homogeneity of the cardboard helped to reduce the acceleration of the upward Spread rates by physically disrupting flow in the boundary layer close to the vertical surface and thereby modifying heating rates of the solid fuel above the pyrolysis region. The results yield alternative scalings that may be better applicable to some situations encountered in practice in warehouse fires. Next, a thermally thick slab of polymethyl methacrylate was used to study the effects of the inclination angle of a fuel surface on upward Flame Spread. By performing experiments on 10 cm wide by 20 cm tall fuel samples it was found that the maximum Flame- Spread rate, occurring nearly in a vertical configuration, does not correspond to the maximum fuel mass-loss rate, which occurs closer to a horizontal configuration. A detailed study of both Flame Spread and steady burning at different angles of inclination revealed the influence of buoyancy-induced flows in modifying heat-flux profiles ahead of the Flame front, which control Flame Spread, and in affecting the heat flux to the burning surface of the fuel, which controls fuel mass-loss rates. Finally, vertical arrays of horizontally protruding wood matchsticks were used to investigate the influence of the spacing of discrete fuel elements on rates of upward Flame Spread. Rates of upward Flame Spread were found to increase dramatically for spacings between 0 cm and 0.8 cm and experienced only a slight increase thereafter. Based on these observations, the influence of convective heating was hypothesized to dominate this Spread mechanism, and predictions of ignition times were developed using convective heat-transfer correlations. Mass-loss rates followed a similar pattern and were predicted along with matchstick burnout times using a droplet burning theory extended for a cylindrical geometry
Amir Khalid - One of the best experts on this subject based on the ideXlab platform.
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Flame Spread Behaviour over Combustible Solid of Paper, Bagasse and Paper/Bagasse
MATEC Web of Conferences, 2017Co-Authors: Afifah Ramli, Mohd Azahari Razali, Azwan Sapit, Normayati Nordin, Mohd Faisal Hushim, Amir Khalid, Nor Anuar MohammadAbstract:Flame Spread over combustible solid must be precisely identify in fire hazard and this is the basic problem in fire safety engineering field. To explore the Flame Spread mechanism over combustible solid, the downward Flame Spread behaviour over paper and bagasse has been investigated in this experiment. It found that the combustion pattern for paper was slightly different from the bagasse on the front view and this was analysed through the observation. The result also showed that the Flame Spread rate for paper is higher compared to the Flame Spread rate for bagasse. It seem that, although bagasse is the combustible solid the rate of Flame Spread is lower and the usage of bagasse can help to control the Flame Spread.
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Thread angle dependency on Flame Spread shape over kenaf/polyester combined fabric
IOP Conference Series: Materials Science and Engineering, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Nor Anuar Mohamad, Normayati Nordin, Azmahani Sadikin, Mohd Faisal Hushim, Norrizam Jaat, Amir KhalidAbstract:Understanding Flame Spread behavior is crucial to Fire Safety Engineering. It is noted that the natural fiber exhibits different Flame Spread behavior than the one of the synthetic fiber. This different may influences the Flame Spread behavior over combined fabric. There is a research has been done to examined the Flame Spread behavior over kenaf/polyester fabric. It is seen that the Flame Spread shape is dependent on the thread angle dependency. However, the explanation of this phenomenon is not described in detail in that research. In this study, explanation about this phenomenon is given in detail. Results show that the Flame Spread shape is dependent on the position of synthetic thread. For thread angle, θ = 0°, the polyester thread is breaking when the Flame approach to the thread and the kenaf thread tends to move to the breaking direction. This behavior produces Flame to be 'V' shape. However, for thread angle, θ = 90°, the polyester thread melts while the kenaf thread decomposed and burned. At this angle, the distance between kenaf threads remains constant as Flame approaches.
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Flame Spread behavior over combustible thick solid of paper, bagasse and mixed paper/bagasse
IOP Conference Series: Materials Science and Engineering, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Mohd Faisal Hushim, Norrizam Jaat, Sofian Mohd, Ahmad Husaini Ismail, Amir KhalidAbstract:Flame Spread behavior on combustible solid is one of important research related to Fire Safety Engineering. Now, there are a lot of combustible solid composed from mixed materials. In this study, experiments have been conducted to investigate Flame Spread behavior over combustible solid composed by paper, bagasse and mixed paper/bagasse. Experimental data is captured by using video recording and examined Flame Spread shape and rate. From the results obtained, shows that the different materials produce different Flame Spread shape and rate. Different Flame shape is seen between all types of samples. Flame Spread rate of 100% paper is faster than the one of 100% bagasse. Based on the result, it is also inferred that the material composition can be influenced on the Flame Spread shape and Flame Spread rate of mixed paper/bagasse.
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thread angle dependency on Flame Spread shape over kenaf polyester combined fabric
Microelectronics Systems Education, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Nor Anuar Mohamad, Normayati Nordin, Azmahani Sadikin, Mohd Faisal Hushim, Norrizam Jaat, Amir KhalidAbstract:Understanding Flame Spread behavior is crucial to Fire Safety Engineering. It is noted that the natural fiber exhibits different Flame Spread behavior than the one of the synthetic fiber. This different may influences the Flame Spread behavior over combined fabric. There is a research has been done to examined the Flame Spread behavior over kenaf/polyester fabric. It is seen that the Flame Spread shape is dependent on the thread angle dependency. However, the explanation of this phenomenon is not described in detail in that research. In this study, explanation about this phenomenon is given in detail. Results show that the Flame Spread shape is dependent on the position of synthetic thread. For thread angle, θ = 0°, the polyester thread is breaking when the Flame approach to the thread and the kenaf thread tends to move to the breaking direction. This behavior produces Flame to be 'V' shape. However, for thread angle, θ = 90°, the polyester thread melts while the kenaf thread decomposed and burned. At this angle, the distance between kenaf threads remains constant as Flame approaches.
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Flame Spread behavior over combined fabric of cotton/polyester
2015Co-Authors: Mohd Azahari Razali, Azwan Sapit, Mohd Faisal Hushim, Amir Khalid, Suzuki Masataro, Masuda WataruAbstract:Experiment has been conducted to study the Flame Spread behavior over combined fabric of cotton/polyester. Samples are ignited from the top edge and Spread to the downward direction. Experiment is conducted for several weft trade angles from 0° to 90°. It is found that a significant difference is seen in the shape of burning front between θ = 0° and θ = 90°. This phenomenon is influenced by the shrinking behavior of polyester thread at most preceding point of Flame front for these angles. The Flame Spread rate is measured, which is obtained from the position of the most preceding point of the burning front at each time, at different weft thread angle. The result shows that the Flame Spread rate decreases as the angle increases.
Kuang-chung Tsai - One of the best experts on this subject based on the ideXlab platform.
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Using cone calorimeter data for the prediction of upward Flame Spread rate
Journal of Thermal Analysis and Calorimetry, 2013Co-Authors: Kuang-chung TsaiAbstract:In a cone calorimeter, the specimen receives uniformly distributed irradiance from the cone heater. Producing a heating environment simulating the heating intensity in real fires, this apparatus consequently is capable of providing information of materials relevant to their fire performance. Several previous upward Flame Spread models utilized the data as input with an assumption of uniformly distributed heat fluxes. Satisfactory Flame Spread rates were predicted. However, the heat flux in the heating region in upward Flame Spread is not uniform. This study introduces an alternative protocol of the cone calorimeter and a sample holder by which the following differences were made, including specimen turned 42° before ignition, lower ignition source before ignition, heater removed after ignition, and specimen moved back to vertical orientation after ignition. The heating environment is more consistent to real wall fire conditions. In addition, the prediction of Flame Spread rate using the alternative test protocol is closer to the measured Flame Spread rate than standard test methods.
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width effect on upward Flame Spread
Fire Safety Journal, 2009Co-Authors: Kuang-chung TsaiAbstract:Abstract One previous experimental study has reported a width effect for upward Flame Spread rate on thermally thin fuels. A similar effect is expected for thermally thick fuels. This study revisited this topic by developing a hypothesis and performing experiments with sidewalls using 18 mm thick, 1000 mm tall PMMA slabs of widths 100, 200, 300, 500 and 700 mm. In the hypothesis, a lateral diffusion throughout the Flame width was proposed to cause thicker Flame along its centerline for wider Flames and enhance combustion efficiency. Higher heat release rate per unit width, larger Flame height, higher Flame temperature and more heat feedback to the surface were consequently present. The corresponding Flame Spread rate was also increased and a power value of 0.35 existed between the Flame Spread rate and width in this study. All the experimental results clearly supported the hypothesis. This study is the first to discuss the width effect on upward turbulent diffusion Flames on thermally thick materials and provide a correlation between the Flame Spread rate and width.
G. W. H. Silcock - One of the best experts on this subject based on the ideXlab platform.
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On the nature, influence and magnitudes of Flame heat transfer during surface Flame Spread
Fire Safety Journal, 2000Co-Authors: M. A. Azhakesan, T. J. Shields, G. W. H. SilcockAbstract:Abstract The basic equation describing steady surface Flame Spread on solid surfaces indicates that the primary characteristics describing surface Flame Spread are Flame heat flux, forward heating length scale and a thermally affected depth of solid material. There is however great variability in the reported estimations of the average Flame heat flux incident over the effective heated length scale, particularly for opposed flow Flame Spread. In addition, there has been little consideration given in the literature as to how Flame heat fluxes derived from different methodologies relate to each other and to the actual processes of surface Flame Spread. This paper addresses these issues with particular regard to opposed flow Flame Spread. It is suggested that the controlling mechanisms of wind aided and opposed flow Flame Spread are similar despite the obvious difference in geometric view factors associated with each mode of Flame Spread. Thus, the attainment of a strong, steady, piloted ignition condition occurring during opposed flow Flame Spread results in transition Flame heat Spreading fluxes that are of similar magnitudes to those which control steady wind aided Flame Spread rates, i.e., 16–33 kW m −2 . It is concluded that the transition ignition and Flame propagation heat fluxes controlling opposed flow Flame Spread encompass a range of 5–70 kW m −2 . The major source of difference between the two generic modes of surface Flame Spread lies in the definition and magnitude of a critical Flame heat influenced length scale, l h which is defined for the case of opposed flow Flame Spread in this paper.
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Combustibility Parameters for Enclosure Lining Materials Obtained During Surface Flame Spread Using a Reduced Scale Ignition and Flame Spread Technique
Fire Technology, 1998Co-Authors: M. A. Azhakesan, T. J. Shields, G. W. H. SilcockAbstract:A reduced scale ignition and Flame Spread technique, RIFT, was implemented in the cone calorimeter system to obtain thermocombustibility properties of enclosure lining materials during Flame Spread over the sample surface. Previously, a thermal model of ignition and opposed flow Flame Spread was used to analyze Flame Spread data obtained using RIFT. Here, a framework is discussed for deducing critical material combustibility parameters from the measured heat release and mass loss rates as the Spreading Flame proceeds to the point of Flame extinction. The nature of the data and analytical framework allows users to deduce Spreading Flame flux from the heat release rate (HRR) and mass loss rate (MLR) data relatively economically and directly. The anomalies highlighted by comparing Flame Spread data in the RIFT system compared to data from the BS 476 Part 7 apparatus indicates that the RIFT system is well-suited for developing and refining models describing ignition, Flame Spread, and mass burning.
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effect of melting behaviour on upward Flame Spread of thermoplastics
Fire and Materials, 1997Co-Authors: Jian Zhang, T. J. Shields, G. W. H. SilcockAbstract:The effect of melting behaviour on upward Flame Spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward Flame Spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and Flame Spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward Flame Spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward Flame Spread models. © 1997 by John Wiley & Sons, Ltd.
Mohd Azahari Razali - One of the best experts on this subject based on the ideXlab platform.
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Flame Spread Behavior over Kenaf Fabric, Polyester Fabric, and Kenaf/Polyester Combined Fabric
Engineering Applications for New Materials and Technologies, 2018Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Azmahani Sadikin, Mohd Faisal Hushim, Norrizam Jaat, Hazahir Bin Peraman, Mirnah SuardiAbstract:Flame Spread behavior is one of the important topics related to fire safety engineering. It is essential to examine factors, which influence the Flame Spread behavior over fabrics. It is known that natural fibers exhibit a different Flame Spread behavior than the one of synthetic fibers. This difference may influence the Flame Spread behavior over combined fabrics. The purpose of this research is to study the effect of materials on the Flame Spread behavior over kenaf/polyester fabrics. Before analyzing this effect, it is important also to know the Flame Spread behavior over 100% kenaf fabric and 100% polyester fabric. Thus, several experiments have been conducted for different materials of fabric made up of 100% kenaf, 100% polyester, and combined fabric of kenaf/polyester. For the combined fabric, experiments have been done for different weft thread angle of θ = 0° and θ = 90°. A burner is used for igniting the fabric at a point on its top edge. The data collected is recorded via videos and captured images for measuring the Flame Spread rate and detail observation of characteristics during the burning process. From the results obtained, it is seen that the material and thread angle influence on the Flame Spread behavior over fabrics. The Flame Spread rate on kenaf is lower than the Flame Spread rate on combined fabrics of kenaf/polyester while the Flame Spread rate on polyester is undetermined. The Flame Spread velocity also changes when the weft thread angle change from θ = 0° to θ = 90°.
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Flame Spread Behaviour over Combustible Solid of Paper, Bagasse and Paper/Bagasse
MATEC Web of Conferences, 2017Co-Authors: Afifah Ramli, Mohd Azahari Razali, Azwan Sapit, Normayati Nordin, Mohd Faisal Hushim, Amir Khalid, Nor Anuar MohammadAbstract:Flame Spread over combustible solid must be precisely identify in fire hazard and this is the basic problem in fire safety engineering field. To explore the Flame Spread mechanism over combustible solid, the downward Flame Spread behaviour over paper and bagasse has been investigated in this experiment. It found that the combustion pattern for paper was slightly different from the bagasse on the front view and this was analysed through the observation. The result also showed that the Flame Spread rate for paper is higher compared to the Flame Spread rate for bagasse. It seem that, although bagasse is the combustible solid the rate of Flame Spread is lower and the usage of bagasse can help to control the Flame Spread.
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Thread angle dependency on Flame Spread shape over kenaf/polyester combined fabric
IOP Conference Series: Materials Science and Engineering, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Nor Anuar Mohamad, Normayati Nordin, Azmahani Sadikin, Mohd Faisal Hushim, Norrizam Jaat, Amir KhalidAbstract:Understanding Flame Spread behavior is crucial to Fire Safety Engineering. It is noted that the natural fiber exhibits different Flame Spread behavior than the one of the synthetic fiber. This different may influences the Flame Spread behavior over combined fabric. There is a research has been done to examined the Flame Spread behavior over kenaf/polyester fabric. It is seen that the Flame Spread shape is dependent on the thread angle dependency. However, the explanation of this phenomenon is not described in detail in that research. In this study, explanation about this phenomenon is given in detail. Results show that the Flame Spread shape is dependent on the position of synthetic thread. For thread angle, θ = 0°, the polyester thread is breaking when the Flame approach to the thread and the kenaf thread tends to move to the breaking direction. This behavior produces Flame to be 'V' shape. However, for thread angle, θ = 90°, the polyester thread melts while the kenaf thread decomposed and burned. At this angle, the distance between kenaf threads remains constant as Flame approaches.
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Flame Spread behavior over combustible thick solid of paper, bagasse and mixed paper/bagasse
IOP Conference Series: Materials Science and Engineering, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Mohd Faisal Hushim, Norrizam Jaat, Sofian Mohd, Ahmad Husaini Ismail, Amir KhalidAbstract:Flame Spread behavior on combustible solid is one of important research related to Fire Safety Engineering. Now, there are a lot of combustible solid composed from mixed materials. In this study, experiments have been conducted to investigate Flame Spread behavior over combustible solid composed by paper, bagasse and mixed paper/bagasse. Experimental data is captured by using video recording and examined Flame Spread shape and rate. From the results obtained, shows that the different materials produce different Flame Spread shape and rate. Different Flame shape is seen between all types of samples. Flame Spread rate of 100% paper is faster than the one of 100% bagasse. Based on the result, it is also inferred that the material composition can be influenced on the Flame Spread shape and Flame Spread rate of mixed paper/bagasse.
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thread angle dependency on Flame Spread shape over kenaf polyester combined fabric
Microelectronics Systems Education, 2017Co-Authors: Mohd Azahari Razali, Azwan Sapit, Akmal Nizam Mohammed, Nor Anuar Mohamad, Normayati Nordin, Azmahani Sadikin, Mohd Faisal Hushim, Norrizam Jaat, Amir KhalidAbstract:Understanding Flame Spread behavior is crucial to Fire Safety Engineering. It is noted that the natural fiber exhibits different Flame Spread behavior than the one of the synthetic fiber. This different may influences the Flame Spread behavior over combined fabric. There is a research has been done to examined the Flame Spread behavior over kenaf/polyester fabric. It is seen that the Flame Spread shape is dependent on the thread angle dependency. However, the explanation of this phenomenon is not described in detail in that research. In this study, explanation about this phenomenon is given in detail. Results show that the Flame Spread shape is dependent on the position of synthetic thread. For thread angle, θ = 0°, the polyester thread is breaking when the Flame approach to the thread and the kenaf thread tends to move to the breaking direction. This behavior produces Flame to be 'V' shape. However, for thread angle, θ = 90°, the polyester thread melts while the kenaf thread decomposed and burned. At this angle, the distance between kenaf threads remains constant as Flame approaches.