The Proceedings of 11th Asia-Oceania Symposium on Fire Science and Technology
Backdraught is an unpredictable and dangerous fire phenomenon, particularly for firefighters duri... more Backdraught is an unpredictable and dangerous fire phenomenon, particularly for firefighters during search, rescue and firefighting activities. Most previous research into backdraught has used methane as fuel, leaving many questions unanswered. A series of reduced-scale backdraught experiments have been carried out using solid polypropylene as a fuel source, and conclusions have been drawn correlating the compartment temperatures to the onset of backdraught. It is found that when the maximum temperature in the compartment is above 350 °C when the door is opened, a backdraught can occur by auto-ignition, and no ignition source is required. However, no correlations could be identified with temperatures near the door or near the floor. It was also found that there is a correlation between compartment temperature and backdraught delay time, with cooler compartment temperatures leading to longer delays.
Three major fire incidents have occurred in the Channel Tunnel since it opened in the early 90s. ... more Three major fire incidents have occurred in the Channel Tunnel since it opened in the early 90s. The fires on the 18 th of November 1996 and the 11 th of September 2008 grew to involve many heavy goods vehicles (HGV) on carrier wagons and caused major damage to the tunnel structure. The fire on the 21 st of August 2006 involved only a single HGV and did not spread, although the adjacent HGV was damaged by heat. Each of these incidents is described and the incidents are compared. The official inquiry into the 2008 fire has not yet been published, so information has been collected from press reports. It is clear that the fire development in 1996 and 2008 was broadly similar, while the fire in 2006 was very different. These differences may be due to the cargo and construction of the vehicles involved, but also may be due to the differences in ventilation during the incidents. The conventional model of fire dynamics in multiple vehicle fires is discussed with reference to the Channel Tu...
Most fire experiments carried out in tunnels to date have focussed on the burning behaviour and s... more Most fire experiments carried out in tunnels to date have focussed on the burning behaviour and smoke production of liquid pool fires and vehicle fires. Other combustible surfaces, commonly found in tunnels, have not been considered in detail. This paper presents the preliminary findings of a research project into the fire behaviour of asphalt road surfaces. Small samples of asphalt material have been studied using a cone calorimeter. Factors such as the critical heat flux for ignition and the heat release rate of these samples have been identified. These factors are discussed in relation to tunnel fires.
This article presents a review of recent research about fires in tunnels, and some concerns raise... more This article presents a review of recent research about fires in tunnels, and some concerns raised by commercially driven fire tests. The deaths of 39 people in the Mount Blanc tunnel in a 1999 fire have spurred more interest in fire safety for tunnels and ways to test it. Fire testing is relatively new, with the first proper one carried out as recently as 1965. The Swedish National Testing and Research Institute is carrying out tests at lab scale, partial scale and full scale. Many elements remain unknown, including how fire spreads from vehicle to vehicle; how car fires respond to changes in ventilation and how tunnel linings can add to the severity of the heat. The author warns that thinking a structure is fireproof is dangerous, as shown by the deaths of 155 people in November 2000 when a "fireproof" train burned in the Austrian Alps.
The durability of various typical tunnel sections in the event of a prescribed 100 MW fire has be... more The durability of various typical tunnel sections in the event of a prescribed 100 MW fire has been assessed. Cast-iron sections, pre-cast concrete sections and in-situ concrete cut and cover sections are all considered to be part of a 1 km long road tunnel. An analysis of the tunnel constructions and surrounding geology (based on a real tunnel) has led to the estimation of failure temperatures for the structural elements, internal cladding systems, jet fans and their fixings. A commercial computational fluid dynamics (CFD) code was used to simulate various fire scenarios and calculate the times to failure of tunnel elements. Simulations were carried out for fires in different locations for the three section types. In parallel to the CFD study, an analytical model was devised to predict gas temperatures in the tunnel. Both models used the same input variables and general assumptions and great attention was given to establish the highest possible accuracy for all input variables and ...
This paper presents a novel and fast modelling approach to simulate tunnel ventilation flows duri... more This paper presents a novel and fast modelling approach to simulate tunnel ventilation flows during fire emergencies. The complexity and high cost of full CFD models and the inaccuracies of simplistic zone or analytical models are avoided by efficiently combining mono-dimensional (1D) and CFD (3D) modelling techniques. A simple 1D network approach is used to model tunnel regions where the flow is fully developed (far field), and a detailed CFD representation is used where flow conditions require 3D resolution (near field). This multi-scale method has previously been applied to simulate tunnel ventilation systems including jet fans, vertical shafts and portals (Colella et al 2009, Build. Environ. 44(12): 23572367) and it is applied here to include the effect of fire both in steady state and transient situations. The methodology has been applied to a modern tunnel of 7 m diameter section and 1.2 km in length. Different fire scenarios ranging from 10 MW to 100 MW are investigated with ...
Two important tunnel safety technologies are addressed. The majority of long road tunnels have ve... more Two important tunnel safety technologies are addressed. The majority of long road tunnels have ventilation systems. In the event of a fire in a tunnel, such systems will influence fire development in a number of different ways. Recent research and observations on these influences are presented. The effects discussed are critical ventilation velocity for smoke control and the influence of ventilation on fire size, fire spread and fire growth. There is no well defined ‘best’ approach to operate tunnel ventilation in a fire emergency. Another technology of growing importance is sprinklers and water mist systems, which are being installed in an increasing number of tunnels. There are some concerns regarding the integration of ventilation and suppression systems, these are discussed. Of particular concern is the interaction between water mist droplets and ventilation flow which may result in the suppression agent being carried long distances downstream, away from the fire. Ventilation an...
This presentation looks at combustion emissions from a smoldering coal heap in north lanarkshire ... more This presentation looks at combustion emissions from a smoldering coal heap in north lanarkshire scotland
The Clyde Tunnel in Glasgow, Scotland, is currently undergoing refurbishment. This refurbishment ... more The Clyde Tunnel in Glasgow, Scotland, is currently undergoing refurbishment. This refurbishment includes the installation of a new tunnel lining / fire protection system in both tunnel tubes. This lining system has already been shown to protect the tunnel structure from high temperatures However, there is a gap at the lower edge of the lining to allow any water accumulated behind the lining to run into a drainage channel within the main tunnel void. There were concerns that this small gap might lead to the exposure of the structural members to very high temperatures in the event of a fire in the tunnel. A heat transfer analysis was carried out. This analysis consisted of the evaluation of the thermal field inside the tunnel using Computational Fluid Dynamics (CFD) computations. This identified the locations in the tunnel which were most likely to be at risk, and predicted the conditions at those locations in the event of a ‘worst case’ fire scenario. On the basis of this informatio...
Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities,... more Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities, occasionally leading to fire-fighter fatalities. Real backdraft incidents involve complex fuel gas mixtures consisting of the products of underventilated burning and pyrolysis following burnout. However, most experimental research into backdraft has used methane gas or flammable liquids as fuel. Some aspects of real backdraft behavior may have been overlooked as a consequence of this simplicity. A reduced scale series of compartment fire tests have been carried out to investigate the critical factors governing the onset of backdraft, using polypropylene and high density polyethylene samples as fuel. It is established that there are critical temperatures for auto-ignition of the pyrolysis gases leading to backdraft which vary with fuel properties. For polypropylene the highest temperature in the compartment must be above 350°C for auto-ignition of the fuel gases, while mixtures in the pr...
Abstract In this paper, the effects of geometric skewness and abutment restraint on the fire resi... more Abstract In this paper, the effects of geometric skewness and abutment restraint on the fire resistance of a real highway bridge have been studied. Four finite element models have been investigated using rectangular and skew shapes with and without modelling the abutment. The investigation has been carried out in three steps: 1) heat transfer analysis under a specified hydrocarbon fire; 2) simulation of the thermo-mechanical response of the bridge superstructure over the entire duration of the fire using beam and shell elements to represent the structural components; 3) detailed processing and interpretation of the simulation results to understand and illustrate the global response of the structure by comparing all the models. Results indicate that a skew bridge may possess greater inherent resistance to fire. For the two-span highway bridge model, restraint from the abutment does not affect the estimated failure time significantly.
Non-prescriptive design within fire engineering is becoming more prevalent as buildings get talle... more Non-prescriptive design within fire engineering is becoming more prevalent as buildings get taller and more complex. This necessitates the increased use of reliable deterministic pre dictions; typically computational fluid dynamics-based models. Driven by time constraints, modellers are required to limit the domain to reduce wall time. This ignores the two-way coupling of a fire and a total building system. A neglection which could embody risk to life. One way to address this risk is the use of coupled hybrid modelling to expand the domain; explicitly quantifying risk-related quantities in the far field whilst maintaining practicable wall times. Fire Dynamics Simulator (FDS) version 5.5 opened the door to coupled hybrid modelling within FDS and introduced the HVAC network submode!. Until FDS version 6.5.3 the submodel did not account for transient transport or mass storage. In this work a new transient transport and mass storage subroutine has been introduced into HVAC which is available in FDS version 6.5.3 onwards. The relevant conservation equations and numerical solution are described. Successful verification cases are presented for various arrangements to test the implementation of the solution scheme. To demonstrate the benefits of the new method, a fire engineering test case is presented. The test case illustrates the potential risks contained within the pre-existing coupled hybrid modelling method. These risks in clude unrealistic predictions of hot layer height and head height temperatures and visibility. The test case demonstrates that the new coupled hybrid modelling method address these shortcomings and could form part of a most robust fire safety engineering solution. Based on experimental benchmarking exercises, recommended model bias factors are put forward. The new model implementation can be used by designers to quantitatively examine the fire hazard embodied within the two-way coupling of a fire and a total building system.
The heat release rate (HRR) of a fire in a tunnel is a crucial factor, both in terms of fire spre... more The heat release rate (HRR) of a fire in a tunnel is a crucial factor, both in terms of fire spread and smoke production. Key factors which influence the HRR are: {1} the nature of the burning item, {2} the tunnel geometry, {3} the ventilation conditions and {4} vehicle separation. This paper reports on work which has been undertaken over a number of years to model the dependence of HRR on these factors; the work is continuing. Specifically, Bayesian probabilistic models have been devised to model the dependence of the HRR of a fire on tunnel geometry and longitudinal forced ventilation and deterministic models have been devised to model fire spread from one item to another in a tunnel similar to the Channel Tunnel; again with longitudinal ventilation. Key interim results are presented.
Ambient density of air (kg/m 2) ∆ @ Heat of combustion of the fuel (kJ/mol or kJ/g) ∆ @3 Temperat... more Ambient density of air (kg/m 2) ∆ @ Heat of combustion of the fuel (kJ/mol or kJ/g) ∆ @3 Temperature difference due to stratification (K) ∆ Local gas temperature rise (K) ∆ %&' Average gas temperature rise (K) Subscripts F Full scale M Model scale
Systems in the built environment are getting bigger and more complex. Fire safety engineers are r... more Systems in the built environment are getting bigger and more complex. Fire safety engineers are required to analyse these structures to ensure acceptable levels of safety. Computational limitations mean that the calculation domain must be curtailed. This ignores the two-way coupling between the total system and a fire. Coupled hybrid modelling (coupling of fire dynamics sub-models with a range of computational costs) expands the domain and analyses this two-way coupling within a reasonable timeframe. This article presents a literature review of this modelling paradigm and has application for those investigating and expanding the method. Over the last quarter of a century, researchers have investigated coupled hybrid modelling but work has been in disconnected streams. There has been no review of coupled hybrid modelling for fire safety engineering. It is unclear where the knowledge gaps are and where future work should be focused. This review demonstrates that the method is numerically feasible and can reduce wall clock time for total system analysis. This review reveals that there is limited validation and a host of unresolved questions (including sub-model choice, interface modelling, domain decomposition and coupling method). This review draws attention to the lack of collaboration which has led to obsolete models and parallel working. This article shows that coupled hybrid modelling has potential but effort is being squandered. This review is a stepping-stone towards a standardised coupled hybrid framework. This review highlights where future collaborative research should be directed.
This paper investigates the length of flame extension for an impinging flame underneath the confi... more This paper investigates the length of flame extension for an impinging flame underneath the confined ceiling in a channel with longitudinal air flow. Previous works in this field have been primarily concerned with un-confined ceilings and no forced air flow conditions. Under longitudinal air flow conditions, the flame extension beneath the channel ceiling is non-symmetrical, that is, different in the upstream and downstream directions from the fire source. In this study, experiments were carried out with two channeled ceilings with widths of 1.5 m and 0.5 m. Square porous gas burners of different sizes were employed as the fire source, using propane as fuel, with various heat release rates and source-ceiling heights. The flame extension lengths beneath the ceiling, both upstream and downstream from the fire source, were measured. Their difference as well as their total length was quantified for different magnitudes of forced longitudinal air flow along the channel. Results show that the flame extension lengths beneath the ceiling increases with heat release rate, but decreases with source-ceiling height, channel width, burner size or longitudinal air flow speed. With a longitudinal air flow, the flame extension is longer downstream than upstream. Non-dimensional correlations are proposed for the flame extension lengths (upstream, downstream and their total length), based on the unburnt fuel distribution upstream and downstream, as well as considering air entrainment of the ceiling flow, which further consumes the unburnt fuel along the ceiling. These correlations are shown to fit the data well.
The University of Edinburgh and its alumni have made significant contributions to knowledge in th... more The University of Edinburgh and its alumni have made significant contributions to knowledge in the field of tunnel fire safety engineering. This paper summarises the situation of tunnel fire safety in the early 1970s, when the department of fire engineering was founded and briefly discusses all the contributions to knowledge in the field, made by Edinburgh and its alumni in the past four decades. Research carried out at Edinburgh has changed the way the tunnel safety industry estimates heat release rates in tunnels, has influenced way design fires are specified and has challenged industry opinion about the use of water sprays in tunnels. This paper is part of a celebration of four decades of fire research at Edinburgh.
The Proceedings of 11th Asia-Oceania Symposium on Fire Science and Technology
Backdraught is an unpredictable and dangerous fire phenomenon, particularly for firefighters duri... more Backdraught is an unpredictable and dangerous fire phenomenon, particularly for firefighters during search, rescue and firefighting activities. Most previous research into backdraught has used methane as fuel, leaving many questions unanswered. A series of reduced-scale backdraught experiments have been carried out using solid polypropylene as a fuel source, and conclusions have been drawn correlating the compartment temperatures to the onset of backdraught. It is found that when the maximum temperature in the compartment is above 350 °C when the door is opened, a backdraught can occur by auto-ignition, and no ignition source is required. However, no correlations could be identified with temperatures near the door or near the floor. It was also found that there is a correlation between compartment temperature and backdraught delay time, with cooler compartment temperatures leading to longer delays.
Three major fire incidents have occurred in the Channel Tunnel since it opened in the early 90s. ... more Three major fire incidents have occurred in the Channel Tunnel since it opened in the early 90s. The fires on the 18 th of November 1996 and the 11 th of September 2008 grew to involve many heavy goods vehicles (HGV) on carrier wagons and caused major damage to the tunnel structure. The fire on the 21 st of August 2006 involved only a single HGV and did not spread, although the adjacent HGV was damaged by heat. Each of these incidents is described and the incidents are compared. The official inquiry into the 2008 fire has not yet been published, so information has been collected from press reports. It is clear that the fire development in 1996 and 2008 was broadly similar, while the fire in 2006 was very different. These differences may be due to the cargo and construction of the vehicles involved, but also may be due to the differences in ventilation during the incidents. The conventional model of fire dynamics in multiple vehicle fires is discussed with reference to the Channel Tu...
Most fire experiments carried out in tunnels to date have focussed on the burning behaviour and s... more Most fire experiments carried out in tunnels to date have focussed on the burning behaviour and smoke production of liquid pool fires and vehicle fires. Other combustible surfaces, commonly found in tunnels, have not been considered in detail. This paper presents the preliminary findings of a research project into the fire behaviour of asphalt road surfaces. Small samples of asphalt material have been studied using a cone calorimeter. Factors such as the critical heat flux for ignition and the heat release rate of these samples have been identified. These factors are discussed in relation to tunnel fires.
This article presents a review of recent research about fires in tunnels, and some concerns raise... more This article presents a review of recent research about fires in tunnels, and some concerns raised by commercially driven fire tests. The deaths of 39 people in the Mount Blanc tunnel in a 1999 fire have spurred more interest in fire safety for tunnels and ways to test it. Fire testing is relatively new, with the first proper one carried out as recently as 1965. The Swedish National Testing and Research Institute is carrying out tests at lab scale, partial scale and full scale. Many elements remain unknown, including how fire spreads from vehicle to vehicle; how car fires respond to changes in ventilation and how tunnel linings can add to the severity of the heat. The author warns that thinking a structure is fireproof is dangerous, as shown by the deaths of 155 people in November 2000 when a "fireproof" train burned in the Austrian Alps.
The durability of various typical tunnel sections in the event of a prescribed 100 MW fire has be... more The durability of various typical tunnel sections in the event of a prescribed 100 MW fire has been assessed. Cast-iron sections, pre-cast concrete sections and in-situ concrete cut and cover sections are all considered to be part of a 1 km long road tunnel. An analysis of the tunnel constructions and surrounding geology (based on a real tunnel) has led to the estimation of failure temperatures for the structural elements, internal cladding systems, jet fans and their fixings. A commercial computational fluid dynamics (CFD) code was used to simulate various fire scenarios and calculate the times to failure of tunnel elements. Simulations were carried out for fires in different locations for the three section types. In parallel to the CFD study, an analytical model was devised to predict gas temperatures in the tunnel. Both models used the same input variables and general assumptions and great attention was given to establish the highest possible accuracy for all input variables and ...
This paper presents a novel and fast modelling approach to simulate tunnel ventilation flows duri... more This paper presents a novel and fast modelling approach to simulate tunnel ventilation flows during fire emergencies. The complexity and high cost of full CFD models and the inaccuracies of simplistic zone or analytical models are avoided by efficiently combining mono-dimensional (1D) and CFD (3D) modelling techniques. A simple 1D network approach is used to model tunnel regions where the flow is fully developed (far field), and a detailed CFD representation is used where flow conditions require 3D resolution (near field). This multi-scale method has previously been applied to simulate tunnel ventilation systems including jet fans, vertical shafts and portals (Colella et al 2009, Build. Environ. 44(12): 23572367) and it is applied here to include the effect of fire both in steady state and transient situations. The methodology has been applied to a modern tunnel of 7 m diameter section and 1.2 km in length. Different fire scenarios ranging from 10 MW to 100 MW are investigated with ...
Two important tunnel safety technologies are addressed. The majority of long road tunnels have ve... more Two important tunnel safety technologies are addressed. The majority of long road tunnels have ventilation systems. In the event of a fire in a tunnel, such systems will influence fire development in a number of different ways. Recent research and observations on these influences are presented. The effects discussed are critical ventilation velocity for smoke control and the influence of ventilation on fire size, fire spread and fire growth. There is no well defined ‘best’ approach to operate tunnel ventilation in a fire emergency. Another technology of growing importance is sprinklers and water mist systems, which are being installed in an increasing number of tunnels. There are some concerns regarding the integration of ventilation and suppression systems, these are discussed. Of particular concern is the interaction between water mist droplets and ventilation flow which may result in the suppression agent being carried long distances downstream, away from the fire. Ventilation an...
This presentation looks at combustion emissions from a smoldering coal heap in north lanarkshire ... more This presentation looks at combustion emissions from a smoldering coal heap in north lanarkshire scotland
The Clyde Tunnel in Glasgow, Scotland, is currently undergoing refurbishment. This refurbishment ... more The Clyde Tunnel in Glasgow, Scotland, is currently undergoing refurbishment. This refurbishment includes the installation of a new tunnel lining / fire protection system in both tunnel tubes. This lining system has already been shown to protect the tunnel structure from high temperatures However, there is a gap at the lower edge of the lining to allow any water accumulated behind the lining to run into a drainage channel within the main tunnel void. There were concerns that this small gap might lead to the exposure of the structural members to very high temperatures in the event of a fire in the tunnel. A heat transfer analysis was carried out. This analysis consisted of the evaluation of the thermal field inside the tunnel using Computational Fluid Dynamics (CFD) computations. This identified the locations in the tunnel which were most likely to be at risk, and predicted the conditions at those locations in the event of a ‘worst case’ fire scenario. On the basis of this informatio...
Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities,... more Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities, occasionally leading to fire-fighter fatalities. Real backdraft incidents involve complex fuel gas mixtures consisting of the products of underventilated burning and pyrolysis following burnout. However, most experimental research into backdraft has used methane gas or flammable liquids as fuel. Some aspects of real backdraft behavior may have been overlooked as a consequence of this simplicity. A reduced scale series of compartment fire tests have been carried out to investigate the critical factors governing the onset of backdraft, using polypropylene and high density polyethylene samples as fuel. It is established that there are critical temperatures for auto-ignition of the pyrolysis gases leading to backdraft which vary with fuel properties. For polypropylene the highest temperature in the compartment must be above 350°C for auto-ignition of the fuel gases, while mixtures in the pr...
Abstract In this paper, the effects of geometric skewness and abutment restraint on the fire resi... more Abstract In this paper, the effects of geometric skewness and abutment restraint on the fire resistance of a real highway bridge have been studied. Four finite element models have been investigated using rectangular and skew shapes with and without modelling the abutment. The investigation has been carried out in three steps: 1) heat transfer analysis under a specified hydrocarbon fire; 2) simulation of the thermo-mechanical response of the bridge superstructure over the entire duration of the fire using beam and shell elements to represent the structural components; 3) detailed processing and interpretation of the simulation results to understand and illustrate the global response of the structure by comparing all the models. Results indicate that a skew bridge may possess greater inherent resistance to fire. For the two-span highway bridge model, restraint from the abutment does not affect the estimated failure time significantly.
Non-prescriptive design within fire engineering is becoming more prevalent as buildings get talle... more Non-prescriptive design within fire engineering is becoming more prevalent as buildings get taller and more complex. This necessitates the increased use of reliable deterministic pre dictions; typically computational fluid dynamics-based models. Driven by time constraints, modellers are required to limit the domain to reduce wall time. This ignores the two-way coupling of a fire and a total building system. A neglection which could embody risk to life. One way to address this risk is the use of coupled hybrid modelling to expand the domain; explicitly quantifying risk-related quantities in the far field whilst maintaining practicable wall times. Fire Dynamics Simulator (FDS) version 5.5 opened the door to coupled hybrid modelling within FDS and introduced the HVAC network submode!. Until FDS version 6.5.3 the submodel did not account for transient transport or mass storage. In this work a new transient transport and mass storage subroutine has been introduced into HVAC which is available in FDS version 6.5.3 onwards. The relevant conservation equations and numerical solution are described. Successful verification cases are presented for various arrangements to test the implementation of the solution scheme. To demonstrate the benefits of the new method, a fire engineering test case is presented. The test case illustrates the potential risks contained within the pre-existing coupled hybrid modelling method. These risks in clude unrealistic predictions of hot layer height and head height temperatures and visibility. The test case demonstrates that the new coupled hybrid modelling method address these shortcomings and could form part of a most robust fire safety engineering solution. Based on experimental benchmarking exercises, recommended model bias factors are put forward. The new model implementation can be used by designers to quantitatively examine the fire hazard embodied within the two-way coupling of a fire and a total building system.
The heat release rate (HRR) of a fire in a tunnel is a crucial factor, both in terms of fire spre... more The heat release rate (HRR) of a fire in a tunnel is a crucial factor, both in terms of fire spread and smoke production. Key factors which influence the HRR are: {1} the nature of the burning item, {2} the tunnel geometry, {3} the ventilation conditions and {4} vehicle separation. This paper reports on work which has been undertaken over a number of years to model the dependence of HRR on these factors; the work is continuing. Specifically, Bayesian probabilistic models have been devised to model the dependence of the HRR of a fire on tunnel geometry and longitudinal forced ventilation and deterministic models have been devised to model fire spread from one item to another in a tunnel similar to the Channel Tunnel; again with longitudinal ventilation. Key interim results are presented.
Ambient density of air (kg/m 2) ∆ @ Heat of combustion of the fuel (kJ/mol or kJ/g) ∆ @3 Temperat... more Ambient density of air (kg/m 2) ∆ @ Heat of combustion of the fuel (kJ/mol or kJ/g) ∆ @3 Temperature difference due to stratification (K) ∆ Local gas temperature rise (K) ∆ %&' Average gas temperature rise (K) Subscripts F Full scale M Model scale
Systems in the built environment are getting bigger and more complex. Fire safety engineers are r... more Systems in the built environment are getting bigger and more complex. Fire safety engineers are required to analyse these structures to ensure acceptable levels of safety. Computational limitations mean that the calculation domain must be curtailed. This ignores the two-way coupling between the total system and a fire. Coupled hybrid modelling (coupling of fire dynamics sub-models with a range of computational costs) expands the domain and analyses this two-way coupling within a reasonable timeframe. This article presents a literature review of this modelling paradigm and has application for those investigating and expanding the method. Over the last quarter of a century, researchers have investigated coupled hybrid modelling but work has been in disconnected streams. There has been no review of coupled hybrid modelling for fire safety engineering. It is unclear where the knowledge gaps are and where future work should be focused. This review demonstrates that the method is numerically feasible and can reduce wall clock time for total system analysis. This review reveals that there is limited validation and a host of unresolved questions (including sub-model choice, interface modelling, domain decomposition and coupling method). This review draws attention to the lack of collaboration which has led to obsolete models and parallel working. This article shows that coupled hybrid modelling has potential but effort is being squandered. This review is a stepping-stone towards a standardised coupled hybrid framework. This review highlights where future collaborative research should be directed.
This paper investigates the length of flame extension for an impinging flame underneath the confi... more This paper investigates the length of flame extension for an impinging flame underneath the confined ceiling in a channel with longitudinal air flow. Previous works in this field have been primarily concerned with un-confined ceilings and no forced air flow conditions. Under longitudinal air flow conditions, the flame extension beneath the channel ceiling is non-symmetrical, that is, different in the upstream and downstream directions from the fire source. In this study, experiments were carried out with two channeled ceilings with widths of 1.5 m and 0.5 m. Square porous gas burners of different sizes were employed as the fire source, using propane as fuel, with various heat release rates and source-ceiling heights. The flame extension lengths beneath the ceiling, both upstream and downstream from the fire source, were measured. Their difference as well as their total length was quantified for different magnitudes of forced longitudinal air flow along the channel. Results show that the flame extension lengths beneath the ceiling increases with heat release rate, but decreases with source-ceiling height, channel width, burner size or longitudinal air flow speed. With a longitudinal air flow, the flame extension is longer downstream than upstream. Non-dimensional correlations are proposed for the flame extension lengths (upstream, downstream and their total length), based on the unburnt fuel distribution upstream and downstream, as well as considering air entrainment of the ceiling flow, which further consumes the unburnt fuel along the ceiling. These correlations are shown to fit the data well.
The University of Edinburgh and its alumni have made significant contributions to knowledge in th... more The University of Edinburgh and its alumni have made significant contributions to knowledge in the field of tunnel fire safety engineering. This paper summarises the situation of tunnel fire safety in the early 1970s, when the department of fire engineering was founded and briefly discusses all the contributions to knowledge in the field, made by Edinburgh and its alumni in the past four decades. Research carried out at Edinburgh has changed the way the tunnel safety industry estimates heat release rates in tunnels, has influenced way design fires are specified and has challenged industry opinion about the use of water sprays in tunnels. This paper is part of a celebration of four decades of fire research at Edinburgh.
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Papers by Ricky Carvel