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Originally published July 16, 2011
From the time he was a graduate student, George Hadjisophocleous’s academic career has been consumed by fire.
The Carleton University professor directs research at one the most unusual laboratories in the country: a $10-million, 10-storey facility where he investigates the behaviour of fire in homes, office buildings, subway cars and tunnels.
He explores how flame and smoke interact with today’s increasingly complex structures in search of better designs and fire defences.
His work involves fluid mechanics, heat transfer, thermodynamics, civil engineering and computer modelling. Even crowd psychology plays a part since fire engineers must consider how people will react in an emergency.
“That’s what makes it so challenging,” says Hadjisophocleous, 55, who holds a prestigious national research chair in fire safety engineering. “There are so many parameters that come into play, but once you know those parameters, you can make predictions about afire and how it will move.”
Fire has been the subject of his professional curiosity for 30 years. And although an essentially logical creature – fire is, after all, governed by physics – its behaviour continues to fascinate Hadjisophocleous, sometimes even frighten him.
“Everyone experiences fire,” he says. “Everyone knows a controlled fire in their fireplace or in a campground. But when it’s an uncontrolled fire, it’s a very scary situation.
“I think most people don’t realize how quickly things can turn the wrong way in a fire.”
Hadjisophocleous has seen it happen – right in his lab.
–
Carleton’s fire research lab is located one hour from the main university campus, on rolling farmland outside Mississippi Mills. The site looks like a small factory: there’s an assortment of concrete buildings, a few trailers and container bins. A crane, with its arm fully extended, stands mysteriously in the lot. Inside, however, the purpose of it all becomes readily apparent: the air is bitter with soot.
Carleton researchers have been setting fires in the laboratory for the past four years. The lab includes a fully instrumented tunnel in which Hadjisophocleous can simulate subway fires. There’s also a 10-storey atrium – researchers use it to investigate the behaviour of smoke in highrise buildings – and a “burn hall” large enough to contain a framed house.
Today, master’s student Devin Glennie, 25, is at work preparing the next conflagration in the cavernous lab.
Glennie has built a metal room with two open windows. He intends to set it alight in order to test the transfer of heat to a nearby “target” wall, and compare results to 12 similar experiments in which he used other window configurations.
Windows affect the amount of oxygen that goes into a room – a critical factor in governing the size of a fire. These experiments will help him understand the conditions under which fire can spread to a neighbouring home.
Glennie uses a long, thin torch to set his purpose-built room on fire: arson in the name of science.
The room, lined with fire-resistant ceramic insulation, has propane burners on the floor calibrated to simulate real fires by producing heavy black smoke. (Smoke is the product of poor combustion as soot particles – bits of unburned carbon – are carried away in hot gases.)
Smoke vents out the top of the atrium through an exhaust chamber that measures oxygen and carbon dioxide levels. Researchers can deduce the intensity of a fire by calculating how much oxygen has been taken from each cubic metre of smoke in the combustion process.
Sensors record temperatures inside the room and on the neighbouring wall, where the transfer of heat onto a given surface (heat flux) is also measured. Nearby computer screens give the researchers realtime data.
Within 10 minutes, flames are boiling inside the room and curling outside the two windows. The room temperature climbs to 700 C, well beyond the “flashover” point at which any combustible material in the room would have ignited. The temperature peaks at 900 C when the fire is fully developed.
By the time the half-hour experiment is over, the lab is uncomfortably smoky.
Glennie inspects the room, which is blackened in places and still radiating heat. He declares the experiment an unqualified success: it’s the first time that none of his equipment has melted.
–
Researchers conduct a burn test at the National Research Council fire lab in Mississippi Mills.
Growing up, George Hadjisophocleous possessed a boy’s fascination with fire but also a Cypriot’s respect for its power. “I liked starting fires: I was like any boy,” he says. “But in Cyprus, bushfires are a common thing because we have long, dry summers. I witnessed several of those very close to our town.”
Hadjisophocleous also took a keen interest in car engines since his father was a truck driver. He studied engineering in university then worked as mechanic in the military during his compulsory service. He spent two more years in The Emirates as an air-conditioning engineer before friends convinced him to join them at the University of New Brunswick.
There, he completed graduate degrees in mechanical engineering and rediscovered his passion for fire. For his PhD thesis, he modelled what would happen when a tanker truck containing liquefied natural gas was exposed to flames.
“My initial interest,” he says, “was to model that complex problem which included the flames, the heat transfer to the liquid, to the gas, the evaporation inside the tanker, the pressure buildup. They were very challenging problems.”
His fascination reignited, Hadjisophocleous accepted a job at National Research Council Canada. He spent the next decade developing computer models to assess and manage fire risk.
In March 2001, he moved to Carleton to launch the fire safety engineering program, which now boasts 19 graduate students.
Carleton researchers have studied the effect of fire on gypsum board, support beams, wooden floors, steel and timber columns. They’ve studied smoke movement in high-rises and in atriums – all with a view toward making buildings safer.
They’re about to turn more of their attention to subways. Later this year, Hadjisophocleous expects to take delivery of four used subway cars from the Toronto Transit Commission, which he will use in Carleton’s specially designed tunnel lab.
The 37.5-metre-long lab has a rail track on the floor to accommodate the cars, a sprinkler system, an air sampling system to measure smoke, and a raft of sensors to measure temperature and heat flux.
Subways have been the target of terrorist attacks in Tokyo (1995), Paris (1995) Moscow (2004) and London (2005). They’ve also been the scene of many deadly fires, including a 2003 incident in Daegu, South Korea that killed 198 people.
Most North American subways rely on tunnel ventilation systems, not sprinklers, as their primary safety feature. The ventilation systems are designed to move smoke in one direction, allowing passengers to escape in the other. Some engineers have argued that sprinkler systems will generate steam in a tunnel fire and injure more people than they help.
But Carleton researchers have established that sprinklers should form part of a subway’s fire safety system. Hadjisophocleous and his team have found that ventilation systems are more effective when used in combination with sprinklers. Sprinkers limit the growth of the fire (even inside a subway car), cool the smoke and reduce the amount flowing back “upstream” into the tunnel.
Hadjisophocleous torched his first subway car earlier this year in an experiment commissioned by South Korea in the wake of the Daegu tragedy. In Daegu, an unemployed taxi driver set fire to two cartons of gasoline inside a subway car; the fire spread to the six-car train then to another that pulled alongside it.
The Koreans shipped a subway car to the Carleton fire lab and asked Hadjisophocleous to assess what would happen to it in a controlled fire. They wanted to better understand such a fire so as to improve the design of fire protection systems in tunnels.
Officials from the City of Ottawa and Ottawa Fire Services were invited to watch the test fire since the city’s rapid transit plan calls for a downtown tunnel.
The subway test, conducted earlier this year in Carleton’s tunnel lab, surprised even Hadjisophocleous.
“It was so interesting and scary at the same time: to see how quickly the tunnel became dark with smoke. It was seconds, I mean seconds,” he says. “That’s something that we did not expect. There was so much smoke. Conditions became so untenable in such a short amount of time … It was very scary.”
TOWARD FLASHOVER: FIVE STAGES OF FIRE DEVELOPMENT
1. IGNITION
A lit cigarette drops unseen onto a living room couch. It triggers pyrolysis, a chemical reaction in which wood, cloth and other materials release combustible gases when heated. The gases mix with oxygen; the mix is ignited by a cigarette ember.
2. GROWTH
The flame feeds itself by radiating down into the couch, releasing more gases. A fire plume, carrying smoke and hot gases, rises toward the ceiling, drawing more air into the fire.
3. BATHTUB EFFECT
Smoke reaches along the ceiling to the walls. Hot gases build below the ceiling in a layer that fills like an inverted bathtub. The layer descends; its increasing heat radiates down.
4. FLASHOVER
Once the layer reaches 500 to 600 C, a critical amount of heat radiates to everything in the room. In an instant – the moment of flashover – anything that’s combustible goes up in flames.
5. FULLY DEVELOPED FIRE
Flashover leads to a dramatic spread of fire. Flames roll across ceilings and out windows. Temperatures spike to more than 1000 C.
FIRE FACTS
Between 2000 and 2009, 40 percent of the fatal fires in Ontario occurred between 10 p.m. and 6 a.m.
Half of those fires were deemed preventable by the Office of the Fire Marshal.
Fire begins at home: The vast majority (86 per cent) of 833 fatal events involved residential fires.
Fatal house fires were most likely to be triggered by cigarette smoking (17 per cent), arson (13 per cent) cooking (10 per cent), mishandled matches or lighters (6 per cent), electrical wiring problems (4 per cent) or candles (3 per cent).
Smoke alarms were not present or did not operate in 36 per cent of the fatal fires.
A 2004 study by the U.S. National Institute of Standards and Technology found that the typical modern fire smoulders longer, but burns hotter and faster than when smoke alarms were introduced in the 1970s.
查看原文...
From the time he was a graduate student, George Hadjisophocleous’s academic career has been consumed by fire.
The Carleton University professor directs research at one the most unusual laboratories in the country: a $10-million, 10-storey facility where he investigates the behaviour of fire in homes, office buildings, subway cars and tunnels.
He explores how flame and smoke interact with today’s increasingly complex structures in search of better designs and fire defences.
His work involves fluid mechanics, heat transfer, thermodynamics, civil engineering and computer modelling. Even crowd psychology plays a part since fire engineers must consider how people will react in an emergency.
“That’s what makes it so challenging,” says Hadjisophocleous, 55, who holds a prestigious national research chair in fire safety engineering. “There are so many parameters that come into play, but once you know those parameters, you can make predictions about afire and how it will move.”
Fire has been the subject of his professional curiosity for 30 years. And although an essentially logical creature – fire is, after all, governed by physics – its behaviour continues to fascinate Hadjisophocleous, sometimes even frighten him.
“Everyone experiences fire,” he says. “Everyone knows a controlled fire in their fireplace or in a campground. But when it’s an uncontrolled fire, it’s a very scary situation.
“I think most people don’t realize how quickly things can turn the wrong way in a fire.”
Hadjisophocleous has seen it happen – right in his lab.
–
Carleton’s fire research lab is located one hour from the main university campus, on rolling farmland outside Mississippi Mills. The site looks like a small factory: there’s an assortment of concrete buildings, a few trailers and container bins. A crane, with its arm fully extended, stands mysteriously in the lot. Inside, however, the purpose of it all becomes readily apparent: the air is bitter with soot.
Carleton researchers have been setting fires in the laboratory for the past four years. The lab includes a fully instrumented tunnel in which Hadjisophocleous can simulate subway fires. There’s also a 10-storey atrium – researchers use it to investigate the behaviour of smoke in highrise buildings – and a “burn hall” large enough to contain a framed house.
Today, master’s student Devin Glennie, 25, is at work preparing the next conflagration in the cavernous lab.
Glennie has built a metal room with two open windows. He intends to set it alight in order to test the transfer of heat to a nearby “target” wall, and compare results to 12 similar experiments in which he used other window configurations.
Windows affect the amount of oxygen that goes into a room – a critical factor in governing the size of a fire. These experiments will help him understand the conditions under which fire can spread to a neighbouring home.
Glennie uses a long, thin torch to set his purpose-built room on fire: arson in the name of science.
The room, lined with fire-resistant ceramic insulation, has propane burners on the floor calibrated to simulate real fires by producing heavy black smoke. (Smoke is the product of poor combustion as soot particles – bits of unburned carbon – are carried away in hot gases.)
Smoke vents out the top of the atrium through an exhaust chamber that measures oxygen and carbon dioxide levels. Researchers can deduce the intensity of a fire by calculating how much oxygen has been taken from each cubic metre of smoke in the combustion process.
Sensors record temperatures inside the room and on the neighbouring wall, where the transfer of heat onto a given surface (heat flux) is also measured. Nearby computer screens give the researchers realtime data.
Within 10 minutes, flames are boiling inside the room and curling outside the two windows. The room temperature climbs to 700 C, well beyond the “flashover” point at which any combustible material in the room would have ignited. The temperature peaks at 900 C when the fire is fully developed.
By the time the half-hour experiment is over, the lab is uncomfortably smoky.
Glennie inspects the room, which is blackened in places and still radiating heat. He declares the experiment an unqualified success: it’s the first time that none of his equipment has melted.
–
Researchers conduct a burn test at the National Research Council fire lab in Mississippi Mills.
Growing up, George Hadjisophocleous possessed a boy’s fascination with fire but also a Cypriot’s respect for its power. “I liked starting fires: I was like any boy,” he says. “But in Cyprus, bushfires are a common thing because we have long, dry summers. I witnessed several of those very close to our town.”
Hadjisophocleous also took a keen interest in car engines since his father was a truck driver. He studied engineering in university then worked as mechanic in the military during his compulsory service. He spent two more years in The Emirates as an air-conditioning engineer before friends convinced him to join them at the University of New Brunswick.
There, he completed graduate degrees in mechanical engineering and rediscovered his passion for fire. For his PhD thesis, he modelled what would happen when a tanker truck containing liquefied natural gas was exposed to flames.
“My initial interest,” he says, “was to model that complex problem which included the flames, the heat transfer to the liquid, to the gas, the evaporation inside the tanker, the pressure buildup. They were very challenging problems.”
His fascination reignited, Hadjisophocleous accepted a job at National Research Council Canada. He spent the next decade developing computer models to assess and manage fire risk.
In March 2001, he moved to Carleton to launch the fire safety engineering program, which now boasts 19 graduate students.
Carleton researchers have studied the effect of fire on gypsum board, support beams, wooden floors, steel and timber columns. They’ve studied smoke movement in high-rises and in atriums – all with a view toward making buildings safer.
They’re about to turn more of their attention to subways. Later this year, Hadjisophocleous expects to take delivery of four used subway cars from the Toronto Transit Commission, which he will use in Carleton’s specially designed tunnel lab.
The 37.5-metre-long lab has a rail track on the floor to accommodate the cars, a sprinkler system, an air sampling system to measure smoke, and a raft of sensors to measure temperature and heat flux.
Subways have been the target of terrorist attacks in Tokyo (1995), Paris (1995) Moscow (2004) and London (2005). They’ve also been the scene of many deadly fires, including a 2003 incident in Daegu, South Korea that killed 198 people.
Most North American subways rely on tunnel ventilation systems, not sprinklers, as their primary safety feature. The ventilation systems are designed to move smoke in one direction, allowing passengers to escape in the other. Some engineers have argued that sprinkler systems will generate steam in a tunnel fire and injure more people than they help.
But Carleton researchers have established that sprinklers should form part of a subway’s fire safety system. Hadjisophocleous and his team have found that ventilation systems are more effective when used in combination with sprinklers. Sprinkers limit the growth of the fire (even inside a subway car), cool the smoke and reduce the amount flowing back “upstream” into the tunnel.
Hadjisophocleous torched his first subway car earlier this year in an experiment commissioned by South Korea in the wake of the Daegu tragedy. In Daegu, an unemployed taxi driver set fire to two cartons of gasoline inside a subway car; the fire spread to the six-car train then to another that pulled alongside it.
The Koreans shipped a subway car to the Carleton fire lab and asked Hadjisophocleous to assess what would happen to it in a controlled fire. They wanted to better understand such a fire so as to improve the design of fire protection systems in tunnels.
Officials from the City of Ottawa and Ottawa Fire Services were invited to watch the test fire since the city’s rapid transit plan calls for a downtown tunnel.
The subway test, conducted earlier this year in Carleton’s tunnel lab, surprised even Hadjisophocleous.
“It was so interesting and scary at the same time: to see how quickly the tunnel became dark with smoke. It was seconds, I mean seconds,” he says. “That’s something that we did not expect. There was so much smoke. Conditions became so untenable in such a short amount of time … It was very scary.”
TOWARD FLASHOVER: FIVE STAGES OF FIRE DEVELOPMENT
1. IGNITION
A lit cigarette drops unseen onto a living room couch. It triggers pyrolysis, a chemical reaction in which wood, cloth and other materials release combustible gases when heated. The gases mix with oxygen; the mix is ignited by a cigarette ember.
2. GROWTH
The flame feeds itself by radiating down into the couch, releasing more gases. A fire plume, carrying smoke and hot gases, rises toward the ceiling, drawing more air into the fire.
3. BATHTUB EFFECT
Smoke reaches along the ceiling to the walls. Hot gases build below the ceiling in a layer that fills like an inverted bathtub. The layer descends; its increasing heat radiates down.
4. FLASHOVER
Once the layer reaches 500 to 600 C, a critical amount of heat radiates to everything in the room. In an instant – the moment of flashover – anything that’s combustible goes up in flames.
5. FULLY DEVELOPED FIRE
Flashover leads to a dramatic spread of fire. Flames roll across ceilings and out windows. Temperatures spike to more than 1000 C.
FIRE FACTS
Between 2000 and 2009, 40 percent of the fatal fires in Ontario occurred between 10 p.m. and 6 a.m.
Half of those fires were deemed preventable by the Office of the Fire Marshal.
Fire begins at home: The vast majority (86 per cent) of 833 fatal events involved residential fires.
Fatal house fires were most likely to be triggered by cigarette smoking (17 per cent), arson (13 per cent) cooking (10 per cent), mishandled matches or lighters (6 per cent), electrical wiring problems (4 per cent) or candles (3 per cent).
Smoke alarms were not present or did not operate in 36 per cent of the fatal fires.
A 2004 study by the U.S. National Institute of Standards and Technology found that the typical modern fire smoulders longer, but burns hotter and faster than when smoke alarms were introduced in the 1970s.
查看原文...
