• Title/Summary/Keyword: Smoke front

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The tracking of a smoke front under a ceiling by a laser sheet and thermocouples (Laser와 열전대를 이용한 연기선단의 위치 추적 비교에 관한 연구)

  • 김명배;한용식;윤명오;김진곤
    • Fire Science and Engineering
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    • v.12 no.3
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    • pp.11-20
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    • 1998
  • A new experimental technique using a laser sheet and thermocouples is introduced to evaluate an intuitive criterion for tracking of a smoke front using thermocouples. From synchronized photos of the smoke front along with temperature signals, the intuitive criterion is shown to be acceptable. Smoke visualization by a laser sheet proves to have several advantages over the conventional techniques such as the use of smoke generators.

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An experimental study of convective smoke filling (유동에 의한 연층 확산에 관한 실험적 연구)

  • 김명배;한용식
    • Fire Science and Engineering
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    • v.11 no.3
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    • pp.3-14
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    • 1997
  • An experimental investigation of smoke spread in a corridor is made using thermocouples and visualization technique with a laser beam sheet. A speed of smoke front under a ceiling is measured by thermocouple trees. Visualization of the ceiling jet formation and of smoke filling process is carried out to observe lowering of the smoke layer. From the results, a large-scale convective motion the corridor plays dominant roles for smoke spread from visualized photos together with temperature records. A circulating motion of fluid transports some smokes to some regions where its momentum is effective. It is therefore showed that the conventional concept of lowering smoke with two-layer zone model has some restrictions for the corridor because the lowering of smoke layer has been thought to be mass transport due to relatively small scale motion such as decrease of buoyancy, mass diffusion and momentum exchange.

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A Visualization of Smoke Front under a Horizontal Plate (평판하 연기선단의 가시화)

  • 한용식;김명배;오광철;유상필
    • Fire Science and Engineering
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    • v.15 no.1
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    • pp.41-46
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    • 2001
  • The flow induced by a vertically impinging circular jet under a horizontal plate is investigated by visualization technique, using kerosene smoke in nitrogen gas to visualize the vortex flow and impinging flow. The light source was the sheet beam of Ar-Ion laser. The vertical and horizontal images scattering of kerosene smoke were recorded by the high speed CCD camera and the video camera. The instantaneous velocity of the vortex and the mean velocity of the smoke front were measured from the acquisited images.

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SMOKE SPREAD IN A CORRIDOR

  • Kim, Myung-Bae;Han, Yong-Shik;Park, Jun-Seok
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 1997.11a
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    • pp.464-471
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    • 1997
  • Convective smoke spread in a corridor is experimentally investigated using thermocouples and visualization technique with a laser beam sheet. The speed of smoke front under a ceiling is measured by a series of thermocouples. Visualization of the ceiling jet formation and of smoke filling process is carried out to observe the lowering of a smoke layer. From the results, a large-scale convective motion plays dominant roles for smoke spread in the vicinity of the end of the corridor from visualized photos along with temperature records. The large-scale convective motion of the smoke is generated from the impingement of the ceiling jet front on the end of the corridor, and thus turning the flows toward the floor. Such a circulating motion of fluid transports some smoke to some region where its momentum is effective. It is therefore shown that the conventional concept of lowering smoke in the two-layer zone model has some restrictions for the corridor because the lowering of smoke layer has been thought to be mass transport due to relatively small scale motions such as the decrease of buoyancy, mass diffusion and momentum exchanges.

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An Experimental Study of Smoke Movement in Tunnel Fires with Natural Ventilation (터널화재시 자연환기에 의한 연기거동에 관한 실험적 연구)

  • 김충익;유홍선;이성룡;박현태
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.3
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    • pp.247-253
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    • 2002
  • In this study, reduced-scale experiments were conducted to analyze smoke movement in tunnel fire with roof vent. The 1/20 scale experiments were carried out under the Froude scaling using gasoline pool fire ranging from 7.3 to 15.4 cm in diameter with total heat release rate from 1.0 to 8.46kw. In case of 1 m high vent, smoke front reached to the tunnel exit at about 16 sec delayed with ventilation. The delay time grew longer with the vent height. The temperature after the vent was lower than that without the vent. The exit temperature declined maximum of $20^{\circ}C$ after passing the vent. It was confirmed that the thickness of smoke layer was maintained uniformly under the 25% height of the tunnel through the visualized smoke now by a laser sheet and the digital camcorder.

An Experimental Study of Smoke Movement in Tunnel Fires with Aspect Ratio of Tunnel Cross Section (터널 화재시 터널 단면의 종횡비에 따른 연기 거동에 관한)

  • Lee, Sung-Ryong;Ryou, Hong-Sun;Kime, Choong-Ik
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.115-120
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    • 2003
  • In this study, smoke movement in tunnel fires was investigated with various aspect ratio(0.5, 0.667, 1.0, 1.5, 2.0) of tunnel cross section. Reduced-scale experiments were carried out under the Froude scaling using 8.27 kW ethanol pool fire. Temperatures were measured under the ceiling and vertical direction along the center of the tunnel. Smoke front velocity and temperature decrease rate were reduced as higher aspect ratio of the tunnel cross-section. Smoke movement was evaluated by analysis of vertical temperature distribution 3 m downstream from the fire source. Elevation of smoke interface according to N percent rule was under about 60% of tunnel height.

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An Experimental Study of Smoke Movement in Tunnel Fires (터널화재시 연기 거동에 관한 실험적 연구)

  • Lee, Sung-Ryong;Kim, Choong-Ik;Ryou, Hong-Sun
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.121-126
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    • 2001
  • In this study, reduced-scale experiments were conducted to understand smoke movements in tunnel fires with the natural ventilation. The 1/20 scale experiments were conducted under the Froude scaling since the smoke movement in tunnels is governed by buoyancy force. Six cases of experiments(pool diameter is 6.5cm, 7.3cm, 8.3cm, 10cm, l2.5cm and l5.4cm), in which vertical vents positioned 1m from the fire source symmetrically, were conducted in order to evaluate the effect of the vent on smoke movement. In case of heat release rate under 2MW, smoke front reached to the tunnel exit about 20 see delayed with ventilation and the smoke velocity was proportional to the power of the heat release rate. Temperature after the vent was lower than without vent. In case of l5.4cm pool, the temperature difference was about $50^{\circ}C$. It was confirmed that the thickness of smoke layer was maintained uniformly under the 35% height of tunnel through the visualized smoke flow by a laser sheet and the digital camcoder.

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An Experimental Study of Smoke Movement in Tunnel Fires with a Vertical Shaft (수직갱이 설치된 터널내 화재시 연기거동에 관한 실험적 연구)

  • 이성룡;유홍선;김충익
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.2
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    • pp.135-141
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    • 2004
  • The present paper concerns a smoke movement in a tunnel fire with a vertical shaft. The model tunnel measured 13.4m long, 0.4m wide and 0.4m high. The cross section is 1: 20 of a full scale tunnel. Ethanol was used as a fuel. The fire size in model tests varied from 1.35 kW to 13.37 kW, which corresponds to full scale fires of 2.41 to 23.91 MW. Smoke front velocity and temperatrue were decreased due to the vertical shaft install. Temperature was reduced maximum about 2$0^{\circ}C$ at ceiling and about 23$^{\circ}C$ at vertical position. CO concentration was reduced as the vent width widened. When vent width was more than 15 cm, CO concentration was not reached 100 ppm. Descent degree of the smoke layer was confirmed through the visualization.