• Title/Summary/Keyword: Fire-wall interaction

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Numerical Analysis on Interaction between Fire Flame and Water Mist according to the Variation of Nozzle Performance (노즐 특성 변화에 따른 미분무수와 화염과의 상호작용에 관한 수치해석)

  • Bae, Kang-Youl;Chung, Hee-Taeg;Kim, Hyoung-Bum
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2983-2988
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    • 2007
  • In the present study, the numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m$ and a water mist nozzle that be installed 1.8m from fire pool. In the study, the parameters of nozzle for simulation are the droplet size and the spray velocity. Finally, the droplet size influences to fire flume on fire suppression than spray velocity because of the effect of terminal velocity, and the optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20m/s, respectively.

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Changes in Fire Characteristics according to the Distance Between the Fire Source and Sidewall in a Reduced-Scale Compartment (축소 구획실에서 화원과 측벽의 거리에 따른 화재특성 변화)

  • Yun, Hong-Seok;Hwang, Cheol-Hong
    • Fire Science and Engineering
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    • v.33 no.1
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    • pp.50-59
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    • 2019
  • Experimental and numerical studies on the fire characteristics according to the distance between the fire source and sidewall under the over-ventilated fire conditions. A 1/3 reduced ISO 9705 room was constructed and spruce wood cribs were used as fuel. Fire Dynamics Simulator (FDS) was used for fire simulations to understand the phenomenon inside the compartment. As a result, the mass loss rate and heat release rate were increased due to the thermal feedback effect of the wall in the compartment fire compared to the open fire. As the distance between the fire source and sidewall was reduced, the major fire characteristics, such as maximum mass loss rate, heat release rate, fire growth rate, temperature, and heat flux, were increased despite the limitations of air entrainment into the flame. In particular, a significant change in these physical quantities was observed for the case of a fire source against the sidewall. In addition, the vertical distribution of temperature was changed considerably due to a change in the flow structure inside the compartment according to the distance between the fire source and sidewall.

Numerical Study on the Effects of Spray Properties of Water Mist on the Fire Suppression Mechanism (미분무수 특성이 화재억제 메커니즘에 미치는 영향에 대한 수치해석적 연구)

  • Bae, Kang-Youl;Chung, Hee-Taeg;Kim, Hyoung-Bum
    • Journal of ILASS-Korea
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    • v.22 no.4
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    • pp.175-184
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    • 2017
  • The numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m^3$ and a water mist nozzle that be installed 1.8 m from fire pool. In the present study, the parameters of nozzle for simulation are the droplet size and the spray velocity. The droplet size influences to fire flume on fire suppression more than the spray velocity because of the effect of the terminal velocity. The optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20 m/s respectively.

Thermal Numerical Simulation on Fire Suppression Characteristics through Mobile Mist Spray Nozzles (이동식 미분무수 노즐의 소화 특성에 대한 수치 시뮬레이션)

  • Bae, K.Y.;Chung, H.T.;Kim, H.B.;Jung, I.S.;Kim, C.
    • Journal of Power System Engineering
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    • v.13 no.5
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    • pp.25-33
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    • 2009
  • In the present study, the numerical investigation has been carried out to see the effects of water mist sprays on the fire suppression mechanism. The special-purposed program named as FDS was used to simulate the interaction of fire plume and water mists. This program solves the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The computational domain was composed of a rectangular space dimensioned as $L{\times}W{\times}H=4.0{\times}4.0{\times}2.5\;m^3$ with a mist-injecting nozzle installed 1.0 m high from the fire pool. In this paper, two types of nozzles were chosen to compare the performance of the fire suppression. Numerical results showed that the nozzle, type A, with more orifices having smaller diameters had poorer performance than the other one, type B because the flow injected through side holes deteriorated the primary flow. The fire-extinguishing time of type A was 2.6 times bigger than that of type B.

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Experimental Study on Interaction of Water Sprayed Curtain on Hot Surface of a Window Glass and its Effects on Glass Surface Temperature in Room Fires (구획화재 시 국부복사열에 노출된 유리면의 수막접촉에 따른 급냉파열특성 관한 실험적 연구)

  • 박형주;지남용
    • Fire Science and Engineering
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    • v.17 no.4
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    • pp.124-130
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    • 2003
  • This research focuses on analysis of a interaction fracture of various glasses due to contact of water sprayed curtain on hot glass surface with high temperature produced from convective heat source near glass wall. A large scaled experimental test was done in order to find the range of the glass surface temperature to be able to cause the breakage of the glasses when water droplets reach on the hot surface. This paper shows the allowable temperature of the glass surface for prevention of the cooling down breakage before water curtain droplets contact the surface. Allowable Temperature if $250^{\circ}C$ for the tempered glass but general glass is very relatively low. Therefore if the water curtain spray system was adequately activated by a thermal detector installed below ceiling adjacent glass wall with water curtain nozzle system, all hot glass would not break out by cooling water droplet's contact on the hot surface due to convective heat released by adjacent fire source near the glass wall.

Heat Transfer Enhancement by an Oscillating Frequency of Vortex Generator (와류발생기의 가진 주파수에 의한 열전달 향상)

  • Bang, Chang-Hoon;Kim, Jung-Soo;Yea, Yong-Taeg
    • Journal of the Korean Society of Safety
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    • v.21 no.2 s.74
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    • pp.7-14
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    • 2006
  • A Problem of low-velocity forced convection in a channel flow with heated wall is of practical importance and widely considered in the design of devices such as heat exchangers, and electronic equipments. Therefore, there is an urgent need for improving heat transfer performance of heated wall in the channel. In the present study, an oscillating vortex generator method is proposed to enhance the heat transfer in a channel. In this method, a rectangular bars are set in the upstream of heated region of the channel. The bars are forced to oscillate normal to the inflow, and then actively and largely generates transverse vortices behind the bars. As a result, this apparatus can enhance the heat transfer rates remarkably. Because of the interaction between the flow and oscillating bars, the variations of the flow and thermal fields become time-dependent state.

Effect of Fuel Nozzle Configuration on the Reduction of NOx Emission in Medium-speed Marine Diesel Engine (연료분사 노즐 형상이 선박용 중형 디젤 엔진의 NOx에 미치는 영향 연구)

  • Yoon, Wook-Hyeon;Kim, Byong-Seok;Ryu, Sung-Hyup;Kim, Ki-Doo;Ha, Ji-Soo
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.13-14
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    • 2005
  • Multi-dimensional combustion analysis and experiment has been carried out to investigate the effects of the injector nozzle hole diameter and number on the NOx formation and fuel consumption in HYUNDAI HiMSEN engine. The behavior of spray and combustion phenomena in diesel engine was examined by FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. Wallfilm model suggested by Mundo, et al. and auto-ignition model suggested by Theobald and Cheng were adopted to investigate the spray-wall interaction characteristics and ignition delay. The information of spray angle and spray tip penetration length was extracted from fuel spray visualization experiment and the fuel injection rate profile was extracted from fuel injection system experiment as an input and verification data for the combustion analysis. Next, the nine different nozzle configurations were simulated to evaluate the effect of injector hole diameter and number on the NOx formation and fuel consumption.

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