• Title/Summary/Keyword: smoke boundary

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A Study on Improvenment of Livingroom Smoke-control System using the FDS (화재 시뮬레이션(FDS)을 이용한 거실제연설비 개선에 관한 연구)

  • Kim, Mi-Seon;Baek, Eun-Seon
    • Fire Science and Engineering
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    • v.31 no.4
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    • pp.26-34
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    • 2017
  • The purpose of this study is to identify and improve the performance of the adjacent room ventilation system in living room ventilation facilities, and compare and analyze the smoke control regulations of the NFPA code and the national fire safety standard (NFSC). The analysis method was fire dynamics simulation (FDS) and was used to analyze the, variations of the air supply amount, width of the boundary, change in indoor combustion and wind velocity of the incoming air. It was found to be advantageous to secure the clean layer when the amount of air supplied is less than the amount of discharged air in the fire room. However, in the supply room, it is more effective to secure the clean layer when the amount of supplied air is larger than the amount of discharged air, as a longer boundary width gives rise to better performance. In addition, it is necessary to consider the amount of air supplied and discharged as a function of the kind of flammable material. Moreover, decreasing the air inlet wind speed and amount of incoming air is advantageous for securing the clean layer of the fire room.

Experimental and Numerical Studies on Heat/Smoke Behavior due to a Fire on Underground Subway Platform (II) - Numerical Approach - (지하철 역사 승강장 화재발생시 열/연기 거동 분석을 위한 실험 및 수치 연구(II) - 수치적 접근 -)

  • Chang, Hee-Chul;Kim, Tae-Kuk;Park, Won-Hee;Kim, Dong-Hyeon
    • Fire Science and Engineering
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    • v.20 no.3 s.63
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    • pp.15-20
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    • 2006
  • In this study the flow characteristics of smoke and heat on a bank type platform of the underground subway station are studied numerically by considering two different emergency operation modes. Effects of the natural flow through the tunnel and the stair ways are considered in the numerical simulations by using the measured velocities presented in Part I as the boundary condition. Distributions of heat, smoke, visible range and toxic gas on the platform are analysed for different smoke extraction flowrates corresponding to the two different emergency operation modes. The numerical results show that the extraction flowrate affects the smoke control performance significantly by improving the smoke removal performance as the extraction flowrate is increased.

Simulation of Ventilation Capability Effect on The Smoke Spread in Railway Station (제연 팬 용량이 철도역사 연기확산에 미치는 영향 분석)

  • Jang, Yong-Jun;Koo, In-Hyuk;Kim, Hag-Beom;Kim, Jin-Ho
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.7-13
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    • 2011
  • Simulation study were performed for ventilation capability effect on the smoke spread in the deeply-underground subway station(DUSS). Singeumho station(The line # 5, Depth: 46m) was modeled and were analyzed for smoke-spread speed difference between the originally-designed-ventilation-capacity and the measured-ventilation-capacity. Field test data for actual fan in DUSS was applied as a boundary condition of a simulation. The whole station was covered in this analysis and total of 4 million grids were generated for this simulation. The fire-driven flow was analyzed case by case to compare the smoke-spread effects. In order to enhance the efficiency of calculation, parallel processing by MPI was employed and large eddy simulation method in FDS code was adopted.

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A Study on the Smoke control Design parameter of Large Volume space by Fire Dynamic Simulation (화재 시뮬레이션(FDS)을 이용한 대형공간의 제연 설계인자에 관한 연구)

  • Choi, Sang-Gon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.237-243
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    • 2018
  • Performance-oriented design has been introduced in fire protection design, and various efforts have been made to minimize the damage caused by fire in the design stage. We conducted a study to provide information for reasonable design factors using a Fire Dynamic Simulation code provided by the NIST on boundary width and amount of supply. This paper shows that using a living-room air-supply system in a large space and dividing the space by a ventilation boundary are the two factors that are considered to have the greatest influence on the design of the living room ventilation. The results show that for performance-based design, the width of the ventilation boundary is designed to be the maximum limit in the initial design. It is judged that reasonable air volume determination should be made through various methods.

Visualization Study on the Boundary Layer and Near-Wake of a Stationary Airfoil at Low Reynolds Numbers (저 레이놀즈수에서 정지된 에어포일의 경계층 및 근접 후류 가시화 연구)

  • Yang, Jae-Hun;Chang, Jo-Won
    • Journal of the Korean Society of Visualization
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    • v.4 no.2
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    • pp.44-50
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    • 2006
  • A visualization study on the boundary layer and near-wake of an NACA 0012 airfoil was con-ducted in order to investigate the influence of boundary layer behavior on the near-wake at low Reynolds numbers. The present study is investigated at static angles of attack ${\alpha}=0^{\circ},\;3^{\circ},\;6^{\circ}$ and $Re=2.3{\times}10^4,\;3.3{\times}10^4,\;4.8{\times}10^4$ by using a smoke-wire technique. The results of this study show that the laminar boundary layer on the airfoil surface is attached to the surface at ${\alpha}=0^{\circ}$, and that laminar separation of boundary layer on the airfoil surface occurs at ${\alpha}=3^{\circ}$. Furthermore, reattachment of the boundary layer occurs in the case of ${\alpha}=6^{\circ}$. In the current study, the location of the laminar separation point moves upstream as the Reynolds number and the angle of attack increase.

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An Estimation of Concentration of Asian Dust (PM10) Using WRF-SMOKE-CMAQ (MADRID) During Springtime in the Korean Peninsula (WRF-SMOKE-CMAQ(MADRID)을 이용한 한반도 봄철 황사(PM10)의 농도 추정)

  • Moon, Yun-Seob;Lim, Yun-Kyu;Lee, Kang-Yeol
    • Journal of the Korean earth science society
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    • v.32 no.3
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    • pp.276-293
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    • 2011
  • In this study a modeling system consisting of Weather Research and Forecasting (WRF), Sparse Matrix Operator Kernel Emissions (SMOKE), the Community Multiscale Air Quality (CMAQ) model, and the CMAQ-Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) model has been applied to estimate enhancements of $PM_{10}$ during Asian dust events in Korea. In particular, 5 experimental formulas were applied to the WRF-SMOKE-CMAQ (MADRID) model to estimate Asian dust emissions from source locations for major Asian dust events in China and Mongolia: the US Environmental Protection Agency (EPA) model, the Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model, and the Dust Entrainment and Deposition (DEAD) model, as well as formulas by Park and In (2003), and Wang et al. (2000). According to the weather map, backward trajectory and satellite image analyses, Asian dust is generated by a strong downwind associated with the upper trough from a stagnation wave due to development of the upper jet stream, and transport of Asian dust to Korea shows up behind a surface front related to the cut-off low (known as comma type cloud) in satellite images. In the WRF-SMOKE-CMAQ modeling to estimate the PM10 concentration, Wang et al.'s experimental formula was depicted well in the temporal and spatial distribution of Asian dusts, and the GOCART model was low in mean bias errors and root mean square errors. Also, in the vertical profile analysis of Asian dusts using Wang et al's experimental formula, strong Asian dust with a concentration of more than $800\;{\mu}g/m^3$ for the period of March 31 to April 1, 2007 was transported under the boundary layer (about 1 km high), and weak Asian dust with a concentration of less than $400\;{\mu}g/m^3$ for the period of 16-17 March 2009 was transported above the boundary layer (about 1-3 km high). Furthermore, the difference between the CMAQ model and the CMAQ-MADRID model for the period of March 31 to April 1, 2007, in terms of PM10 concentration, was seen to be large in the East Asia area: the CMAQ-MADRID model showed the concentration to be about $25\;{\mu}g/m^3$ higher than the CMAQ model. In addition, the $PM_{10}$ concentration removed by the cloud liquid phase mechanism within the CMAQ-MADRID model was shown in the maximum $15\;{\mu}g/m^3$ in the Eastern Asia area.

ANALYSIS OF STEADY FIRE-DRIVEN FLUID FLOW FOR RAILWAY TUNNEL BY DIFFERENT VELOCITY CONDITIONS AT THE END OF TUNNEL (종단부 유속조건 변화에 따른 철도터널 내 정상상태 화재유동해석)

  • Lee, D.C.;Lee, D.H.;Jung, W.S.;Park, S.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.208-213
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    • 2010
  • In this study CFD(Computational Fluid Dynamics) analysis of the steady fire-driven fuid flow for the performance test of ventilation at railway tunnel between Heuksok and Nodeul Station from Seoul Metro 9 is performed. There were fans with exhaust and intake modes and each was installed at the middle and both ends of the tunnel. For this test, the pool fire source of methyl alcohol with 1.5MW and smoke generators were installed between the middle of tunnel and Heuksok Station. In this test, the smoke behavior from natural convection was observed for 10 minutes from the ignition of pool fire and then fans with intake-modes at both sides of Heuksok effect of fan-on with intake mode located in the opposite side of the tunnel nearby Heuksok Station on fire-driven fluid flow is studied on when the boundary conditions of fan-on at the tunnel between Heuksok and Nodeul Station are the same as test. FLUENT, a commercial CFD code, is used for this analysis.

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A Numerical Study on Smoke Movement in Longitudinal Ventilation Tunnel Fires Using a Zone Model (존 모델을 이용한 종류식 배연 터널 화재시 연기 거동에 대한 수치해석적 연구)

  • Kim, Hyun-Jeong;Roh, Jae-Seong;Kim, Dong-Hyeon;Jang, Yong-Jun;Ryou, Hong-Sun
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1319-1324
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    • 2007
  • Many researches have been performed to analyze the smoke movement in tunnel fires by using field model. Recently, FDS(Fire Dynamics Simulator) v.4, which is one of the field model and developed from NIST(National Institute of Standards and Technology), is widely used. In tunnel fires, FDS can show detail results in local point, but it has difficulties in boundary condition and taking long computing time as the number of grid increases. So, there is a need to use alternative method for tunnel fire simulation. A zone model is different kind of CFD method and solves ordinary differential equation based on conservation and auxiliary equations. It shows good macroscopic view in less computing time compared to field model. In this study, therefore, to confirm the applicability of CFAST in tunnel fire analysis, numerical simulations using CFAST are conducted to analyze smoke movement in longitudinal ventilation reduced-scale tunnel fires. Then the results are compared with experimental results. The differences of temperature and critical velocity between numerical results and experimental data are over $30^{\circ}C$ and 0.9m/s, respectively. These values are out of error range. It shows that CFAST 6.0 is hard to be used for tunnel fire simulation.

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The 1D-3D Simulation for Smoke Ventilation in a Rescue Station of a Railroad Tunnel under the Fire (장대 터널 내 구난역의 열차 화재 시 제연을 위한 1D-3D 연계 해석)

  • Jung, Jae-Hyuk;Hur, Nahm-Keon;Lee, Jung-Pyo;Kim, Jin-Kon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.10
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    • pp.665-671
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    • 2010
  • In the present study a 1D-3D numerical simulation was performed to analyze the fire safety in a rescue station of a long railroad tunnel equipped with a mechanical ventilation. The behavior of hot air was studied for the emergency operation mode of ventilation system in case of fire in the rescue station. The 1D simulation was carried out for entire tunnel region. Detailed 3D CFD simulation was performed for the rescue station area in the central region of the tunnel by using the result of the 1D simulation as the boundary condition of the 3D simulation. Various type of cross passage installation were evaluated for the prevention of smoke diffusion to suggest the optimized interval of the cross passages in the rescue tunnel.

Unsteady Aerodynamic Characteristics depending on Reduced Frequency for a Pitching NACA0012 Airfoil at Rec=2.3×104

  • Kim, Dong-Ha;Chang, Jo-Won;Sohn, Myong Hwan
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.8-16
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    • 2017
  • Most of small air vehicles with moving wing fly at low Reynolds number condition and the reduced frequency of the moving wing ranges from 0.0 to 1.0. The physical phenomena over the wing dramatically vary with the reduced frequency. This study examines experimentally the effect of the reduced frequency at low Reynolds number. The NACA0012 airfoil performs sinusoidal pitching motion with respect to the quarter chord with the four reduced frequencies of 0.1, 0.2, 0.4 and 0.76 at the Reynolds number $2.3{\times}10^4$. Smoke-wire flow visualization, unsteady surface pressure measurement, and unsteady force calculation are conducted. At the reduced frequency of 0.1 and 0.2, various boundary layer events such as reverse flow, discrete vortices, separation and reattachment change the amplitude and the rotation direction of the unsteady force hysteresis. However, the boundary layer events abruptly disappear at the reduced frequency of 0.4 and 0.76. Especially at the reduced frequency of 0.76, the local variation of the unsteady force with respect to the angle of attack completely vanishes. These results lead us to the conclusion that the unsteady aerodynamic characteristics of the reduced frequency of 0.2 and 0.4 are clearly distinguishable and the unsteady aerodynamic characteristics below the reduced frequency of 0.2 are governed by the boundary layer events.