• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2009년도 춘계학술논문발표회 논문집
• /
• pp.570-575
• /
• 2009

본 논문에서는 피난해석에 사용되는 BuildingEXODUS code의 HAZARD에 피난의 환경 조건으로서 화재모사전용 FDS code의 계산결과를 직접 피난의 환경조건으로 생성하는 프로그램 개발 내용을 다루었다. 계산결과의 변환과정에는 수치기법이 적용되었으며, FDS의 Single Block 또는 Multi-Block Meshes에도 적용이 가능하도록 하였다. 본 프로그램의 개발로 피난해석 수행 시 대규모의 화재해석데이터의 입력의 편리성을 높이고, 화재에 대한 피난 해석 과정을 단축하게 되었다.

• 한국철도학회논문집
• /
• 제10권2호
• /
• pp.224-230
• /
• 2007

The performance and applicability of FDS code is analyzed for flow simulation in railway tunnel. FDS has been built in NIST(USA) for simulation of fire-driven flow. RANS and DNS's results are compared with FDS's. AJL non-linear ${\kappa}-{\epsilon}$[7,8] model is employed to calculate the turbulent flow for RANS. DNS data by Moser et al.[9] are used to prove the FDS's applicability in the near wall region. Parallel plate is used for simplified model of railway tunnel. Geometrical variables are non-dimensionalized by the height (H) of parallel plate. The length of streamwise direction is 50H and the length of spanwise direction is 5H. Selected Re numbers are 10,667 for turbulent flow and 133 for laminar low. The characteristics of turbulent boundary layer are introduced. AJL model's predictions of turbulent boundary layer are well agreed with DNS data. However, the near wall turbulent boundary layer is not well resolved by FDS code. Slip conditions are imposed on the wall but wall functions based on log-law are not employed by FDS. The heavily dense grid distribution in the near wall region is necessary to get correct flow behavior in this region for FDS.

• 한국전산구조공학회논문집
• /
• 제24권6호
• /
• pp.663-673
• /
• 2011

본 연구에서는 FDS code를 이용하여 교량하부창고 화재발생원과 교량높이의 영향을 분석하였다. 헵탄을 이용한 단위가연물의 연소실험, 실물모형 연소실험 결과와 FDS code를 이용한 해석결과의 비교를 통하여 FDS code의 유효성을 검증하였다. 이를 이용하여 교량하부 표준창고구조물의 실제 화재시나리오를 적용하여 교량높이 및 창고내부 가연물에 따른 콘크리트의 폭렬, 강도손실, 보강철근의 강도손실로 나누어 교량의 화재안전성을 평가하였다. 연구결과, 대부분의 교량이 하부창고화재에 대해 폭렬에 취약한 것을 확인할 수 있었다. 화재강도는 도서류가 가장 강하며 30m 높이 교량에 콘크리트의 강도저하, 폭렬 및 보강철근 강도저하를 가장 크게 발생시킬 것으로 예측되었으며, 고무류 창고화재의 경우 30m 이상 높이의 교량에 대해 화재안전성을 확보할 수 있었다.

• 대한기계학회논문집B
• /
• 제33권3호
• /
• pp.156-163
• /
• 2009

In this study, comparative analysis on the back-layer phenomena in the tunnel-fire driven flow is performed using numerical simulation with LES and RANS. FDS(Fire Dynamics Simulator) code is employed to calculate the fire-driven turbulent flow for LES and Smartfire code is used for RANS. Hwang and Wargo's data of scaling tunnel fire experiment are employed to compare with the present numerical simulation. The modeled tunnel is 5.4m(L) ${\times}$ 0.4m(W) ${\times}$ 0.3m(H). Heat Release Rate (HRR) of fire is 3.3kW and ventilation-velocity is 0.33m/s in the main stream. The various grid-distributions are systematically tested with FDS code to analyze the effects of grid size. The LES method with FDS provides an improved back-layer flow behavior in comparison with the RANS (${\kappa}-{\epsilon}$) method by Smartfire. The FDS solvers, however, overpredict the velocity in the center region of flow which is caused by the defects in the tunnel-entrance turbulence strength and in the near-wall turbulent flow in FDS code.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1594-1600
• /
• 2011

본 연구에서는 가장 최근에 NIST(National Institute of Standards and Technology)에서 LES(large eddy simulation)기법을 사용하여 개발한 3D 화재유동 해석용 FDS5의 중요한 기능 중 Werner-Wengle wall law의 성능을 평가하기 위하여 평행 평판에서의 유동을 조사하였다. 격자 형성을 위하여 $y^+$ 값은 11 이상으로 유지하도록 하였으며, 총 사용격자는 $32{\times}32{\times}32$를 사용하였다. 입구와 출구에서는 반복(periodic) 경계조건이 주어졌고, 양측면에서는 대칭(symmetry) 경계조건이 주어졌다. 충분히 발달된 난류에서의 유동조건을 조사하기 위하여 Re=10,700을 사용하였다. 시뮬레이션으로 구하여진 결과는 DNS(Direct Numerical Simulation) 결과 및 이론값과 비교하여 분석하였다. 또한 FDS 결과를 RANS의 난류 유동 해석 결과와도 비교하였다.

• 한국전산유체공학회지
• /
• 제20권3호
• /
• pp.94-103
• /
• 2015

The turbulent flow characteristics in the channel flow are investigated using large eddy simulation(LES) of FDS code, built in NIST(USA), in which the near-wall flow is solved by Werner-Wengle wall function. The periodic flow condition is applied in streamwise direction to get the fully developed turbulent flow and symmetric condition is applied in lateral direction. The height of the channel is H=1m, and the length of the channel is 6H, and the lateral length is H. The total grid is $32{\times}32{\times}32$ and $y^+$ is kept above 11 to fulfill the near-wall flow requirement. The Smagorinsky model is used to solve the sub-grid scale stress. Smagorinsky constant $C_s$ is 0.2(default in FDS). Three cases of Reynolds number(10,700, 26,000, 49,000.), based on the channel height, are analyzed. The simulated results are compared with direct numerical simulation(DNS) and particle image velocimetry(PIV) experimental data. The linear low-Re eddy viscosity model of Launder & Sharma and non-linear low-Re eddy viscosity model of Abe-Jang-Leschziner are utilized to compare the results with LES of FDS. Reynolds normal stresses, Reynolds shear stresses, turbulent kinetic energys and mean velocity flows are well compared with DNS and PIV data.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2009년 춘계학술대회논문집
• /
• pp.202-207
• /
• 2009

본 연구에서는 대심도 지하역사에서 화원 위치에 따른 연기거동의 특징을 분석하였다. 전산수치해석에 FDS code가 사용되었다. 화재에 의한 유체거동을 모사하기 위하여 난류모델은 LES를 사용하였으며, 빠른 계산을 수행하기 위하여 병렬수치해석기법을 사용하였다. 본 연구를 통하여 대심도 역사에서 화재시 피난을 저해하는 화원의 위치에 대하여 검토하였다.

• 한국철도학회논문집
• /
• 제9권6호
• /
• pp.625-629
• /
• 2006

This paper describes the effect of the droplet breakup process on fire suppression using a water-mist system, which is considered as a alternative to sprinkler fire suppression system. In the evolution of the water-mist, the droplet breakup process is an important phenomenon because it may significantly affect the droplet evaporation rate. The Fire Dynamics Simulator (FDS, Ver. 4.0) code, which is widely used for the simulation of fire dynamics, is used for the present simulation, and it is modified to consider the droplet breakup phenomena. The Prediction by the modified code shows good agreement with experimental data for the temperature. The original FDS predicts higher temperature about $30^{\circ}C$ than experimental data. From the results, it is concluded that the droplet breakup phenomena must be considered for more precise simulation of fire suppression process.

• 한국전산유체공학회지
• /
• 제21권3호
• /
• pp.31-38
• /
• 2016

The FDS-HCIB method is expanded to simulate water-oil-air flows around oil booms under relative motion, which is intended to increase the thickness of contained oil. The FDS scheme captures discontinuity in the density field and abrupt change of the tangential velocity across an interface without smearing. The HCIB method handles relative motions of thin oil booms with ease. To validate the developed FDS-HCIB code for water-oil-air flow around a moving body, the computed results are compared with the reported experimental results on the shape, length, and thickness of the oil slicks under towing. It is observed that the increase in pressure field between two barriers lifts the oil slick and the interfacial wave propagates and reflects as one barrier gets closer to the other barrier.

• 한국안전학회지
• /
• 제28권6호
• /
• pp.6-10
• /
• 2013

A numerical reproducibility of the backdraft phenomena in a compartment was investigated. The prediction performance of two combustion models, the mixture fraction and finite chemistry models, were tested for the backdraft phenomena using the FDS code developed by the NIST. The mixture fraction model could not predict the flame propagation in a fuel-air mixture as well as the backdraft phenomena. However, the finite chemistry model predicted the flame propagation in the mixture inside a tube reasonably. In addition, the finite chemistry model predicted well the backdraft phenomena in a compartment qualitatively. The flame propagation inside the compartment, fuel and oxygen distribution and explosive fire ball behavior were well simulated with the finite chemistry model. It showed that the FDS adopted with the finite chemistry model can be an effective simulation tool for the investigation of backdraft in a compartment.