• International Journal of Air-Conditioning and Refrigeration
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• 제10권3호
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• pp.162-175
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• 2002

To investigate smoke movement with radiation in a room fires, a numerical and experi-mental analysis were performed. In this paper, results from a field model based on a self-developed SMEP (Smoke Movement Estimating Program) were compared with Stockier's ex-periment and the experiments on various sized pool fires in a room with door The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k- $\varepsilon$ turbulence model with buoyancy term. Also it solves the radiation equation using the S-N discrete ordinates method (DOM). The result of the cal-culated smoke temperature considering radiation effect has shown good agreement compared with the experimental data, although there are large discrepancy in the hot smoke layer be-tween the temperature predicted by the SMEP with only convection effect and obtained by the experimental result. This large discrepancy is caused from the radiation effect of $H_2O$ and $CO_2$ gas under smoke productions. Hence the radiation effect under smoke in fire is the point to be specially considered in order to produce more realistic result.

• 대한기계학회논문집
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• 제18권10호
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• pp.2738-2750
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• 1994

The Effects of radiative heat transfer on turbulent flow in a partitioned enclosure is studied numerically. The enclosure is partially divided by a thin, poorly conducting vertical divider projecting from the ceiling of the enclosure. The low Reynolds number $k-{\epsilon}$ model is adopted to calculate the turbulent flow field. The solutions to the radiative transfer equations are obtained by the discrete ordinates method(DOM). This method is based on control volume method and is compatible with the SIMPLER algorithm used to solve the momentum and energy equations. The effects of optical thickness and Planck number on the flow, temperature fields and heat transfer rates are investigated for a moderate Rayleigh number($=10^9$). The changes in buoyant flow fields and temperature distributions due to the variation of baffle length are also analyzed. From the predictions, radiant heat exchange between the baffle and the sidewalls strongly influences the temperature distribution in the baffle and its vicinity and total heat transfer increases as the optical thickness and the baffle length decrease. It is possible to neglect the radiative heat transfer effect when Planck number is over one.

• 한국안전학회지
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• 제12권1호
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• pp.77-93
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• 1997

The natural convection and combined heat transfer induced by fire in a rectangular enclosure is numerically studied. The model for this numerical analysis is partially opened, it is divided by a vertical baffle projecting from ceiling. The solution procedure Includes the standard k- $\varepsilon$ model for turbulent flow and the discrete ordinates method (DOM ) is used for the calculation of radiative heat transfer equation. In this study, numerical simulation on the combined naturnal convection and radiation is carried out in a partial enclosure filled with absorbed-emitted gray media, but is not considered scattering problem. The velocity vectors, streamlines, and isothermal lines are compared the results of pure convection with those of the combined convection-radiation, the combined heat transfer. Comparing the results of pure convection with those of the combined convection-radiation, the combined heat transfer analysis shows the stronger circulation than those of the pure convection. Three different locations of heat source are considered to observe the effect of heat source location on the heat transfer phenomena. As the results, the circulation and the heat transfer In the left region from heating block are much more influenced than those in the right region. It is also founded that the radiation effect cannot be neglected in analyzing the building in fire.

• 대한기계학회논문집B
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• 제27권2호
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• pp.215-226
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• 2003

Experimental and numerical studies have been done to examine the effects of excess air ratio and tertiary air swirl number on the formation characteristics of NOx in a pilot scale combustor adopting a multi-air staged burner. In numerical calculation the mathematical models for turbulence, radiation and nitric oxide chemistry were taken into account. The radiative transfer equation was solved using the discrete ordinates method with the weighted sum of gray gases model. In the NOx chemistry model, the chemical reaction rates for thermal and prompt NOx were statistically averaged using a probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-staged air burner has been designed and fabricated. Using the numerical simulation developed here, a variation of thermal and prompt NOx formation was predicted by changing the excess air ratio and tertiary air swirl number. As the excess air ratio increased up to 1.9, the formation of the total as well as thermal NOx at exit increased while the prompt NOx decreased. The formation of thermal NOx was more affected by concentration of $O_2$ and $N_2$ than gas temperature. When the tertiary air swirl number increased, the formation of the total as well as the prompt NOx slightly decreased.

• 한국화재소방학회논문지
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• 제11권1호
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• pp.21-35
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• 1997

The natural convection and combined heat transfer induced by fire in a rectangular enclosure is numerically studied. The model for this numerical analysis is partially opened right wall. The solution procedure includes the standard k-$\varepsilon$ model for turbulent flow and the discrete ordinates method (DOM) is used for the calculation of radiative heat transfer equation. In numerical study, SIMPLE algorithm is applied for fluid flow analysis, and the investigations of combustion gas induced by fire is performed by FAST model of HAZARD I program. In this study, numerical simulation on the combined naturnal convection and radiation is carried out in a partial enclosure filled with absorbed-emitted gray media, but is not considered scattering problem. The streamlines, isothermal lines, average radiation intensity and kinetic energy are compared the results of pure convection with those of the combined convection-radiation, the combined heat transfer. Comparing the results of pure convection with those of the combined convection-radiation, the combined heat transfer analysis shows the stronger circulation than those of the pure convection. Three different locations of heat source are considered to observe the effect of heat source location on the heat transfer phenomena. As the results, the circulation and the heat transfer in the left region from heating block are much more influenced than those in the right region. It is also founded that the radiation effect cannot be neglected in analyzing the building in fire. And as the results of combustion gas analysis from FAST model, it is found that O2 concentration is decreased according to time. While CO and CO2 concentration are rapidly increased in the beginning(about 100sec), but slowly decreased from that time on.