• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.19-22
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• 2012

본 연구에서는 폭발사고가 반복되고 있는 마그네슘합금(Mg-Al alloy) 분진의 예방대책을 위한 안전자료로 활용하기 위하여 폭발특성평가 실험과 화염전파속도를 추정하였다. 화염전파속도는 폭발과압 강도에 영향을 주지만 분진폭발에서는 화염의 확산에 따른 피해예측에도 중요한 자료로 활용될 수 있다. 밀폐공간의 분진폭발에서 화염전파속도를 계산하기 위하여 분진의 연소시간과 화염면의 도달시간을 고려하여 폭발압력으로부터 추정하는 방법을 제시하고 마그네슘합금의 성분비율에 따라 폭발에 따른 화염전파속도를 계산하였다. 그 결과, Mg-Al(60:40 wt%), Mg-Al(50:50 wt%), Mg-Al(40:60 wt%)의 최대화염전파속도는 각각 15.5, 18, 15.2 m/s로 추정되었으며 성분비율에 따라 최대화염속도는 변화하는 경향을 나타냈다.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.46-52
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• 2010

Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantity the triple flame propagation velocity, Bilger presents the triple flame propagation velocity, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the flame radius of curvature and scalar dissipation rate. In the present research, there was discussion about the radius of flame curvature and scalar dissipation rate, through the numerical study. As a result, we have known that the flame propagation velocity was linear with the nozzle exit velocity and scalar dissipation rate decreases nonlinearly with the flame propagation velocity and radius of curvature of flame increases linearly. Also radius of curvature of flame decreases non-linearly with the scalar dissipation rate. Therefore, we ascertained that there was corelation among the scalar dissipation rate, radius of flame curvature and flame propagation velocity.

• Journal of Energy Engineering
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• v.3 no.1
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• pp.62-69
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• 1994

화염중에 존재하는 이온 및 전자의 전기적 성질을 이용하여 연소실내의 화염전파속도를 파악하기 위해 실린더 헤드에 이온 프로브를 삽입하여 천연가스 및 가솔린의 화염전파속도를 측정하였다. 본 연구에 이용된 이온전류장치 설계에 의한 방법은 광학적 측정 장비에 비해 간단하며 쉽게 측정할 수 있고 가격도 저렴하고 응답성도 우수하였다. 이온 프로브의 제작과 신호처리에 관한 기초적인 지식을 얻었으며 천연가스 및 가솔린의 연소시 연소압력의 상승지점과 이온발생지점이 일관성있게 나타났다. 기관회전수의 증가에 따라서 연소실내의 화염전파속도가 증가했으며 같은 연소조건이라고 할 수 있는 동일 기관회전수, 당량비의 조건에서 점화시간에 대한 화염전파속도를 비교해 보면 메탄의 경우가 이론치보다 6 ms∼9 ms 정도 늦었다. 또한, 메탄가스 및 가솔린에 대해 이온 전류강도 및 화염 도달시간을 측정하였으며 연소실 벽면에서는 열전달에 의한 냉각효과로인해 화염 전파속도 및 이온농도가 감소했다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.250-258
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• 1985

비균열 접선속도장에 기인한 화염스트레치 인자와 확산선호도가 예혼합화염의 전파속도에 미치는 영향을 연소가스와 예혼합기의 대향류 유동장을 모델로 하여 접합 전개 방법을 이용하여 일반 인 Lewis수 및 기체팽창을 고려하여 해석하였다. 이 결과 스트레치가 작은 경우에는 확산선호 도에 따라 화염특성이 급격히 변화하는데 이는 곡률을 가진 자유전파화염의 특성과 동일하며 스트레치가 큰 경우에는 확산선호도에 관계없이 화염전파속도는 감소하는 특성을 보여주었다. 또한, 화염스트레치의 실험적 측정 및 이론적 해석에 있어서의 정의 및 화염스트레치의 영향에 관한 현상적 설명에 대하여 재검토하였다.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.47-56
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• 2011

Flame propagation velocity is the one ofmainmechanismof the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there was not presented any relation of these variables, triple flame propagation velocity, radius of flame curvature and scalar dissipation rate indirectly. In the present research, we have checked the results of numerical simulation with experiment and numerical analysis and verified the flame propagation velocity with a scalar dissipation rate proposed by Bilger through the numerical simulation. Also we have clarified that flame propagation velocity was depended on the radius of flame curvature and scalar dissipation rate.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.705-709
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• 2009

Based on experimental study of lycopodium dust particles' behavior, we suggest the flame propagation model through dust clouds. With dust concentration, flame velocity reaches a maximum value at $170g/m^3$ to exceed the stoichometric concentration for lycopodium-air mixture combustion and decreases slightly in the richer side of $500g/m^3$. At $47{\sim}200g/m^3$, mean velocity of particle increases in proportion to flame velocity. As the sum of burning rate and particle velocity is approximate in flame velocity, the flame propagation velocity with lycopodium dust concentration can be estimated by the calculation and it was found that behavior of particles is useful for better understanding of dust flame propagation velocity.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.250-258
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• 2010

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.34-39
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• 2010

Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity through the experiment, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the radius of flame curvature. In the present research, a relation of the flame propagation velocity is proposed with the radius of flame curvature for the flame stabilization mechanism. As a result, we have shown that the height of lifted flame is determined with the nozzle diameter and exit velocity of fuel and presented that the radius of flame curvature is proportion to the nozzle exit velocity of fuel and height of lifted flame. Therefore, the importance of the radius of flame curvature has to be recognized. To discribe the flame stabilization mechanism, Bilger's formula has to be modified with flame curvature effect.

• Fire Science and Engineering
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• v.22 no.3
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• pp.252-257
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• 2008

With the rapid exuberant growth of the forest, the number and size of forest fires and the costs of wildland fires have increased. The flame spread rate of forest fires is depending on the environmental variables like the wind velocity, moisture of grassland, etc. If we know the effects of the environmental variables on the fire growth, it is useful for wildland fiIre suppression. But analysis of the spread rate of wildland fire for these effects have not been established. In this study, the effects of wind velocity and height of grassland fuel have been investigated using the WFDS which is developed at NIST for prediction of the spread of wildland fires. The results showed that the relation between the height of the fuel and the spread rate of the head fires is, and the spread rates related to the wind velocity are predicted 17% less than the experimental results of Australia. When the wind velocity is over 7.5m/s, the concentration of pyrolyzed gas phase fuel is getting low due to fast movement of pyrolyzed gas, the flame spread rate becomes slow.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.145-152
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• 1998

실내에서 가스폭발시 피해를 예측하기 위해서 폭발 화염면의 전파를 수치해석을 통해 해석했다. 확산방정식에 의해 가스누출에 의한 실내의 가스확산분포를 구했으며 문헌에서 선택한 누출의 초기조건을 사용했다. 화염온도를 계산하기 위해 각 가스 혼합비에 따른 엔탈피와 화학식에 대한 reduced mechanism을 사용했으며 문헌에서 찾은 각 가스의 농도별 층류 연소속도를 혼합가스의 층류연소속도에 적용시켰다. k-$\varepsilon$ 모델에서 turbulance energy를 층류연소속도와 결합시켜 난류화염 전파속도를 모델링 했다. 화염면의 전파를 분석하기 위해 실내의 위치에는 직각, 화염면의 전파에는 원통좌표계를 사용했다. 유리창의 파손에 의한 화염전파면의 변화에 따른 압력상승 요인을 해석하였으며 창문의 크기에 따라서 점화위치에 따른 실내 압력상승의 영향이 서로 다르게 나타나는 결과를 얻었다.