• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.249-252
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• 2012

Experiments have been conducted to clarify flame spread behavior over electrical wire near the end of wire with applied AC electric fields. It is seen that the flame spread behavior near the end of wire with applied AC electric fields are quite different from that in temporally linearly-increasing flame position. The flame spread behavior can be categorized into three regimes based on the relevance of flame shape and the slanted direction of spread flame to spread rate. Detailed explanations on the characteristics are made through thermal balance mechanism. Also, the effect of drop of molten PE and fuel vapor-jet in flame spread is also discussed.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.32-38
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• 2006

A premixed flame propagating in a tube suffers strong variation in its shape and structure depending on boundary conditions. The effects of thermal boundary conditions and flow fields on flame propagation are numerically investigated. Navier-Stokes equations and species equations are solved with a one-step irreversible global reaction model of methane-air mixture. Finite volume method using an adaptive grid method is applied to investigate the flame structure. In the case of an adiabatic wall, friction force on the wall significantly affected the flame structure while in the case of an isothermal wall, local quenching near the wall dominated flame shapes and propagation. In both cases, variations of flow fields occurred not only in the near field of the flame but also within the flame itself, which affected propagation velocities. This study provides an overview of the characteristics of flames in small tubes at a steady state.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.485-490
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• 2004

Sawtooth mixing device used in a non-premixed burner is evaluated for flame stabilization and NO$_{x}$ reduction. Three mixers with different blade angles are tested. Methane is delivered through the fuel jet and air passes through the co-flow annulus. The flame mode changes (attached flame, lifted flame and extinction) against the fuel flow speed are measured, and the stability diagram is drawn. Moreover, by traversing thermocouple and sampling probe in the flame, the distribution of temperature and NO$_{x}$ mole fraction are measured. With the change in blade angle, flame shape, flame stabilization, the distribution of temperature and NO$_{x}$ mole fraction are changed considerably.rably.

• 대한기계학회논문집B
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• 제31권6호
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• pp.547-557
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• 2007

This study was conducted to investigate the flow and combustion characteristic of the experimental burner which was manufactured for the reflection of the oven and broil burner features. As slot shape, spacing between slots, and slot arrangement of the exit area which emits the mixing gas are different in case of oven burners and broil turners, the purpose of this study is to know the affection of the flame interaction and combustion characteristic according to the change of shape factors such as slot shape, slot arrangement, and slot-to-slot spacing. With no relation of the slot shape, as the spacing between slots became narrow, the occurrence of a lift-flame was delayed. So the combustion was possible in the leaner region, but the appearance of yellow-tip became a little fast. Slit slot port had the broadest operating range among the other slot shapes. Specially, from the side of lift-flame, as the jet that spreads downstream in the longitudinal slot was nearly circular just a few slot lengths away from the orifice, slot-to-slot spacing of the Slit port was closer than the other ports. These results could be expected through the computer numerical method and had a good agreement. As the spacing between slots increased, in case of Slit and Mix port, NOx emission rate was constant or decreased, but the NOx emission of Hole port was increased. CO emission rate of Slit and Hole port was increased as the slot-to-slot spacing was broadened.

• 대한기계학회논문집B
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• 제26권3호
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• pp.402-409
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• 2002

Experiments were performed with double-concentric diffusion flame(DDF) in order to investigate the characteristics of soot formation and temperature distributions. The flame size and shape of the DDF are similar to those of the well-known normal co-flow diffusion flame(WF), except the formation of a tiny inverse flame near the central tube exit. A laser light extinction technique was used to measure the soot volume fractions. The temperature distributions in the flame were measured by rapid insertion of a R-type thermocouple. Soot concentrations along the flame axis of the DDF were higher than those of the NDF. However, the maximum soot volume fraction of the DDF along the periphery of the flame was lower than that of the NDF. It is mainly due to the effect of nitrogen-dilution from the inner air. Measured temperature distribution explains these trends of soot concentration. The temperature along the flame axis was also higher in DDF than that of the NDF. However, the flame temperatures at the flame front of the two flames were almost same regardless of the inner flame. This phenomenon means that the inverse flame inside the DDF did not affect on the flame structure including the temperature and soot concentration, except the region around the flame axis.

• 항공우주기술
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• 제6권2호
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• pp.14-20
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• 2007

본 연구에서는 램제트 엔진의 연소기용 제트분사식 화염안정기의 특성을 분석하였다. 제트화염안정기는 분사각 및 제트운동량 변화를 통하여 화염을 손쉽게 제어할 수 있으며 별도의 열손상방지장치를 장착하지 않아도 된다는 장점이 있다. 또한 제트류와 주류간의 난류혼합효과로 인해 기계식 화염안정기보다 더 뛰어난 화염안정효과를 보였다. 이러한 제트화염안정기는 램 제트엔진의 제어성능을 더욱 향상시킬 수 있을 것이다.

• 오토저널
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• 제14권4호
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• pp.50-60
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• 1992

Flame characteristics of periodic fuel jets were studied experimentally by supplying the fuel periodically using solenoid valve. Flame was observed using a high speed camera, a 35 mm camera and a cathetometer. Hot-wire ananometer was used to meature the speed of fuel flow at the nozzle exit to analyze the flow characteristics. Various types of flame characteristics such as the flame lift-off and extinction were observed for different ranges of period, duty, and flow rate, but the flame shape was not affected much by the variation in the flow rate. Decreasing duty of the pulses applied to the solenoid valve promotes lift-off and enhances premixed flame characteristics.

• 조명전기설비학회논문지
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• 제25권5호
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• pp.79-84
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• 2011

In this study, breakdown characteristics of a vertical sphere-plane air gap in the presence of combustion flame were examined under the application of a.c. and d.c. high-voltages in order to investigate the effect of flame on the dielectric strength of air. Propane gas is used as the fuel of the flame, and the temperature distribution of air around the flame is measured. The polarity effects for the d.c. voltages and breakdown voltages of air when applied both of a.c. and d.c. voltages were examined in the case of the variation of the gap length and the horizontal distance between the flame and the high-voltage sphere electrode. The influence of relative air density, electrification and shape changes of the flame as factors that affect the breakdown voltages were discussed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.216-217
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• 2020

As the fire inside the building grows rapidly, ejected flame from an opening occurs due to flashover. As a result, the number of cases where the flame spreads to the exterior of the building and rapidly expands to the upper floor is increasing. In particular, in the case of the fire in the Daebong Green Apartment, Uijeongbu in 2015, it was a case where the flame spread to adjacent buildings due to the opening eruption flame from the first ignited building, causing great damage to three apartments. Therefore, this study is to introduce an international standard under development that estimates the shape and properties of the ejected flame from an opening and quantitatively evaluates the radiant heat flux received by the exterior wall of the building by assuming the occurrence of the ejected flame from an opening.

• 대한기계학회논문집
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• 제15권1호
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• pp.328-340
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• 1991

본 연구에서는 혼합기를 연소실 내로 공급하기 전에 필터를 이용하여 일정 크 기의 미립자를 제거함으로서 가능한 Mie산란의 영향을 감소시키고, 또 화학 발광의 영 향을 제거하기 위하여 광학장치의 개선 및 광학 필터를 사용하였다. 뿐만 아니라 연 소실 내의 배경광 및 반사산란광을 제거하기 위한 방법으로 입사창 및 연소실 내를 모 두 코팅을 하였다. 따라서 레이저 레일레이 산란을 이용하여 지금까지 나타난 문제 점들을 위와 같은 방법으로 개선하였을 뿐만 아니라 측정기술을 향상시켜 정적연소실 내에서의 온도를 측정함으로서 정적연소실 내에서의 온도측정이 가능하다는 것을 확인 하고, 또 그 적응성을 조사하는데 중점을 두어 실험을 하였다.