• Title/Summary/Keyword: Flame mode

Search Result 133, Processing Time 0.029 seconds

Dynamic Behaviors of Oscillating Edge-Flame in Low Strain Rate Counterflow Diffusion Flames (저신장율 대향류확산화염에서 진동불안정성을 갖는 에지화염의 동적거동)

  • Park, June-Sung;Kim, Hyun-Pyo;Park, Jeong;Kim, Jeong-Soo;Keel, Sang-In
    • 한국연소학회:학술대회논문집
    • /
    • 2006.10a
    • /
    • pp.65-72
    • /
    • 2006
  • Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Critical mole fraction at flame extinction is examined with velocity ratio and global strain rate. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate and added nitrogen mole fraction to fuel stream (fuel Lewis number). It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations in low strain rate flames are experimentally described well and are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames. Important contribution of lateral heat loss even to edge flame oscillation is clarified.

  • PDF

A Study on the Combustion Characteristics of a Hybrid Cyclone Jet Combustor (하이브리드 사이클론 제트 연소기의 연소특성에 관한 연구)

  • Jung, Won-Suk;Hwang, Chul-Hong;Lee, Gyou-Young;Lee, Chang-Eon
    • 한국연소학회:학술대회논문집
    • /
    • 2002.11a
    • /
    • pp.149-155
    • /
    • 2002
  • A promising new approach to achieve low pollutants emission and improvement of flame stabilities is tested experimentally using a hybrid cyclone jet combustor employing both premixed and diffusion combustion mode, Three kind of nozzles are used for LNG(Liquified Natural Gas) as a fuel. The combustor is operated by two method, One is ATI(Air Tangential Injection) mode, generated swirl flow by air as general swirl combustor, and the other is PTI(Premixed gas Tangential Injection) mode, The PTI mode consists of diffusion flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion flame. The results showed that the stable region of the PTI mode is more larger than the ATI mode. In addition, the reduction of NOx emission in PTI mode, as compared with that for the ATI mode is at least 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, the cyclone jet combustor has high performance of flame stability.

  • PDF

The Combustion Characteristics of a New Cyclone Jet Hybrid Combustor for Low Pollutant Emission and High Flame Stability (저공해와 고안정성을 위한 신개념의 사이클론 제트 하이브리드 연소기의 연소특성)

  • Jung, Won-Suk;Hwang, Chul-Hong;Lee, Gyou-Young;Lee, Chang-Eon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.28 no.2
    • /
    • pp.146-153
    • /
    • 2004
  • A Promising new approach to achieve low pollutant emissions and improvement of flame stability is tested experimentally using a cyclone jet hybrid combustor employing both premixed and diffusion combustion mode. Three kinds of nozzle are tested for mixing enhancement of fuel and air. The LNG (Liquified Natural Gas) is used as a fuel. The combustor is operated by two methods. One is DC (Diffusion Combustion) mode generated swirl flow by air as general swirl combustor, and the other is HC (Hybrid Combustion) mode. The HC mode consists of diffusion jet flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion jet flame. The results showed that the flame stability of HC mode is significantly enhanced than that of DC mode through the change of mixing characteristics by modifications of fuel nozzle. In addition, the reductions of CO and NOx emission in HC mode, as compared with that for the DC mode, is large than about 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, it is identified that the cyclone jet hybrid combustor has the high performance of flame stability.

Experimental Study for Oxygen Methane MILD Combustion in a Laboratory Scale Furnace (Laboratory Scale 연소로를 적용한 산소 메탄 MILD 연소에 대한 실험적 연구)

  • Lee, Pil Hyong;Hwang, Sang Soon
    • Journal of the Korean Society of Combustion
    • /
    • v.21 no.4
    • /
    • pp.6-15
    • /
    • 2016
  • The oxygen fuel MILD (Moderate or Intense Low-oxygen Dilution) combustion has been considered as one of the promising combustion technology for flame stability, high thermal efficiency, low emissions and improved productivity. In this paper, the effect of oxygen and fuel injection condition on formation of MILD combustion was analyzed using lab scale oxygen fuel MILD combustion furnace. The results show that the flame mode was changed from a diffusion flame mode to a split flame mode via a MILD combustion flame mode with increasing the oxygen flow rate. A high degree of temperature uniformity was achieved using optimized combination of fuel and oxygen injection configuration without the need for external oxygen preheating. In particular, the MILD combustion flame was found to be very stable and constant flame temperature region at 7 KW heating rate and oxygen flow rate 75-80 l/min.

Effects of Heat Losses on Edge-flame Instabilities in Low Strain Rate Counterflow Diffusion Flames (저신장율 대향류확산화염에서 에지화염 불안정성에 관한 열손실 효과)

  • Park June-Sung;Hwang Dong-Jin;Kim Jeong-Soo;Keel Sang-In;Kim Tae-Kwon;Park Jeong
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.30 no.10 s.253
    • /
    • pp.996-1002
    • /
    • 2006
  • Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Critical mole fraction at flame extinction is examined with velocity ratio and global strain rate. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate and added nitrogen mole fraction to fuel stream (fuel Lewis number). It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations in low strain rate flames are experimentally described well and are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames. Important contribution of lateral heat loss even to edge flame oscillation is clarified

Observation on Double-droplet Combustion Speed in Premixed Spray Flame (예혼합 분무화염내의 이중적 액적 연소속도에 관한 관찰)

  • Lee, Chi-Woo;Shim, Han-Sub
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.12 no.6
    • /
    • pp.119-126
    • /
    • 2004
  • In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

A Study on the Temperature Characteristics and Flame Stabilization of Surface Combustor using the Metal Fiber (메탈화이버를 이용한 표면연소기의 화염안정화 및 온도특성에 관한 연구)

  • Lee, Jin-Seok;Lee, Young-Hoo;Yun, Bong-Seok;Lee, Do-Hyung
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • 2002.05a
    • /
    • pp.92-97
    • /
    • 2002
  • By changing the excess air ratio which affects strongly to the combustion characteristics, the flame stability range in the metal fiber burner were found and the range of the blue flame male and radiant mode were distinguished by direct photography. The results in our experiments for the flame stability zone were from a=1.4($354 KW/m^2$) to a=2.06($240 KW/m^2$), and then the blue flame mode zone was form a=1.87($266 KW/m^2$) to a=2.06($240 KW/m^2$) and the radiant mode one was form a=1.4($354 KW/m^2$) to a =1.78($278 KW/m^2$). And the flame was not fired when a is less than the lean condition a=2.45($202 KW/m^2$).

  • PDF

An Experimental Study on Flame Spread in One-Dimensional Droplet Array with Forced Convection (강제 대류하에서 일차원 액적 배열내의 화염 퍼짐에 관한 실험적 연구)

  • Park, Jeong;Lee, Kiman;Niioka, Takashi
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.24 no.1
    • /
    • pp.68-74
    • /
    • 2000
  • Experimental investigation on flame spread along suspended droplet arrays have been conducted with various droplet spacings and ambient air velocities. Especially, an opposed air stream is introduced to simulate fundamental flame spread behaviors in spray combustion. High-speed chemiluminescence imaging technique of OH radicals has been adopted to measure flame spread rates and to observe various flame spread behaviors. The fuel used is n-Decane and the air velocity varies from 0 to 17cm/s. The pattern of flame spread is grouped into two: a continuous mode and an intermittent one. It is found that there exists droplet spcings, above which flame spread does not occur. The increase of ambient air velocity causes the limit droplet spacing of flame spread to become small due to the increase of apparent flame stretch. As the ambient air velocity decreases, flame spread rate increases and then decreases after taking a maximum flame spread rate. This suggests that there exists a moderate air flowing to give a maximum flame spread rate due to enhanced chemical reaction by the increase of oxidizer concentration.

A Study on Blend Effect of Fuel in Flame Spread Along An One-Dimensional Droplet Array (일차원 액적 배열의 화염 퍼짐에 있어서 연료의 혼합 효과에 관한 연구)

  • Park, Jeong;Kobayashi, Hideaki;Niioka, Takashi
    • Journal of the Korean Society of Combustion
    • /
    • v.3 no.2
    • /
    • pp.1-11
    • /
    • 1998
  • Experimental investigation on flame spread of blended fuel droplet arrays has been conducted for droplet diameters of 1.0mm and 0.75mm using high-speed chemiluminescence images of OH radical. The flame spread rate is measured with blended fuel composition, droplet diameter, and droplet spacing. Flame spread is categorized into two: a continuous mode and an intermittent one. There exist a limit droplet spacing, above which flame does not spread, and a droplet spacing of maximum flame spread, which is closely related to flame diameter. It is seen that flame spread rate is mainly dependent upon the relative position of flame zone within a droplet spacing. In case of large droplet, the increase of % volume of Heptane induces the shift of limit droplet spacing to a larger spacing since volatile Heptane plays a role of an enhancer of flame spread rate. In case of small droplet, the increase of % volume of Heptane leads to the shift of limit droplet spacing to a smaller droplet spacing. This is so because of the delayed chemical reaction time by the rapid increase of mass flux of fuel vapor for small droplet.

  • PDF

An Experimental Study on Smoke Generation of Rubber Floor for Railway Vehicle (철도차량용 고무바닥재의 연기발생에 관한 실험적 연구)

  • Park, Young Ju
    • Journal of the Korean Society of Safety
    • /
    • v.33 no.4
    • /
    • pp.15-20
    • /
    • 2018
  • In this study, we have performed the Cone Calorimeter test and Smoke density test in accordance with ISO 5660-1 and ASTM E662 respectively to check the smoke production characteristics of rubber flooring materials for railway vehicle. Early in the ASTM E662 test, more smoke was produced in the flame mode test than non-flame mode test, but later more smoke was produced in non-flame mode test. The correlation($R^2$) between TSR(Total Smoke Release) by ISO 5660-1 and Ds(Specific Optical Density) by ASTM E662 Flame mode was 0.782. The $R^2$ between TSR by ISO 5660-1 and Ds by ASTM E662 Non-flame was 0.930.