• 제목/요약/키워드: Pilot flame

검색결과 59건 처리시간 0.019초

불활성기체로 희석된 동축류 확산화염의 파일럿화염에 의한 안정화 (Stabilization of Inert-Gas-Diluted Co-Flow Diffusion Flame by a Pilot Flame)

  • 안태국;이원남;박선호
    • 한국연소학회지
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    • 제20권4호
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    • pp.19-25
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    • 2015
  • An experimental study was conducted to find the effect of a pilot flame on the flammability of inert-gas-diluted methane and propane. The diffusion pilot flame was formed with propane at the innermost nozzle of a concentric triple co-flow burner. The main diffusion flame was formed with nitrogen-diluted methane or propane at the outermost nozzle of the burner. An air flow was located in-between. The results showed that the existence of the pilot flame helped stabilizing the main flame even at the flammability limit concentration of nitrogen-diluted fuel. The co-flow burner generated re-circulation zones and local variation of equivalence ratio depending on the flow rates of the reactants, which are known to help flame stabilization. Hot-wire experiments confirmed that both heating of the reactants and supplying of active chemical species by the pilot flame contributed to stabilization of the main flame. The results of this study would suggest a design concept for an efficient SVRU system that minimizes the emission of unburned hydrocarbon fuel from ship fuel tanks.

이중선회 연소기에서 화염형상과 파일럿과 주 화염의 상호작용에 관한 연구 (A Study on the Flame Shape and the Interaction between Pilot and Main Flames in a Dual Swirl Combustor)

  • 조준익;박태준;황철홍;이기만
    • 한국추진공학회지
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    • 제18권4호
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    • pp.33-42
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    • 2014
  • 이중선회 연소기에서 다양한 화염거동과 파일럿 화염과 주 화염의 상호작용에 관한 연구가 수행되었다. 주 선회각이 $45^{\circ}$로 고정된 상태에서 파일럿 선회각도, 총 열 발생률 그리고 주 화염의 당량비가 주요 변수로 검토되었다. 주요한 결과로써, 이중선회 연소기의 상세한 화염안정화 영역이 총 발열량과 주화염의 당량비 변화를 통해 발생되는 5가지 화염모드를 통해 확인되었다. 파일럿 화염의 선회각도는 파일럿 화염의 위치 및 연소기 전체의 유동구조에 가장 큰 영향을 미치게 되며, 그 결과 내부 및 외부 화염간의 상호작용의 큰 변화를 가져온다.

난류 부분예혼합화염과 로테이팅 아크 플라즈마를 이용한 난연성 유증기의 연소처리 (Reduction of Lean VOC Emission by Reforming with a Rotating Arc Plasma and Combustion with a Turbulent Partially-Premixed Flame)

  • 안태국;이대훈;박선호
    • 한국연소학회지
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    • 제22권1호
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    • pp.23-31
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    • 2017
  • Large-scale fuel tanks emit massive amount of hardly-combustible VOC mixtures which are light hydrocarbon species in dilution with nitrogen and carbon dioxide. We have developed a lab-scale burner to combust those VOC mixtures by use of a turbulent partially-premixed flame as a pilot flame. For a higher HC treatment ratio, the mixture gases were reformed by a rotating arc plasma device. The results showed that the nitrogen mole fraction and the injecting speed of the VOC mixture influence on the performance of the burner. It was also found that the size of the pilot flame and the power supplied to the plasma device determine the overall HC treatment ratio and the concentrations of CO and NOx in the exhaust gas.

파일롯 화엄에 의해 고정된 관내 예혼합 화염의 진동 특성 (Vibration Characteristics of Lean Premixed Flame Anchored by a Hydrogen Pilot Flame in a Tube)

  • 곽영태;오광철;신현동
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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    • pp.42-48
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    • 2004
  • Lean laminar premixed propane and methane flames which were anchored by a hydrogen-pilot flame in a tube were investigated experimentally. The flame shapes were observed by varying mean velocity from 10cm/s to 140cm/s and equivalence ratio from 0.45 to 0.8. In this study, behaviors of flames are divided into five regions such as tail-out, flash-back, flickering, stable and vibrating flames with respect to the mean velocity and the equivalence ratio. Although the flames are unstable in both the flickering and the vibrating region, they have different characteristics such as the frequency, sound generation and creation process of flame curvature. The flickering region exists near the flammability limit and the flame flickers in a frequency of about 10Hz. When flame front is bended, the propane flame front is straightened and the methane flame front is bended more by thermo-diffusive instability. In the vibrating region, the flame vibrates emitting audible sound in a frequency of about 100Hz. In the boundary of vibrating region, the vibration of flame changes between two modes such as single frequency vibration and dual frequency vibration. Increase and decrease of vibration in each mode are determined by thermo-acoustic instability.

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파일럿 안정화 제트버너의 예혼합 화염이 미연가스 영역 난류특성에 미치는 영향 (Effects of Premixed Flame on Turbulence Properties in a Pilot Flame Stabilized Jet Burner)

  • 이대훈;권세진
    • 대한기계학회논문집B
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    • 제23권9호
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    • pp.1172-1177
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    • 1999
  • Comparisons of measured turbulence properties in the unburned gas region of turbulent premixed flame stabilized by pilot flame, in cases of combusting and non-combusting flow conditions, are presented. Methane-air premixed jet at fuel equivalence ratio of 0.6 and 1.0 and Reynolds number of 7,000 was diagnosed using two-color laser velocimeter to obtain turbulence statistics. Same set of measurements was repeated at 21 locations within the unburned gas region of both combusting and non-combusting conditions. Velocity data were analyzed to evaluate the spatial distribution of turbulence properties including Reynolds stress, probability densities, joint probability densities and auto correlations. Contrary to assumptions of current theoretical models, significant influence of flame was observed in every property that was studied in the present investigation. The effective viscosity increased ten-fold when flame was on from cold flow values. The effect of mixing on joint probability as well as in turbulence intensity was suppressed by the flame. The measurements suggest that common assumptions of premixed flame model may result in sizable error in prediction of flame length and temperature distribution in near-field.

파일럿분사에 의한 바이오디젤유의 연소과정에 관한 연구 (A Study on Combustion Process of Biodiesel Fuel with Pilot Injection in a Common-rail Diesel Engine)

  • 방중철;김성훈
    • 한국자동차공학회논문집
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    • 제19권3호
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    • pp.146-153
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    • 2011
  • American NREL (National Renewable Energy Laboratory) reported that BDF20 could reduce PM, CO, SOx, and cancerogenic matters by 13.6%, 9.3%, 17.6%, and 13% respectively, compared to diesel fuel. BDF20 has been being tested on garbage trucks and official vehicles at Seoul City, which is positive on air environment, but negative on combustion by higher viscosity in winter season. This study investigated the combustion characteristics by applying pilot injection for improving the deterioration of combustibility caused by the higher viscosity of the BDF20 with the combustion flames taken by a high-speed camera and the cylinder pressure diagram. A 4-cycle single-cylinder diesel engine was remodeled to a visible 2-cycle engine taking the flame photographs, which has a common-rail injection system. The test was done laboratory temperature at $5{\sim}6^{\circ}C$. The results obtained are summarized as follows, (1) In the case of without pilot injection, the flame propagation speed was slowed and the maximum combustion pressure became lower. The phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of with pilot injection, early stage of combustion such as rapid ignition timing and flame propagation was activated since intermediate products formed by pilot injection act as a catalyst for combustion of main fuel.

마이크로 가스터빈을 위한 하이브리드/이중 선회제트 연소기의 개발 (Part II: 비반응 유동구조에 관한 수치해석) (Development of a Hybrid/Dual Swirl Jet Combustor for a Micro-Gas Turbine (Part II: Numerical Analysis on Isothermal Flow Structure))

  • 문선여;황해주;황철홍;이기만
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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    • pp.201-202
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    • 2012
  • The isothermal flow structure and mixing characteristics of a hybrid/dual swirl jet combustor for micro-gas turbine were numerically investigated. Location of pilot nozzle, angle and direction of swirl vane were varied as main parameters with constant fuel flow rates for each nozzle. As a result, the variation in location of pilot nozzle resulted in significant change in turbulent flow field near burner exit, in particular, center toroidal recirculation zone (CTRZ) as well as turbulent intensity, and thus flame stability and emission characteristics might be significantly changed. The swirl angle of $45^{\circ}$ provided similar recirculating flow patterns in a wide range of equivalence ratio (0.5~1.0). Compared to the co-swirl flow, the counter-swirl flow leaded to the reduction in CTRZ and fuel-air mixing near the burner exit and a weak interaction between the pilot partially premixed flame and the lean premixed flame. With the comparison of experimental results, it was confirmed that the case of co-swirl flow and swirl $angle=45^{\circ}$ would provided an optimized combustor performance in terms of flame stability and pollutant emissions.

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유증기 연소처리를 위한 난류 부분예혼합화염의 활용 및 유동장 가시화 (Utilization and Visualization of Turbulent Partially-premixed Flame for Combustion of Inert-gas-diluted VOC)

  • 안태국;남연우;박선호
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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    • pp.193-196
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    • 2015
  • Combustion of low concentration VOC in inert gas around the flammability limit has been experimentally studied. Streams of nitrogen and propane mixture with various compositions and flow conditions were treated by a turbulent partially-premixed pilot flame. HC and CO contents in exhaust gas measured and the flow patterns were visualized. The results suggested that there exists an optimal mixture velocity range for efficient combustion treatment for each flow condition and composition of the mixture.

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파일럿 분사시의 커먼레일식 직분식 가시화 디젤엔진의 연소 및 Soot분포 특성에 관한 연구 (A Study on the Combustion Characteristic and Soot Distribution of a Common Rail Type D.I.Diesel Visualized Engine with Pilot Injection)

  • 이재용;한용택;이기형;이창식
    • 한국자동차공학회논문집
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    • 제11권6호
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    • pp.37-43
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    • 2003
  • The objective of this work is to investigate the effect of swirl, injection pressure and pilot injection on D.I. diesel combustion by using a transparent engine system. The test engine is equipped with common rail injection system to obtain high pressure and to control injection timing and duration. In this study, the combustion analysis and steady flow test were conducted to estimate the heat release rate from in-cylinder pressure. Soot distribution in diffusion flame according to swirl ratio, injection pressure and pilot injection was investigated by using LII technique. As the results, high injection pressure was found to shorten ignition delay as well as enhance peak pressure and heat release rate was greatly affected by injection timing and pilot injection. In addition, the results showed that the period of soot formation corresponded to the diffusion flame.

음향가진과 보염기형상이 확산화염의 특성에 미치는 영향 (Effect of Acoustical Excitation and Flame Stabilizer on a Diffusion Flame Characteristics)

  • 전충환;장영준
    • 한국연소학회지
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    • 제3권1호
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    • pp.1-10
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    • 1998
  • Lots of techniques are adopted for a flame stabilization and a high-load combustion. But the techniques being used were passive control method which have to change combustor shape like pilot flame, flame stabilizer, pressure profile, etc. Active control method which is not necessary to transform its shape is employed. Acoustical excitation is broadly used for its convenience in changing frequency and intensity. Both acoustical excitation and flame stabilizers were adopted to study their relationship. So, we investigated flammability limits. Flame visualization. And mean temperature in the condition of various frequencies, intensities, and flame stabilizers. As a consequence, flammability limit were advanced in acoustically excited flame at some frequencies. Coherent structure was extended to the downstream region through acoustical excitation and a size of vortice was curtailed. Also width of recirculation zone was magnified. In addition, Effects of acoustical excitation was stood out at 25mm flame stabilizer rather than another ones.

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