• 제목/요약/키워드: Initial flame

검색결과 208건 처리시간 0.02초

대형 LPG 엔진의 흡입 스월비에 따른 연소성능에 관한 연구 (The Effect of Intake Swirl Ratios on Combustion Performance in a Heavy-Duty LPG Engine)

  • 한병주;김창업;강건용;이창식
    • 한국자동차공학회논문집
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    • 제9권5호
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    • pp.46-53
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    • 2001
  • To optimize the intake flow condition in the heavy-duty LPG SI engine, five different swirl ratios of intake port were investigated experimentally by oil spot method, LDV and single cylinder engine test. The flow characteristics near the piston surface were observed by oil spot method and magnitudes of swirl flow were measured quantatively by LDV method in the steady flow rig. The engine performances of various swirl flow were also tested with the heavy-duty LPG SI single cylinder engine. In the results, high swirl ratio, above $R_s$=2.3, was not suitable to develope a stable flame kernel and to produce high engine performance. Especially it was more serious under lean burn conditions, since turbulence intensity was smaller than bulk flow though those are increased together. These results were also confirmed by LDV measurement and oil spot method. On the contrary, low swirl ratio($R_s$=1.3) is not good to propagate a flame since the turbulence intensity and bulk flow are vanished during compression stroke and low swirl ratio has too weak initial energy for stable combustion. Therefore, the of optimized swirl ratio f3r the heavy-duty LPG engine in this work was found around $R_s$=2.0.

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TiO2가 코팅된 Polyethylene 입자를 이용한 페놀과 톨루엔의 광분해 (Photo-degradation of Phenol and Toluene by Using the TiO2-coated Polyethylene Particles)

  • 김동주;최상근;조준형;김교선
    • 산업기술연구
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    • 제24권B호
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    • pp.133-138
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    • 2004
  • The photodegradation of phenol and toluene with the $TiO_2$-coated polyethylene (PE) particles were investigated in the slurry type photocatalytic reactor, changing the $TiO_2$ particle sizes, initial phenol and toluene concentrations, and the oxygen flow rate. The nano-sized $TiO_2$ photocatalyst particles were prepared by the diffusion flame reactor and they were coated onto PE particles by using the hybridization system for the efficient recollection of $TiO_2$-coated particles after photodegradation experiments. The degradation efficiencies of phenol and toluene with the $TiO_2$-coated PE particles were more than 90% after photodegradation of 80 minutes for most cases. The efficiencies of photodegradation with the $TiO_2$-coated PE particles were found to be lower than those by the pure $TiO_2$ particles by 50%, because of the decrease in specific surface area of $TiO_2$ particles in PE particles.

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면 편성물의 방염처리에 의한 형태안정성의 변화 (Changes of Dimensional Stability of Cotton Knitted Fabrics after Flame Resistant Treatment)

  • 지주원
    • 한국의류학회지
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    • 제29권9_10호
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    • pp.1274-1284
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    • 2005
  • Effect of fixation methods and relaxation treatment on the dimensional stability and physical properties of MDPPA/HMM treated cotton knitted fabrics were studied. Combination of four different fixation methods - relaxation, swelling agent treatment, pad dry cure fixation, and wet fixation - were applied to flame retardant finish of 4 kinds of cotton knitted fabric with MDPPA/HMM. Then these fabrics were washed 10 times. As a result, In swelling treatment on 10G showed relatively higher value of length shrinkage than 14G. Length and width shrinkage were increased by initial washing treatment and no further change was shown after 6 washing cycles. After 10 washing cycles, length and width shrinkage decreased. The KES standardized basic value of B/W, 2HB/W and bursting strength of interlock were relatively larger than those of single jersey. The values of B/W and 2HB/W of cotton knitted fabrics were increased by relaxation and washing treatment but were decreased by swelling treatment. In addition, the bursting strength of the cotton knitted fabrics was decreased after fusing, washing and relaxation treatment.

액적배열연소의 상호간섭에 관한 실험적 연구 (An Experimental Study About Interaction of Droplet Array Combustion)

  • 김흥식;백승욱;박준성
    • 대한기계학회논문집B
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    • 제26권10호
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    • pp.1355-1363
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    • 2002
  • An experimental study was conducted to investigate the interaction phenomena of droplet array combustion in ambient environment. The droplet with 1 mm in diameter was supported from an optical fiber and ignited with a hot wire. Combustion lifetimes and burning rate constants were measured for fuel of nheptane according to parameters, which were junction and suspender spacings, and array configuration. Results show that the burning process considerably depends on the initial away configuration. The d$^2$-law is found to be correct when applied to both of the droplets in away and the single droplet. For separation distance of about 5mm, there exists a critical state. So the transition from a merged flame to separated flames occurs and burning velocity is much faster than before. Combustion lifetime of the lower droplet is shorter than that of the upper droplet in the two-dimensional arrays combustion. Burning rate constants of the droplets in arrays are smaller than that of the single droplet, while they become higher as separation distance increases. Combustion lifetimes of the droplets in arrays are longer than that of the single droplet and decrease as separation distance increase. It is concluded that the array configuration and the mergedness of the flame are the most important factors governing multi-droplet combustion.

Determination of Trace Amounts of Lead and Copper in Water Samples by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

  • Shemirani, Farzaneh;Abkenar, Shiva Dehghan;Khatouni, Asieh
    • Bulletin of the Korean Chemical Society
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    • 제25권8호
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    • pp.1133-1136
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    • 2004
  • The need for highly reliable methods for the determination of trace metals is recognized in analytical chemistry and environmental science. A method based on the cloud-point extraction (CPE) technique for the trace analysis of Pb and Cu in water samples is described in this study. The analytes in the initial aqueous solution are complexed with pyrogallol, and 0.1%(w/v) Triton X-114 is added as surfactant. Following phase separation at $50^{\circ}C$, based on the cloud point of the mixture and dilution of the surfactant-rich phase with acidified methanolic solution, the enriched analytes are determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, the enrichment factors of Pb and Cu were found to be 72 and 85, respectively. Under optimum conditions, the preconcentration of 60 mL of samples in the presence of 0.1%(w/v) Triton X-114 permitted the detection of 0.4 ${\mu}gL^{?1}$ of Pb and 0.05 ${\mu}gL^{?1}$ of Cu. The proposed method was applied successfully to the determination of Pb and Cu in water samples.

직접분사식 디젤기관의 연소실 형상과 화염의 발달 (2)-유화액연료용 연소실의 형상- (The Effect of Air and Spray Turbulence on the Progress in a D.I. Diesel Engine(II)-Combustion Chamber Design for the Use of Emulsified Diesel Oil with Water Particles-)

  • 방중철;태전간랑
    • 대한기계학회논문집
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    • 제19권11호
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    • pp.3054-3062
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    • 1995
  • Recently, the improvement of fuel economy and the reduction of exhaust smoke and NOx have been successfully achieved by supplying diesel engines with emulsified diesel oil with water particles. In the present paper, the difference between the combustion of injected emulsified fuel and that of diesel oil spray is clarified by means of taking high-speed and color photographs of the flames in the engine cylinder. As the results, the two kinds of fuels show different combustion behavior each other in the growth of initial flame and in the termination of combustion process in the cylinder. Then, suitable combustion chamber design for the use of emulsified fuel is discussed on the basis of experimental data for various distribution of spray in different kinds of piston cavities. Some methods of clearing troubles caused by emulsified fuel injection are also discussed on the basis of performance tests with a remodeling test engine.

연료 희박 재연소 과정에 의한 NOx 저감 및 CO 발생에 대한 실험적 연구 (Experimental Study on NOx Reduction and CO Emission by Fuel Lean Reburning Process)

  • 이창엽;김학영;백승욱;김세원
    • 대한기계학회논문집B
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    • 제32권3호
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    • pp.216-223
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    • 2008
  • Reburning is a useful technology in reducing nitric oxide through injection of a secondary hydrocarbon fuel. In this paper, an experimental study has been conducted to evaluate the effect of fuel lean reburning on $NO_X/CO$ reduction in LPG flame. Experiments were performed in flames stabilized by a co-flow swirl burner, which was mounted at the bottom of the furnace. Tests were conducted using LPG gas as the reburn fuel as well as the main fuel. The effects of reburn fuel fraction and injection location of the reburn fuel were studied when the fuel lean reburning system was applied. The paper reports data on flue gas emissions and temperature distribution in the furnace for a wide range of experimental conditions. At steady state, temperature distribution and emission formation in the furnace have been measured and compared. This paper makes clear that in order to decrease both NOx and CO concentrations in the exhaust when the fuel lean reburning system was adapted, it is important that the control of some factors such as initial equivalence ratio, reburn fuel fraction and temperature of reburn fuel injection region. Also it shows the fuel lean reburning is also effective method to reduce NOx as much as reburning.

SOOT YIELD OF TURBULENT PREMIXED PROPANE-OXYGEN-INERT GAS FLAMES IN A CONSTANT-VOLUME COMBUSTOR AT HIGH PRESSURES

  • Bae, M.W.;Bae, C.W.;Lee, S.K.;Ahn, S.W.
    • International Journal of Automotive Technology
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    • 제7권4호
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    • pp.391-397
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    • 2006
  • The soot yield has been studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effect of pressure, temperature and turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degrees intervals in order to observe the soot formation under high temperature and high pressure. The eight converged flames compress the end gases to a high pressure. The laser schlieren and direct flame photographs with observation area of 10 mm in diameter are taken to examine the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in-situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. The changes of pressure and temperature during soot formation are controlled by varying the initial charging pressure and the volume fraction of inert gas compositions, respectively. It is found that the soot yield increases with dropping the temperature and raising the pressure at a constant equivalence ratio, and the soot yield in turbulent combustion decreases as compared with that in laminar combustion because the burnt gas temperature increases with the drop of heat loss for laminar combustion.

비정상 대향류 확산 화염의 소화 한계 확장에 대한 실험적 연구 (An Experimental Study on the Extinction Limit Extension of Unsteady Counterflow Diffusion Flames)

  • 이은도;이기호;오광철;이의주;신현동
    • 대한기계학회논문집B
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    • 제29권3호
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    • pp.390-401
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    • 2005
  • In this study, extinction limit extension of unsteady $(CH_{4}+N_{2})$/air diffusion flames was investigated experimentally. A spatially locked flame in an opposing jet burner was perturbed by linear velocity variation, and time-dependent flame luminosity, transient maximum flame temperature and OH radical were measured over time with the high speed camera, Rayleigh scattering method and OH laser-induced fluorescence, respectively. Unsteady flames survive at strain rates that are much higher than the extinction limit of steady flames, and unsteady extinction limits extend as the slope of the strain rate increases or the initial strain rate decreases. We verified the validity of the equivalent strain rate concept by comparing the course of unsteady extinction process and steady extinction process, and it was found that the equivalent strain rate concept represents well the unsteady effect of a convective-diffusive zone. To investigate the reason of the unsteady extinction limit extension, we subtracted the time lag of the convective-diffusive zone by using the equivalent strain concept. Then the modified unsteady extinction limits become smaller than the original unsteady extinction limits, however, the modified unsteady extinction limits are still larger than the steady extinction limits. These results suggest that there exist the unsteady behavior of a diffusive-reactive zone near the extinction limit due to the chemical non-equilibrium states associated with unsteady flames.

50 N급 아산화질소/에탄올 추력기의 점화 과도 유동장 가시화 (Visualization of Transient Ignition Flow-field in a 50 N Scale N2O/C2H5OH Thruster)

  • 김도헌;박재현;유명곤;이경은;구자예
    • 한국추진공학회지
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    • 제18권6호
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    • pp.11-18
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    • 2014
  • 아산화질소/에탄올 추진제 조합을 사용하는 50 N급 추력기 분사기 인접부에서 shadowgraph 기법을 사용하여 연소 유동장을 가시화하였다. 설계 작동조건에서 폭발성 점화가 일어났으며, 급격히 팽창하는 연소가스에 의해 순간적으로 소염되는 현상이 관찰되었다. 최초 점화로부터 약 83 ms 뒤 추진제 분무는 재점화 되었으며, 그로부터 약 23 ms 후 화염이 안정화되는 것이 관찰되었다. 동일한 시퀀스에서 설계 조건보다 산화제 유량을 증가시킨 경우, 소염 현상 없이 완만한 연소 압력 과도 특성을 보였으며 최초 점화로부터 약 17 ms이내에 화염 안정화가 이루어졌다. 이는 점화 직전의 연소기 내부 미연 추진제 혼합 향상에 의한 것으로 생각되었다.