• Journal of the Korean Society of Combustion
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• v.3 no.2
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• pp.13-27
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• 1998

The optimization of frontal device including fuel nozzle and swirler is required to secure the mixing of fuel and air and the combustion stability leading the reduction of pollutant emissions and the increase of combustion efficiency in gas turbine combustor. The effects of injection nozzle and swirler on the flow field, spray characteristics and consequently the combustion stability, were experimentally investigated by measuring the velocity field, droplet sizes of fuel spray, lean combustion limit and the temperature field in the main combustion region. Flow fields and spray characteristics were measured with APV(Adaptive Phase Doppler Velocimetry) under atmospheric condition using kerosine fuel. Temperatures were measured by Pt-Pt13%Rh, R-type thermocouple which was 0.2mm thick. Spray and flame was visualized by ICCD(Intensified Charge Coupled Device) camera. It was found that the dual swirler resulted in the biggest recirculation zone with the highest reverse flow velocity at the central region, which lead the most stable combustion. The various combustion characteristics were observed as a function of the geometries of injector and swirler, that gave a tip for the better design of gas turbine combustor.

• Journal of the Korean Society of Combustion
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• v.20 no.4
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• pp.10-18
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• 2015

Combustion instability is a major issue in design and maintenance of gas turbine combustors for efficient operation with low emissions. With the thermoacoustic view point the instability is induced by the interaction of the unsteady heat release of the combustion process and the change in the acoustic pressure in the combustion chamber. In an effort to study the combustion dynamics of gas turbine combustors, Morgans et al (2014) have developed OSCILOS (open source combustion instability low order simulator) code and it is currently available online. In this study the code has been utilized to predict the combustion instability of a reported case for lean premixed gas turbine combustion, and then its prediction results have been compared with the corresponding experimental data. It turned out that both the predicted and the experimental combustion instability results agree well. Further the effects of some typical inlet acoustic boundary conditions on the prediction have been investigated briefly. It is believed that the validity and effectiveness of the open source code is reconfirmed through this benchmark test.

• 방재와보험
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• s.131
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• pp.54-57
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• 2009

불은 물질이 산소와 화합하여 연소하는 물리적 현상이지만 신앙적 믿음과 종교적 의례에서는 다양하게 상징화되어 문화적 암호로 쓰여온지 오래다. 그래서 불은 인간사에서 어느 것보다도 중요한 구실을 해 왔으며 오늘날 현대인들이 누리고 있는 온갖 문명도 불이 있기에 가능한 것이다. 그러나 현대인의 관념에서는 불에 대한 존엄성이 점차적으로 희박해지고 있는 게 사실이다. 그렇지만 종교 신앙적 측면에서는 아직도 불은 그 어느 것보다도 중요하게 다루어지고 있다. 특히 무속신앙과 가신신앙에서는 불에 대한 관념이 명확할 뿐만 아니라 불에 대한 활용도 옛 법에 따라 적절하게 대응하고 있음을 알 수 있다. 따라서 본 글에서는 무속신앙에서 불신(조왕신)이 어떠한 구실을 하고 있는지, 그리고 불이 마을신으로 모셔지는 경위는 어떠한 것인지와 더불어 가신신앙에서의 조왕그릇과 조왕동토부에 대해 알아 보고자 한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.57-60
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• 1999

순환유동층 보일러는 연소로 (상승관: riser)내에 공기를 고속으로 주입하여 비말동반되는 고체입자를 사이클론에서 포집 하여 재주입하는 유동층을 이르는 것으로, 난류유동층(turbulent fluidized bed), 고속유동층(fast fluidized bed) 그리고 희박상 유동(dilute phase flow) 영역에서 조업이 이루어진다. 순환유동층은 비교적 높은 기체 유속에서 조업이 이루어지기 때문에 고체입자의 혼합 및 비산 그리고 재순환이 격렬하게 이루어지고, 기-고체간 접촉효율 및 전열계수가 높아 전체적인 처리량 및 효율이 좋은 장점을 가지고 있다.(중략)

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.98-106
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• 2011

This paper reviews the state-of-the-art thermoacoustic(TA) modeling techniques and research trend to predict major parameters determining combustion instabilities in lean premixed gas turbine combustors. Linear TA modeling results give us an information on eigenfrequencies and initial growth rate of the instabilities. For the prediction, linear relation equation between acoustic waves and heat release oscillations should be derived in the determined system. Key information for this analysis is to determine the heat release fluctuations in the combustor, which is typically obtained by using n-${\tau}$ function from flame transfer function measurements and/or predictions. Great advancement in the linear TA modeling has been made over a couple of decades, and some successful prediction results have been reported in actual gas turbine combustors. However nonlinear TA model developments which are required to analyze nonlinear system behaviors such as limit cycle saturation and transition phenomena are still limited in a very simple system. In order to fully understand combustion instabilities in a complicated real system, nonlinear flame dynamics and acoustic wave interaction with nonlinear system boundary conditions should be explained from the nonlinear TA model developments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.4
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• pp.309-315
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• 2012

Catalytic combustion is generally accepted as one of the environmentally preferred alternatives for heat and power from fossil fuels, as it has the advantage of stable combustion under very lean conditions with such low emissions as UHC, CO, and NOx. In this work, therefore, comparative numerical studies on the catalytic combustion behaviors over Pd-based catalysts have been conducted with the gaseous $CH_4$, $C_2H_6$, and $C_3H_8$. In the following, after introducing the governing equations with 1D channel and Langmuir-Hinshelwood models, numerical investigations on the catalyst performance are conducted by changing such various parameters as inlet temperature, excess air ratio, and space velocity. The numerical results show that outlet temperature and conversion of $C_3H_8$ are highest among others because of its chemical structure and reactivity.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.149-151
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• 2014

The blowoff phenomenon was experimentally investigated in a ducted combustor according to the acoustic excitation. The blowoff equivalence ratio rapidly increases at specific acoustic excitation frequencies. A resonance phenomenon occurs when the excitation frequency approaches the harmonic frequency of the combustor. The resonance increases the velocity fluctuation in the combustor and the infiltration velocity of the unburned gas in the shear layer. Consequently, the mixture velocity exceeds the burning velocity and the blowoff occurs at the higher equivalence ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.36-48
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• 1997

In order to establish the ignition system for lean burn, the influence of the number of spark plug, spark times and spark intervals on discharge pattern of spark energy on ignitability and combustion characteristics were evaluated. It showed that, ignitability remarkably increased with the case of multiple spark ignition system than with the case of single spark and the lean limit extended fuel/air equivalence ratio by 0.1, the increase of magnitude and lasting time of capacity component and inductance component was multi spark discharge in a row.

• Journal of the Korean Society of Combustion
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• v.10 no.2
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• pp.35-41
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• 2005

Behaviors of lean premixed flame of propane/air and methane/air flame anchored by a pilot flame in a tube were investigated experimentally varying the mean velocity from 10 to 140 cm/s and the equivalence ratio from 0.45 to 0.8. Behaviors of both flames are divided into five regions of stable, flash-back, tail-out, flickering and vibrating. General characteristics of each region and Le number effect are investigated. Two main instabilities, flickering and vibration, are both unstable but the instability mechanism, the frequency and the amplitude of pressure fluctuation are different. In the edge of the vibrating region, pressure fluctuation repeats generation and extinction. Repeated growth and decrease of the amplitude of pressure fluctuation are explained by Rayleigh#s index.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.80-89
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• 1992

An experimental study of in-cylinder of flow and combustion characteristics in two gasoline engines of different intake ports which are denoted as original port and masked shroud head (MSH) ports is presented. The flows generated by the MSH and the original port are invest- igated by laser Doppler velocimeter(LDV) under steady flow and motoring (non-firing) condit -ions. Combustion characteristics with different swirl levels produced by two intake ports are analyzed by combustion pressure measurement and statistical calculation. The swirl inside the cylinder of the MSH port engine is found to be much higher than the original port, and the MSH has a large eddy motion of cylinder diameter size. Using ensemble average method to valuate engine turbulence under motoring condition, the MSH port engine is shown to have h -igher turbulence intensity than the original port, so that the effect of the MSH port on fast burn is shown. Also the cyclic variations of peak pressure and the reaching time in the MSH port are apparently reduced.