• Research Article

    An Effect of Dilution and Turbulence on Formation of MILD Combustion

    희석율과 난류강도에 따른 수소 MILD 연소 형성

    Ho Yeon Lee, Sang Soon Hwang

    이호연, 황상순

    An effect of dilution and turbulence on the formation of MILD combustion was numerically analyzed using κ-ε (SKE) and Eddy Dissipation Concept … + READ MORE
    An effect of dilution and turbulence on the formation of MILD combustion was numerically analyzed using κ-ε (SKE) and Eddy Dissipation Concept (EDC) model appropriate to MILD combustion simulation. Results show that the temperature distribution of hydrogen and methane were similar under the condition of 3% diluted oxygen but the combustion reaction rate of hydrogen is increased as the flame temperature was about 80 degrees higher. This higher reaction rate tends to narrow MILD zone compared to methane case. As the dilution effect is increased and the dilution oxygen concentration becomes lower, the MILD area with Da<1 is shown to be wider with no significant difference. When the turbulence intensity is increased from 2.5% to 5%, the MILD region with Da<1 tends to be formed in a wider area, which is more favorable condition for hydrogen MILD combustion. - COLLAPSE
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    31 March 2023

  • Research Article

    Combustion Instability Characteristics according to Swirl Number and Combustion Chamber Length in a Gas Turbine Combustor

    가스터빈 연소기에서 스월 수와 연소실 길이에 따른 연소불안정 특성

    Sunwoo Han, Shinwoo Lee, Donghyun Hwang, Kyubok Ahn

    한선우, 이신우, 황동현, 안규복

    Combustion instability characteristics were investigated through combustion tests using ethylene and air in a model gas turbine combustor. At various flow conditions, … + READ MORE
    Combustion instability characteristics were investigated through combustion tests using ethylene and air in a model gas turbine combustor. At various flow conditions, the swirl number and combustion chamber length were changed independently. Dynamic pressure transducer and photomultiplier tube with a bandpass filter were used to measure pressure oscillations and heat release fluctuations. Analysis of phase difference and flame structure showed that the unstable mode had resonant frequencies of the combustion chamber and the inlet mixing section. When the swirl number increased, it was confirmed that the instability mode corresponding to the resonance frequency of the inlet mixing section disappeared. In addition, resonance mode analysis was performed using the OSCILOS code and compared with the experimental results. - COLLAPSE
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    31 March 2023

  • Research Article

    A Numerical Study of Unsteady Combustion Characteristics of H2 Enriched Natural Gas

    수소가 첨가된 천연가스의 비정상연소특성에 대한 수치해석적 연구

    Tae-Kyun Oh

    오태균

    The increase of 1.5°C global warming above the pre-industrial level has directly caused large risks of ecosystem and human life as well … + READ MORE
    The increase of 1.5°C global warming above the pre-industrial level has directly caused large risks of ecosystem and human life as well as severe changes in the climate. Electricity production in Korea is achieved in a large portion(44% as of 2020) by coal thermal power generation during which it discharges greenhouse gases, PM and nitric oxide responsible for photochemical smog in a crowded city. The hydrogen enriched LNG is a powerful alternative of coal as a fuel generation because it emits less pollutants and is considered a clean fuel for thermal power generation. In the present study, combustion analyses have been numerically done on various mixed fuels of methane, ethane and hydrogen as a model of hydrogen enriched natural gas in a gas turbine combustor. GRI3.0 kinetic mechanism which consists of 53 chemical species and 325 reaction steps has been used to calculate steady and unsteady combustion process of hydrogen enriched natural gas. Emissions, heat release rate and ignition delay time in a premixed flame have been numerically investigated through post-processing procedure to simulate gas turbine combustion in a thermal power station. - COLLAPSE
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    31 March 2023

  • Research Article

    Flame Structure and NO emission in A Single-stage (Methane +Ammonia)/Air Premixed Single Combustor

    (메탄+암모니아)/공기 예혼합 1단 연소기에서의 화염구조와 NO 배출

    Juhan Kim, Chun Sang Yoo, Suk Ho Chung, Jeong Park

    김주한, 유춘상, 정석호, 박정

    Numerical study is conducted to clarify flame structures and NO emissions in a single-staged (ammonia + methane)/air premixed combustion, which can be … + READ MORE
    Numerical study is conducted to clarify flame structures and NO emissions in a single-staged (ammonia + methane)/air premixed combustion, which can be presumed with a counterflow configuration. To clarify the important role of downstream interaction on flame characteristics and NO emissions, injecting (80% methane+20% ammonia)/air mixtures to the ambiences of nitrogen and air is studied. When lean blended fuel/air premixed mixtures are injected to the ambiences of nitrogen and air, there are no significant change in flame structure and NO emission. When the rich premixed mixtures are injected to air (nitrogen) ambience, an interacting flame consisting of a rich premixed flame and a diffusion flame (a single rich premixed flame) is generated. The difference in such flame configurations completely alters flame structure and NO emission behavior. The present results can be utilized as a baseline case in reducing NO emission via various combinations such as ammonia-air, methane-air, pure air, and (ammoniar+methane)/air in the secondary zone of a two-stage ammonia blended methane/air premixed combustor. - COLLAPSE
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    31 March 2023

  • Technical Notes

    A Study on Reduction of Startup Period of Catalytic Combustor for CO2 Generator

    촉매연소형 이산화탄소 발생기의 시동기간 단축에 관한 연구

    Pilsoo Jeong, Byungchul Choi, Donguk Park, Hyunjo Kwon, Woobin Kim, Changmin Jin

    정필수, 최병철, 박동욱, 권현조, 김우빈, 진창민

    The objective of this study is to investigate reduction method of startup period that is a kind of combustion instability of catalytic … + READ MORE
    The objective of this study is to investigate reduction method of startup period that is a kind of combustion instability of catalytic combustors with various ambient humidity and temperatures. Ignition did not occur in a high humidity environment with a relative humidity of 80% or more, and a longer preheating time was required in 15°C environmental condition. To solve the problem, we devised a method by adding a small amount of ethanol during the preheating period at specified catalyst temperature conditions. It was possible to stably ignite the catalyst even in a high humidity environment. The ignition time was able to shorten the preheating time by up to 55% regardless of the influence of ambient temperature and humidity. The optimum ethanol supply condition is to inject a total amount of 20 cc at a injection rate of about 0.8 cc/s when the range of catalyst temperature is 200 to 220°C. - COLLAPSE
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    31 March 2023

  • Research Article

    Influence of Pairing Asymmetry on Thermoacoustic Instabilities in a Can-annular Combustor

    페어링 비대칭성이 캔-환형 연소기의 열음향 불안정에 미치는 영향

    Dahyun Bae, Kihun Moon, Kyu Tae Kim

    배다현, 문기훈, 김규태

    The influence of pairing asymmetry on thermoacoustic instabilities was experimentally investigated in an odd-numbered can-annular combustion system, using 3D FEM-based Helmholtz simulation … + READ MORE
    The influence of pairing asymmetry on thermoacoustic instabilities was experimentally investigated in an odd-numbered can-annular combustion system, using 3D FEM-based Helmholtz simulation and acoustic wave decomposition method. We show that a pair of degenerate mode is split into two modes with a frequency difference of 6 Hz, which is induced by a pairing-asymmetry-related geometrical property. Interestingly, the modal interaction between splitting modes gives rise to the periodic transition between standing and spinning azimuthal instabilities in the annular cross-talk section. - COLLAPSE
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    31 March 2023
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