• Research Article

    Effect of H2O addition on Downstream Interaction in CO-O2 Premixed Flames

    CO-O2 예혼합화염의 후류상호작용에 관한 H2O 첨가 효과

    Gyeong Taek Kim, Chun Sang Yoo, Jeong Park, Suk Ho Chung and Oh Boong Kwon

    김경택, 유춘상, 박정, 정석호, 권오붕

    Numerical study is conducted to understand the effects of additional H2O on downstream interaction in CO-O2 counterflow premixed flames. … + READ MORE
    Numerical study is conducted to understand the effects of additional H2O on downstream interaction in CO-O2 counterflow premixed flames. Adding 1% H2O to fuel side for freely-propagating premixed flame with CO-O2 mixture increases laminar burning velocity from 5.3 cm/s to 81.8 cm/s in a way that the main oxidation reaction is changed from CO + 0.5O2 → CO2 to CO + OH → CO2 + H. When global strain rate reaches 23.5 s-1 for interacting CO-O2 premixed flames, the flames cannot be sustained. While for (0.1% H2O + CO)-O2 premixed flames, the flame is extinguished at 2687 s-1. Because the fuel Lewis number and effective one are larger than unity, downstream interaction are mainly through chemical one. For lean-lean (rich-rich) flames, the production of O (H) radical is vigorous, resulting in the formation of OH via H2O + O → OH + OH (H2O + H → OH + H2). These different chemical situations can influence downstream interactions in various flame configurations. Such interesting aspects in chemical interactions are presented and discussed in detail. - COLLAPSE
    31 March 2022
  • Research Article

    Self-Excited Azimuthal Instabilities in a Can-Annular Combustion System

    캔-환형 연소기의 방위 방향 자발 불안정성

    Kihun Moon and Kyu Tae Kim

    문기훈, 김규태

    Driving mechanisms of self-excited azimuthal instabilities of can-annular lean-premixed combustors were experimentally investigated in combination with 3D FEM-based eigenvalue analysis and acoustic … + READ MORE
    Driving mechanisms of self-excited azimuthal instabilities of can-annular lean-premixed combustors were experimentally investigated in combination with 3D FEM-based eigenvalue analysis and acoustic wave decomposition method. We show that the fluctuation energy required to excite a standing azimuthal mode in annular cross-talk section is supplied locally in individual combustors by meeting the Rayleigh criterion, while the behavior in four combustor sections is dictated by degenerate longitudinal-mode at the same frequency. - COLLAPSE
    31 March 2022
  • Research Article

    Artificial Neural Network for the Representation of Chemical Kinetics in Reactive Flows

    인공신경망을 이용한 반응유동 수치해석의 반응기구 대체 연구

    Jeongyong Lee and Bok Jik Lee

    이정용, 이복직

    Reducing the computational cost of chemical kinetics is essential to implement detailed reaction mechanisms into realistic numerical simulations. The present study introduces … + READ MORE
    Reducing the computational cost of chemical kinetics is essential to implement detailed reaction mechanisms into realistic numerical simulations. The present study introduces an artificial neural network (ANN) that can predict the chemical source terms of each species for the given species mass fractions and temperature, replacing the conventional chemical terms based on Arrhenius rate equations. The ANN was trained using numerical solutions of opposed-flow flames that can cover a wide range of combustion problems. The OPPDIF code and a detailed reaction mechanism for hydrogen and air with 9 species and 19 reactions were used to generate a training dataset comprised of species mass fractions, temperature, chemical source terms. A physics-guided loss function that considers mass conservation of elemental species was employed. Using the trained ANN, a modified OPPDIF, named OPPDIF-ANN, was prepared by replacing the CKWYP with CKWYP-ANN evaluating the chemical sources via the trained ANN. For multiple global strain rate conditions, the solutions using ANN-based source terms were proven to be identical to those using Arrhenius source terms. - COLLAPSE
    31 March 2022
  • Research Article

    Measurement and Calculation of Flame Speed of LFG at Lean Burn and Turbocharged Engine Conditions

    LFG 엔진의 희박 과급 연소 조건에서 화염 속도 측정 및 계산

    Wonil Jeon, Kyoungsu Kim, Kyungho Choi, Minwoo Cheon, Jooil Kim, Jeongbae Park, Bada Kim, Jeongho Lee and Daeyup Lee

    전원일, 김경수, 최경호, 천민우, 김주일, 박정배, 김바다, 이정호, 이대엽

    In order not to release Landfill gas (LFG) having a high global warming potential into the atmosphere and to burn in an … + READ MORE
    In order not to release Landfill gas (LFG) having a high global warming potential into the atmosphere and to burn in an internal combustion engine for power generation, a study was conducted to measure and calculate flame speed under turbocharged and lean burn conditions of spark ignition engine. By changing the ratio between methane and carbon dioxide, which are the main components of LFG, experiments were conducted to measure the flame speed using a constant volume combustion chamber. Also comparative analysis was performed with data obtained using CHEMKIN library with GRI 3.0 mechanisms. In addition, using the data obtained through numerical analysis the correlations were derived to calculate the flame speed as a function of equivalence ratio. This study concludes that the overall trend of LFG flame speed is in good agreement between the experimental and calculated results. Using the correlated equation derived from the results of this study, it is possible to estimate the flame speed of LFG under turbocharged and lean burn of spark ignition engine. - COLLAPSE
    31 March 2022
  • Technical Notes

    Survey on Research and Development of E-Fuel

    탄소중립연료(E-Fuel) 연구개발 현황

    Jongyoon Lee and Bok Jik Lee

    이종윤, 이복직

    As climate change menaces the existence of humankind, the realization of carbon neutrality through decarbonization has been raised as the prime objective … + READ MORE
    As climate change menaces the existence of humankind, the realization of carbon neutrality through decarbonization has been raised as the prime objective of this century. Unlike passenger cars which can be easily electrified, ships and aircrafts powered by battery or fuel cell are difficult to realize since these vehicles require fuels with high energy density. In these circumstances, e-Fuel is emerging as a next-generation liquid fuel with which net-zero emission can be achieved. E-Fuel is synthesized from captured carbon dioxide and green hydrogen, and it can directly replace conventional fossil fuels. Carbon dioxide released while burning e-Fuel in an engine is recaptured during the synthesizing process of e-Fuel itself so that the closed carbon cycle can be established. In this paper, fundamental introduction to e-Fuel and the current status of research and development of e-Fuel are presented. - COLLAPSE
    31 March 2022