• Research Article

    Study on Flame Structure and Combustion Instability in a Swirl-Stabilized Combustor

    스월-안정화 연소기에서 화염구조와 연소불안정에 대한 연구

    Donghyun Hwang, Sujin Bak, Kyubok Ahn

    황동현, 박수진, 안규복

    Flame structure and combustion instability characteristics in a swirl-stabilized combustor were investigated by changing fuel, inlet mean velocity, equivalence ratio, and swirler ... + READ MORE
    Flame structure and combustion instability characteristics in a swirl-stabilized combustor were investigated by changing fuel, inlet mean velocity, equivalence ratio, and swirler geometry. Two different premixed gases consisting of air and hydrocarbon fuels (C2H4, CH4) were supplied to a combustion chamber through an inlet section and an axial swirler. Dynamic pressure transducer and ICCD camera with a bandpass filter were used to measure pressure fluctuations and flame structures, respectively. The experimental results showed that the pressure fluctuations significantly increased, accompanied by the flame structure transition under certain conditions. Hollow cone flames were mainly formed under stable combustion, but heat release was distributed near the central axis of the combustion chamber under the combustion instability. - COLLAPSE
    June 2020
  • Research Article

    Development and Application of a Numerical framework for the Simulation of Supercritical Diesel Combustion using Pressure based SLAU2 with Real Fluid Flamelet Progress Variable Model

    초임계 디젤연소 모사를 위한 압력기반 SLAU2와 실제유체 FPV 모델을 활용한 수치해석 기법의 개발과 적용

    Namsu Kim, Yongmo Kim

    김남수, 김용모

    A numerical framework for efficient and robust simulation of supercritical Diesel combustion is developed in this study. One major problem in supercritical ... + READ MORE
    A numerical framework for efficient and robust simulation of supercritical Diesel combustion is developed in this study. One major problem in supercritical flow simulation is appearance of non-physical pressure oscillation at the interface of fluids with a large magnitude density gradient. To simulate supercritical flow without the spurious pressure oscillation, the pressure based SLAU2 scheme is implemented using OpenFOAM library. Also, the flamelet progress variable model with real fluid equation of state is utilized to efficiently describe combustion process. The numerical framework is applied for the Spray A benchmark case of the Engine Combustion Network. The simulation results indicate that the proposed numerical framework can capture basic features of supercritical Diesel spray mixing and combustion. - COLLAPSE
    June 2020
  • Research Article

    Numerical Simulation on MILD Combustion Characteristics with Ethanol Fuel using FGM

    FGM을 이용한 에탄올 연료의 MILD 연소특성에 대한 수치해석 연구

    Chun Loon Cha, Sang Soon Hwang

    차천륜, 황상순

    MILD combustion has been considered as one of the promising combustion technology for high thermal efficiency and reducing nitrogen oxides and carbon ... + READ MORE
    MILD combustion has been considered as one of the promising combustion technology for high thermal efficiency and reducing nitrogen oxides and carbon dioxide emissions. Recently, many studies have revealed the potential of MILD combustion in various power systems but most studies have been focused on gas-phase fuel MILD combustion. Therefore further study on MILD combustion using liquid fuel is needed. In this work, we will focus on the numerical simulation of the effects of diluted gas velocity on the formation of liquid fuel MILD combustion using FGM using ethanol fuel as a carbon-neutral fuel. A two-stage combustion structure similar to ‘Deft jet in hot co-flow’ configuration was used to study the formation of liquid fuel MILD combustion for the validation purpose. The diluted burnt gas velocity from the first premixed combustion chamber can be controlled by an open ratio of the nozzle between two combustion chambers. The results show that the local high-temperature region was decreased and the flame temperature was uniformly distributed due to the intense mixing by the higher momentum of ejected diluted burnt gas from the venturi type nozzle considering atomization and vaporization of the injected liquid fuel. - COLLAPSE
    June 2020
  • Research Article

    Emission Characteristics of Ultra-Fine Particulate Matter (PM<0.1µm) from Red-Heated Metal Fiber Flame Burners

    적열된 메탈파이버 연소기의 극미세입자(PM<0.1µm) 배출 특성

    Dong Seok Jeon, Ji Hun Yeo, Hui Man Yang, Hye Jin Jang, Nam Il Kim

    전동석, 여지훈, 양희만, 장혜진, 김남일

    Generation and emission of particulate matter (PM) from methane-air premixed flame burners were investigated experimentally. Three types of burner surfaces were employed ... + READ MORE
    Generation and emission of particulate matter (PM) from methane-air premixed flame burners were investigated experimentally. Three types of burner surfaces were employed; i.e., a metal fiber, a perforated plate, and a sintered mat. In addition to NOx emission, the total weight and number distribution of PM were measured with the variation of the total flow rate and equivalence ratio. Usually, emission of NOx and PM increased as the total flow rate became larger and the equivalence ratio approached to stoichiometry from the fuel-lean conditions. Conclusively, even in the case of large NOx emission (100 ppm), the total mass of PM10 and PM2.5 were acceptable. However, the number of ultra-fine particles (<0.1 µm) significantly increased when the flow rate was excessively small and flame could heat up burner surfaces. It was suggested that an additional regulation for the ultra-fine dust would be necessary if premixed burners are operated at excessively low flow rate with surface heating. - COLLAPSE
    June 2020
  • Research Article

    Time Series Analysis of Acoustic Interactions in Multiple Gas Turbine Combustors

    다중 가스터빈 연소기의 음향 상호작용 시계열 분석

    Kihun Moon, Kyu Tae Kim

    문기훈, 김규태

    Strong acoustic interactions via a cross-talk section were investigated in two coupled model gas turbine combustors. In particular, we focused on the ... + READ MORE
    Strong acoustic interactions via a cross-talk section were investigated in two coupled model gas turbine combustors. In particular, we focused on the dynamical state of different acoustic interaction modes using several time series analysis methods, including phase portraits, Poincaré maps, correlation dimensions, and histograms. Our results demonstrate that a period-1 limit cycle occurs for a push-push mode. By contrast, when a push-pull mode is excited in the system, a period-3 attractor emerges in the cross-talk section. - COLLAPSE
    June 2020