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직접 수치 해법을 이용한 난류 예혼합 연소의 화염 면적 밀도 연구
한인석(Insuk Han),허강열(Kang Yul Huh) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
One of the difficulties in modeling turbulent premixed flame is that the reaction progress variable is not a conserved scalar as the mixture fraction in non-premixed flame. DNS has been a useful tool to extract critical information not easily available from measurements for modeling. In previous work it was shown that the maximum flame surface density is one of the critical parameters to determine turbulent burning velocity. In this study parametric investigation is performed to find the effects of turbulent intensity, integral length scale and laminar flame speed on the maximum flame surface density. Turbulent premixed flames have been reproduced in this study by three-dimensional direct numerical simulation (DNS) with inflow/outflow boundary condition to get a flame brush in a statistically steady state. Fully compressible Navier-Stokes equations are solved with single step chemistry. Initial and inflow turbulence are assumed to be homogeneous and isotropic.
한인석(Insuk Han),허강열(Kang-Yul Huh) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
Flame surface area is a critical parameter determining turbulent flame speed. Three-dimensionaldirect numerical simulations(DNS) were conducted to figure out the evolution process of flame surface area. Fully compressible Navier-Stokes equations are solved to reproduce premixed flame embedded in isotropic decaying turbulent flow. The tangential straining and curvature of propagating surface affect development of flame area. In this study, four different turbulent intensity flows and three different Le number flames are investigated to force changes in straining and curvature effects. Consistent results are obtained for the probability density functions (PDF) of strain and curvature with previous researches. It is revealed that displacement speed, which is a speed of flame surface relative to unbumt flow, controls the balance between sink and source of flame surface area.
한인석(Insuk Han),허강열(Kang-Yul Huh) 한국연소학회 2007 한국연소학회지 Vol.12 No.2
Flame surface area is a critical parameter determining turbulent flame speed. Three-dimensional direct numerical simulations(DNS) were conducted to figure out the evolution process of flame surface area. Fully compressible Navier-Stokes equations are solved to reproduce premixed flame embedded in isotropic decaying turbulent flow. The tangential straining and curvature of propagating surface affect development of flame area. In this study, four different turbulent intensity flows and three different Le number flames are investigated to force changes in straining and curvature effects. Consistent results are obtained for the probability density functions (PDF) of strain and curvature with previous researches. It is revealed that displacement speed, which is a speed of flame surface relative to unburnt flow, controls the balance between sink and source of flame surface area.
한인석(Insuk Han),권세일(Se-il Kwon),이선국(Sun-kuk Lee),이종빈(Jongbin Lee),이성진(Sung-Jin Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Forging products, which are used for power plants and ships, are made by a mold casting process and manufactured as a desired size and shape by repeating heating and open-die forging processes. Temperatures of a workpiece are important because they determine flow stress. An experiment to measure temperatures of an ingot has been conducted and the results are compared with that of a three dimensional heat transfer analysis considering gas radiation in the furnace. Surface temperatures of a workpiece during a forging process also have been measured using a pyrometer. A program is developed to predict temperatures of a workpiece from the casting to the final forging process. It is shown that a phase transformation, which involves energy change, induces a sudden increase of temperature at the center of an ingot. It is also revealed that temperature at the center of a workpiece may decrease in the beginning time of reheating processes.
한인석(Insuk Han),허강열(Kang Y. Huh) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
There has been recent interest in prediction of size distribution including submicron particles as well as total number density and mass fraction of soot emissions from a diesel engine. Computation of soot remains a challenging area with uncertainties in surface reaction and particle dynamics. Prediction of the soot particle size distribution function in engine operating conditions would be a significant contribution even if some uncertainty with turbulence effects may be left as future work. Here the conditional moment closure(CMC) for turbulent combustion is integrated in KIVA to get flame structures including the soot precursor. The problem may be solved by the CMC model based on decoupled treatment of local PDF and flame structure with detailed chemical mechanism. Chemical mechanism includes n-heptane pyrolysis and soot precursor formation. Pyrene is the crucial soot precursor species which is involved in the nucleation process of soot. Preliminary results are obtained for different averaging procedure of the KIVA results for the cylinder to provide input for the SWEEP program as a post-processing step.
복수 화염 구조와 조건 평균 방법을 이용한 디젤 엔진 연소 연구
한인석(Insuk Han),허강열(Kang Y. Huh) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Combustion of turbulent sprays in a direct injection diesel engine is modeled by the conditional moment closure (CMC) model. The CMC routines are combined with the KIVA code to provide conditional flame structures to determine the mean state variables, instead of the mean reaction rate. An independent transport equation is solved for each flam group with equal mass of sequentially evaporating fuel vapor. CMC calculation begins as the fuel mass for each flame group begins to evaporate with corresponding initialization conditions. Comparison is made with the measured pressure traces for two different direct injection diesel engines. Results show that the CMC model with multiple flame histories can successfully be applied to the ignition and mixing-controlled combustion phases of a diesel engine.
조건 평균 방법을 이용한 소형 고속 직분식 디젤 엔진의 난류 연소 3차원 모사 연구
한인석(Insuk Han),허강열(Kang Y.Huh),박남섭(Namseob Park) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Turbulent spray combustion in a direct injection diesel engine is investigated numerically by the first order Conditional Moment Closure (CMC) model. This model allows employment of detailed chemistry for simulation of autoignition, nonpremixed combustion and pollutant formation in a consistent manner. KIVA 3V and CHEMKIN 2 are used to solve the governing equations for flow field and chemistry. Simplified CMC equations are applied to with KIVA adopting a complicated moving grid system. Validation is performed against experimental pressure data for different injection conditions and engine speeds with discussions for obvious deviation in the early combustion phase with and without pilot injection.<br/>
순환경제의 실현을 추구하는 자동차 내장재용 텍스타일의 변화양상 분석
한인석 ( Insuk Han ),김선미 ( Sunmee Kim ) 한국패션비즈니스학회 2021 패션 비즈니스 Vol.25 No.3
The study aims to evaluate changes in textiles for automotive interior and suggest directions that the textile-development should take in order to achieve sustainability, and enter a circular economy system in the future. The main content and results of the study are as follows: First, we cover the overall sustainability study in the fashion and textile fields; in particular, the certification system is well established through the provision of information on the whereabouts of products to consumers and verification by external environmental auditors. Second, we considered the criteria of C2C in order to derive the necessary criteria for sustainability certification in the field of textiles. Third, we looked at the latest development trends of textile materials for automobile interiors which were divided into three categories: natural originated materials, circular economic consideration materials, and functional supplementary lightweight materials. In addition, we identified to what extent the trend of changes aggregated in the examples was satisfied and what was lacking when applied to the Basic criterion of C2C. As such, this study links and applies the sustainability criteria pursued in the fashion and textile fields to the textile for automotive interior materials, suggesting a direction for the textile field for automotive internal materials in the future. Based on the results of this study, it is hoped that studies on textiles for automotive interior considering the net economy will continue, and practical development in the industry will be realized.
고압 분사식 연료분사계 수치해석에 의한 디젤엔진 배기 예측
이석영(Sukyoung Lee),한인석(Insuk Han),허강열(Kang Y. Huh) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Numerical simulation has been carried out to investigate the effect on combustion and emissions in a common rail injection system. The relevant injection parameters are accumulator volume, control chamber initial volume, control orifice diameter, needle valve diameter and nozzle chamber initial volume, etc. Spray and combustion characteristics are examined by KIVA-3V with the conditional moment closure (CMC) model to predict the turbulent mean reaction rate. Conditional flame structures are estimated by the CMC model to determine mean state variables, instead of mean reaction rates. The main focus of this research is on optimization of a common rail injection system with respect to the various injection parameters under investigation.