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FIRE를 이용한 디젤 엔진 연소, NOx 및 매연 모사 계산 및 검증
허강열(Kang. Y. Huh),이용운(Yongun Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
In this study parametric investigation is performed for a diesel engine with respect to EGR rate, injection timing. The engine is a heavy duty diesel engine operated with early injection timings to simulate an HCCI engine mode at a low rpm. The commercial code FIRE is employed for prediction of in-cylinder spray, combustion and production of NOx and soot emissions. Different sprays models including no breakup with a fixed SMD and Huh-Gosman model are tested for comparison with measurements. The Arrhenius type Shell ignition model is used with the standard set of constants for autoignition. The eddy dissipation model and characteristic time scale model are used for comparison during premixed and diffusion controlled combustion phases. Models for spray atomization and turbulent combustion involve some arbitrary constants, which require tuning for given specific cases. However results do not show much dependence on choice of the constants in reasonable ranges. Simulation results agree well with the measured data set for pressure traces, NOx and soot emissions for all 9 parametric cases.
허강열(Kang Y. Huh) 한국가시화정보학회 2004 한국가시화정보학회지 Vol.2 No.1
Conditional sampling measurement is required for conditional averages as well as unconditional Favre averages to resolve different flame structures of turbulent combustion. A Favre average can be obtained as an integral of conditional average and Favre PDF in terms of the mixture fraction, which is a preferred choice as a sampling variable in diffusion controlled turbulent combustion. MILD combustion data are presented as an example for a conditionally averaged data set and comparison with CMC calculation results.
허강열(Kang Y. Huh) 한국가시화정보학회 2005 한국가시화정보학회지 Vol.3 No.2
내연기관 연소는 난류유동, 분무, 연소, 열전달의 복합적인 현상으로서 열역학적 해석이 주류를 이루어 왔으나 컴퓨터의 발전에 따라 효율 개선과 공해 저감을 목표로 전산유체해석 기법이 적극적으로 도입되고 있다. 내연 기관 연소의 근간을 형성하는 난류 연소 모델링의 기본 개념으로서 가솔린엔진에서의 예혼합연소와 디젤엔진에서의 확산연소에 대한 영역조건평균(zone conditional averaging) 모델과 조건평균닫힘(conditional moment closure) 모델에 대해 설명하였으며 NOx와 soot 예측에 대한 적용과 엔진응용 사례를 소개하였다.
직접 관계 그래프(DRG)를 이용한 디젤 연료의 상세 화학 반응 기구 축소화
이영재(Young J. Lee),허강열(Kang Y. Huh) 한국연소학회 2011 한국연소학회지 Vol.16 No.2
It is a challenging task to apply large detailed chemical mechanisms of fuel oxidation in simulation of complex combustion phenomena. There exist a few systematic methodologies to reduce detailed chemical mechanisms to smaller sizes involving less computational load. This research work concerns generation of a skeletal chemical mechanism by a directed relation graph with specified accuracy requirement. Two sequential stages for mechanism reduction are followed in a perfectly stirred reactor(PSR) for high temperature chemistry and to consider the autoignition delay time for low and high temperature chemistry. Reduction was performed for the detailed chemical mechanism of n-heptane consisting of 561 species and 2539 elementary reaction steps. Validation results show acceptable agreement for the autoignition delay time and the PSR calculation in wide parametric ranges of pressure, temperature and equivalence ratio.