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디젤 기관 단일 영역 모델 열발생율 계산의 오차 보상에 관한 연구
류승협,김기두,윤욱현,하지수,Ryu Seung-Hyup,Kim Ki-Doo,Yoon Wook-Hyeon,Ha Ji-Soo 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.5
Accurate heat release analysis based on the cylinder pressure trace is important for evaluating combustion process of diesel engines. However, traditional single-zone heat release models (SZM) have significant limitations due mainly to their simplified assumptions of uniform charge and homogeneity while neglecting local temperature distribution inside cylinder during combustion process. In this study, a heat release analysis based on single-zone model has been evaluated by comparison with computational simulation result using Fire-code, which is based on multidimensional model (MDM). The limitations of the single-zone assumption have been estimated, To overcome these limitations, an improved model that includes the effects of spatial non-uniformity has been applied. From this improved single-zone heat release model (Improved-SZM), two effective values of specific heat ratios, denoted by ${\gamma}_V$ and ${\gamma}_H$ in this study, have been introduced. These values are formulated as the function of charge temperature changing rate and overall equivalence ratio. Also, it is applied that each equation of ${\gamma}_V$ and ${\gamma}_H$ has respectively different slopes according to several meaningful periods during combustion progress. The heat release analysis results based on improved single-zone model gives a good agreement with FIRE-code results over the whole range of operating conditions of target engine, Hyundai HiMSEN H21/32.
중형 엔진 터보차져의 원심압축기에 관한 공력학적 3차원 형상 및 구동용 연소기 설계
김홍원,류승협,갈상학,하지수,김승국 한국유체기계학회 2006 한국유체기계학회 논문집 Vol.9 No.2
An aerodynamic design for centrifugal compressor which was applied to medium speed diesel engine has been done. First of all, exact compressor specifications must be defined by accurate engine system matching. This matching program has been developed. Using the meanline prediction method, geometric design and performance curves for compressor were established and verified by comparing three dimensional viscous CFD results. The deviation at the design point was about 2.3%. Combustor has been designed and manufactured for the performance test of medium speed diesel engine turbocharger. Fuel nozzle of combustor was designed and its characteristics was analyzed by PIV and PDPA test equipment. Through these results, spray characteristics were studied and flow coefficient equation was deduced.1. 서 론* (주)현대중공업 산업기술연구소
강기중,오채호,심태영,송재혁,류승협,최경민,김덕줄 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
The autoignition characteristics of n-heptane/ethanol were investigated both experimentally and numerically. The effects of nitrogen dilution and exhaust gas recirculation on the autoignition characteristics were evaluated. A rapid compression machine was employed to measure ignition delay times of blended fuels. A numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to calculate ignition delay time and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with increasing nitrogen dilution rate due to the thermal load effect of nitrogen. The oxidation reaction of n-heptane in a low temperature regime was limited with increasing nitrogen dilution rate. The ignition delay time sharply decreased with exhaust gas recirculation because of the intermediate species in the exhaust gas. Exhaust gas recirculation reduced first ignition delay dramatically. However, the time interval between the first and main ignition increased with increased exhaust gas recirculation.