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김봉곤(B. G. Kim),하종률(J. Y. Ha),권순석(S. S. Kwon) 한국자동차공학회 1990 오토저널 Vol.12 No.1
This study has been conducted by experiments for distribution of concentration of helium gas, which is jetted into stationary atmosphere at the normal temperature and pressure.<br/> It is able to obtain the data for concentration of helium and air mixtures by the use of hot wire probe which has fast response. At an up stream, the concentration gradient which is attained is steep. At a down stream, the mixing time of helium and air is gradually shortened with the lapse of time in front of a jet. The arrival frequency of a jet in an unsteady area is mostly constant from 0% to 100% up to 80mm, but the time which is reaching to 100% is gradually to lengthen as a descending downstream. After starting a jet and the point of 90%, the mixing time is especially to lengthen. This reason comes from the turblent intensity which causes for mixing of helium and air. This time difference which causes according to lengthen a jet should be considered in the design of combustion chamber.
이상석(Lee S S),김근민(Kim K M),김봉곤(Kim B G),정성식(Jung S S),하종률(Ha J Y) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
In this study. to more percisely and systematically analyze the process of combustion of the impinging spray. Helium spray was impinged on the 3 types of piston cavity geometry into the quiescent atmosphere with a room temperature and pressure to simplify the state of the real combustion chamber and hot wire probe was used for analyze non-steady flow characteristics of impinging spray. and ensemble average technique method was used for data process. and consequently re-entrant type has larger entrainment then others and vortex appear at the sperical region.<br/>
[論文] 直噴式 디젤機關에서 Cavity形狀이 燃燒特性과 排出微粒子에 미치는 영향
이상석(S. S. Lee),김희년(H. N. Kim),김봉곤(B. G. Kim),하종률(J. Y. Ha) 한국자동차공학회 1990 오토저널 Vol.12 No.6
The combustion chamber geometry, especially cavity geometry have an effect on the air-fuel mixture process, gas flow in cylinder and combustion itself.<br/> Three types of piston cavity model were compared in order to investigate with the effect of cavity geometry on combustion characteristics, engine performance and exhaust gas emission;as the results Reflex type has superior performance compared with the other cavity types.
탄소발열체의 외부유속 및 직경변화에 대한 비정상상태에서의 수치해석적 연구
배강열(K. Y. Bae),이윤환(Y. H. Lee),이상용(S. Y. Lee),이칠순(C. S. Lee),김봉곤(B. G. Kim),이상철(S. C. Lee) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This paper represents the numerical analysis in unsteady state on the variation of diameter and environmental velocity of carbon heating source. In general heating system, the oil and sheath heater is widely used, but these systems have many problems. So, the heating source with carbon ingredient has been researched in many country about manufacture, thermal and electrical properties. In this research; the carbon heating source was studied through numerical analysis on several conditions of unsteady state, heat generation, diameter and environmental velocity. The temperature distributions at steady state are appeared as a non-proportional linear pattern with variations of environmental velocity due to the Nesselt number with convective heat flux is proportioned to 0.805 of Reynolds number. As the radius is increasing, the temperature distributions is appeared the minus tilt because of the environmental condition is cooling by constant temperature. So, the correlation equation between temperature at steady state and environmental velocity was obtained.
비정상 충돌 분류의 Cavity 형상에 따른 공간 농도 분포 및 거동해석
이상석,김근민,김봉곤,정성식,하종률 한국액체미립화학회 1996 한국액체미립화학회지 Vol.1 No.2
In case of a high-speed D.I. diesel engine, the injected fuel spray is unavoidable that the impinging on the wall of piston cavity and in this case the geometry of piston cavity has a great influence on the atomization structure and air flow fields. In the field of combustion and in many other spray applications, there are clear evidence of correlation between spray structure and emission of pollutants. Ordinary, the combustion chamber of driving engine have unsteady turbulent flow be attendant on such as the change of temperature, velocity and pressure. So the analysis of spray behavior is difficult. In this study, a single spray was impinged on each cavity wall at indicated angle in a quiescent atmosphere at room temperature and pressure, as being the simplest case, and 3 types of piston cavity such as Dish, Toroidal and Re-entrant type was tested for analyzing the influence of cavity geometry. And hog wire probe was used for analyze non-steady flow characteristics of impinging spray, and to investigate the behavior of spray, the aspects of concentration c(t), standard deviation σ (t) and variation factor (v.f.) was measured with the lapse of time.