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최하성(Ha-sung Choi),박종상(Jong-sang Park),하종률(Jong-yul Ha),정성식(Sung-sik Chung) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.2002 No.3
An experimental study was carried out to obtain a series of fundamental data about radical controlled and induced injection effect on the combustion of pre-mixture in the main-chamber. The volume of the sub-chamber is set up to occupy less than 1.5% of whole combustion chamber, the equivalence ratio of pre-mixture in the main chamber and sub-chamber is uniform, and numerous narrow passage holes are arranged to induce simultaneous multi-point ignition in the main chamber by flame jets including radicals from the sub-chamber.<br/> In the case of radical ignition method(RI), the overall burning time including the ignition<br/> delay time became very short compared with that of the spark ignition method(SI).<br/> With the increase of the diameter of passage holes and the volume of the sub-chamber, the<br/> combustion characteristics of the Rl becomes similar to that of the Sl.<br/> By the result of the visualization of combustion in the main chamber, while the Sl shows<br/> the traditional flame propagation, the RI shows the phenomena as bulk combustion.<br/>
최하성(Ha-sung Choi),박종상(Jong-sang Park),하종률(Jong-yul Ha),정성식(Sung-sik Chung) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.2002 No.10
An experimental study was carried out to obtain fundamental data about effect of radical induced injection on the combustion of pre-mixture in a constant volume chamber with a tiny sub-chamber. Volume of the sub-chamber was set up to occupy less than 1.5% of whole combustion chamber volume, some narrow passage holes were arranged to induce simultaneous multi-point ignition in the main chamber by flame jets including radicals from the sub-chamber, and the equivalence ratios of pre-mixture in the main-chamber and sub-chamber were the same. And also, visualization for combustion process was performed in the main chamber.<br/> In the case of radical ignition(RI) method, the overall burning time including the ignition delay was very short to that of the spark ignition(SI) method. As diameter of the passage holes and the volume of sub-chamber increase, the combustion characteristic of the RI method was similar to that of the SI method.
하동흔(Dongheun Ha),김민철(Mincheol Kim),박종상(Jongsang Park),염정국(Jungkuk Yeum),하종률(Jongyul Ha),정성식(Sungsik Chung) 한국자동차공학회 2008 한국자동차공학회 지부 학술대회 논문집 Vol.2008 No.11
This study was carried out to investigate the availability of using CNG fuel in a commercial two-cylinder gasoline engine and to derive the optimum performance of the engine. The results of this study is used to determine the optimized injection quantity at the time of dual injection and to improve the engine efficiency through comparing and investigating the performance of a PFI(Port Fuel Injection) and a sub-chamber DI(Direct Injection) type engine in order to establish the base of using PFI and sub-chamber DI type together in a multi-cylinder engine. A gasoline engine was adapted for this study, and air excess ratio was controlled using Lambda sensor and handle accelerator, and spark timing and injection timing were controlled using the ECU that was made personally. Combustion characteristics in accordance with air excess ratio and injection timing were investigated by multi-point injection using CNG fuel. On the basis of PFI type, the standard of fuel injection duration is obtained and it is applied to DI type. According to the air excess ratio, in-cylinder pressure, rate of heat release, IME(Indicated Mean Effective pressure), mass fraction burned, COVimep(Coefficient Of Variation), and so on are derived. As a result, the engine operation in PFI type is the safest at stoichiometric ratio and the engine operation in sub-chamber DI type is the safest at lean mixture ratio. This result is applied to the next study in order to obtain the optimized injection quantity and to improve the efficiency.
정성식,하종률,이중순,이상석,Jeong, Seong-Sik,Ha, Jong-Ryul,Lee, Jung-Sun,Lee, Sang-Seok,Kawaguchi, O 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.6
An experimental study has been performed to obtain the effect of relative velocity between droplet and environmental gas on the evaporation of a n-heptane free droplet of 180 $\mu$m in diameter flying in a hot and normal pressure air flow. Measurement of droplet diameter and velocity was conducted in a series of time by an electrically controlled optical system. From the experimental results, an empirical equation associated with the relation between evaporation rate constant and relative velocity was obtained.
박종상,이태원,하종률,정성식,Park, Chong-Sang,Lee, Tae-Won,HA, Jong-Yul,Chung, Sung-Sik 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.3
As the combustion process of CWM consists of the water evaporation, the release and combustion of volatile matter, and the combustion of char for every particle, it is more complex than that of existent liquid fuel. Though the many studies on CWM combustion have been carried out by the single droplet using hanging methods or the multiple droplet using atomization methods, any report don't presents definite solution about the effects by the initial water evaporation and combustion of volatile. When CWM is suddenly exposed in the high temperature surroundings, the internal water evaporates and then each droplet builds up pores. Besides, porosity rate changes along the temperature of surroundings, the composition ratio of CWM, and the initial diameter of droplet. In result, because it affects the whole combustion rate, the combustion of CWM has complex mechanism as compared with the combustion of liquid or gas fuel. Therefore, concentrating on porous structure of CWM, this study has proceeded to acquire the basic data on the CWM injection combustion and closely examines the effects of the first stage combustion on the whole combustion by measuring the diameter variations, pore rate, mass fraction burned, and the internal temperature changes of CWM droplet. The results demonstrate that $60{\sim}70%$ of initial mass is reduced during water evaporation and volatile combustion period, and swelling rate, mass faction burned, and density variation are greatly concerned with atomization of CWM etc.