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난류연소장치를 이용한 스파크 점화 화염의 성장에 관한 연구-스파크 출력의 영향
조용석(Y.S.Cho) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
An experimental study to evaluate the effect of spark power on the growth rate of spark-ignited flame kernels was conducted in an optically-accessible turbulent flow combustion system at latm, 300K conditions. All measurements were made with premixed, propane-air at a fuel/air equivalence ratio of 0.93. Two flow conditions were studied: a low turbulence intensity case and a high turbulence intensity case. The growth of the spark-ignited flame kernel was recorded over a time interval from 83μsec to 20msec following the start of ignition using high speed laser shadowgraphy. In order to evaluate the effect of spark power, tests were conducted with a long duration (-4msec) inductive discharge ignition system with an average spark power of 14 watts and two short duration (∼100nsec) breakdown ignition systems with average spark powers of<br/> 6×10⁴ and 6×10^5 watts.<br/>
LDV 와 유동가시화를 이용한 CCC 입구의 유동분포 측정 및 수치해석
조용석(Y.S.Cho),김득상(D.S.Kim),정태용(T.Y.Jung),왕희준(H.J.Wang),김용관(Y.K.Kim),주영철(Y.C.Joo),한민섭(M.s.Han) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
Results from an experimental study of flow distribution in a close-coupled catalytic converter (CCC) are presented. The experiments were carried out with a flow measurement system under steady and transient flow conditions. The flow distribution of the CCC was measured by LDV system and flow visualization. Results from numerical analysis are also presented.<br/> Experimental results showed that in steady flow conditions, the flow through each exhaust pipe made some flow concentrations on a small region of the CCC inlet. The transient test results showed that the flow through each exhaust pipe in the engine firing order interacted with each other to make the flow distribution uniform. The results of numerical analysis supported the experimental results, and helped explain the flow in the entry region of CCC.<br/>
조용석(Y.S.Cho),김득상(D.S.Kim),이윤석(Y.S.Lee),송대근(D.K.Song),주영철(Y.C.Joo),한민섭(M.S.Han) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
Results from an experimental study to measure the conversion efficiency of a close-coupled catalytic converter (CCC) are presented. Exhaust gases upstream and downstream of the catalyst are sampled by a sampling probe, and analyzed by an exhaust gas analyzer. The distribution of the exhaust species and catalyst conversion efficiency over the catalyst face is compared with the velocity distribution in the catalytic converter.<br/> Results showed that the conversion efficiency is not strongly dependent on the velocity distribution, but the species concentration distribution correlates well with the velocity distribution. It was found that the non-uniform velocity distribution results in non -uniform species distribution over the catalyst face and speed up the aging process in a specific region of the catalyst.<br/>
조용석(Y.S.Cho) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2
The results show that fluctuations in local mixture strength due to incomplete fuel-air mixing cause flame kernel surfaces to become wrinkled and distorted. Incomplete fuel-air mixing was also found to result in a significant increase in "cyclic" variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24o%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.<br/>
조용석(Y.S.Cho),이윤석(Y.S.Lee) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
In order to satisfy the ULEV emissions regulation, fast light-off of a catalyst is essential for reduction of HC and CO emissions during the cold start. Cranking Exhaust Gas Ignition (CEGI) method developed in this study showed that the catalyst reaches the light-off temperature in a few seconds. The CEGI stops the ignition signal for a few seconds during the cranking period, so the unburned fuel-air mixture bypasses the combustion chamber and flows through the exhaust manifold. When the unburned mixture reaches two glow plugs installed upstream of the catalyst, it burns and releases the thermal energy to heat up the catalyst. In the FTP-75 vehicle tests, the CEGI showed that the exhaust emissions reduced by 47.7% for THC and by 88.6% for CO in the cold-transient phase of the test.<br/>