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4-밸브 SI 엔진에서 텀블, 스월 유동이 연소에 미치는 영향
배충식(C.S.Bae),이재호(J.H.Lee),강건용(K.Y.Kang),오승묵(S.M.Oh) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.11_1
The effects of tumble and swirl flows on the combustion were investigated exprementally in a 4-valve SI engine. The tunble flow pattems were generated by various intake ports of different entry angle; 25˚, 20˚ and 15˚. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. The combustion duration was calculated by heat release analysis of the pressure in an operating engine.<br/> It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame davelopment. Inclined tumble was proved to be more beneficial than the pure tumlbe for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images and comtustion durations.<br/>
배충식(C.Bae),정경석(K-S.Jeong) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
The flow characteristics of five different 4-valve cylinder heads were investigated in a steady flow rig using laser-Doppler velocimetry. The tumble flow of each head with pentroof combustion chamber was quantified by nondimensional tumble number using a tumble adaptor. The formation of tumbling vortex was examined in an optical single-cylinder engine which has windows for in-cylinder LDV measurements. Tumble vortex ratio was estimated from the tumble flow measurement.<br/> The four-valve cylinder heads with pent-roof combustion chamber showed the tumble vortex from the intake process. which was investigated in the steady flow test. The tumble adaptor which converts the tumble into swirl flow was found to be feasible in predicting the tumble flow in the real engine. The tumble strength in the steady flow test coincides with that in the real engine experiment within 15%. It was found that the steady flow test on the four-valve cylinder heads provides the tip for a better design of cylinder head.<br/>
배충식(C.S. Bae),이재호(J.H. Lee),오승묵(S.M. Oh),강건용(K.Y. Kang) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2
A single-cylinder optical research engine for combustion visualization has been developed by modifying a 4-cylinder DOHC. spark-ignition engine. The design tips for the optical engine development are described and the visualized flame images are given. The optical engine has a piston-top window in the extended piston which allows optical access into the combustion chamber for flow and combustion research. The flame propagation at 800rpm was imaged by an ICCD camera for stoicheometric mixture under idling condition. Flame images imply that the initial flames are convected by the organized tumbling flow in the pent-roof combustion chamber.<br/>
링간 틈새체적에서의 가스유동이 UHC 배출물에 미치는 영향
김창기(C.G.Kim),배충식(C.S.Bae),최상민(S.M.Choi) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
The effect of the inter-ring crevice, the volume between the top and the second piston rings, on unburned hydrocarbon (UHC) emission was experimentally and numerically investigated. The ultimate goal of this study was to reduce the level of UHC emission by minimizing the blow-up of the unburned gases trapped in the inter-ring crevice. For this purpose, the unburned mixture trapped in the inter-ring crevice was extracted to the crankcase during the late period of the expansion stroke and the early period of the exhaust stroke through the engraved grooves on the lower part of the cylinder wall. The extraction of the mixture from the inter-ring crevice resulted in significant reductions of UHC emission over a range of speeds and loads, without any losses of efficiency and power. A physical model for predicting the gas flow into and from the inter-ring crevice was also adopted to simulate the effect of the grooves on the lower part of cylinder wall. The calculated results agreed well with the measurements and could explain the mechanism of UHC emission reduction achieved with the grooved cylinder liners. This consistency has confirmed the importance of the inter-ring crevice on UHC emission in an SI engine.<br/>
[가솔린엔진] 고압 선회분사기 노즐의 성능-전산유체 해석
장창수(C.S. Jang),배충식(C.S. Bae),최상민(S.M. Choi) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A computational fluid dynamic tool was used to predict the performance of a prototype high-pressure swirl injector nozzle with respect to design parameters. Performance of the' prototype nozzle was investigated in terms of the flow rate and the initial spray angle. Design parameters included needle lift. needle-seat angles. orifice diameter and length. and needle-seat contact diameter. The most important parameter was found to be the orifice diameter. Transient flow rate was also examined. The needle-opening time was found to have influence on the linearity of the dynamic flow rate
링간 혼합기가 SI 엔진의 미연탄화수소 배출에 미치는 영향
김창기(C.G.Kim),최상민(S.M.Choi),배충식(C.S.Bae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
The effect of the inter-ring crevice, the volume between the top and the second piston rings, on unburned hydrocarbon (UHC) emission was experimentally investigated. The ultimate goal of this study is to reduce the level of UHC emission by minimizing the effect of the inter-ring crevice. For this purpose, the unburned mixture trapped in the inter-ring crevice was extracted to the crankcase during the late period of the expansion stroke and the early period of the exhaust stroke through the engraved grooves on the lower part of the cylinder wall. The extraction of the mixture resulted in significant reductions of UHC emission over a range of speeds and loads, without any losses of efficiency and power. The effect of the inter-ring crevice on UHC emission in an SI engine was obvious.<br/>