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4밸브엔진의 압축과정에서 거시적 유동구조에 관한 수치해석적 연구
백제현(J.H.Baek),정동수(D.s.Jung),강건용(K.Y.Kang),박민영(M.Y.Park) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1994 No.11_1
The three-dimensional code for simulation of in-cylinder flow in arbitrary engines has been developed and applied to the selected 4-vaJvc pant-roof-headed model engine. This code adapts a finite-volume method based on non-orthogonal moving coordinate formulation of governing equation with covariant velocity component. A k-ε turbulence model modified for compressibility is used to represent turbulent transport of momentum. Computations are performed from intake valve opening to compression TDC. Our principal interests are made in the intake-generated lage-scale flow structures, their break-up mechanism at late-compression and their influence on near-TDC flow structure and turbulence. Results for four kinds of inlet flow conditions are presented for various seat angles. Results show that appropriately-low seat angle of valve and definite orientation of inlet flow are favorable for formation of well-defined large-scale flow structures and converting mean flow energy into turbulence.
강건용(K.Y.Kang),이진욱(J.W.Lee),정동수(D.S.Jeong),정석용(S.Y.Jeong),백제현(J.H.Baek) 한국자동차공학회 1993 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper describes frequency analysis of the turbulent flow inside the cylinder of an engine under motoring(non-firing) conditions, with intake port and engine speed variations. Using LDV data cycle resolved turbulence intensity, cyclic variation, temporal autocorrelation coefficient, and turbulence kinetic energy spectrum with respect to crank angle are presented and discussed in detail.<br/>
자동차용 포핏밸브형 2-행정기관의 정상상태 소기유동(Ⅰ); 실험적 연구
강건용(K.Y.Kang),이진욱(J.W.Lee),우세종(S.J.Woo),홍순철(S.C.Hong),정용일(Y.I.Jeong) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1994 No.11_1
Two-stroke engine has inherent advantages over four-stroke engine of greater torque and power, less torque fluctuation and more compactness. At the same time, it has main drawback of the direct short-circuiting and excessive oil consumption. In these days, however, the oil consumption problem has been solved by adapting poppet valve system instead of port type. For the first step study the scavenging flow characteristics of an automotive two-stroke engine is investigated by flow visualization technique under steady condition, in order to ultimately optimize scavenging process using RSSV (rotatable shrouded scavenging valve) system. As working fluid, water is used instead of air to effectively visualize the flow pattern with applying Reynolds analogy.<br/>
가시화 모터링엔진의 흡기포트형상에 따른 텀블유동 LDV측정
강건용(K.Y.Kang),이진욱(J.W.Lee),정동수(D.S.Jeong),정석용(S.Y.Jeong) 한국자동차공학회 1993 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper describes the tumble flow measurements inside the cylinder of a 4-valve S.I. engine using laser Doppler velocimetry(LDV) under motoring(non-conditions. This is conducted on an optically assesed single<br/> <br/> cylinder research engine under motored conditions at an engine speed 0 1000 rpm. Three different cylinder head intake port configurations are studied to develope a better understanding of the tumble flow generation, development, and breakdown mechanisms.<br/>
강건용(K.Y.Kang),이진욱(J.W.Lee),정동수(D.S.Jeong) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Tumbling motion is very effective for turbulence enhancement during compression process in the cylinder of 4-valve engines. In this paper the effect of tumble flow on turbulence was investigated using LDV (laser Doppler velocimetry) measured data under motored condition, and discussed with a newly defined turbulence enhancement factor.<br/> <br/>
강건용(K.Y.Kang),이진욱(J.W.Lee),백제현(J.H.Baek) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
Turbulence at the end of the compression stroke, which plays an important role in improving the combustion, can be generated by the breakdown of large scale structures persisting through induction and compression strokes. Recently many engines have adopted four-valve systems with pent-roof type cylinder head due to the need to increase engine performance. In these engines, tumble, a large scale motion, has been considered to be more effective to generate the small-scale turbulences. This study describes the turbulence characteristics during compression in a 4-valve engine with tumble flows, using the data obtained by cycle-resolved LDV measurement. The turbulence is characterized in terms of turbulence intensity, time scales, and length scales.<br/>
강건용(K. Y. Kang),오승묵(S. M. Oh),이진욱(J. W. Lee),배충식(C. S. Bae) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_2
Tumble flow is very effective for turbulenece enhancement near the spark timing, and eventually improves the combustion performances in spark-ignition engines. In this paper the effects of tumble flow on combustion characteristics in a four-valve engine was investigated by using LDV measurements and combustion pressures inside engine cylinder. Tumble flow patterns was changed by intake port flow angles which is implemented by an aluminum cassette. The results show that high tumble flow can be generated during intake by a moderate inlet angle and decreases burning duration in lean mixture operation condition.
강건용(K.Y.Kang),이진욱(J.W.Lee),백제현(J.H.Baek) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
Tumble, a large scale motion which plays an important role in generating turbulence at the end of the compression stroke by its breakdown, has been considered to be more effective to generate the small-scale turbulences. This study describes the turbulence structure variation with tumble flow during compression in a 4-valve engine, using the data obtained by cycle-resolved LDV measurement. The turbulence is analysed in terms of turbulence energy spectrum, with three different defintion algorithms for turbulence integral time scale.<br/>
강건용(K.Y.Kang),이진욱(J.W.Lee),백제현(J.H.Baek) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1994 No.11_1
The turbulent flow field in an engine plays an important role in determining the combustion characteristics and thermal efficiency. In order to characterize a turbulent flow field in an engine, turbulence length scale and time scale should be determined as well as turbulence intensity. Moreover turbulence energy spectrum analysis is also very useful to better understand the mechanism of turbulence production and decay mechanisms. In this study, several determination algorithms for the engine turbulence characteristics are investigated and compared, using LDV measured data and a cycle resolved velocity analysis.<br/>