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4행정 가솔린 기관의 배기계 맥동압력 전달특성에 대한 주파수 해석
이준서(J.S.Lee),정광국(K.K.Chung),박종남(J.N.Park),유병구(B.K.Yoo),박세만(S.M.Bahk),차경옥(K.D.Cha) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Pulsating pressure of exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating gas flow is closely<br/> concerned to engine power loss according to back pressure and exhaust noise. However, because of nonlinear effect due to large amplitude of pulsating pressure. it is difficult to exactly calculate pulsating pressure propagation in exhaust system of typical engine, Moreover, in case of estimating exhaust system performance, conventional prediction method which is based on linear theory, gives many restrictions and overestimate.<br/> As the first step for solving this problem, this paper contains experimental model to measure pulsating pressure propagation and shows power spectrum density, frequency response function, coherence in frequency domain for characterize pulsating pressure propagation in exhaust system of typical engine.<br/>
[디젤엔진부문] 직분식 단기통 디젤엔진 실린더내 스월비 변화에 따른 유동장 계측 및 해석
이준열(J.Y. Lee),최붕기(B.K. Choi),이진욱(J.W. Lee),강건용(K.Y. Kang),장영준(Y.J. Chang) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This study involves several measurement techniques to analyze swirl flow in 'a four-valve HSDI 2.0L diesel engine; swirl meter measurements and LDV measurements. Flow characteristics of a four-valve cylinder head were examined in a steady test rig for different SCV angles to quantity swirl ratio. Then the measurement of swirl mean velocity and turbulence intensity have been made for motoring condition(500,800rpm) using a laser Doppler velocimetry system which was applied in backward scattering method from top-view and bottom-view. This study also analysed some parameters of swirl ratio, swirl averaging velocity. Obtained results about the optimal intake port configuration are expected to be a suitable guide line in the analysis of the swirl flow characteristics.
4-行程機關 排氣系의 脈動波傳達 特性에 대한 兩端子 回路網 分析法의 應用. Ⅰ
이준서(J.S.Lee),박진용(J.Y.Park),유병구(B.K.Yoo),김재근(J.K.Kim),차경옥(K.O.Cha) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine.<br/> The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis.Also, it shows coherence function,frequency response function,back pressure, and gradient of temperature in exhaust system.<br/>
高次스펙트럼을 利用한 機關 排氣系의 非線型 脈動壓力 解釋에 관한 硏究
이준서(J.S.Lee),이민호(M.H.Lee),김명균(M.G.Kim),김봉각(B.K.Kim),임인권(I.G.Lim),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
The engine exhaust noise is mainly made of the pulsating gas flow and pulsating pressure at a very high pressure level. Frequently, this pulsating pressure level is out of the pressure level range which the linear acoustic theory is applicable. The conventional prediction method which is based on the linear acoustic theory gives an overestimate in comparison with results measured in operating engines. This paper, as the first step for solving this problem, proposes a non linear effect of pulsating pressure waves. The phenomenon proposed here is identified by using of higher order spectrum(bicoherence),<br/>