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[論文] 엔진룸 내의 열유체 유동의 2차원 수치시뮬레이션
유정열(J. Y. Yoo),윤홍열(H. Y. Yoon),이훈구(H. G. Lee) 한국자동차공학회 1992 오토저널 Vol.14 No.6
The complex geometry of the engine room of a passenger car has been modelled two-dimensionally and the thermal and fluid flow therein have been analyzed by using a commercially available code, PATRAN/FLOTRAN. FLOTRAN adopts a finite element method with streamline upwind formulation for convective terms and the k-ε turbulence model to solve the three dimensional turbulent flow and heat transfer problems. Velocity vectors, pressure and temperature distributions have been obtained for various cases with different aITII.ngements of license plates. underbody-covers and air dams. The results show that the numerical analysis using PATRAN/FLOTRAN can predict qualitatively well the practical phenomena.
유정열(J.Y.Yoo),윤홍열(H.Y.Yoon),이훈구(H.G.Lee) 한국자동차공학회 1992 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The complex geometry of a two-dimensional engine room has been modelled and the thermal and fluid flow therein have been analyzed by using a commercially available code, PATRAN/FLOTRAN. FLOTRAN adopts a finite element method with streamline upwind formulation for convective terms and the k-? turbulence model to solve the three dimensional turbulent flow and heat transfer problems. Velocity vectors, pressure and temperature distributions have been obtained for various cases with different arrangements of license plates, underbody-covers and air dams. The results show that the numerical analysis using PATRAN/FLOTRAN can predict qualitatively well the practical phenomena.<br/>
류종우(J.Ryu),조성권(S.K.Cho),양준모(J.M.Yang),유정열(J.Y.Yoo),최해천(H.Choi),이준식(J.S.Lee) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_2
Numerical and experimental studies are performed to investigate the effect of the underbody shape of the simplified road vehicle on drag and lift. Four different vehicle models with front and rear slanted variations at the lower surface are used in this study. Cases with a slanted underbody surface at front have smaller drag than those without a slanted surface. Also, cases with a slanted underbody surface at rear have smaller lift than those without a slanted surface. Pressure distributions along the model surfaces and velocity fields at the wake region are examined in detail. In general, numerical solutions are in agreement with experimental results.<br/>
PDMS 채널 내 전단유도에 의한 입자의 운동특성에 관한 연구
김영원(Y. W. Kim),유정열(J. Y. Yoo) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
An experimental study has been conducted to quantitatively characterize particle motion under shear-induced migration in square-PDMS microchannels by applying μ-PTV technique, and to compare with previous results carried out in macro-scale flow through a tube. It is shown that as the Reynolds number (Re) is increased, neutrally buoyant particles drift away from the wall and away from the center of the channel due to inertial migration. Particles are accumulated at the equilibrium position of 0.67H, with H being a half width of the channel, which is analogous to that of tube flow. Equilibrium position is nearly independent of Re and the maximum value of particle probability density function (PDF) is linearly increased as Re is increased. The outermost edge of particle cluster is in good agreement with previous results, and it is rapidly converged to about 0.7 at L₃ (reduced tube length proposed by Segre & Silberberg) = 1. Our study quantitatively presents an understanding of shear-induced particle migration in square microchannels and is associated with the study performed in macro scale. Furthermore, the present study gives optimum factors for designing of microfluidic systems.
양희천(H.C.Yang),유정열(J.Y.Yoo),이준식(J.S.Lee),최해천(H.Choi) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_1
In this paper three-dimensional external airflow around road vehicle models was numerically studied to investigate the aerodynamic characteristics. FVM based on a general curvilinear coordinate system was used to solve the governing equations. The drag coefficients by the calculation were about 40-50% higher than the experimental values.<br/>
[論文] 온도보상을 고려한 열선형 공기유량 측정시스템에 관한 실험적 연구
이민형(M.H.Lee),유정열(J.Y.Yoo),고상근(S.K.Kauh),윤준원(J.W.Yun),김사량(S.R.Kim),김동성(D.S.Kim) 한국자동차공학회 1991 오토저널 Vol.13 No.4
The purpose of this study is to perform modelings and experiments to measure air flow rate using hot-wires and a CTA(Constant Temperature Anemometer). The flow rate can be obtained by measuring the heat loss of the hot-wire due to the variations of flow velocity when the hot-wire is maintained at uniform temperature. But the defect of this method is that the output signal changes not only by the flow rate but also by the ambient temperature. Thus, in the present study, a method which compensates the variations of the ambient temperature has been introduced to measure exact flow rate. To be more specific, the bridge circuit of the usual hot-wire anemometer system has been modified in such a way that a temperature resistance sensor and a variable resistance are placed in one of the legs to compensate the different temperature coefficients of both the hot-wire and the temperature compensating resistance for flow velocity or for flow mass up to the flow temperature of 50℃. Comparing the modeling and experimental results, it has been shown that the compensating point differs as the flow rate varies. Therefore, optimum compensation points are sought to construct the circuit. The present modeling and experimental results may be applied to the design of actual air flow meters for automobiles.