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최근우(G.-W. Choi),박권종(G.-J. Park),김윤제(Youn J. Kim) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-
The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve port: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient(Cv) and the resistance coefficient(K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and Cv and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.
[디젤엔진부문] 틈새 간극이 Roots형 과급기 성능에 미치는 영향
김윤제(Youn J. Kim),최근우(G.W. Choi) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The effects of clearance on the performance of Roots-type supercharger is investigated numerically. A computer program is developed for creation of a new lobe shape. Numerical analyses are preformed for the flowfields in the pocket volumes formed by various lobe shapes. The governing equations for the two-dimensional, turbulent, operational processes in the housing are discretized by the finite volume method that insures the conservative characteristics to be satisfied in the calculation domain, and they are solved by a modified SIMPLE algorithm. Numerical results show that the effect of clearance between lobe and stator on the leakage flow rate is smaller than that of between two lobes. Results also show that Cassini lobes have smaller the leak flow rate than the other lobe shapes.