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- 저자 : 이택식(T. S. Lee) (검색결과 4 건)
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감압밸브를 사용한 탄광갱내 공조용 냉수 공급시스템의 과도현상 해석
강신형,이택식,이상산,Kang, S.H.,Lee, T.S.,Lee, S.S. 대한설비공학회 1988 설비저널 Vol.17 No.4
Transient flow in a cold-water supply system for cooling the inside of a coal mining pit was numerically simulated. Properly designed and presetted pressure reducing valves control the level of pressures of the piping system at normal or emergent conditions Quasi-steady relations to simulate the valve motion are obtained and the transient performance of the valve is investigated in the present paper. The present method reasonably simulate transient phenomena in the system including the pressure reducing valve. Excessive valve motion and column separation are simulated when the flow is abruptly reduced. A calculated example of the real system is also presented. The simulation can be used for the safety-check and the guidance for design and operation in emergent cases of the system.
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비정상 자연대류에 의한 온도성층화의 동특성에 관한 연구
강보선,이준식,이택식,노승탁,Kang, B.S.,Lee, J.S.,Lee, T.S.,Ro, S.T. 대한설비공학회 1988 설비저널 Vol.17 No.4
Dynamic characteristics of thermally-forced stratification process in a square enclosure with a linear temperature profile at the side walls have been investigated through flow visualization experiment and numerical analysis. The experiment was performed on air with the Rayleigh numbers of order $10^5$. A particle tracer method is used for the flow visualization and to obtain a sudden linear temperature profile at the side walls copper blocks which already have a linear temperature profile are come into contact with the thin copper plates of the test section. Immediately a meridional circulation is developed and heat transfer takes place from the wall to the interior region by circulation of fluid and finally a thermal stratification is achieved. In the numerical study, QUICK scheme for convective terms, SIMPLE algorithm for pressure correction, and the implicit method for the time marching are adopted for the integration of conservation equations. Comparison of flow visualization and numerical results shows that the developing flow patterns are very similar in dynamic nature even though there is a time lag due to the inevitable time delay in setting up a linear temperature profile. For high Rayleigh numbers, the oscillatory motion is likely to take place and stratified region is extended. However, initial temperature adjustment process is much slower than that for low Rayleigh numbers.
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장성원(S. W. Chang),유정열(J. Y. Yoo),이택식(T. S. Lee) 한국자동차공학회 1990 오토저널 Vol.12 No.3
A wind tunnel experiment for the flow around a 1/5 scale passenger vehicle model has been carried out. A 5-hole Pitot tube is used for measuring velocity distributions around the model and a scanivalve with 48 ports is used for measuring surface pressure distribution at various Reynolds numbers. In order to observe the flow on the surface and in the wake region, a flow visualization experiment has been perfonned using wool tuft with and without paper cones. In addition, a 2-dimensional viscous calculation considering only the mid-plane section of the model has been performed.<br/> A complex wake structure in the immediate rear of the model has been confirmed. The distributions of the surface pressure coefficient are not sensitively dependent on the Reynolds Number. In the first half of the model, they do not seem to vary from section to section. However, in the second half, they do vary from section to section, especially at the bottom surface, which indicates that the cross flow vortex is more affected by the bottom surface than the top surface. The qualitative agreement of the measured and calculated velocity field also explains the usefulness of the 2-dimensional calculation in the limited sense.
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선택적 투과성면을 가진 직사각형 밀폐공간에서의 표면복사 및 자연대류해석
박대성,이택식,이준식,Park D. S.,Lee T. S.,Lee J. S. 대한설비공학회 1987 설비저널 Vol.16 No.2
A numerical study has been conducted on the combined radiation-natural convection heat transfer characteristics in a square cavity with a selectively transparent wall. The fluid in the cavity is assumed to be transparent to the thermal radiation. The effect of the wall emissivity is mainly considered in view of the temperature and flow fields. The comparison of the radiative heat flux and conductive heat flux variations along the isothermal wall is presented as well. The results show that the Nusselt number distribution is fairly uniform due to the com-pensative interaction of the radiation and convection heat transfer.
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