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설승윤,Seol, Seoung-Yun 한국초전도저온공학회 2000 한국초전도저온공학회논문지 Vol.2 No.2
The stability of variable cross-sectional area HTS current lead is considered. The cross-sectional area is varied to have a constant safety factor which is defined as the ratio of operating current and critical current of superconductor. As the constant area HTS lead, the variable cross-sectional area HTS lead also has three steady states above the bifurcation point and only one steady state below the bifurcation point. The temperature profiles and current sharing ratios for each steady state are calculated. The heat dissipation into cryogenic system for super-conducting, intermediate, and upper states are compared. For Bi-2333 sheathed with silver-gold alloy 2m length of current lead, and the maximum temperature of upper state seems to be burn-out free below 5m length.
사이클론 집진기의 벽면구배에 따른 압력손실과 컷 사이즈 변화 예측 모델 개발
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In previous studies, Convex cyclone are proposed to reduce pressure loss which are design cyclone wall with a single continuous curve. Studies about a prediction model for pressure loss and cut-size has focused on conventional cylinder-on-con cyclone. Therefore, the models do not perform well for uncommon design. In this study, a predict model for pressure loss and cut-size depend on cyclone wall curvature are developed. The tangential velocity below vortex-finder is obtained with consideration about friction area and momentum loss on the cyclone wall, and with this the variation of vortex-core and core velocity is obtained. Pressure loss is predicted using a Rankine vortex hypothesis. The prediction results are well agreed with experiments and CFD results.
연속적인 곡선으로 정의 되는 볼록한 형상의 사이클론에 대한 연구
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun),리진철(Li Zhen-Zhe) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A cyclone design concept named Convex cyclone was developed to reduce pressure losses. Contrary to conventional cylinder-on-con type cyclone, inner wall of Convex cyclone are defined with a continuous curve and it has convex shape body. The discontinuity of inner diameter variation rate of cylinder-on-con type cyclone cause additional pressure loss. Continuous wall of Convex cyclone prevent additional pressure loss. In order to verify Convex cyclone design concept, we make a comparative experiments between Stairmand HE and Convex cyclone. Experimental Convex cyclone designed based on Stairmand HE model, and inner wall are defined with circular arch. The experimental result clearly shows that Convex cyclone can achieve maximum 50% pressure loss reduction with a few percent of collection efficiency drop. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall.
Convex 사이클론의 등급집진효율과 압력 손실에 관한 실험적 연구
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Cyclone separator is one of the most widely used devices to separate and recover the industrial dusts from air or process gases. We developed Convex cyclone to reduce pressure losses. The body of Convex cyclones are designed with single continuous curve and convex shape as a substitute for cylinder-on-cone geometry. With a previous studies, experimental result shows that Convex cyclone are efficient for pressure loss reduction. However, there seems to be no clear explanation about collection efficiency. In this study, we perform additional experiments for a in-depth comprehension of Convexcyclone with particle counting collection efficiency measurement method. The experimental result shows that Convex cyclone can achieve maximum 40% pressure loss reduction with about 0.5㎛ cut-size increasement. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall.
코어유동모델과 익형이론을 이용한 사이클론 동압회복 기구의 설계
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9
Pressure loss of cyclone consists of cyclone body friction loss and dynamic pressure loss of vortex finder which hold most of cyclone pressure loss. The pressure recovery vane or rectifier is generally used mechanism to convert rotational flow in vortex finder into axial flow. Conventional circular arc rectifier has no theoretical design guide line and depends on trial error. In this paper, we propose a theoretical design method of pressure recovery vane to reduce pressure loss in cyclone vortex finder. Core flow model is used to decide the angle of attack and width of vane. Theory shows that there exists an effective width of vane. The shape of pressure recovery vane is borrowed from the static blade of axial blower using NACA airfoil data. The design method of axial blower static blade provides theoretical guide line that can decide number of vane and stagger angle.
등급집진효율 곡선의 기울기가 2단 사이클론의 집진효율에 미치는 영향
허광수(Heo Kwang Su),설승윤(Seol Seoung-Yun),김민하(Kim Min Ha) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
A collection efficiency of cyclone is influenced by cut-size and slope of grade efficiency curve. It has been recognized that the collection efficiency is improved when the cut-size is reduced. However, effects of the slope have never been studied so far. In this study, we analyze a relationship between slope of grade efficiency and collection efficiency in two-stage cyclones. In single stage cyclones, higher slope cyclones have high efficiency. On the contrary to single stage cyclone, collection efficiency of two-stage cyclone have the maximum value when the first cyclone has a lower slope and second cyclone is high.
Swirl Tube 집진기 내의 입자 거동에 대한 연구
허광수(Kwang Su Heo),설승윤(Seoung Yun Seol) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In order to offer basic guidelines for efficient design of swirl tube separator, the particle behavior of undecayed fully developed rotational flow with different swirl number are simulated. The velocity field of swirl tube are obtained by Large eddy simulation and the particle motion is modeled using Basset-Boussinesq-Oseen equation and integrated with forth order Runge-Kutta method. It is assumed that the density of particle is much larger than that of fluid, Basset force and added mass term are therefore neglected. The required flight time to reach separator inner wall and exit are calculated and compared with the result of conventional time of flight model. Particle rebounce at the inner wall that is a important reason of collection efficiency decrease, are also simulated.
사이클론 집진기의 벽면 구배에 따른 압력손실과 등급집진효율에 대한 수치적 연구
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A pressure loss and dust collection performance of a cyclone dust separator have a relationship that trade off each other. Therefore, the design of the cyclone dust separator is a process in a quest for reasonable balance between collection efficiency and pressure loss. A number of theories about collection efficiency and pressure drop are introduced. However, those theories do not complete enough to be used to find an optimal design for a given operation condition directly. Therefore, there is a wide range of cyclone geometries in use, studies on new cyclone geometry are conducted lively. Our previous experiments show that the Convex cyclones are very effective for pressure loss reduction. The body of Convex cyclones are designed with single continuous curve and convex shape as a substitute for cylinder-on-cone geometry. In this study, we perform CFD simulation for a in-depth comprehension about flow pattern and particle behaviour of Convex cyclone.