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지하주차장 내 수소연료 자동차의 수소 누설로 인한 수소 확산에 대한 수치해석 연구
최종락(J. Choi),허남건(N. Hur),이은덕(E. D. Lee),이광범(K. B. Lee) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
In the present study, the diffusion process of hydrogen leaking from a FCV (Fuel Cell Vehicle) in an underground parking lot was analyzed by numerical simulations in order to assess the risk of a leakage accident. The temporal and spatial changes of the hydrogen concentration as well as the flammable region in the parking lot were predicted numerically. The effects of the leakage flow rate and an additional ventilation fan were investigated to evaluate the ventilation performance in the parking lot to relieve the accumulation of the leaked hydrogen gas. The present numerical analysis can provide useful information such as the distribution of the leaked hydrogen concentration for safety of various hydrogen applications.
최종락(J. Choi),신희종(H.J. Shin),김원섭(W. Kim),허남건(N. Hur) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.2
In the tractor transaxle, the components such as gears, shafts and bearings cause the oil churning so that the air may flow into the hydraulic suction pipe, and the hydraulic components may be mis-operated by the entrained air. In order to simulate the phenomenon of air inflow into the hydraulic pipe, three-dimensional transient multi-phase numerical simulations were carried out by adopting an overset mesh technique for rotating parts. Several possible locations of hydraulic suction pipe on the transaxle casing are considered in the present study to minimize the amount of air intake to the suction pipe due to the air/oil churning flow caused by the rotating parts. As a result of a present study a new location of the hydraulic suction pipe on the transaxle casing is suggested. With experimental test and some structural design considerations, this design change can be adopted in a final design of the transaxle casing.
산업용 3상 교반기 내 기체와 고체 입자의 체적 균일도 지수를 활용한 교반 성능 예측
최한호(H. Choi),최종락(J. Choi),허남건(N. Hur),정광훈(G. Jeong),임선영(S. Lim),옥태준(T. Ok) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.3
In this study, transient multiphase flow simulations were carried out to evaluate the new volume uniformity indices of gas and solid particles concentrations within the 3-phase industrial stirred vessel. In the initial state, the solid phase is located at the bottom portion of the vessel with the liquid phase positioned on top. Afterwards, the gas is injected at the middle-section of the vessel from four nozzles and discharged to the top of the vessel and in the process commences the reaction between the liquid and particle phases. To focus on the mixing phenomena, this reaction process was not simulated. A sliding grid technique was adopted to describe the rotating motion of the impellers at three different stages. The mixture flows between gas, liquid, and solid particles were simulated using the Eulerian multiphase model with STAR-CCM+ V.2020.3. Since the conventional method defines volume uniformity indices based on the entire domain, there was a limitation to predict the details of volume uniformity indices of a specific phase. For the above reason, the new volume uniformity indices of the gas and solid particles in the liquid phase were proposed and compared with the conventional method by conducting the 3-phase simulations. The new volume uniformity indices of concentrations were more effective in predicting the degree of mixing level quantitatively. In such a 3-phase flow, the actual mixing degree in the stirred vessel can be determined using the proposed volume uniformity indices of concentration, which can be used to represent the stirring performance.