• Korean Chemical Engineering Research
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• 제54권4호
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• pp.479-486
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• 2016

순산소 전로 후드의 일산화탄소와 열회수를 위해서는 고효율의 증기를 발생시키는 증기드럼의 장착이 필요하다. 그러나 제선 제강공정에서 증기발생은 간헐적이거나 주기적인 산소 취입공정기간에 제한적이다. 따라서, 증기드럼은 전로의 주기에 따른 산소의 취련기간 동안 효율적으로 증기를 발생시키도록 최적 설계되어야 한다. 따라서 본 연구에서는 다양한 운전조건 및 기하학적 형상변화가 증기드럼 내의 열유동 특성과 성능에 미치는 효과를 예측할 수 있는 3차원 전산유체역학 모델을 제안하였다. 본 모델은 유체유동 및 열전달 뿐만 아니라 계면유동에서의 증발 및 응축을 유한체적법을 사용하여 고려하였다. 본 모델의 예측성능을 검증하기 위하여 실험에서 구한 증기발생량과 비교하였으며 3.2%의 상대오차를 보였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.33-34
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• 2005

The internal state of an automotive engine is very severe. A piston exposes burnt gas of over $2000^{\circ}$ nd is shocked by high pressure at the time of explosion. Furthermore strong friction is caused by high speed motion. A study on the cooling of the piston requires because the cooling and lubrication of the piston has an effect on the life and efficiency of engine directly. The previous system of oil jet cooled only the bottom of the piston. In order to improve the cooling efficiency, the oil gallery is made inside the piston, and oil flows into the oil gallery. The flow rate of oil at the entrance of oil gallery is important because of the cooling efficiency. The purpose of this study is the investigation of fluid flow characteristics of oil jet and flow rate into the oil gallery.

• 한국전산유체공학회지
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• 제7권3호
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• pp.44-52
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• 2002

An analytic methodology was developed for free surface motions between liquid metal coolant and cover gas in order to calculate the phenomena of gas entrainment in hot pool surface through IHX EMP and reactor core. The methodology was setup by applying the first order VOF convection model to CFX4 general purpose fluid dynamics analysis code. The methodology was validated by applying it to an experimental apparatus designed for free surface motions of KALIMER reactor. The distributions of free surface calculated by the present methodology were almost coincident with the experimental data. The developed methodology was applied to the KALIMER reactor of full power operating condition. The shapes of the free surface were nearly uniform. From the results, it was found that the altitude of the free surface from the IHX inlet nozzle of KALIMER reactor is high enough not to affect to free surface motions of generating gas bubbles from the turbulent shear flows such as hydraulic jump and water falls.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.23-26
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• 2007

Liquid water in flow channel is an important factor that limits the steady and transient performance of PEM fuel cells. A computational fluid dynamics study based on the volume-of-fluid (VOF) multi-phase model is conducted to understand the transport behavior of liquid water in flow channel. The liquid water transport in $180^{\circ}$ bends is investigated and the effect of chamfering is discussed. The effect of wall adhesion is also considered by varying the contact angle of channel surfaces. The result of this study is believed to provide a useful guideline for design optimization of flow patterns or channel configurations of PEM fuel cells.

• Journal of Advanced Research in Ocean Engineering
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• 제4권3호
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• pp.135-145
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• 2018

This paper deals with the added resistance of a ship in waves using computational fluid dynamics (CFD). The ship added resistance is one of the key considerations in the design of energy-efficient ship. In this study, the added resistance of a LNG carrier in head waves is computed using a CFD code to consider the nonlinearity and the viscous effects. The unsteady Reynolds Averaged Navier-Stokes equation (RANS) is numerically solved and the volume of fluid (VOF) approach is used to simulate the free surface flows. The length of incident wave varies from half the ship length to twice the ship length. To investigate the nonlinearity effect, both the linear wave condition and the nonlinear wave condition are considered. The heave and pitch motions are calculated along with the added resistance, and the wave contours are obtained. Grid convergence test is conducted thoroughly to achieve the converged motion and resistance values. The calculated results are compared and validated with experimental data.

• 한국생산제조학회지
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• 제23권5호
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• pp.471-477
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• 2014

The purpose of this study was to predict the load effect on a damper installed at a nuclear power plant building after a tsunami using a volume of fluid (VOF) numerical analysis method. The wave height was determined by a sine wave function and the tsunami condition was estimated by the wave length. Also, using computational fluid dynamics (CFD), the maximum damper load was set as a boundary condition for the structural analysis that verified how stress and deformation affect the damper. As a result, such simulations estimated the highest stress distribution for a wave length of 350 m with a maximum stress present at the cross point of stiffness installed at the rear end of the damper. The total deformation was approximately 32 mm at the center of damper.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.77-83
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• 2009

In this study, we conducted resistance and propulsion performance test of ship composed of the Resistance Test, Propeller Open Water Test and Self Propulsion Test using the CFD(Computational Fluid Dynamics). We used commercial RANS(Reynolds Averaged Navier Stokes equation) solver, as a calculating tool. The unstructured grids were used in a bow and stern of ship, having complex shape, for a convenience of generating grids, and the structured grids were adopted in a central hull and rest of hull having a relatively simple shape which is called hybrid grid method. In addition, The sliding mesh method was adopted to rotate a propeller directly in the Propeller Open Water and Self Propulsion Test. The Resistance Test and Self Propulsion Test were calculated using Volume of Fluid (VOF) model and considering a free surface. And all The three cases were applied realizable k-epsilon model as the turbulence model. The results of calculations were verified for the suitability of calculations by comparing MOERI's EFD results.

• 한국주조공학회지
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• 제12권1호
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• pp.51-61
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• 1992

주조시 주형내의 유동해석을 위해서는 시간에 따라 변화하는 자유표면 위치에 대한 정확한 정보가 요구되는 관계로 난제로 여겨져 왔다. 따라서 대부분의 연구는 초기치 속도를 정의하기 위해서 순간충입(instantaneous filling)을 가정하여 수치 해석을 하였던 것이다. 본 연구는 Modified Solution Algorithm-Volume of Fluid Method (MSOLA-VOF)를 개발하는 주조시 주형내의 유동을 수치적으로 해석하며, 유속이 수평 주조, 수직 주조의 경우에 어떤 영향을 미치는가에 대하여 연구하였다. 결론으로 응고 연구에 있어서 초기의 순간충입은 비현실적인 가정이라는 것이 밝혀졌으며, 충입시 초기 속도 분포와 결정 생성은 밀접한 관계가 있음을 알 수 있었다.

• 한국가시화정보학회지
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• 제21권1호
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• pp.47-56
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• 2023

Bubble condensation, which involves the interaction of bubbles within the subcooled liquid flow, plays an important role in the effective control of thermal devices. In this study, numerical simulations are performed using a VOF (Volume of Fluid) model to investigate the effect of tube diameter on bubble condensation. As the tube diameter decreases, condensation bubbles persist for a long time and disappear at a higher position. It is observed that for small tube diameters, the heat transfer coefficients of condensation bubbles, which is a quantitative parameter of condensation rate, are smaller than those for large tube diameters. When the tube diameter is small, the subcooled liquid around the condensing bubble is locally participated in the condensation of the bubble to fill the reduced volume of the bubble due to the generation of a backflow in the narrow space between the bubble and the wall, so that the heat transfer coefficient decreases.

• 한국전산유체공학회지
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• 제11권3호
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• pp.14-21
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• 2006

A numerical simulation of the binary collision dynamics of water drops for size ratios of 1 and 0.75, for the Weber number range of 5 to 100, and for all impact parameter is reported. Two different types of separating collisions, namely reflexive and stretching separations, are identified. A numerical method is based on a fractional-step method with a finite volume formulation and the interface is tracked with Volume of Fluid(VOF) method, including surface tension. Numerical results for size ratios 1 and 0.75 are reasonablely compared with Ashgriz and Poo's experimental results.