• Title, Summary, Keyword: Oil Fence

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Effect of tip configuration of an oil fence on wake structure behind the fence (오일펜스의 tip 형상이 후류유동에 미치는 영향에 관한 연구)

  • Koh, Min-Seok;Lee, Sang-Joon;Lee, Choung-Mook;Chung, Sang-Kook
    • Proceedings of the KSME Conference
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    • pp.772-776
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    • 2001
  • The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

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Efficiency of Model Oil Fences for One Vessel Using a Physical Experiment and Numerical Calculation (모형 실험과 수치 해석을 통한 단선용 모형 오일펜스의 성능 해석)

  • Kim, Tae-Ho;Jang, Duck-Jong;Yang, Kyung-Uk;Na, Sun-Chol;Kim, Dae-An
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.41 no.2
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    • pp.140-149
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    • 2008
  • This study evaluated the efficiency of an oil fence and spreading devices for one vessel in a towing tank. A series of model experiments and numerical calculations were conducted using an existing oil fence for two vessels and a new method for one vessel. Models of the oil fence and spreading devices were constructed on $1/20^{th}$ scale from waterproofed nylon fabric and canvas. The tensions acting on the model of the oil fences and the horizontal distance between the spreading devices were calculated numerically while the oil fences were being towed. The results were extremely close to the results of the model experiments. The ratio of the opening width to the total length of the oil fence, which shows the efficiency of the oil fence for one vessel, was 49.7% in 0.4 m/sec. Therefore, the proposed oil fence system should be very useful for oil containment at sea. As the opening width of the oil fence is not proportional to the length of the towing rope, it may be reasonable to maintain the towing rope at approximately 100 m. Furthermore, a reasonable towing speed, when operating the oil fence for one vessel equipped with spreading devices, was within 0.4 m/sec.

Analysis of Effectiveness of Tandem Oil Fences (이중유벽의 유효성에 관한 해석)

  • Han Dong Gi;Lee Choung Mook
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.4 no.1
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    • pp.38-46
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    • 2001
  • To assess the oil-containment effectiveness of tandem oil fences placed in currents, the movement of oil droplets in the fore and aft region of the fences is investigated by experimental and numerical methods. The effect of the flexibility of the fence skirt of single fence on the fence effectiveness is also investigated. Laboratory experiment is conducted to trace the path of a spherical solid particle of equivalent density to an oil droplet which was released in a uniform stream ahead of a model oil fence. Depending upon the releasing position and the flow condition there, it was observed that the particle floated up to the free surface, collided with the fence, or escaped below the fence. By analyzing the droplet trajectories, a numerical method is developed to predict the region ahead of the fore fence where an oil droplet initiating its motion eventually escapes beneath the fence. The effect of the relative sizes of the drafts of the fore and aft fences, the fence separation, and the bottom depth of the sea bed on the effectiveness of tandem fences is investigated using the numerically obtained trajectories of oil droplets.

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Prediction of Deformation of an Oil-fence by using Fluid$\cdot$Structure Interaction Method (유체$\cdot$구조물 상호 작용 기법을 이용한 오일 펜스의 변형 예측)

  • Kim T. G.;Kim W.;Hur N.
    • Journal of computational fluids engineering
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    • v.5 no.3
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    • pp.16-22
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    • 2000
  • In the present study a method of computing fluid-structure interaction is presented to simulate the deformation shape of an oil fence which is used to contain or to divert the split oil in sea water. The computation is performed by taking into account of the force and moment balance in each computational element of the oil fence. The forces and moments acting on each element of the structure is computed from the flow analysis, which in turn is used to predict deformed shape of the structure until the procedure converges. The flexibility of the oil fence was also considered in the analysis. It is shown from the present study that the predicted deformed shapes agree quite well with the available experiment data.

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Oil Fence 에 발생하는 전장력에 관한 실험적 연구

  • 안성모;청목신일
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • pp.139-142
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    • 1997
  • 최근 우리나라를 비롯해 세계 여러 나라에서 Oil Tanker에 의한 사고가 빈번히 일어나고 있다. 이와 같은 사고의 대책으로 Oil Tanker의 2중화 등 여러 가지 면에서 대책에 총력을 기울이고 있지만, 일단 사고가 발생하게 되면 이러한 모든 대책은 무용지물이 되고 만다. 사고 발생 후 확산되는 Oil의 집적에 현재 일반적으로 사용되어지는 도구인 Oil Fence는 다양한 형태의 많은 개발품이 사용되어 지고 있지만, 이러한 Oil Fence 및 Oil 회수 장치에 의해 회수되어지는 양은 전체 확산되어지는 양의 고작 15%정도에 그친다. (중략)

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Analysis of Containment Capability of Oil Fence in Currents and Waves (조류와 파랑중에서의 유벽의 보유성능 해석)

  • Lee Choung Mook;Kang Kwan Hyoung
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.1 no.1
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    • pp.29-38
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    • 1998
  • This paper summarizes the results of the investigations performed by the authors for a number of years on the performance of oil fences in currents and waves. The leakage inception velocity of currents, the wave-exciting motion of fences and the deformation of the fence skirt due to currents are investigated. The results show that improvement of the fence performance is necessary in order to utilize the oil fences as an effective containing device for spilt oils in ocean environments. As an approach toward improving the fence effectiveness, tandem fences in currents are investigated. It was found that an appropriate deployment of tandem fences of identical configuration could significantly improve the oil containment capability.

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Development of an Efficient Calculation Method of Pressure Acting on a Bluff Body and the Deformation of Flexible Oil Fences in Currents (뭉뚝한 물체에 작용하는 압력의 효율적인 계산법 개발과 조류중에서의 유연한 유벽의 변형)

  • Kang, Kwan Hyoung;Lee, Choung Mook
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.4
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    • pp.22-31
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    • 1996
  • An efficient calculation method of pressure acting on a bluff body is developed. The method is applied to assess the containment capability of an oil fence, considering skirt deformation in current. The pressure on the frontal side of the oil fence is determined by analyzing the potential flow, substituting the wake region as a rigid body which has its boundary at the closed separation streamlines. The pressure at the downstream side of the fence, the so called base pressure, is obtained from the existing experimental results. To verify the calculation method, pressure drag of some bluff bodies in an infinite-fluid medium is calculated, which shows good agreement with the experimental results. The deformed shape of the oil fence is obtained by solving, iteratively, the coupled equations governing the flow field and the deformation of the oil fence, respectively. The deformed shape and the decrease of draft of oil fences with different ballast mass in various current conditions are investigated.

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Characteristics of Flow Field at Curved Section of Oil Fence using PIV Measurements and CFD Simulations (PIV 계측과 CFD 해석을 통한 오일펜스 만곡부 단면에서의 유동장 특성)

  • Kim, Tae-Ho;Jang, Duck-Jong;Na, Sun-Chol;Bae, Jae-Hyun;Kim, Dae-An
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.17 no.1
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    • pp.29-37
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    • 2011
  • PIV measurements of the velocity field, pressure field, vorticity, and turbulent intensity in the rear of curved section of an oil fence with current speed showed that the flow directions in the rear of flow boundary area were similar to those in the front of it. As the current speed increased, the patterns of pressure distribution were changed, and the turbulent flow became more irregular. CFD simulations under the same conditions as the PIV tests showed that the flow patterns of the wake were similar to those by PIV tests in speed of 0.3 m/s and less, but were distinctively deviated from those in 0.4 m/s due to the flexibility of the oil fence, which was not properly taken care of in CFD modeling.