• 한국가스학회지
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• 제12권1호
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• pp.36-41
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• 2008

본 논문에서는 완전밀폐식 LNG 저장탱크의 외부탱크 측벽면과 지붕 구조물에 대한 강도안전성을 유한요소법으로 해석하였다. 예응력 콘크리트 구조물로 건설된 외부탱크는 내부탱크의 붕괴로 인해 발생하는 LNG 유체정압과 유체동압, 그리고 태풍을 포함한 외부의 풍압하중을 받는다. FEM 해석결과에 의하면, 외부탱크의 측벽면과 지붕 구조물이 서로 연결되는 링빔 구조물은 저장탱크에 작용하는 대부분의 내 외부 하중을 담당하고 있다. 이러한 해석결과는 외부탱크의 설계 포인트를 링빔에 두고, 그 다음은 지붕구조물의 중심부에 대한 설계 안전성을 검토하는 것이다. 완전밀폐식 LNG 저장탱크 해석에서 사용한 해석모델은 LNG 누설에 의한 내부압력 및 태풍과 같은 외부압력이 결합된 복합하중에서도 안전한 강도안전성을 유지하고 있음을 알 수 있다.

• Wind and Structures
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• 제18권6호
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• pp.651-668
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• 2014

Wind tunnel tests are conducted to investigate the wind loads on vertical fixed-roof cylindrical tanks with a very low aspect ratio of 0.275, which is a typical ratio for practical tanks with a volume of $100,000m^3$. Both the flat-roof tank and the dome-roof tank are investigated in present study. The first four moments of the measured wind pressure, including the mean and normalized deviation pressure, kurtosis and skewness of the pressure signal, are obtained to study the feature of the wind loads. It is shown that the wind loads are closely related to the behavior of flow around the structure. For either tank, the mean wind pressures on the cylinder are positive on the windward area and negative on the sides and the wake area, and the mean wind pressures on the whole roof are negative. The roof configurations have no considerable influence on the mean pressure distributions of cylindrical wall in general. Highly non-Gaussian feature is found in either tank. Conditional sampling technique, envelope method, and the proper orthogonal decomposition (POD) analysis are employed to investigate the characteristics of wind loads on the cylinder in more detail. It is shown that the patterns of wind pressure obtained from conditional sampling are similar to the mean pressure patterns.An instantaneous pressure coefficient can present a wide range from the maximum value to the minimum value. The quasi-steady assumption is not valid for structures considered in this paper according to the POD analysis.

• Wind and Structures
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• 제10권1호
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• pp.23-44
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• 2007

Wind tunnel experiments on small scale groups of tanks are reported in the paper, with the aim of evaluating the pressure patterns due to group effects. A real tank configuration is studied in detail because one tank buckled during a hurricane category 3. Three configurations are studied in a wind tunnel, two with several tanks and different wind directions, and a third one with just one blocking tank. The pressures were measured in the cylindrical part and in the roof of the tank, in order to obtain pressure coefficients. Next, computational buckling analyses were carried out for the three configurations to evaluate the buckling pressure of the target structure. Finally, imperfection-sensitivity was investigated for one of the configurations, and moderate sensitivity was found, with reductions in the maximum load of the order of 25%. The results help to explain the buckling of the tank for the levels of wind experienced during the hurricane.

• Journal of Advanced Marine Engineering and Technology
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• 제36권8호
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• pp.1024-1029
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• 2012

DME는 천연가스로부터 합성할 수 있는 대량의 미래 에너지원으로 한국가스공사는 이의 국내 공급을 위해 해외 자원 확보와 함께 해양에서 생산과 저장을 할 수 있는 FPSO의 건조를 추진하고 있다. 본 논문은 저장탱크 내부에서의 DME의 거동을 분석하여 제시함으로써 관련 기술자의 설계나 DME운영에 도움이 되고자 하였다. DME 증발량과 압력변화의 해석결과는 DME탱크 내 액체의 저장량이 증가할수록 증가하였다. 만선인 98%의 충전에서는 저장압력이 급격히 상승하게 되므로 하루 이상 장기간 저장하여야 할 경우는 만선저장을 피하는 것이 바람직하다.

• Coupled systems mechanics
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• 제4권4호
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• pp.317-336
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• 2015

The present paper deals with the analysis of water tank with elastic separator wall. Both fluid and structure are discretized and modeled by eight node-elements. In the governing equations, pressure for the fluid domain and displacement for the separator wall are considered as nodal variables. A method namely, direct coupled for the analysis of water tank has been carried out in this study. In direct coupled approach, the solution of the fluid-structure system is accomplished by considering these as a single system. The hydrodynamic pressure on tank wall is presented for different lengths of tank. The results show that the magnitude of hydrodynamic pressure is quite large when the distances between the separator wall and tank wall are relatively closer and this is due to higher rotating tendency of fluid and the higher sloshed displacement at free surface.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.520-526
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• 2011

In recent years, it is very important that hydrogen storage system is safe for user in any circumstances in case of crash and fire. Because the hydrogen vehicle usually carry high pressurized cylinders, it is necessary to do safety design for fire. The Global Technical Regulation (GTR) has been enacted for localized and engulfing fire test. High pressure hydrogen storage system of fuel cell electrical vehicles are equipped with Thermal Pressure Relief Device (TPRD) installed in pressured tank cylinder to prevent the explosion of the tank during a fire. TPRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. In this paper, we observed the localized and engulfing behavior of tank safety, regarding the difference of size and types of the tanks in accordance with GTR.

• 한국추진공학회지
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• 제6권4호
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• pp.47-58
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• 2002

압력조절 레귤레이터는 KSR-III 추진제 탱크의 압력 조절용으로 개발하였다. KSR-III 가압 시스템은 가압 탱크, 압력조절용 레귤레이터, 추진제 탱크로 구성된 가장 기본적인 시스템이며 레귤레이터는 헬륨 탱크, 파이로밸브, 헬륨주입밸브와 더불어 가장 핵심적인 부품이다. 1차 시제품으로 기밀, 강도, 기본 성능을 만족하는 상세 설계를 완성하였고 2차 시제품으로 추진기관 종합수류시험을 수행하였다. 2차시험을 통해서 밸브의 용량(Cv)을 늘려야 할 필요성이 나타났다. 3차 시제품에 이를 개선하였으며 추진기관 종합 실추진제 시험과 연소시험을 통해 최종 검증하였다.

• 대한조선학회논문집
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• 제58권5호
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• pp.271-280
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• 2021

The code developed using a pressure-based method for unified conservation laws of incompressible/compressible fluids is expanded to handle moving or deforming body boundaries using the hybrid Cartesian/immersed boundary method. An instantaneous pressure field is calculated from a pressure Poisson equation for the whole fluid domain, including the compressible gas region. The polytropic gas is assumed for the compressible fluid so that the energy equation is decoupled. Immersed boundary nodes are identified based on edges crossing body boundaries. The velocity vector is reconstructed at the immersed boundary node using an interpolation along the assigned local normal line. The developed code is validated by comparing the time histories of pressure and wave elevation for sloshing in a rectangular and a membrane-type tank. The validated code is applied to simulate air cushion effects in a rectangular tank under sway motion. Time variations of pressure fields are analyzed in detail as the air pocket pulsates. It is shown that the contraction and expansion of the air pocket dominate the pressure loads on the wall of the tank. The present results are in good agreement with other experimental and computational results for the amplitude and the decay of the pressure oscillations measured at the pressure gauges.

• 항공우주시스템공학회지
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• 제18권3호
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• pp.8-16
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• 2024

수소는 매우 낮은 밀도를 갖기 때문에 화석연료와 동일한 수준의 에너지량을 저장하기 위해서는 기존과 다른 저장방식이 요구된다. 수소의 밀도를 높이는 방법으로는 수소를 액화하여 저장하는 방법이 있다. 하지만, 수소의 액화온도는 -252 ℃의 극저온이기 때문에 외부 열 유입에 의해 쉽게 기화된다. 액체수소가 기화되면 탱크 내부의 압력이 증가되는 자가증압 현상을 발생하므로, 탱크 설계 시 이 상승하는 압력을 잘 예측해야 한다. 따라서, 본 논문에서는 극저온 액체수소 연료탱크의 액체수소 충전 비율에 따른 내부 압력을 예측하였다. 탱크 내부의 압력 상승을 예측하기 위하여 1차원 열역학적 모델을 적용하였다. 열전달 모델은 열 유입, 액체수소의 기화, 연료 배출에 현상이 고려되었다. 최종적으로 연료탱크 내의 액체수소의 충전 비율에 따라 압력 상승 거동과 최대 상승 압력에 큰 차이가 있음을 확인하였다.

• Ocean Systems Engineering
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• 제9권4호
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• pp.409-422
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• 2019

Sloshing is a phenomenon which may lead to dynamic stability and damages on the local structure of the tank. Hence, several anti-sloshing devices are introduced in order to reduce the impact pressure and free surface elevation of liquid. A fixed baffle is the most prevailing anti-sloshing mechanism compared to the other methods. However, the additional of the baffle as the internal structure of the LNG tank can lead to frequent damages in long-term usage as this structure absorbs the sloshing loads and thus increases the maintenance cost and downtime. In this paper, a novel type of floating baffle is proposed to suppress the sloshing effect in LNG tank without the need for reconstructing the tank. The sloshing phenomenon in a membrane type LNG tank model was excited under sway motion with 30% and 50% filling condition in the model test. A regular motion by a linear actuator was applied to the tank model at different amplitudes and constant period at 1.1 seconds. Three pressure sensors were installed on the tank wall to measure the impact pressure, and a high-speed camera was utilized to record the sloshing motion. The floater baffle was modeled on the basis of uniform-discretization of domain and tested based on parametric variations. Data of pressure sensors were collected for cases without- and with-floating baffle. The results indicated successful reduction of surface run-up and impulsive pressure by using a floating baffle. The findings are expected to bring significant impacts towards safer sea transportation of LNG.