Multiphase Fluid Dynamics in Storage Tanks of Varying Geometry

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Obai Kargbo ◽  
Mi-An Xue ◽  
Jinhai Zheng
Keyword(s):  
Dynamic Pressure ◽  
Numerical Approach ◽  
Offshore Platforms ◽  
Storage Tanks ◽  
Fluid Sloshing ◽  
Hydrodynamic Response ◽  
Wave Heights ◽  
Free Surface Wave ◽  
Multiphase Fluid ◽  
Liquid Natural Gas

Abstract Sloshing control is key in the offshore storage and transportation of petroleum and other liquid phased products such as liquid natural gas (LNG). It is of interest in the enhancement of the structural stability of offshore platforms and floating production storage and offloading units. This work presents a numerical approach in the study and analysis of the effect of storage tank configurations on the hydrodynamic response of a multiphase-layered fluid undergoing sloshing. The study showed that tank configurations had an effect on the internal and free surface wave heights of the multiphase fluid sloshing in the tank, as well as on the dynamic pressure intensity being exerted on the tank walls, with some configurations exhibiting comparatively greater sloshing wave and pressure damping.

Development of Operational Limit Diagrams for Offshore Lifting Procedures

2015 ◽  
Author(s):  
Leonardo Roncetti ◽  
Fabrício Nogueira Corrêa ◽  
Carl Horst Albrecht ◽  
Breno Pinheiro Jacob
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Technological Development ◽  
Automatic Generation ◽  
Dynamic Responses ◽  
Offshore Platforms ◽  
Peak Period ◽  
Significant Wave ◽  
Wave Heights ◽  
Offshore Crane

Lifting operations with offshore cranes are fundamental for proper functioning of a platform. Despite the great technological development, offshore cranes load charts only consider the significant wave height as parameter of environmental load, neglecting wave period, which may lead to unsafe or overestimated lifting operations. This paper aims to develop a method to design offshore crane operational limit diagrams for lifting of personnel and usual loads, in function of significant wave height and wave peak period, using time domain dynamic analysis, for a crane installed on a floating unit. The lifting of personnel with crane to transfer between a floating unit and a support vessel is a very used option in offshore operations, and this is in many cases, the only alternative beyond the helicopter. Due to recent fatal accidents with lifting operations in offshore platforms, it is essential the study about this subject, contributing to the increase of safety. The sea states for analysis were chosen covering usual significant wave heights and peak periods limits for lifting operations. The methodology used the SITUA / Prosim software to obtain the dynamic responses of the personnel transfer basket lifting and container loads on a typical FPSO. Through program developed by the author, it was implemented the automatic generation of diagrams as a function of operational limits. It is concluded that using this methodology, it is possible to achieve greater efficiency in the design and execution of personnel and routine load lifting, increasing safety and a wider weather window available.

scholarly journals A Numerical Approach to the Dynamic Response of the Deployment System during a Circular Cylinder Crossing through the Wave Zone

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Xiaozhou Hu ◽  
Daojun Cai ◽  
Yiyao Jiang
Keyword(s):  
Circular Cylinder ◽  
Dynamic Response ◽  
Numerical Approach ◽  
Dynamic Responses ◽  
Regular Waves ◽  
Cable Dynamics ◽  
Input Parameters ◽  
Solution Methods ◽  
Wave Heights ◽  
Phase Angles

The dynamic response of the deployment system while deploying a circular cylinder crossing wave surface and the following submerging process are investigated numerically. The present numerical approach is based on the combination of solution methods of cable dynamics and computational fluid dynamics (CFD). For the implementation of the numerical approach, a cosimulation platform based on a CFD code and MATLAB is developed to study the fluid-solid interaction problem in the process. To generate regular waves, a numerical wave tank is built based on a piston-type wave generation method and a wave damping method applying porous media. Numerical simulations are performed based on the cosimulation platform. The sensitivities of cable tension, velocity, and acceleration of deployed body to different input parameters are investigated, including phase angles, wave heights, and periods of regular waves and deploying velocities, and the effects of those input parameters on dynamic responses of the deployment system are also discussed.

scholarly journals Rollover of Liquid Natural Gas in a Storage Tank: A Numerical Simulation

2021 ◽  
Author(s):  
Yinbin Lu ◽  
Chenwei Liang
Keyword(s):  
Natural Gas ◽  
Storage Tank ◽  
Initial Density ◽  
Critical Density ◽  
Liquefied Natural Gas ◽  
Density Difference ◽  
Storage Tanks ◽  
Exponential Functions ◽  
Double Exponential ◽  
Liquid Natural Gas

In the filling and transportation processes of liquefied natural gas (LNG), the safety of LNG storage tanks is compromised because of rollover phenomenon. As such, the rollover factors of LNG in a storage tank should be identified to prevent or weaken the rollover intensity of LNG. In this study, the rollover behavior of LNG in a storage tank is numerically simulated. The density of the two layers in a LNG storage tank is related to temperature in our numerical model. It is found that the greater the significant initial density difference (range of 1-12 kg·m-3) is, the more obvious the LNG rollover will be. A density difference of 7.5 kg·m-3 is found as the critical density difference in the present work. When the initial density difference exceeds the critical density difference, the LNG rollover coefficients increase dramatically. Moreover, an LNG rollover model with two daughter models is proposed, which are divided by the critical initial density difference, i.e., a cubic relationship between rollover coefficients and the initial density difference when the density difference is less than 7.5 kg·m-3 and secondly, a linear relationship between the rollover coefficient and the double exponential functions when the density difference is larger than 7.5 kg·m-3.

scholarly journals Pemodelan Kecepatan Arus dan Tinggi Gelombang Pada Rencana Breakwater Kolam Pelabuhan Meulaboh Dengan Menggunakan Program Delft3D

2019 ◽  
Vol 5 (2) ◽  
pp. 11-19
Author(s):  
Ichsan Syahputra ◽  
Heny Yuliana
Keyword(s):  
Wave Height ◽  
Open Water ◽  
Initial Operation ◽  
The West ◽  
Hydrodynamic Response ◽  
Aceh Province ◽  
Wave Heights ◽  
The Indian Ocean ◽  
The Impact ◽  
Pool Area

The Meulaboh port in West Aceh Regency is one of the ports in the west coast of Aceh Province. Initial operation of this port began in 2016 and currently serves crossing activities with the Meulaboh - Sinabang pass. The Meulaboh port is located in open water facing the Indian Ocean. In extreme conditions, ships often have to delay shipping due to high waves that cause shocks to the ship. Based on these problems, the study will provide an overview of the impact and hydrodynamic response of the Meulaboh port pool area and analyze the impact of wave heights on activities in the port pond based on several Breakwater construction layout scenarios. Alternative handling scenarios are carried out using the Delft3D program. The distribution of wave height at the direction of the wind from the Southwest with Hs = 4.908 m, and Ts = 7.254 seconds which shows the dominant wave from the Southwest restrained by Breakwater and the wave height in front of the port mouth ranges from between 0-1 meters so it is safe against activities cruise.

scholarly journals Effect of Double-Side Curved Baffle on Reducing Sloshing in Tanks under Surge and Pitch Excitations

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Aimeng Zhu ◽  
Mi-An Xue ◽  
Xiaoli Yuan ◽  
Feng Zhang ◽  
Wei Zhang
Keyword(s):  
Effective Stress ◽  
Laboratory Experiments ◽  
Hydrodynamic Pressure ◽  
Structural Safety ◽  
Tank Wall ◽  
Motion Platform ◽  
Liquid Storage ◽  
Wave Elevation ◽  
Wave Heights ◽  
Free Surface Wave

Sloshing is associated with the structural safety of liquid storage vessel. Installing the baffles inside the containers would be beneficial for the mitigating the damage due to the severe sloshing. In this study, an innovative type of double-side curved baffle was proposed to evaluate its effect on reducing sloshing in a rectangular tank under surge and pitch excitation. For comparison with conventional baffles, effects of the vertical baffle and the T-type baffle on mitigating sloshing were also studied experimentally and numerically by analyzing the free surface wave elevation as well as the hydrodynamic pressure on the tank wall. The effective stress at the double-side curved baffle along the height direction of the baffle is much smaller than that at the T-type baffle although they have the same mitigation effect on sloshing wave heights. The sloshing-induced effective stress on the double-side curved baffles was analyzed by varying their radian. Findings show that the effective stress on the baffle tends to decrease with the increase in the radian. The velocity field was presented to observe effect of the baffles on sloshing with the aid of ADINA and laboratory experiments conducted on a hexapod motion platform.

Hydrodynamic experiments with rigid cylindrical tanks subjected to transient motions*

1951 ◽  
Vol 41 (4) ◽  
pp. 313-346
Author(s):  
Lydik S. Jacobsen ◽  
Robert S. Ayre
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Vertical Plane ◽  
Storage Tanks ◽  
Direction Parallel ◽  
Fluid Damping ◽  
Hydrodynamic Experiments ◽  
Wave Heights ◽  
Equivalent Mass ◽  
Cylindrical Tanks

Abstract Four tanks, from 6 inches to 4 feet in diameter, have been subjected simultaneously to transient, horizontal “ground motions” of simplified type. The important parameters, in addition to size of tank, were depth of fluid and frequency, duration, and amplitude of ground motion. The envelopes of the gravity-wave profiles have been recorded on a vertical plane of symmetry placed within each tank in a direction parallel to the ground motion. The data include samples of the wave envelopes, photographic studies of the wave formation, maximum wave heights and the locations of these maxima, and the fluid damping coefficients. Equivalent mass and overturning moment due to the fluid have been shown for various degrees of confinement of the upper surface, from complete confinement (owing to use of a rigid cover) to a free surface. The study relates to the effect of earthquakes and other ground motions on oil and water storage tanks. The results can be extrapolated with reasonable certainty to full-scale tanks.

A New Method for Determining the Design Sloshing Loads for LNG FPSOs

2014 ◽  
Author(s):  
Jeom Kee Paik ◽  
Sang Eui Lee ◽  
Bong Ju Kim ◽  
Jung Kwan Seo ◽  
Yeon Chul Ha ◽  
...  
Keyword(s):  
Natural Gas ◽  
Flow Chart ◽  
New Method ◽  
Storage Tanks ◽  
Operational Conditions ◽  
Oceanic Region ◽  
Liquid Natural Gas

The aim of this study was to develop a new method for determining nominal values for sloshing loads in the design of storage tanks in LNG FPSO (liquid natural gas, floating production, storage and offloading units). Details of the procedure are presented in a flow chart showing the key sub-tasks. The applicability of the method is demonstrated using an example of a hypothetical LNG FPSO operating in a natural gas site off a hypothetical oceanic region. It is concluded that the developed method is useful for determining the design sloshing loads of storage tanks in ship-shaped offshore LNG installations in combination with virtual metocean data and operational conditions.

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