A Model Experiment of a Free Standing Riser in the Deep-Sea Basin

2013 ◽  
Author(s):  
Marcio Yamamoto ◽  
Sotaro Masanobu ◽  
Satoru Takano ◽  
Shigeo Kanada ◽  
Tomo Fujiwara ◽  
...  
Keyword(s):  
Deep Sea ◽  
Model Experiment ◽  
Scale Model ◽  
Vertical Pipe ◽  
Free Standing ◽  
Visual Measurement ◽  
Smooth Cylinder ◽  
Induced Motion ◽  
Reduced Scale ◽  
A Current

An experiment using a 1/70 reduced scale model of a Free Standing Riser (FSR) was carried in the Deep-Sea Basin of the National Maritime Research Institute in Japan. For instance, the model’s vertical pipe was about 32m long and the jumper was about 8m long. The FSR model had several measurement stations attached along the vertical pipe, subsurface buoy and jumper; and the motion of each station was measured in 3D by the Visual Measurement System. During the experiment, the effects of the jumper’s top end oscillation on the whole system were investigated. In this case, the top oscillation had propagated along the jumper; however the top oscillation had a reduced effect on the dynamics of the subsurface buoy and vertical pipe. In another experimental case, a current was generated in order to investigate the Vortex Induced Motion (VIM) on the FSR’s Subsurface Buoy. The VIM experiment was repeated for two different buoy models (a smooth cylinder and a cylinder with 3-start heli-coidally strakes) and the results were compared. In this article, some of the experimental results are presented and discussed.

The Effects of Solid-Liquid Internal Flow on the Dynamic Behavior of a Reduced-Scale Jumper for Deep-Sea Mining

2020 ◽  
Author(s):  
Marcio Yamamoto ◽  
Tomo Fujiwara ◽  
Shigeo Kanada ◽  
Masao Ono ◽  
Satoru Takano ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Measurement System ◽  
Deep Sea ◽  
Forced Oscillation ◽  
Internal Flow ◽  
Differential Pressure ◽  
Scale Model ◽  
Flexible Pipe ◽  
Visual Measurement ◽  
Reduced Scale

Abstract For the exploitation of seafloor massive sulfides, we have investigated the dynamic behavior of the jumper, a piece of flexible pipe that connects the seafloor mining tool to the subsea slurry pump. In this article, we present the results of the experiment using a 1/5 reduced-scale model of the jumper. This experiment was carried out in Deep-Sea Basin. During the experiment, a slurry fluid was conveyed throughout the jumper’s model. In addition, an oscillator generated harmonic motion on the top end of the model. In terms of instrumentation, we installed load cells on the top and bottom ends of the model and a 3D visual measurement system tracked the motion of measurement stations attached to the model. We present the experimental results measured by the 3D visual measurement system, loads cells, and differential pressure gauges in the cases where a vertically forced oscillation is imposed on the top of the jumper. In this experiment, we could observe the effects of slurry on the jumper reduced-scale model. Since the slurry has a larger density than the single liquid phase, the slurry flow changed, as expected, the static shape of the jumper compared to a jumper conveying only water. The vertical top force average and differential pressure average increase with the volume concentration of solid, while their amplitudes increase quadratically with the forced oscillation frequency.

Simulation of a Free Standing Riser Model and Validation With Experimental Results

2014 ◽  
Author(s):  
Marcio Yamamoto ◽  
Sotaro Masanobu ◽  
Satoru Takano ◽  
Shigeo Kanada ◽  
Tomo Fujiwara ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Previous Experiment ◽  
Numerical Results ◽  
Experimental Results ◽  
Previous Article ◽  
Scale Model ◽  
Analysis Software ◽  
Free Standing ◽  
Reduced Scale

In this article, we present the numerical analysis of a Free Standing Riser. The numerical simulation was carried out using a commercial riser analysis software suit. The numerical model’s dimensions were the same of a 1/70 reduced scale model deployed in a previous experiment. The numerical results were compared with experimental results presented in a previous article [1]. Discussion about the model and limitations of the numerical analysis is included.

scholarly journals Examination of Vehicle Motion Characteristics of a Maglev Train Set Using a Reduced-scale Model Experiment Apparatus

2012 ◽  
Vol 53 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Hironori HOSHINO ◽  
Erimitsu SUZUKI ◽  
Takenori YONEZU ◽  
Ken WATANABE
Keyword(s):  
Model Experiment ◽  
Scale Model ◽  
Maglev Train ◽  
Vehicle Motion ◽  
Motion Characteristics ◽  
Reduced Scale

Experimental Set-Up for Analysis of Subsea Equipment Installation

2011 ◽  
Author(s):  
Pedro C. de Mello ◽  
Felipe Rateiro ◽  
Andre´ L. C. Fujarra ◽  
Anderson T. Oshiro ◽  
Cassiano R. Neves ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Companion Paper ◽  
Scale Model ◽  
Illustrative Case ◽  
Preliminary Evaluation ◽  
Hydrodynamic Properties ◽  
Wave Basin ◽  
Servo Actuator ◽  
Induced Motion ◽  
Reduced Scale

This paper and the companion paper (Rateiro et al., 2011) present an illustrative case of the joint application of experimental tests and numerical simulations for the proper analysis of a complex offshore operation (launching of a sub-sea equipment using one or two vessels). The main idea of the whole study is to compare two methodologies and operational procedures for the installation of the equipment in the seabed, using either one vessel (conventional operation) or two vessels in a synchronized operation in a Y-configuration. The experiment was conducted under a simplified configuration, and uses ODF (one degree of freedom) servo-actuator to emulate the vessels induced motion. The hydrodynamic properties of the equipment was then calculated, and some preliminary conclusions about system dynamics could also be drawn. After that, numerical simulations were conducted, considering the coupled dynamics of the vessels, cables and equipments under irregular sea state. Those simulations were used for determining the limiting environmental condition for a safe operation, and are described in the companion paper. This paper describes the reduced scale experimental setup used for evaluating the hydrodynamic properties of the equipment during a subsea installation under waves excitation. The reduced scale model of the equipment was attached to one or two servo-actuator, that emulate the wave-induced motion. The tests were conducted at the physical wave basin of Numerical Offshore Tank (Tanque de Provas Nume´rico – TPN). The experiments enabled the preliminary evaluation of the dynamic behavior of the equipment when submerged by one or two launching cables. In the later case (two launching cables), several tests considering phase shifts between the servo-actuator have been conducted. The reduction in the dynamic amplification of cable traction could also be experimentally verified.

scholarly journals Reduced-scale Model Experiment for Examination of Natural Vent and Fire Curtain Effects in Fire of Theater Stage

2019 ◽  
Vol 33 (4) ◽  
pp. 41-49 ◽  
Author(s):  
Seon A Baek ◽  
Ji Hyun Yang ◽  
Chan Seok Jeong ◽  
Chi Young Lee ◽  
Duncan Kim
Keyword(s):  
Model Experiment ◽  
Scale Model ◽  
In Fire ◽  
Reduced Scale

VIM Suppression for a FSR With a Co-Centric Porous Sheath Around the Buoyancy Can: Effects of Mesh Orientation and Diameter Ratio

2018 ◽  
Author(s):  
Jessica Crosswell ◽  
Cheslav Balash
Keyword(s):  
Natural Frequency ◽  
Motion Tracking ◽  
Cross Flow ◽  
Porous Metal ◽  
Diameter Ratio ◽  
Scale Model ◽  
Free Standing ◽  
Induced Motion ◽  
Lock In ◽  
Flow Velocities

Here, we experimentally studied the vortex-induced motion (VIM) of a free-standing riser (FSR; 1:65 scale model) with and without a porous metal screen (‘sheath’) placed co-centrically around the buoyancy can (BC). Specifically, we investigated the effects of mesh orientation (square and square rotated 45° in its own plane) and screen-BC diameter ratio (1.1 and 1.2) over a range of flow velocities. BC motions were recorded with a submersible camera; and inline (IL) and cross-flow (CF) amplitudes were then estimated with a motion tracking software. As expected, the installation of the screen changed the natural frequency of the models. Furthermore, the screen increased the reduced velocity at which the lock-in occurred, delaying it by a factor of ∼1.2 and ∼1.4 for the CF and IL respectively. All sheathed models had a prominent reduction in IL amplitudes compared to the bare/unsheathed BC; and at smaller flow velocities, the sheathed models also exhibited significantly lower CF motions, particularly those with a greater screen-BC diameter ratio.

Experimental Analysis of Reduced-Scale Jumper for Deep-Sea Mining

2019 ◽  
Author(s):  
Marcio Yamamoto ◽  
Tomo Fujiwara ◽  
Shigeo Kanada ◽  
Masao Ono ◽  
Satoru Takano ◽  
...  
Keyword(s):  
Deep Sea ◽  
Numerical Models ◽  
Oscillation Amplitude ◽  
Internal Flow ◽  
Differential Pressure ◽  
Scale Model ◽  
Pressure Amplitude ◽  
Flexible Riser ◽  
Flexible Pipe ◽  
Reduced Scale

Abstract In the Deep-Sea Mining, the seafloor mining tool is connected to the subsea slurry pump by a piece of flexible pipe named jumper. The jumper’s shape is similar to a steep-wave flexible riser. Compared to a flexible riser, the jumper is a reinforced hose and has a shorter length. Numerous studies shed light on the dynamic behavior of flexible riser; however, all studies were carried out by the way of numerical analysis. We carried out, in the Deep-Sea Basin, an experiment using 1/5 reduced scale model of the jumper. Unhappily, the model’s bending stiffness had to be distorted. During the experiment, an oscillator generated harmonic motion on the top end of the model and a centrifugal pump circulated water throughout the model. In addition, we installed load cells on the top and bottom ends of the model. Our Basin is equipped with a visual measurement system. Thus, we measured the displacement of targets attached to the model. The initial results show that axial tension amplitude increases with the frequency of the top end oscillation. This response is due to the drag force on the lower bend increases with the frequency of top motion. We also could observe that the internal flow may increase the vertical motion amplitude. The jumper’s motion generates an oscillation on the internal differential pressure between both ends and the flow velocity. The differential pressure amplitude increases with the top oscillation frequency, but it is proportional to the top end oscillation amplitude. We will use these experimental results to validate our numerical models. Further, it is important to understand the internal flow effects to design the actual pump used to convey the slurry through the jumper.

Structural Analysis for a Reduced Scale Model of a Hydropower Plant Debris Containment Grid

2017 ◽  
Author(s):  
Felipe Santos de Castro ◽  
Eduardo Tadashi Katsuno ◽  
Andre Mitsuo Kogishi ◽  
José Marcos Paz de Souza ◽  
Joao Lucas Dozzi Dantas Dantas
Keyword(s):  
Structural Analysis ◽  
Hydropower Plant ◽  
Scale Model ◽  
Plant Debris ◽  
Reduced Scale
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