Experimental Studies of Hydrodynamic Properties and Screening of Riser Fairing Concepts for Deep Water Applications

2015 ◽  
Author(s):  
Rolf Baarholm ◽  
Kjetil Skaugset ◽  
Halvor Lie ◽  
Henning Braaten
Keyword(s):  
Experimental Studies ◽  
Real Life ◽  
Cross Flow ◽  
Free Vibrations ◽  
The Body ◽  
Scale Model ◽  
Small Scale ◽  
Structural Fatigue ◽  
And Performance ◽  
Set Up

The VIV oscillations of marine risers are known to increase drag, and lead to structural fatigue. One proven method of suppressing this vibration is the use of fairings and strakes. These coverings essentially modify the flow along the cylinder, tripping the production of Karman vortices so that they act less coherently or far enough downstream so they interact less with the body. The Norwegian Deepwater Programme (NDP) has conducted a project with the objective to develop and qualify effective low drag fairing concepts with respect to VIV mitigation and galloping. Furthermore, emphasis is put on easy handling and installation. This paper describes the work and findings in an early phase of the development. This includes small scale model test campaigns. In addition to the bare riser for reference, the behaviour and performance of a total of 10 different fairing concepts are evaluated. Free oscillation tests are performed in a towing tank, where 2D fairings were tested in a pendulum set-up. The set-up enables free vibrations in up to 3 DOF (in-line and cross-flow vibrations and yaw). Fix tests with the purpose of establishing hydrodynamic coefficients for the various fairings have been performed in a large cavitation tunnel. Clear differences in performance have been noticed; particular for drag and galloping responses. Based on the results from the 2D tests, a screening of the fairing designs has been performed and the findings have set the course for further development of the most promising candidates for real life applications.

Drilling Riser VIV Tests With Prototype Reynolds Numbers

2013 ◽  
Author(s):  
Halvor Lie ◽  
Henning Braaten ◽  
Jamison Szwalek ◽  
Massimiliano Russo ◽  
Rolf Baarholm
Keyword(s):  
Cross Flow ◽  
Effect Study ◽  
Full Scale ◽  
Scale Model ◽  
Small Scale ◽  
Scaling Effects ◽  
Research Activity ◽  
Forced Motion ◽  
Auxiliary Lines ◽  
Viv Suppression

For deep-water riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale riser model. The rigid riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction. The paper reports results from a drilling riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable riser systems with auxiliary lines by adding riser fins. These fins are normally used as devices for protection of the auxiliary lines. The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published. A bare riser model was used in a Reynolds number (Rn) scaling effect study. The riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant. The elastically mounted riser was also towed with various drilling riser configurations in order to study VIV/galloping responses. One configuration included a slick joint riser model with 6 kill & choke lines; another has added riser fins too. The riser model is based on a specific drilling riser and the kill and choke lines have various diameters and have a non-symmetrical layout. The various riser configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later. Scaling effects appear to be a significant uncertainty and further research on the subject is recommended. The slick joint drilling riser configuration generally increased the displacements compared to displacements of the bare riser model. The drilling riser configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare riser model. For both riser systems, tests showed that the response is sensitive to the heading of the current.

scholarly journals Weavers & Warriors? Gender and Online Identity in 1997 and 2007 V1.0

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Deirdre Ruane
Keyword(s):  
Preliminary Investigation ◽  
The Body ◽  
Internet Technology ◽  
Online Identity ◽  
Men And Women ◽  
Online Interactions ◽  
And Performance ◽  
And Gender ◽  
Set Up ◽  
Active Exploration

In 1997 the Internet was seen by many as a tool for radical reinterpretation of physicality and gender. Cybertheorists predicted we would leave our bodies behind and interact online as disembodied minds, and that the technology would reshape the way we saw ourselves. However, physicality has proved to be an inextricable part of all our interactions. Changing Internet technology has allowed Net users to find a myriad ways to perform and express their gender online. In this paper I consider attitudes to gender on the Net in 1997, when the main concerns were the imbalance between men and women online and whether it was possible or desirable to bring the body into online interactions. In much of the discourse surrounding gender online, a simple binary was assumed to exist. I go on to consider the extent to which those attitudes have changed today. Through my own experience of setting up a women’s community on Livejournal, and my observations of a men’s community set up in response, I conclude that though traditional attitudes to gender have largely translated to the Net and the binary is still the default view, some shifts have occurred. For example, between 1997 and today there seems to have been a fundamental change in perceptions of women’s attitudes to adversarial debate, and an increase in awareness of genders beyond the binary. In addition, experience and preliminary investigation lead me toward a hypothesis that today’s female-identified Net users are engaged in more conscious and active exploration and performance of their gender online than male-identified users are.

scholarly journals An Induction Motor Based Wind Turbine Emulator

2014 ◽  
Vol 51 (2) ◽  
pp. 11-21 ◽  
Author(s):  
A. Sokolovs ◽  
L. Grigans ◽  
E. Kamolins ◽  
J. Voitkans
Keyword(s):  
Wind Turbine ◽  
Induction Motor ◽  
Frequency Converter ◽  
Real Life ◽  
Power Coefficient ◽  
Small Scale ◽  
Ac Drive ◽  
Set Up ◽  
Ac Induction Motor ◽  
Good Agreement

Abstract The authors present a small-scale wind turbine emulator based on the AC drive system and discuss the methods for power coefficient calculation. In the work, the experimental set-up consisting of an AC induction motor, a frequency converter, a synchronous permanent magnet generator, a DC-DC boost converter and DC load was simulated and tested using real-life equipment. The experimentally obtained wind turbine power and torque diagrams using the emulator are in a good agreement with the theoretical ones.

Design and Testing of an Airbag System for High-Mass, High-Velocity Deceleration

1997 ◽  
Vol 119 (4) ◽  
pp. 631-637 ◽  
Author(s):  
T. Snyder ◽  
J. Sitter ◽  
J. N. Chung
Keyword(s):  
Impact Velocity ◽  
Flow Analysis ◽  
High Mass ◽  
Scale Model ◽  
Small Scale ◽  
Overall Performance ◽  
And Performance ◽  
Design And Testing ◽  
Small Scale Model ◽  
The Ideal

The design and performance evaluation of an airbag system capable of decelerating masses in the range of hundreds to thousands of kilograms with impact velocities in the range of tens to hundreds of kilometers per hour is presented. First, a simplified incompressible flow analysis of the airbag is utilized to derive the orifice venting area corresponding to the ideal deceleration for a given impact velocity and package mass. Second, testing with a small-scale model found three distinct control intervals during the deceleration. Finally, a full-scale airbag system was constructed and data is presented on the deceleration, deceleration force, deceleration velocity, airbag stopping power, and overall performance. The deceleration was experimentally optimized for a single impact velocity and package mass and an approximate correction factor was developed to predict the actual air venting required for each of the three control intervals in order to achieve the optimum deceleration for any impact velocity and package mass.

Pore Scale Investigation of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Scale Model ◽  
Small Scale ◽  
High Porosity ◽  
Pore Scale ◽  
Open Cell

In this paper, a numerical model employing an approximately realistic three-dimensional (3D) foam structure represented by Weaire–Phelan foam cell is developed to study the steady-state heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. The conduction problem is considered in a cubic representative computation unit of the composite material with a constant temperature difference between one opposite sides of the cubic unit (the other outer surfaces of the cubic unit are thermally insulated). The effective thermal conductivities (ETCs) of metal foam/paraffin composites are calculated with the developed pore-scale model considering small-scale details of heat conduction, which avoids using adjustable free parameters that are usually adopted in the previous analytical models. Then, the reason why the foam pore size has no evident effect on ETC as reported in the previous macroscopic experimental studies is explored at pore scale. Finally, the effect of air cavities existing within solid paraffin in foam pore region on conduction capacity of metal foam/paraffin composite is investigated. It is found that our ETC data agree well with the reported experimental results, and thus by direct numerical simulation (DNS), the ETC data of different metal foam/paraffin composites are provided for engineering applications. The essential reason why pore size has no evident effect on ETC is due to the negligible interstitial heat transfer between metal foam and paraffin under the present thermal boundary conditions usually used to determine the ETC. It also shows that overlarge volume fraction of air cavity significantly weakens the conduction capacity of paraffin, which however can be overcome by the adoption of high conductive metal foam due to enhancement of conduction.

scholarly journals Optimization of the process of mixing liquid-phase heterogeneous products

2021 ◽  
Vol 83 (1) ◽  
pp. 204-210
Author(s):  
L. E. Glagoleva ◽  
N. P. Zatsepilina ◽  
M. V. Kopylov ◽  
S. O. Rodionov
Keyword(s):  
Software Package ◽  
Raw Materials ◽  
Food Additives ◽  
Whey Proteins ◽  
Experimental Studies ◽  
Good Health ◽  
The Body ◽  
Biologically Active ◽  
Raw Material ◽  
And Performance

The leading direction in the field of nutrition is the creation of a range of products that contribute to improving health when they are used daily in the diet. The urgency of studying bovine colostrum-colostrum, which is an immune-modeling animal raw material, has been substantiated. Colostrum is a natural source of all the ingredients needed to build immunity. Biologically active substances contained in cow colostrum contribute to: restoration of immunity; restoration of the intestines and stomach; strengthening the nervous system; renewal of brain cells; improving emotional tone and mood; increasing vitality and performance; slowing down the aging process; protection against diseases of the intestines and stomach, cardiovascular system, respiratory tract, diabetes, allergies, osteoporosis and a number of other diseases. Colostrum contains a minimum of 37 immune factors and 8 growth factors that help the body fight disease and promote good health and longevity. The classes of immunoglobulins contained in colostrum, which represent the bulk of whey proteins, have been studied. Colostrum is a limited source of raw materials, its production period is short, there are many opportunities for industrial use, but due to the small amount of raw materials, the market remains undeveloped, with the exception of food additives. Taking into account the extensive therapeutic and medicinal properties of colostrum, its unique composition and properties, its composition and physicochemical properties were investigated, the fractionation parameters were determined using various systems. To process the experimental studies, the STATISTICA 12 software package was used. To obtain the regression equation, the matrix data were processed using the Microsoft Excel 2010 software package. The analysis of the data obtained indicates the possibility and prospects of using colostroma in food production technology.

scholarly journals Numerical and Experimental Investigations of Composite Solar Walls Integrating Sensible or Latent Heat Thermal Storage

2020 ◽  
Vol 10 (5) ◽  
pp. 1854 ◽  
Author(s):  
Enghok Leang ◽  
Pierre Tittelein ◽  
Laurent Zalewski ◽  
Stéphane Lassue
Keyword(s):  
Weather Conditions ◽  
Energy Performance ◽  
Cold Season ◽  
Experimental Investigations ◽  
Small Scale ◽  
Storage Element ◽  
Storage Wall ◽  
And Performance ◽  
Set Up ◽  
Solar Wall

This article studies a composite solar wall with latent storage (TES) designed to heat rooms inside buildings during the cold season. No numerical model of the composite solar wall is currently available in the Dymola/Modelica software library. The first objective of this work is to develop one such model. The article describes the elementary components, along with the equations that allow modeling the heat transfers and storage phenomena governing both the thermal behavior and performance of the solar wall. This model was built by assembling various existing basic elements from the software’s “Building” library (e.g., models of heat transfer by convection, radiation and conduction) and then creating new elements, such as the storage element incorporating the phase change material (PCM). To validate this solar wall model, numerical results are compared to experimental data stemming from a small-scale composite solar wall manufactured in our laboratory, and the experimental set-up could be tested under real weather conditions. After verifying the level of confidence in the model, the energy performance of two solar walls, one with a conventional storage wall (sensible heat storage) the other containing a PCM (the same as in the experiment), are compared. The result indicates that the solar wall incorporating a PCM does not in this case release any more energy in the room to be heated.

Explaining Ground Effect Aerodynamics via a Real-Life Reference Frame

2014 ◽  
Vol 553 ◽  
pp. 229-234
Author(s):  
Philip Close ◽  
Tracie J. Barber
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Computational Simulation ◽  
Real Life ◽  
Computational Modelling ◽  
Ground Effect ◽  
The Body ◽  
Moving Body ◽  
Set Up ◽  
Insight Into

The principle of relative motion as the cause of forces on a body submersedin a uid is foundational in the study of uid mechanics. In aerodynamics the wind tunnelis used as a convenient and safe method by which to test the aerodynamic performance ofbodies. This body-stationary convention has carried over into the computational world withthe development of CFD, though there is no practical reason why the moving body/stationaryuid set-up that corresponds to reality cannot be used for computational modelling. This pointbecomes particularly important as the concept of ground e ect is introduced. With an extraboundary nearby it becomes harder to appropriatel y match the experimental set-up with reality,and the extra boundary condition also adds complexity to computational simulation. A studywas undertaken to compare the body-stationary and body-moving reference frames in grounde ect. The moving reference frame velocity elds allowed new insight into the aerodynamics ofground e ect.

Small-Scale Models for Testing Masonry Structures

2010 ◽  
Vol 133-134 ◽  
pp. 497-502 ◽  
Author(s):  
Alvaro Quinonez ◽  
Jennifer Zessin ◽  
Aissata Nutzel ◽  
John Ochsendorf
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Model Testing ◽  
Scale Model ◽  
Small Scale ◽  
Material Strength ◽  
Masonry Structures ◽  
Scale Models ◽  
Set Up

Experiments may be used to verify numerical and analytical results, but large-scale model testing is associated with high costs and lengthy set-up times. In contrast, small-scale model testing is inexpensive, non-invasive, and easy to replicate over several trials. This paper proposes a new method of masonry model generation using three-dimensional printing technology. Small-scale models are created as an assemblage of individual blocks representing the original structure’s geometry and stereotomy. Two model domes are tested to collapse due to outward support displacements, and experimental data from these tests is compared with analytical predictions. Results of these experiments provide a strong understanding of the mechanics of actual masonry structures and can be used to demonstrate the structural capacity of masonry structures with extensive cracking. Challenges for this work, such as imperfections in the model geometry and construction problems, are also addressed. This experimental method can provide a low-cost alternative for the collapse analysis of complex masonry structures, the safety of which depends primarily on stability rather than material strength.

scholarly journals EXPERIMENTAL STUDIES ON THE ETIOLOGY OF TYPHUS FEVER

1921 ◽  
Vol 34 (6) ◽  
pp. 525-535
Author(s):  
Peter K. Olitsky
Keyword(s):  
Staphylococcus Aureus ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Experimental Studies ◽  
The Body ◽  
Febrile Reaction ◽  
Cultivable Bacteria ◽  
Set Up ◽  
Typhus Fever ◽  
And Staphylococcus Aureus

The work reported in this paper relates to the bacteria which can be cultivated from the blood and spleen of guinea pigs at different stages of infection with the virus of typhus fever. The studies show that during the period of incubation and before the onset of fever no ordinary bacteria appear in the cultures, while on the 1st day of the febrile reaction different bacteria were found in 6 of 26 guinea pigs cultured; on the 2nd day, in 10 of 16; on the 3rd day, in 3 of 4; and on the 4th day in cultures of all of the 4 guinea pigs observed. The findings indicate that the virus of typhus fever is distinct from ordinary cultivable bacteria, and, as the disease set up by the virus progresses, the infected guinea pigs become subject to invasion by secondary or concurrent bacteria which thus induce a mixed infection. The bacteria which under the influence of the virus of typhus fever thus invade the body of the guinea pig are of several kinds, and vary not only among themselves, but also with the day of the fever on which the examination is made. Thus, on the 1st day of the fever Plotz' bacilli were recovered twice and anaerobic streptococci, proteus bacilli, aerobic diphtheroids, Gärtner type bacilli, and Staphylococcus aureus each once. On the 2nd day Plotz' bacilli were found four times, anaerobic streptococci three times, Gärtner type bacilli, aerobic diphtheroids, Bacillus welchii, aerobic Gram-positive diplobacilli, and Staphylococcus aureus each once. On the 3rd day Plotz' bacilli were recovered once, as were anaerobic streptococci and Grtner type bacilli. On the 4th day Staphylococcus aureus was found twice and Plotz' bacilli and Bacillus proteus each once. This variation in the kind of bacteria as well as the lack of predominance of one kind over another during the different stages of the febrile reaction in guinea pigs leads us to infer that they occur concurrently with the typhus virus. And since the more unusual of these organisms, the Plotz bacillus, the anaerobic streptococcus, the aerobic diphtheroid, and the diplobacillus are non-pathogenic for guinea pigs, while the more common bacteria such as the Gärtner type bacillus, Welch's bacillus, the proteus bacillus, and the staphylococci induce distinctive effects, and since all the bacteria could be suppressed without their reappearance in guinea pig passages of the virus containing them, we believe that they are independent and unrelated to the true virus of typhus fever.

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