Station-Keeping Trials in Ice: Project Overview

2018 ◽  
Author(s):  
Pavel Liferov ◽  
Thomas McKeever ◽  
Francesco Scibilia ◽  
Sigurd Henrik Teigen ◽  
Andreas Kjøl ◽  
...  
Keyword(s):  
Primary Objective ◽  
Project Planning ◽  
Maximum Amount ◽  
Full Scale ◽  
Physical Models ◽  
Station Keeping ◽  
Floating Structure ◽  
Quality Requirements ◽  
Drifting Ice ◽  
Scale Data

In March 2017, Statoil performed station-keeping trials in drifting ice in the Bay of Bothnia with two anchor handling tug supply vessels, Magne Viking and Tor Viking. The primary objective of the Station-keeping Trials in Ice project (SKT) was to gather full-scale data on a stationary floating structure in ice. The data will be used for validation of numerical and physical models, that will in turn increase confidence in modelling tools for design and operation in ice-covered waters. The principal requirement of the project was to safely collect the maximum amount of data meeting the quality requirements within the available budget and timeframe. This paper presents the overall project planning and execution, while more details are provided in the companion papers.

Resource Scalability at Wave Energy Test Sites

2014 ◽  
Author(s):  
Brendan Cahill
Keyword(s):  
Wave Energy ◽  
Energy Resource ◽  
Ocean Waves ◽  
Primary Objective ◽  
Full Scale ◽  
Physical Models ◽  
Small Scale ◽  
Marine Energy ◽  
Lake Washington ◽  
Guide Device

Harnessing the power of ocean waves offers enormous potential as a source of renewable energy. To date the technologies for capturing this resource, collectively known as wave energy converters (WECs), have yet to reach commercial viability and continued research and development efforts are required to move wave energy to the industrial scale. Integral to this process is ensuring that technologies progress along a staged development pathway; proving WEC concepts using small scale physical models in controlled settings such as laboratory wave tanks before eventually advancing to testing sub-prototype and full scale devices in real sea conditions. The primary objective of this research is to improve the understanding of how best to address the scaling of wave resource measurements and wave energy device power production when analyzing the results of sea-trials. This paper draws on measured data from three test sites; Galway Bay in Ireland, the Pacific Marine Energy Test Centre off the coast of Oregon, and Lake Washington, and assesses how accurately they recreate, at reduced scale, the conditions that commercial WEC installations are likely to encounter at exposed deployment locations. Appropriate techniques for extrapolating these results to predict the performance of commercial WECs at energy-rich locations on the west coasts of Ireland and the US are also demonstrated and discussed. The output from this research will be a set of protocols for addressing wave energy resource scalability to help guide device developers through this important stage of technology progression. Improved knowledge regarding resource scalability will allow for more streamlined progression of WEC concepts from wave tanks to sea-trials, and eventually to full-scale ocean deployment. It will also result in a reduced uncertainty about device power output and survivability, which are key drivers in determining the economic viability of projects.

Station-Keeping Trials in Ice: Dynamic Positioning in Ice — Results and Learnings

2018 ◽  
Author(s):  
Sofien Kerkeni ◽  
Pavel Liferov ◽  
Nicolas Serré ◽  
Robert Bridges ◽  
Finn Jorgensen
Keyword(s):  
Full Scale ◽  
Control Algorithms ◽  
Dynamic Positioning ◽  
Station Keeping ◽  
Positioning Systems ◽  
Ice Conditions ◽  
Drifting Ice ◽  
External Loads

Dynamic Positioning Systems are used in numerous types of marine operations. Due to the important differences in the external loads acting on the vessel, standard DP systems may fail to perform in ice conditions. Moreover, specific principles and position keeping philosophies should be applied in ice covered waters. The objective of the paper is to elaborate on these aspects by presenting and analyzing full scale DP tests. These tests were a part of the station-keeping trials performed in March 2017 in drifting ice in the Bay of Bothnia. Control algorithms limitations of Standard DP Systems are presented, showing the necessity of new control principles. The importance of crew training is also demonstrated along with the approaches to keep position in ice.

Station-Keeping Trials in Ice: Data Acquisition, Post-Processing, Storage and Visualization

2018 ◽  
Author(s):  
Erik Almkvist ◽  
Andreas Kjøl ◽  
Claes Tisell ◽  
Joakim K. Lindvall ◽  
Claes Ingers ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Numerical Models ◽  
Data Acquisition System ◽  
Full Scale ◽  
Acquisition System ◽  
Post Processing ◽  
Station Keeping ◽  
Project Phases ◽  
The Individual ◽  
Scale Data

In March 2017, Statoil performed station-keeping trials in drifting ice in the Bay of Bothnia with the two AHTS (anchor handling tug supply) vessels, Magne Viking and Tor Viking. The main objective of the SKT project was to collect full scale data for calibration of numerical models. This paper describes the design and setup of the tailor-made data acquisition system, including description of the individual sensors in the system as well as how the data was handled during the different project phases. A description of how all data was recorded, time synced and stored is given. Data post-processing, storage and visualization done within the scope is also described.

Benchmarking of Truss Spar Vortex Induced Motions Derived From CFD With Experiments

2005 ◽  
Author(s):  
John Halkyard ◽  
Senu Sirnivas ◽  
Samuel Holmes ◽  
Yiannis Constantinides ◽  
Owen H. Oakley ◽  
...  
Keyword(s):  
Scale Up ◽  
Vertical Cylinder ◽  
Reynolds Numbers ◽  
Full Scale ◽  
Scale Model ◽  
Current Direction ◽  
Test Results ◽  
Helical Strakes ◽  
Truss Spar ◽  
Scale Data

Floating spar platforms are widely used in the Gulf of Mexico for oil production. The spar is a bluff, vertical cylinder which is subject to Vortex Induced Motions (VIM) when current velocities exceed a few knots. All spars to date have been constructed with helical strakes to mitigate VIM in order to reduce the loads on the risers and moorings. Model tests have indicated that the effectiveness of these strakes is influenced greatly by details of their design, by appurtenances placed on the outside of the hull and by current direction. At this time there is limited full scale data to validate the model test results and little understanding of the mechanisms at work in strake performance. The authors have been investigating the use of CFD as a means for predicting full scale VIM performance and for facilitating the design of spars for reduced VIM. This paper reports on the results of a study to benchmark the CFD results for a truss spar with a set of model experiments carried out in a towing tank. The focus is on the effect of current direction, reduced velocity and strake pitch on the VIM response. The tests were carried out on a 1:40 scale model of an actual truss spar design, and all computations were carried out at model scale. Future study will consider the effect of external appurtenances on the hull and scale-up to full scale Reynolds’ numbers on the results.

Probabilistic Fatigue Assessment of a Mooring Line Based on Station-Keeping Trials in Ice

2021 ◽  
Author(s):  
Chana Sinsabvarodom ◽  
Bernt J. Leira ◽  
Wei Chai ◽  
Arvid Naess
Keyword(s):  
Fatigue Damage ◽  
Probabilistic Models ◽  
Full Scale ◽  
Mooring Line ◽  
Stress Range ◽  
Station Keeping ◽  
Probability Models ◽  
Line System ◽  
Fatigue Assessment ◽  
Rainflow Counting

Abstract The intention of this work is to perform a probabilistic fatigue assessment of a mooring line due to loads associated with the station-keeping of a ship in ice. In March 2017, the company Equinor (Statoil) conducted full-scale tests by means of station-keeping trials (SKT) in drifting ice in the Bay of Bothnia. The vessel Magne Viking was employed in order to represent a supply vessel equipped with a mooring line system, and the realtime loading during the full-scale measurement was recorded. The second vessel Tor Viking was serving as an ice breaker in order to maintain the physical ice management activities with different ice-breaking schemes, i.e. square updrift pattern, round circle pattern, circular updrift pattern and linear updrift pattern. The fatigue degradation corresponding to these different patterns were investigated. The peaks and valleys of the mooring tension are determined using the min peak prominence method. For the purpose of probabilistic fatigue assessment, the Rainflow-counting algorithm is applied to estimate the mooring stress range. Fatigue assessment based both on Rainflow counting and fitted probabilistic models were performed. For the latter, the stress range distributions from the observed data of mooring loads are fitted to various probability models in order to estimate the fatigue damage. It is found that the stress ranges represented by application of the Weibull distribution for the probabilistic fatigue approach provides results of the fatigue damage most similar to the Rainflow counting approach. Among the different scenarios of Ice management schemes, the circular updrift pattern provides the lowest magnitude of the fatigue degradation.

Elimination of viruses, bacteria and protozoan oocysts by slow sand filtration

2004 ◽  
Vol 50 (1) ◽  
pp. 147-154 ◽  
Author(s):  
W.A.M. Hijnen ◽  
J.F. Schijven ◽  
P. Bonné ◽  
A. Visser ◽  
G.J. Medema
Keyword(s):  
Pilot Plant ◽  
Pathogenic Bacteria ◽  
Laboratory Experiments ◽  
Full Scale ◽  
Sand Filters ◽  
E Coli ◽  
Thermotolerant Coliforms ◽  
Filter Bed ◽  
Scale Data ◽  
Bacteria Removal

The decimal elimination capacity (DEC) of slow sand filters (SSF) for viruses, bacteria and oocysts of Cryptosporidium has been assessed from full-scale data and pilot plant and laboratory experiments. DEC for viruses calculated from experimental data with MS2-bacteriophages in the pilot plant filters was 1.5-2 log10. E. coli and thermotolerant coliforms (Coli44) were removed at full-scale and in the pilot plant with 2-3 log10. At full-scale, Campylobacter bacteria removal was 1 log10 more than removal of Coli44, which indicated that Coli44 was a conservative surrogate for these pathogenic bacteria. Laboratory experiments with sand columns showed 2-3 and >5-6 log10 removal of spiked spores of sulphite-reducing clostridia (SSRC; C. perfringens) and oocysts of Cryptosporidium respectively. Consequently, SSRC was not a good surrogate to quantify oocyst removal by SSF. Removal of indigenous SSRC by full-scale filters was less efficient than observed in the laboratory columns, probably due to continuous loading of these filter beds with spores, accumulation and retarded transport. It remains to be investigated if this also applies to oocyst removal by SSF. The results additionally showed that the schmutzdecke and accumulation of (in)organic charged compounds in the sand increased the elimination of microorganisms. Removal of the schmutzdecke reduced DEC for bacteria by ±2 log10, but did not affect removal of phages. This clearly indicated that, besides biological activity, both straining and adsorption were important removal mechanisms in the filter bed for microorganisms larger than viruses.

An Analysis of the Aerodynamic Characteristics of Split Flaps

1940 ◽  
Vol 44 (352) ◽  
pp. 338-349
Author(s):  
A. P. West
Keyword(s):  
Experimental Data ◽  
Aerodynamic Characteristics ◽  
Full Scale ◽  
The Other ◽  
Aircraft Industry ◽  
The Past ◽  
The Many ◽  
Lift And Drag ◽  
Scale Data

During the past few years an extensive amount of experimental data on split flaps has been made available to the aircraft industry, through the publications of aeronautical research laboratories, both in this country and abroad. In general, each publication deals with one particular aspect of the problem, and when the effect of wing flaps on the performance of an aircraft is being estimated a certain amount of difficulty may be experienced in deciding which of the many reports available gives results most readily applicable to the case being considered ; and what allowances, if any, should be made for wing taper, flap cut-out, fuselage, etc.In this report the available data has been analysed with a view to answering these questions, and presented in such a form that it may be readily applied to determine the most probable change in the aerodynamic characteristics of a wing that may be expected from the use of this type of flap.From the appendix an estimate of the accuracy of the method can be obtained, as a comparison with full-scale data is given for lift and drag, and for the other flap characteristics the original curves have been reproduced.

Determination of textile dyeing wastewater COD components by comparison with respirometry and full‐scale data

2010 ◽  
Vol 31 (11) ◽  
pp. 1191-1201 ◽  
Author(s):  
Jing‐Jie Yu ◽  
Guo‐Wei Gu ◽  
Giovanni Esposito ◽  
Massimiliano Fabbricino ◽  
Shao‐Po Wang ◽  
...  
Keyword(s):  
Full Scale ◽  
Dyeing Wastewater ◽  
Textile Dyeing ◽  
Scale Data ◽  
Textile Dyeing Wastewater

Prediction of First-Order Vessel Responses with Applications to Decision Support Systems

2015 ◽  
Author(s):  
Ulrik D. Nielsen ◽  
Toshio Iseki
Keyword(s):  
Decision Support ◽  
Decision Support Systems ◽  
Support Systems ◽  
Simple Approach ◽  
Full Scale ◽  
Uncertainty Measure ◽  
First Order ◽  
Future Developments ◽  
Vessel Response ◽  
Scale Data

The paper presents a practical and simple approach for making vessel response predictions. Features of the procedure include a) predictions which are scaled so to better agree with corresponding true, future values to be measured at the time the predictions apply at; and b) predictions that are assigned an uncertainty measure to reflect a level of confidence. The approach is tested with full-scale data and the obtained results/predictions agree well with measured values. Potentially, the procedure is therefore very useful in future developments of general decision support systems.

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