Investigation on the Effects of Current in the Dynamics of Floating Systems

2011 ◽  
Author(s):  
Felipe Rateiro ◽  
Edgard Borges Malta ◽  
Andre´ L. C. Fujarra
Keyword(s):  
Dynamic Behavior ◽  
Potential Theory ◽  
Model Tests ◽  
Experimental Results ◽  
Numerical Code ◽  
Additional Investigation ◽  
Floating Systems ◽  
Investigation Procedure

This paper presents the experimental results obtained by means of model tests, focused on the analysis of the influence of current effects in the dynamic behavior of a semi-submersible. The tests were accomplished with and without current, in order to establish the comparison basis. As an additional investigation procedure, the experimental results were compared to a numerical code based on the potential theory. As will be seen, considerable changes in the natural periods and in the damping levels was observed.

Investigation on the Effects of Risers in the Dynamics of Floating Systems

2010 ◽  
Author(s):  
Felipe Rateiro ◽  
Edgard Borges Malta ◽  
Andre´ L. C. Fujarra ◽  
Daniel Prata Vieira ◽  
Kazuo Nishimoto
Keyword(s):  
Dynamic Behavior ◽  
Large Diameter ◽  
Model Tests ◽  
Towing Tank ◽  
Dynamic Simulator ◽  
Offshore Industry ◽  
Technological Research Institute ◽  
The University ◽  
Floating Systems ◽  
Significant Increment

This paper presents the experimental results obtained from the model tests performed at the IPT (State of Sa˜o Paulo Technological Research Institute) towing tank, located in Sa˜o Paulo, Brazil. The model used was the semi-submersible ITTC-SR192, at a scale 1:105. The main focus of this study is the analysis of the risers influence on the floating unit dynamics, taking into account damping effects caused by the lines. In order to establish basis of comparison the tests were performed with and without risers. These were modeled as a group of large diameter hoses that are able to provide a significant increment in the damping of the system. By such approach, it was possible to evaluate the changes on the dynamic behavior of the unit induced by the presence of risers. As an additional investigation tool, these results were analyzed with the aid of the software Numerical Offshore Tank (Tanque de Provas Nume´rico - TPN), which is a dynamic simulator of offshore systems based on parallel-processing developed by means of a partnership between the University of Sa˜o Paulo, Petrobras and other Brazilian research institutions. By means of the comparisons between the model tests results with and without risers and of the results from the numerical tool, TPN, the dynamic behavior of the floating unit was investigated in terms of the effects caused by the presence of risers, which is a very relevant subject as offshore industry walks towards ultra-depth waters.

Evaluation of the Dynamic Behavior of the P50 FPSO System Using Dynasim: Comparison With Experimental Results

2003 ◽  
Author(s):  
Fabio G. Palazzo ◽  
Joa˜o V. Sparano ◽  
Alexandre N. Simos ◽  
Isaias Q. Masetti ◽  
Eduardo A. Tannuri
Keyword(s):  
Dynamic Behavior ◽  
Experimental Results ◽  
Numerical Code ◽  
Mooring Line ◽  
Simulation Code ◽  
Campos Basin ◽  
Anchoring System ◽  
Under Construction ◽  
Validation Tests ◽  
The University

The P50 system is a Floating Production Storage and Offloading System under construction for future operation at Brazil’s Campos Basin, in a water depth of approximately 1200 m. The system is based on a VLCC vessel, moored in DICAS (Differential Compliance Anchoring) system and presents a reasonably large riser porch on the portside for 77 lines. In this paper the dynamic behavior of the offshore system is evaluated using Dynasim, a time-domain simulation code for moored offshore systems, developed by the University of Sa˜o Paulo and Petrobras. Simulations are compared with experimental results. Two kinds of tests were performed: “Calibration” tests were carried out in order to obtain static coefficients of the hull under isolated current and wind loads. “Validation” tests were conducted to evaluate the dynamic behavior under extreme environmental conditions combining current and wave excitation. First and second-order motions were measured as well as mooring line tensions for three different drafts of the ship. A generally good agreement was observed between numerical simulations and experimental results, reassuring the reliability of the numerical code.

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

Numerical investigation of the propagation of shock waves in rigid porous materials: development of the computer code and comparison with experimental results

1996 ◽  
Vol 324 ◽  
pp. 163-179 ◽  
Author(s):  
A. Levy ◽  
G. Ben-Dor ◽  
S. Sorek
Keyword(s):  
Porous Materials ◽  
Initial Conditions ◽  
Computer Code ◽  
Experimental Results ◽  
Numerical Code ◽  
Materials Development ◽  
Numerical Predictions ◽  
Wide Range ◽  
Dimensional Version ◽  
The One

The governing equations of the flow field which is obtained when a thermoelastic rigid porous medium is struck head-one by a shock wave are developed using the multiphase approach. The one-dimensional version of these equations is solved numerically using a TVD-based numerical code. The numerical predictions are compared to experimental results and good to excellent agreements are obtained for different porous materials and a wide range of initial conditions.

Performance and Boundary Layer Development of a High Turning Compressor Cascade at Sub- and Supercritical Flow Conditions

2012 ◽  
Author(s):  
Christoph Bode ◽  
Dragan Kožulović ◽  
Udo Stark ◽  
Heinz Hoheisel
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Density Ratio ◽  
Boundary Layer Separation ◽  
Experimental Results ◽  
Numerical Code ◽  
Compressor Cascade ◽  
Boundary Layer Development ◽  
Boundary Layer Interaction ◽  
Inlet Angle

Based on current numerical investigations, the present paper reports on new Q2D midspan-calculations and results for the well known high turning (Δβ = 50°) supercritical (Ma1 = 0.85) compressor cascade V2. A Q2D treatment of the problem was chosen in order to avoid the difficult modelling of the porous endwalls in a corresponding 3D approach. All simulations were done with the RANS solver TRACE of the DLR Cologne in combination with modified versions of the Wilcox turbulence model and Langtry/Menter transition model. Existing experimental Q2D midspan-results for the V2 compressor cascade were used to demonstrate the improved ability of the numerical code to determine performance characteristics, blade pressure and Mach number distributions as well as boundary layer parameter and velocity distributions. The loss characteristics show minimum loss regions when plotted against inlet angle or axial velocity density ratio. Within these regions, increasing with decreasing Mach number, the experimental results were adequately predicted. Outside these regions it turned out difficult to reproduce the experimental results due to increasing boundary layer separation. Furthermore, the prediction quality was very good for subsonic conditions (Ma1 = 0.60) and still reasonable for supercritical conditions (Ma1 = 0.85), where shock/boundary layer interaction made the prediction more difficult.

Experiment on the Attenuation Characteristics of Shock Wave Interacting with Open and Closed Foam

2014 ◽  
Vol 1035 ◽  
pp. 445-452
Author(s):  
Jian Wang ◽  
Bao Gui Wang ◽  
Gang Tao
Keyword(s):  
Shock Wave ◽  
Internal Friction ◽  
Dynamic Behavior ◽  
Solid Phase ◽  
Experimental Results ◽  
Reflection And Transmission ◽  
Attenuation Characteristics

For understanding the dynamic behavior of open and closed foam subject to a shock wave, this paper through experiments, to gain a deeper understanding of the incidence, reflection and transmission of a shock wave when it interacted with cellular foam. Moreover, by analyzing the loss of the peak overpressure and positive impulse, we were able to respectively know the positive impulse of the incidence, reflection and transmission shock wave. The experimental results indicated that the attenuation capability for foam to the shock wave was caused by the internal friction and deformation of solid phase, which would absorb the energy of the shock wave. From the results we gain an understanding that the mechanical phenomenon of open foam to shock wave are not fully consistent with those of closed foam , while the attenuation of open foam to shock wave is more effective than that of closed foam.

Experimental Assessment of the Performance of CECO Wave Energy Converter in Irregular Waves

2018 ◽  
Author(s):  
Claudio A. Rodríguez ◽  
F. Taveira-Pinto ◽  
P. Rosa-Santos
Keyword(s):  
Wave Energy ◽  
Transfer Functions ◽  
Nonlinear Effects ◽  
Model Tests ◽  
Experimental Results ◽  
Irregular Waves ◽  
Scale Model ◽  
Experimental Assessment ◽  
Simplified Approach ◽  
Wave Basin

A new concept of wave energy device (CECO) has been proposed and developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (FEUP). In a first stage, the proof of concept was performed through physical model tests at the wave basin (Rosa-Santos et al., 2015). These experimental results demonstrated the feasibility of the concept to harness wave energy and provided a preliminary assessment of its performance. Later, an extensive experimental campaign was conducted with an enhanced 1:20 scale model of CECO under regular and irregular long and short-crested waves (Marinheiro et al., 2015). An electric PTO system with adjustable damping levels was also installed on CECO as a mechanism of quantification of the WEC power. The results of regular waves tests have been used to validate a numerical model to gain insight into different potential configurations of CECO and its performance (López et al., 2017a,b). This paper presents the results and analyses of the model tests in irregular waves. A simplified approach based on spectral analyses of the WEC motions is presented as a means of experimental assessment of the damping level of the PTO mechanism and its effect on the WEC power absorption. Transfer functions are also computed to identify nonlinear effects associated to higher waves and to characterize the range of periods where wave absorption is maximized. Furthermore, based on the comparison of the present experimental results with those corresponding to a linear numerical potential model, some discussions are addressed regarding viscous and other nonlinear effects on CECO performance.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

Numerical Simulation of Flows through Labyrinth Seals

2016 ◽  
Vol 821 ◽  
pp. 16-22 ◽  
Author(s):  
Jiří Fürst
Keyword(s):  
Numerical Simulation ◽  
Numerical Solution ◽  
Finite Volume ◽  
Stokes Equations ◽  
Control Volume ◽  
Experimental Results ◽  
Numerical Code ◽  
Labyrinth Seals ◽  
Flow Method ◽  
Rotordynamic Coefficients

A numerical code for calculation of leakage flowand rotordynamic coefficients of labyrinth seals has beendeveloped. The code is based on the solution of Reynolds-averagedNavier-Stokes equations combined with a two-equation turbulencemodel. The numerical solution is achieved with finite volume methodand the rotordynamic coefficients are evaluated from severalsimulations with different rotor precessions. The solution iscompared to single control volume based bulk flow method[Williams, 1998] and to the experimental results for look-throughlabyrinth seal [Schettel, 2004].

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