41.
Raven, Hoyte
A new correction procedure for shallow-water effects in ship speed trials Conference
Proceedings of PRADS2016, 4th – 8th September, 2016, Copenhagen, Denmark, 2016.
@conference{Raven2016,
title = {A new correction procedure for shallow-water effects in ship speed trials},
author = {Raven, Hoyte},
url = {http://www.marin.nl/web/Publications/Papers/A-new-correction-procedure-for-shallowwater-effects-in-ship-speed-trials.htm},
year = {2016},
date = {2016-09-04},
booktitle = {Proceedings of PRADS2016, 4th – 8th September, 2016, Copenhagen, Denmark},
abstract = {To correct ship speed trials for limited shallow-water effects,
Lackenby’s method is currently recommended by the ITTC.
This method appears to be based on very few and inadequate
data. To replace it, a new procedure is proposed. It corrects
separately for the effects of shallow water on the different
components of ship resistance. These have been identified by
computational studies.A simple algorithm is proposed to
estimate a power increase for equal speed in shallow water.
This new correction method has been applied to dedicated
shallow-water trials for two ships and was found to perform
much better than Lackenby’s method.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
To correct ship speed trials for limited shallow-water effects,
Lackenby’s method is currently recommended by the ITTC.
This method appears to be based on very few and inadequate
data. To replace it, a new procedure is proposed. It corrects
separately for the effects of shallow water on the different
components of ship resistance. These have been identified by
computational studies.A simple algorithm is proposed to
estimate a power increase for equal speed in shallow water.
This new correction method has been applied to dedicated
shallow-water trials for two ships and was found to perform
much better than Lackenby’s method.
Lackenby’s method is currently recommended by the ITTC.
This method appears to be based on very few and inadequate
data. To replace it, a new procedure is proposed. It corrects
separately for the effects of shallow water on the different
components of ship resistance. These have been identified by
computational studies.A simple algorithm is proposed to
estimate a power increase for equal speed in shallow water.
This new correction method has been applied to dedicated
shallow-water trials for two ships and was found to perform
much better than Lackenby’s method.
42.
Joy; Veldhuis Klinkenberg, Christian
CFD for twin gondola aft ship design Conference
Proceedings of PRADS2016, 4th – 8th September, 2016, Copenhagen, Denmark, 2016.
@conference{Klinkenberg2016,
title = {CFD for twin gondola aft ship design},
author = {Klinkenberg, Joy; Veldhuis, Christian},
url = {http://www.marin.nl/web/Publications/Papers/CFD-for-twin-gondola-aft-ship-design.htm},
year = {2016},
date = {2016-09-04},
booktitle = {Proceedings of PRADS2016, 4th – 8th September, 2016, Copenhagen, Denmark},
abstract = {This paper shows a test case in the optimization for a twingondola
ship. In optimizing ships, one can optimize for minimal
resistance or for minimal power. For twin-gondola this
choice is of great importance, due to the asymmetric nature of
the flow coming into the propeller. We first show the optimization
of a twin-gondola ship for resistance only, where the
decrease in resistance is found to be 1.5%. When including the
propeller, using RaNS-BEM coupling, a large difference is
found between inward and outward rotating propeller. The
ship with the largest resistance, requires the least power if the
propeller turns in the right direction. We show that RaNSBEM
coupling could be an efficient method of taking the
propeller rotation direction into account in an optimization
process. The results are also compared to a model test of the
same ship, showing the same trend.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This paper shows a test case in the optimization for a twingondola
ship. In optimizing ships, one can optimize for minimal
resistance or for minimal power. For twin-gondola this
choice is of great importance, due to the asymmetric nature of
the flow coming into the propeller. We first show the optimization
of a twin-gondola ship for resistance only, where the
decrease in resistance is found to be 1.5%. When including the
propeller, using RaNS-BEM coupling, a large difference is
found between inward and outward rotating propeller. The
ship with the largest resistance, requires the least power if the
propeller turns in the right direction. We show that RaNSBEM
coupling could be an efficient method of taking the
propeller rotation direction into account in an optimization
process. The results are also compared to a model test of the
same ship, showing the same trend.
ship. In optimizing ships, one can optimize for minimal
resistance or for minimal power. For twin-gondola this
choice is of great importance, due to the asymmetric nature of
the flow coming into the propeller. We first show the optimization
of a twin-gondola ship for resistance only, where the
decrease in resistance is found to be 1.5%. When including the
propeller, using RaNS-BEM coupling, a large difference is
found between inward and outward rotating propeller. The
ship with the largest resistance, requires the least power if the
propeller turns in the right direction. We show that RaNSBEM
coupling could be an efficient method of taking the
propeller rotation direction into account in an optimization
process. The results are also compared to a model test of the
same ship, showing the same trend.
43.
Tomasz; van der Ploeg Gornics, Auke; Scholcz
Trim wedge optimization with viscous free surface computations Conference
Proceedings of PRADS2016, Copenhagen, Denmark, 2016.
@conference{Gornics2016,
title = {Trim wedge optimization with viscous free surface computations},
author = {Gornics, Tomasz; van der Ploeg, Auke; Scholcz, Thomas},
url = {http://www.marin.nl/web/Publications/Papers/Trim-wedge-optimization-with-viscous-free-surface-computations.htm},
year = {2016},
date = {2016-09-04},
booktitle = {Proceedings of PRADS2016, Copenhagen, Denmark},
abstract = {A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
44.
Lafeber, Frans Hendrik; Bosschers, Johan
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, no. ID105, 2016.
@conference{Lafeber2016,
title = {Validation of computational and experimental prediction methods for the underwater radiated noise of a small research vessel},
author = {Frans Hendrik Lafeber and Johan Bosschers},
url = {http://www.marin.nl/web/Publications/Papers/Validation-of-computational-and-experimental-prediction-methods-for-the-underwater-radiated-noise-of-a-small-research-vessel.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
number = {ID105},
abstract = {The underwater radiated noise of a small research vessel, The Princess Royal, has been predicted using computational methods and model tests and has been compared to full-scale data. For the model tests, a correction for the Lloyd’s mirror effect has been implemented in the analysis. The results are then compared to data from full-scale measurements. After correcting for the viscous scale effects on vortex cavitation, there is a good agreement between the model tests and full scale at the lowest speed. For the higher speeds (more cavita-tion), the agreement is good at the low and high frequency range, but there is a difference of about 10 dB between the model tests and full scale at mid frequency range.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The underwater radiated noise of a small research vessel, The Princess Royal, has been predicted using computational methods and model tests and has been compared to full-scale data. For the model tests, a correction for the Lloyd’s mirror effect has been implemented in the analysis. The results are then compared to data from full-scale measurements. After correcting for the viscous scale effects on vortex cavitation, there is a good agreement between the model tests and full scale at the lowest speed. For the higher speeds (more cavita-tion), the agreement is good at the low and high frequency range, but there is a difference of about 10 dB between the model tests and full scale at mid frequency range.
45.
M. Kerkvliet, Carette; Straten, O. van
Analysis of free surface anti-roll tank using URANS. Verification and validation Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Kerkvliet2016,
title = {Analysis of free surface anti-roll tank using URANS. Verification and validation},
author = {Kerkvliet, M., Carette, N. and Straten, O. van},
url = {http://www.marin.nl/web/Publications/Papers/Analysis-of-free-surface-antiroll-tank-using-URANS.-Verification-and-validation-1.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID055},
abstract = {To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.
46.
Abeil, Bastien
Experimental prediction of anti roll tanks on the rolling of ships Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Abeil2016,
title = {Experimental prediction of anti roll tanks on the rolling of ships},
author = {Bastien Abeil},
url = {http://www.marin.nl/web/Publications/Papers/Experimental-prediction-of-anti-roll-tanks-on-the-rolling-of-ships.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID146},
abstract = {Over the last years MARIN has developed an integrated model testing approach for the prediction of the performance of free-surface Anti Roll Tanks (ART) in reducing the roll motion of vessels. Beside the tailor-made test programme, the approach is mostly characterised by the specific test set-up that allows the measurement of the reaction forces generated by the ART on the ship model during seakeeping tests in a wave basin. After a brief introduction of the working principle of free-surface ARTs and the MARIN test set-up and programme, the paper describes in detail the measurements obtained from ARTs during a series of seakeeping test campaigns.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Over the last years MARIN has developed an integrated model testing approach for the prediction of the performance of free-surface Anti Roll Tanks (ART) in reducing the roll motion of vessels. Beside the tailor-made test programme, the approach is mostly characterised by the specific test set-up that allows the measurement of the reaction forces generated by the ART on the ship model during seakeeping tests in a wave basin. After a brief introduction of the working principle of free-surface ARTs and the MARIN test set-up and programme, the paper describes in detail the measurements obtained from ARTs during a series of seakeeping test campaigns.
47.
Reint Dallinga Nicolas Carette, Geert Kapsenberg
On the design of anti-roll tanks Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Carette2016b,
title = {On the design of anti-roll tanks},
author = {Nicolas Carette, Reint Dallinga, Geert Kapsenberg},
url = {http://www.marin.nl/web/Publications/Papers/On-the-design-of-antiroll-tanks.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID030},
abstract = {Traditionally, the procedure to design anti-roll tanks is limited to the assessment of the reaction moment due to a regular roll motion. Although this procedure may seem adequate for a badly rolling ship, the neglect of the sway motion is by no means trivial for a well stabilized ship, which is the very purpose of the stabilizing tank. Moreover, older literature and previous studies showed that the response of the tank is non-linearly dependent on the amplitude and frequency of this complex excitation. The present work summarizes how the complex performance of the tank can be understood and what the consequences of this understanding are for the use of frequency domain methods to predict the motion response of a stabilized ship.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Traditionally, the procedure to design anti-roll tanks is limited to the assessment of the reaction moment due to a regular roll motion. Although this procedure may seem adequate for a badly rolling ship, the neglect of the sway motion is by no means trivial for a well stabilized ship, which is the very purpose of the stabilizing tank. Moreover, older literature and previous studies showed that the response of the tank is non-linearly dependent on the amplitude and frequency of this complex excitation. The present work summarizes how the complex performance of the tank can be understood and what the consequences of this understanding are for the use of frequency domain methods to predict the motion response of a stabilized ship.
48.
Sergio Fernandez Ruano Rob Grin, Nick Bradbeer; Koelman, Herbert
On the prediction of weight distribution and its effect on seakeeping Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Grin2016,
title = {On the prediction of weight distribution and its effect on seakeeping},
author = {Rob Grin, Sergio Fernandez Ruano, Nick Bradbeer and Herbert Koelman},
url = {http://www.marin.nl/web/Publications/Papers/On-the-prediction-of-weight-distribution-and-its-effect-on-seakeeping.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID054},
abstract = {During the design of any ship it is normal to assess its seakeeping behavior. Whether numerical or experimental methods are used, they require accurate knowledge of the ship’s radii of inertia, usually only calculable in the latter stages of design. Various estimation methods are available to predict the radii of gyration earlier in the design process, but this paper shows that they frequently fail to predict the correct value. A semi-empirical estimation method, suitable for use in the early stages of design, has been proposed in earlier work by the authors and was found to give good predictions of the eventual radii of inertia. This paper expands the range of ships against which this method was validated from five to nine (and sixteen total conditions). The method continues to provide good predictions of the radii of inertia over this in-creased range of ships, and remains suitable for use during the basic design stage.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
During the design of any ship it is normal to assess its seakeeping behavior. Whether numerical or experimental methods are used, they require accurate knowledge of the ship’s radii of inertia, usually only calculable in the latter stages of design. Various estimation methods are available to predict the radii of gyration earlier in the design process, but this paper shows that they frequently fail to predict the correct value. A semi-empirical estimation method, suitable for use in the early stages of design, has been proposed in earlier work by the authors and was found to give good predictions of the eventual radii of inertia. This paper expands the range of ships against which this method was validated from five to nine (and sixteen total conditions). The method continues to provide good predictions of the radii of inertia over this in-creased range of ships, and remains suitable for use during the basic design stage.
49.
Erik Rotteveel, Auke van der Ploeg; Hekkenberg, Robert
Optimization of ships in shallow water with viscous flow computations and surrogate modeling Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Rotteveel2016,
title = {Optimization of ships in shallow water with viscous flow computations and surrogate modeling},
author = {Erik Rotteveel, Auke van der Ploeg and Robert Hekkenberg},
url = {http://www.marin.nl/web/Publications/Papers/Optimization-of-ships-in-shallow-water-with-viscous-flow-computations-and-surrogate-modeling.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID083},
abstract = {Shallow water effects change the flow around a ship significantly which can affect the optimum design of the hull. This paper describes a study into the optimization of the aft ship region for various water depths. The research focuses on variations of the following parameters of a hull form: The athwart ship’s propeller location, the tunnel top curvature, the flat-of-bottom shape in the stern region and the stern bilge radius. All hull form variants are evaluated in 3 different water depths using a viscous flow solver, and a surrogate model is created for each water depth. Pareto plots are used to present the trade-off between the optimization for one or another water depth. Finally, specific hull forms are chosen and the differences in flow behavior among hull forms and water depths are explained.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Shallow water effects change the flow around a ship significantly which can affect the optimum design of the hull. This paper describes a study into the optimization of the aft ship region for various water depths. The research focuses on variations of the following parameters of a hull form: The athwart ship’s propeller location, the tunnel top curvature, the flat-of-bottom shape in the stern region and the stern bilge radius. All hull form variants are evaluated in 3 different water depths using a viscous flow solver, and a surrogate model is created for each water depth. Pareto plots are used to present the trade-off between the optimization for one or another water depth. Finally, specific hull forms are chosen and the differences in flow behavior among hull forms and water depths are explained.
50.
J. Liu, Quadvlieg; Hekkenberg, R.
Impacts of the rudder profile on manoeuvring performance of ships Journal Article
In: Ocean Engineering, 2016, vol. 124, pp. 226-240, 2016.
@article{Liu2016,
title = {Impacts of the rudder profile on manoeuvring performance of ships},
author = {Liu, J., Quadvlieg, F.H.H.A. and Hekkenberg, R.},
url = {http://www.marin.nl/web/Publications/Papers/Impacts-of-the-rudder-profile-on-manoeuvring-performance-of-ships.htm},
doi = {10.1016/j.oceaneng.2016.07.064},
year = {2016},
date = {2016-09-01},
journal = {Ocean Engineering, 2016},
volume = {124},
pages = {226-240},
abstract = {The profile of a ship rudder influences the forces it generates, which in turn influence the manoeuvring performance of a ship. Thus, rudder forces and moments should be calculated considering the profile. Instead of an empirical estimation of the rudder normal force coefficient, this paper applies a RANS method to determine the hydrodynamic characteristics of various profiles, i.e. lift and drag coefficients. The RANS method is validated with a classic NACA 0012 profile and applied to 9 profiles from the NACA series, the wedge-tail series, and the IFS series. Furthermore, the 2D open-water RANS results are corrected for the effects of the propeller slipstream and the rudder aspect ratio. New regression formulas of the normal force coefficients are proposed for the tested profiles. These formulas are then integrated into a standard MMG model. Taking the KVLCC2 tanker as a reference ship, the manoeuvring model is validated with free-running tests executed by MARIN. Finally, the manoeuvring performance of the reference ship with various rudder profiles are quantified with turning and zigzag manoeuvres. The simulation results confirm that the wedge-tail series is most effective (largest manoeuvring forces) while the NACA series is most efficient (highest lift to drag ratio) among the tested profiles. The IFS series achieves a balance of effectiveness and efficiency.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The profile of a ship rudder influences the forces it generates, which in turn influence the manoeuvring performance of a ship. Thus, rudder forces and moments should be calculated considering the profile. Instead of an empirical estimation of the rudder normal force coefficient, this paper applies a RANS method to determine the hydrodynamic characteristics of various profiles, i.e. lift and drag coefficients. The RANS method is validated with a classic NACA 0012 profile and applied to 9 profiles from the NACA series, the wedge-tail series, and the IFS series. Furthermore, the 2D open-water RANS results are corrected for the effects of the propeller slipstream and the rudder aspect ratio. New regression formulas of the normal force coefficients are proposed for the tested profiles. These formulas are then integrated into a standard MMG model. Taking the KVLCC2 tanker as a reference ship, the manoeuvring model is validated with free-running tests executed by MARIN. Finally, the manoeuvring performance of the reference ship with various rudder profiles are quantified with turning and zigzag manoeuvres. The simulation results confirm that the wedge-tail series is most effective (largest manoeuvring forces) while the NACA series is most efficient (highest lift to drag ratio) among the tested profiles. The IFS series achieves a balance of effectiveness and efficiency.
51.
Gerco; Hooijmans Hagesteijn, Patrick; van der Meij
Proceedings of the ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2016, Busan, South Korea, 2016.
@conference{Hagesteijn2016,
title = {Correlation allowances in model tests results: A delicate balance between performance, accuracy and commercial interests?},
author = {Hagesteijn, Gerco; Hooijmans, Patrick; van der Meij, Karola},
url = {http://www.marin.nl/web/Publications/Papers/Correlation-allowances-in-model-tests-results-A-delicate-balance-between-performance-accuracy-and-commercial-interests.htm},
year = {2016},
date = {2016-06-19},
booktitle = {Proceedings of the ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2016, Busan, South Korea},
abstract = {Model tests at ballast and design draught are used to
convert the sea trial results from the ballast trial draught to the
contractual design draught. Correlation allowances in model test
results and their effect on the trial performance prediction are of
major importance. Nowadays it is not only typical to verify the
contract speed but also the EEDI certification requires a
verification of the speed power performance of the vessel. The
use of a to favorable CA-value may lead to attractive
performance figures, but also leads to higher fuel consumption
figures than expected. Furthermore the design point of the
propeller is affected, which leads to a too low light running
margin and in some cases to erosive cavitation.
During a study, large spreading in the values of the
correlation allowances for design draughts have been found for
merchant vessels tested at different model test institutes, but at
ballast trial draught the spreading is much less. Can it happen
that some institutes select favorable correlations allowances on
the basis of inaccurate trial data of shipyards? Or should we
accept a large spreading in correlation allowances and have
these indeed been confirmed by sea trials at design draught?
This paper will present a discussion using the experience of a
large full scale trial database as well as the accuracy of model
and full scale tests.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Model tests at ballast and design draught are used to
convert the sea trial results from the ballast trial draught to the
contractual design draught. Correlation allowances in model test
results and their effect on the trial performance prediction are of
major importance. Nowadays it is not only typical to verify the
contract speed but also the EEDI certification requires a
verification of the speed power performance of the vessel. The
use of a to favorable CA-value may lead to attractive
performance figures, but also leads to higher fuel consumption
figures than expected. Furthermore the design point of the
propeller is affected, which leads to a too low light running
margin and in some cases to erosive cavitation.
During a study, large spreading in the values of the
correlation allowances for design draughts have been found for
merchant vessels tested at different model test institutes, but at
ballast trial draught the spreading is much less. Can it happen
that some institutes select favorable correlations allowances on
the basis of inaccurate trial data of shipyards? Or should we
accept a large spreading in correlation allowances and have
these indeed been confirmed by sea trials at design draught?
This paper will present a discussion using the experience of a
large full scale trial database as well as the accuracy of model
and full scale tests.
convert the sea trial results from the ballast trial draught to the
contractual design draught. Correlation allowances in model test
results and their effect on the trial performance prediction are of
major importance. Nowadays it is not only typical to verify the
contract speed but also the EEDI certification requires a
verification of the speed power performance of the vessel. The
use of a to favorable CA-value may lead to attractive
performance figures, but also leads to higher fuel consumption
figures than expected. Furthermore the design point of the
propeller is affected, which leads to a too low light running
margin and in some cases to erosive cavitation.
During a study, large spreading in the values of the
correlation allowances for design draughts have been found for
merchant vessels tested at different model test institutes, but at
ballast trial draught the spreading is much less. Can it happen
that some institutes select favorable correlations allowances on
the basis of inaccurate trial data of shipyards? Or should we
accept a large spreading in correlation allowances and have
these indeed been confirmed by sea trials at design draught?
This paper will present a discussion using the experience of a
large full scale trial database as well as the accuracy of model
and full scale tests.
52.
L. Eça, Vaz; Abreu, H.
Validation: What, Why And How Conference
OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea, 2016.
@conference{Eça2016,
title = {Validation: What, Why And How},
author = {Eça, L., Vaz, G., Koop, A., Pereira, F. and Abreu, H.},
url = {http://www.marin.nl/web/Publications/Papers/Validation-What-Why-And-How.htm},
year = {2016},
date = {2016-06-19},
booktitle = {OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea},
pages = {OMAE2016-54005},
abstract = {Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
53.
G. Fernandes, Kapsenberg; Walree, F. van
Towards Accurate Computations of Active Stabiliser Fins, focusing on Dynamic Stall Conference
15th International Ship Stability Workshop, Stockholm, Sweden, 2016.
@conference{Fernandes2016,
title = {Towards Accurate Computations of Active Stabiliser Fins, focusing on Dynamic Stall},
author = {Fernandes, G., Kapsenberg, G.K., Kerkvliet, M. and Walree, F. van},
url = {http://www.marin.nl/web/Publications/Papers/Towards-Accurate-Computations-of-Active-Stabiliser-Fins-focusing-on-Dynamic-Stall.htm},
year = {2016},
date = {2016-06-13},
booktitle = {15th International Ship Stability Workshop, Stockholm, Sweden},
abstract = {Steps towards accurate and efficient characterisation of the hydrodynamic behaviour of active stabiliser fins have been conducted using computational fluid dynamics. Conditions seen at hydrodynamic testing facilities (Reynolds number = 135,000), with an angle of attack variation described as alpha(t) = 10 deg + 15 deg * sin(omega*t) have been modelled in two dimensions with various RANS turbulence models (k-omega SST, kskl, Spalart-Allmaras & LCTM) for reduced frequencies k=0.1 & 0.05. Solutions were compared to experimental results and results from other calculation methods (LES) and to results from a typical sea keeping code. The results showing the hysteresis loop for CL and CD show that a good agreement was seen to the literature. For seakeeping applications, moderate refinement in time and space is sufficient, and that the k-omega SST turbulence model best matches the CL and CD curves found in the literature. The increased knowledge of stabiliser fins dynamics will be used to improve time-domain seakeeping codes and possible also the control laws for active stabilizer fins},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Steps towards accurate and efficient characterisation of the hydrodynamic behaviour of active stabiliser fins have been conducted using computational fluid dynamics. Conditions seen at hydrodynamic testing facilities (Reynolds number = 135,000), with an angle of attack variation described as alpha(t) = 10 deg + 15 deg * sin(omega*t) have been modelled in two dimensions with various RANS turbulence models (k-omega SST, kskl, Spalart-Allmaras & LCTM) for reduced frequencies k=0.1 & 0.05. Solutions were compared to experimental results and results from other calculation methods (LES) and to results from a typical sea keeping code. The results showing the hysteresis loop for CL and CD show that a good agreement was seen to the literature. For seakeeping applications, moderate refinement in time and space is sufficient, and that the k-omega SST turbulence model best matches the CL and CD curves found in the literature. The increased knowledge of stabiliser fins dynamics will be used to improve time-domain seakeeping codes and possible also the control laws for active stabilizer fins
54.
Carette, Nicolas F. A. J.
15th International Ship Stability Workshop, Stockholm, Sweden, 2016.
@conference{Carette2016,
title = {Fast time domain evaluation of Anti-Roll Tank and ship coupling using non-linear retardation functions},
author = {Nicolas F.A.J. Carette},
url = {http://www.marin.nl/web/Publications/Papers/Fast-time-domain-evaluation-of-AntiRoll-Tank-and-ship-coupling-using-nonlinear-retardation-functions-1.htm},
year = {2016},
date = {2016-06-13},
booktitle = {15th International Ship Stability Workshop, Stockholm, Sweden},
pages = {2_2},
abstract = {Anti-Roll Tanks (ART) have been used for more than a century to damp the roll motion of ships. These devices exist in various configurations, passively and actively controlled. All versions rely on resonant water motions in a chamber which, by essence, is a very non-linear process. To account for these non-linearities, several approaches have been proposed, where the most recent and complete one is the direct coupling of time domain seakeeping codes with a CFD models of the ART. However, this approach comes at the price of relatively high computation effort. This is in contradiction with the need for long simulations to establish the effects of the non-linearities in the ART reaction forces on extreme events. To reduce the computation costs of a direct simulation, a new technique is proposed which uses retardation functions based on harmonic ART response data. The technique proposed here uses a family of retardation functions with a Hilbert transform method for time dependent interpolations to capture the non-linearity in the response of the tank as a function of excitation amplitude.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Anti-Roll Tanks (ART) have been used for more than a century to damp the roll motion of ships. These devices exist in various configurations, passively and actively controlled. All versions rely on resonant water motions in a chamber which, by essence, is a very non-linear process. To account for these non-linearities, several approaches have been proposed, where the most recent and complete one is the direct coupling of time domain seakeeping codes with a CFD models of the ART. However, this approach comes at the price of relatively high computation effort. This is in contradiction with the need for long simulations to establish the effects of the non-linearities in the ART reaction forces on extreme events. To reduce the computation costs of a direct simulation, a new technique is proposed which uses retardation functions based on harmonic ART response data. The technique proposed here uses a family of retardation functions with a Hilbert transform method for time dependent interpolations to capture the non-linearity in the response of the tank as a function of excitation amplitude.
55.
D. van Heel, Klinkenberg; Ouwerkerk, M.
Tracking Stress and Workload in the Maritime/Tugboat World Conference
24th International Tug, Salvage & OSV Convention (ITS), Boston, MA, 2016.
@conference{Heel2016,
title = {Tracking Stress and Workload in the Maritime/Tugboat World},
author = {Heel, D. van, Klinkenberg, K., Blankertz, B., Miklody, D., Uitterhoeve, W. and Ouwerkerk, M.},
url = {http://www.marin.nl/web/Publications/Papers/Tracking-Stress-and-Workload-in-the-MaritimeTugboat-World.htm},
year = {2016},
date = {2016-05-25},
booktitle = {24th International Tug, Salvage & OSV Convention (ITS), Boston, MA},
abstract = {The Dutch research institute MARIN, the Technical University of Berlin, Philips and k+s projects would like to present the findings of a pilot study into stress/workload measurements during training in a ship-handling simulator. Working on a tug has unique demands, made more challenging by fatigue and a high workload, and influenced by special demands such as noise, the intense mixture of private and work life and what often prove to be extreme environmental challenges. The objective of this pilot study is to determine the most suitable tool to determine the workload a person experiences when executing complex tug manoeuvres. Scenarios are selected strictly according to real life on the bridge, focusing on tugboat reality. Measurements include heartbeat rate and skin conductivity, plus an EEG, but also include simulator signals. The human body is a very sophisticated control circuit, and to choose different ways of looking at the way a human expresses himself is like joining puzzle elements to a complete picture. Together they pinpoint what is most challenging for the test person. The findings will be evaluated to assess which signals are most suitable to obtain a reliable workload indicator. This tool can be used to study the impact of job procedures, modern bridge design and time/work shift systems, but also to measure the effectiveness of training programmes. The pilot study is the follow up of the demonstration of 'Training meets Science' during ITS 2014 in Hamburg, initiated and organised by k+s projects, University of Applied Sciences Bremen and University of Technology Berlin.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The Dutch research institute MARIN, the Technical University of Berlin, Philips and k+s projects would like to present the findings of a pilot study into stress/workload measurements during training in a ship-handling simulator. Working on a tug has unique demands, made more challenging by fatigue and a high workload, and influenced by special demands such as noise, the intense mixture of private and work life and what often prove to be extreme environmental challenges. The objective of this pilot study is to determine the most suitable tool to determine the workload a person experiences when executing complex tug manoeuvres. Scenarios are selected strictly according to real life on the bridge, focusing on tugboat reality. Measurements include heartbeat rate and skin conductivity, plus an EEG, but also include simulator signals. The human body is a very sophisticated control circuit, and to choose different ways of looking at the way a human expresses himself is like joining puzzle elements to a complete picture. Together they pinpoint what is most challenging for the test person. The findings will be evaluated to assess which signals are most suitable to obtain a reliable workload indicator. This tool can be used to study the impact of job procedures, modern bridge design and time/work shift systems, but also to measure the effectiveness of training programmes. The pilot study is the follow up of the demonstration of 'Training meets Science' during ITS 2014 in Hamburg, initiated and organised by k+s projects, University of Applied Sciences Bremen and University of Technology Berlin.
56.
C. Fureby, Toxopeus; Petterson, K.
A computational study of the flow around the KVLCC2 model hull at straight ahead conditions and at drift Journal Article
In: Ocean Engineering, 2016, vol. 118, pp. 1-16, 2016.
@article{Fureby2016,
title = {A computational study of the flow around the KVLCC2 model hull at straight ahead conditions and at drift},
author = {Fureby, C., Toxopeus, S.L., Johansson, M., Tormalm, M. and Petterson, K.},
url = {http://www.marin.nl/web/Publications/Papers/A-computational-study-of-the-flow-around-the-KVLCC2-model-hull-at-straight-ahead-conditions-and-at-drift-1.htm},
doi = {10.1016/j.oceaneng.2016.03.029},
year = {2016},
date = {2016-05-01},
booktitle = {Ocean Engineering},
journal = {Ocean Engineering, 2016},
volume = {118},
pages = {1-16},
abstract = {The flow around the KVLCC2 model tanker hull at 0 deg, 12 deg and 30 deg drift is investigated using classical Reynolds Averaged Navier–Stokes (RANS) models from two different proprietary codes, hybrid RANS-LES models from one of these proprietary codes, and Large Eddy Simulation (LES) models from a third, semi-proprietary code. Understanding the three-dimensional (3D) flow around a ship hull and in the wake of the hull on straight course or during maneuvering is important for many design and operational aspects, as well as from an environmental perspective. Tetrahedral grids of 13 million and 74 million cells respectively are used for the RANS and hybrid RANS-LES; for the LES, grids of between 120 and 200 million tetrahedral cells are used. The objectives are to generally increase knowledge of the flow past a ship hull both at straight-ahead and at static-drift conditions, and to assess the predictive capabilities of RANS, hybrid RANS-LES and LES computational methods. Using these computational results, the focus is specifically on understanding the complex vortical topology and associated surface-flow characteristics, and how these change when the drift angle increases. The RANS and time-averaged hybrid RANS-LES and LES predictions are compared against each other and against experimental data to further validate the simulation models and to provide additional insight into the flow physics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The flow around the KVLCC2 model tanker hull at 0 deg, 12 deg and 30 deg drift is investigated using classical Reynolds Averaged Navier–Stokes (RANS) models from two different proprietary codes, hybrid RANS-LES models from one of these proprietary codes, and Large Eddy Simulation (LES) models from a third, semi-proprietary code. Understanding the three-dimensional (3D) flow around a ship hull and in the wake of the hull on straight course or during maneuvering is important for many design and operational aspects, as well as from an environmental perspective. Tetrahedral grids of 13 million and 74 million cells respectively are used for the RANS and hybrid RANS-LES; for the LES, grids of between 120 and 200 million tetrahedral cells are used. The objectives are to generally increase knowledge of the flow past a ship hull both at straight-ahead and at static-drift conditions, and to assess the predictive capabilities of RANS, hybrid RANS-LES and LES computational methods. Using these computational results, the focus is specifically on understanding the complex vortical topology and associated surface-flow characteristics, and how these change when the drift angle increases. The RANS and time-averaged hybrid RANS-LES and LES predictions are compared against each other and against experimental data to further validate the simulation models and to provide additional insight into the flow physics.
57.
Toxopeus, S. L.; Bhawsinka, K.
Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD Conference
Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany, 2016.
@conference{Toxopeus2016,
title = {Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD},
author = {Toxopeus, S.L. and Bhawsinka, K.},
url = {http://www.marin.nl/web/Publications/Papers/Calculation-of-hydrodynamic-interaction-forces-on-a-ship-entering-a-Lock-using-CFD.htm},
doi = {10.18451/978-3-939230-38-0_34},
year = {2016},
date = {2016-05-01},
booktitle = {Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany},
pages = {6_01},
abstract = {Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
58.
Henk; Flikkema Prins, Maarten; Schuiling
Green retrofitting through optimisation of hull-propulsion interaction - GRIP Conference
Proceedings of 6th Transport Research Arena, Warsaw, Poland, 2016.
@conference{Prins2016,
title = {Green retrofitting through optimisation of hull-propulsion interaction - GRIP},
author = {Prins, Henk; Flikkema, Maarten; Schuiling, Bart; Xing-Kaeding, Y; Voermans, A. A. M.; Müller, M; Coache, S; Hasselaar, Thijs; Paboeuf, S},
url = {http://www.marin.nl/web/Publications/Papers/Green-retrofitting-through-optimisation-of-hullpropulsion-interaction-GRIP.htm },
year = {2016},
date = {2016-04-18},
booktitle = {Proceedings of 6th Transport Research Arena, Warsaw, Poland},
abstract = {In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
59.
H.J. Prins, Flikkema
Suppression Of underwater Noise Induced by Cavitation: SONIC Conference
6th European Transport Research Conference, Warsaw, Poland, 2016.
@conference{Prins2016b,
title = {Suppression Of underwater Noise Induced by Cavitation: SONIC},
author = {Prins, H.J., Flikkema, M.B., Bosschers, J., Koldenhof, Y., Jong, C.A.F. de, Pestelli, C., Mumm, H., Bretschneider, H., Humphrey, V., Hyensjö, M.},
url = {http://www.marin.nl/web/Publications/Papers/Suppression-Of-underwater-Noise-Induced-by-Cavitation-SONIC.htm},
year = {2016},
date = {2016-04-01},
booktitle = {6th European Transport Research Conference, Warsaw, Poland},
abstract = {In EU FP7 project SONIC, partners set out in October 2012 to study the underwater radiated noise of ships and shipping. The objectives of the project were (1) to study the numerical and experimental techniques to determine the underwater noise; (2) to develop methods for mapping the noise of ships and shipping; and (3) to determine mitigation measures to reduce the underwater radiated noise.
Numerical methods focused on determination of the cavitation extent and dynamics on propellers which is the main source of noise of commercial shipping. Research also focused on methods to determine the underwater radiated noise from machinery. Experimental methods in model test facilities have been studied and validated against dedicated full scale measurements. The ship noise source levels obtained from these numerical and experimental methods provide input to shipping noise mapping tools to determine the overall underwater noise in a certain sea area.
Based on the experience gained in the SONIC project, a set of guidelines for regulators concerned with underwater radiated noise of ships were developed together with the AQUO project. These guidelines discuss the definitions, numerical and experimental methods and mitigation solutions for underwater radiated noise.
This paper gives an overview of the work done by all partners in the SONIC project.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In EU FP7 project SONIC, partners set out in October 2012 to study the underwater radiated noise of ships and shipping. The objectives of the project were (1) to study the numerical and experimental techniques to determine the underwater noise; (2) to develop methods for mapping the noise of ships and shipping; and (3) to determine mitigation measures to reduce the underwater radiated noise.
Numerical methods focused on determination of the cavitation extent and dynamics on propellers which is the main source of noise of commercial shipping. Research also focused on methods to determine the underwater radiated noise from machinery. Experimental methods in model test facilities have been studied and validated against dedicated full scale measurements. The ship noise source levels obtained from these numerical and experimental methods provide input to shipping noise mapping tools to determine the overall underwater noise in a certain sea area.
Based on the experience gained in the SONIC project, a set of guidelines for regulators concerned with underwater radiated noise of ships were developed together with the AQUO project. These guidelines discuss the definitions, numerical and experimental methods and mitigation solutions for underwater radiated noise.
This paper gives an overview of the work done by all partners in the SONIC project.
Numerical methods focused on determination of the cavitation extent and dynamics on propellers which is the main source of noise of commercial shipping. Research also focused on methods to determine the underwater radiated noise from machinery. Experimental methods in model test facilities have been studied and validated against dedicated full scale measurements. The ship noise source levels obtained from these numerical and experimental methods provide input to shipping noise mapping tools to determine the overall underwater noise in a certain sea area.
Based on the experience gained in the SONIC project, a set of guidelines for regulators concerned with underwater radiated noise of ships were developed together with the AQUO project. These guidelines discuss the definitions, numerical and experimental methods and mitigation solutions for underwater radiated noise.
This paper gives an overview of the work done by all partners in the SONIC project.
60.
L. Eça, Klaij; Pereira, F. S.
On code verification of RANS solvers Journal Article
In: Journal of Computational Physics, 2016, vol. 310, pp. 418-439, 2016.
@article{Eça2016b,
title = {On code verification of RANS solvers},
author = {Eça, L., Klaij, C.M., Vaz, G., Hoekstra, M. and Pereira, F.S.},
url = {http://www.marin.nl/web/Publications/Papers/On-code-verification-of-RANS-solvers.htm},
doi = {10.1016/j.jcp.2016.01.002},
year = {2016},
date = {2016-04-01},
journal = {Journal of Computational Physics, 2016},
volume = {310},
pages = {418-439},
abstract = {This article discusses Code Verification of Reynolds-Averaged Navier Stokes (RANS) solvers that rely on face based finite volume discretizations for volumes of arbitrary shape. The study includes test cases with known analytical solutions (generated with the method of manufactured solutions) corresponding to laminar and turbulent flow, with the latter using eddy-viscosity turbulence models. The procedure to perform Code Verification based on grid refinement studies is discussed and the requirements for its correct application are illustrated in a simple one-dimensional problem. It is shown that geometrically similar grids are recommended for proper Code Verification and so the data should not have scatter making the use of least square fits unnecessary. Results show that it may be advantageous to determine the extrapolated error to cell size/time step zero instead of assuming that it is zero, especially when it is hard to determine the asymptotic order of grid convergence. In the RANS examples, several of the features of the ReFRESCO solver are checked including the effects of the available turbulence models in the convergence properties of the code. It is shown that it is required to account for non-orthogonality effects in the discretization of the diffusion terms and that the turbulence quantities transport equations can deteriorate the order of grid convergence of mean flow quantities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This article discusses Code Verification of Reynolds-Averaged Navier Stokes (RANS) solvers that rely on face based finite volume discretizations for volumes of arbitrary shape. The study includes test cases with known analytical solutions (generated with the method of manufactured solutions) corresponding to laminar and turbulent flow, with the latter using eddy-viscosity turbulence models. The procedure to perform Code Verification based on grid refinement studies is discussed and the requirements for its correct application are illustrated in a simple one-dimensional problem. It is shown that geometrically similar grids are recommended for proper Code Verification and so the data should not have scatter making the use of least square fits unnecessary. Results show that it may be advantageous to determine the extrapolated error to cell size/time step zero instead of assuming that it is zero, especially when it is hard to determine the asymptotic order of grid convergence. In the RANS examples, several of the features of the ReFRESCO solver are checked including the effects of the available turbulence models in the convergence properties of the code. It is shown that it is required to account for non-orthogonality effects in the discretization of the diffusion terms and that the turbulence quantities transport equations can deteriorate the order of grid convergence of mean flow quantities.
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