Hamburg, Germany
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Reimer N.,Hamburg Ship Model Basin
Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions, POAC | Year: 2011

Today the prediction of resistance and propulsion in ice covered waters is usually carried out using well established semi empiric methods. These methods are based on a subdivision of resistance into several components with regard to the physical origin (e.g. breaking, submersion or friction). For each component different parameters (hull shape data and ice properties) are included. Nevertheless, the range of ships of reference these methods are based on is naturally restricted and today many ships operating in ice covered waters differ significantly regarding their hull shape parameters. A second inadequacy of the existing methods is that due to the subdivision of resistance into components, simultaneous effects are hardly taken account. To offer a prediction method including the correlation between different parameters (e.g. ice thickness and speed) and at the same time enlarge the range of validity concerning hull shape parameters, a prediction method based on artificial neural networks (ANN) was developed in scope of a master thesis in cooperation between Hamburg Ship Model Basin and Hamburg University of Technology. Neural networks offer the possibility of learning multiple functional relations without using explicit approaches and are therefore able to include correlation of simultaneous influences. To learn the relations the networks are trained by gradient descent methods on a data set including both input and output parameters. After successful training the networks are then able to generalize the relation to predict the output parameters for an unknown input data set. For prediction on resistance and propulsion of ships in ice covered waters the networks were trained with data collected at Hamburg Ship Model Basin including data from model tests and full scale trials. The results turned out to have an acceptable accuracy. Copyright © (2011) by Port and Ocean Engineering under Arctic Conditions (POAC 2011).


Myland D.,Hamburg Ship Model Basin | Reimer N.,Hamburg Ship Model Basin | Hinse P.,Hamburg Ship Model Basin
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013

The research project IRO-2 (Ice Forecast and Route Optimization) aims at the development of a route optimization tool for the Arctic environment. Therefore model tests in ice ridges, ice floes and tests under lateral side pressure were carried out in HSVA's Large Ice Model Basin. The results will be implemented in the tool to find the optimum route for a ship with regard to efficiency. The main objective of this paper is the description of the preparation of the above mentioned ice conditions and the testing procedures. The subsequent test analysis focuses on model tests in ice floes. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).


Repetto-Llamazares A.H.V.,Norwegian University of Science and Technology | Hoyland K.V.,Norwegian University of Science and Technology | Evers K.-U.,Hamburg Ship Model Basin
Cold Regions Science and Technology | Year: 2011

The strength of freeze-bonds in thin saline ice has been investigated through two series (in 2008 and 2009) of experiments in the Hamburg Ship Model Basin (HSVA) as a function of the normal confinement (σ), the submersion time (δt) and the initial ice temperature (Ti). The freeze-bonds were mostly formed in a submerged state, but some were also formed in air. The experimental set-up was improved in the 2009 experiments. In 2008 a ductile-like failure mode dominated (78%), whereas in 2009 the brittle-like dominated (93%). We suggest that this is a combined ice and test set-up effect. The 2009 experimental procedures allowed for careful sample handling giving higher strength and it was softer. Both these things should provoke a more brittle-like force-time response. The average freeze-bond strength in brittle-like samples was around 9kPa while in ductile-like samples was around 2kPa. The maximum freeze-bonds strength were measured for short submersion times, from 1 to 20min, and reached a maximum value of 30kPa. A Mohr-Coulomb like failure model was found appropriate to represent the freeze-bond shear strength as function of the normal confinement. Saline freeze-bonds in saline water had cohesion/friction angle around 4 and 1.4. kPa/25° for the brittle- and ductile-like samples respectively, which fitted well with previously published data.A bell-shape dependence for τc vs δt was found, which agreed with the predictions by Shafrova and Høyland (2007). We suggest that this is essentially a freeze-bond porosity effect and propose three phases in time with subsequent cooling, heating and equilibrium to account for this trend. Qualitative experiments showed that the submersion time and the initial ice temperature were strongly coupled. To account for the connection between contact time, block dimensions and ice properties and the freeze-bond strength, dimensionless number were used. Fourier scaling was more appropriate than Froude scaling to scale freeze-bonds. The freeze-bonding made in air developed fast (in less than 30. s) when the ice was cold and dry, but no freeze-bonding occurred for the same contact times when the ice was warm and wet. © 2010 Elsevier B.V.


Hisette Q.,Hamburg Ship Model Basin
Ship Technology Research | Year: 2016

A simulation tool for physical ice management operations is described in this paper. From the dimensions of the structure that has to be protected against drifting ice, the ice management vessel(s) characteristics and the ice conditions, vessel(s) trajectories are computed in order to perform ice management for a defined target floe size according to linear, sector and circular management techniques. Ship resistance and manoeuvrability in level ice and in floes are estimated thanks to semi-empirical methods. Manoeuvrability results are then calibrated and validated by comparison with model test data. © 2016, © University of Duisburg-Essen 2016.


Myland D.,Hamburg Ship Model Basin
International Journal of Offshore and Polar Engineering | Year: 2014

Within the research project IRO-2 (Ice Forecast and Route Optimization), the process of ships breaking through first-year sea ice ridges was analyzed. To understand the process of a ship breaking through ridges, six ridge ramming model tests with systematically varied keel depths were performed in HSVA’s large ice model basin. Based on the model test results, a general method to predict the ship’s average transit velocity in first-year sea ice ridges was established. The method serves as a precondition for developing an efficient route optimization tool for ice-covered seas and will be embedded in this tool. In conclusion, the model test results were compared with ice resistance measurements in the Baltic Sea. © by The International Society of Offshore and Polar Engineers.


Valanto P.,Hamburg Ship Model Basin | Hong Y.,Hamburg Ship Model Basin
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2015

Measurements on wave added resistance of a cruise ship model were carried out in regular waves in seven wave directions. The motivation for the investigation is the powering performance of ships in wave conditions. A new towing arrangement allows the ship model practically free motions in oblique seas, but makes it simultaneously possible to measure the towing resistance. The maximum resistance was encountered in bow quartering seas. The measurements show that practically all ship motion components have a clear effect on the wave added resistance. The wave elevation measured around the ship shows a clear correlation with the measured wave added resistance values. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE).


Schroder C.,Hamburg Ship Model Basin
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2015

To better understand the environmental impact of shipping in arctic areas, this paper will focus on the development of a tool to determine the traveling time, consumed type of fuel and corresponding exhaust emissions. This tool has been developed during the European Union funded research project ACCESS (Arctic Climate Change, Economy and Society) (HSVA, 2014). The results depend on ship parameters like hull shape, propulsion system, engine characteristic and consumed type of fuel as well as the environmental conditions which are mainly influenced by the climate change. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE).


Reimer N.,Hamburg Ship Model Basin
RINA, Royal Institution of Naval Architects - International Conference on the Ice Class Ships 2012 | Year: 2012

Within the IRO-2, Ice Forecast and Ice-Route-Optimisation project funded by the Federal Ministry of Economics and Technology in Germany, running from October 2011 till September 2014 a joined group of experts with different scientific background is working on the development of an ice route optimisation based on an ice forecast and ice navigation model. The Hamburg Ship Model Basins (HSVA) contribution within IRO-2 will be the development of this ice navigation model and route optimisation tool. The ice forecast obtained from a fine scaled, regional ice model and a coarse ice model which is based on satellite data will deliver input ice conditions for the navigation program. Additionally data on the specific ice breaking capability of the ship will be used to determine the resistance in different ice conditions and thereby (including propulsion and engine output) predict the maximum available safe speed in order to assess different possible routes. © 2012: The Royal Institution of Naval Architects.


Ehle D.,Hamburg Ship Model Basin
RINA, Royal Institution of Naval Architects - International Conference on the Ice Class Ships 2012 | Year: 2012

Within the research project IRO-2 (Ice Forecast and Route Optimization) the process of ships breaking through first-year sea ice ridges was analysed. Therefore ridge ramming model tests with systematically varied keel depths were carried out in HSVA's Large Ice Model Basin. Based on the model test results a general method to predict the average transit velocity of ships breaking through first year sea ice ridges was established. The method serves as a precondition for developing an efficient route optimization tool for ice covered seas and will be embedded in this tool. © 2012: The Royal Institution of Naval Architects.


Streckwall H.,Hamburg Ship Model Basin | Xing-Kaeding Y.,Hamburg Ship Model Basin
MARINE 2015 - Computational Methods in Marine Engineering VI | Year: 2015

The design of a well performing pre-swirl stator (PSS) should strictly account for the full scale flow environment as met individually by each stator fin. In the European GRIP project an actual design has been delivered for a bulk carrier and was installed for trials. The results of the speed/power measurements could be compared to the trial data obtained 2 weeks earlier, when the stator was not mounted. The power gain with mounted stator was considerable. As the design was adapted to a computed full scale flow environment, the question arises whether such results could have been predicted prior by model tests performed with geometrical similar stator and propeller. For this purpose we analysed the model propulsion mode numerically. In summary the model scale analysis revealed considerable differences to the full scale setup, if the performance of the fins is compared individually. However in this numerical assessment of scale effects the overall decrease of power at the propeller showed only minor changes between model and full scale. The second question coming up after the trials have been completed addresses the propeller and its drop in RPM, an expected and forecasted result. Such an RPM change in itself will have a positive effect on the required power due to a reduction of viscous effects on torque. On the other hand due to requirements from the engine side it will usually be necessary to adapt the propeller geometry and compensate the RPM drop. It is investigated numerically, to what extent the required power will increase for such an RPM adapted propeller.

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