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Item type:Publication, Access status: without files , Model scale investigation of aspects influencing the ice resistance of ships sailing ahead in level ice(2020-01-02); For a reliable prediction of the total resistance in ice in an early ship design stage, it is of great importance to have knowledge on the different influencing aspects. Three of the quite poorly investigated aspects of ship resistance in ice are evaluated for a contemporary common ice-breaking ship type with model tests in ice: The different components of the total resistance in ice are investigated by tests in pre-sawn ice. The additional resistance of a skeg in the bow area is analysed with model tests in ice with an instrumented skeg. The ship bottom ice coverage is determined by means of an underwater image analysis methodology. The results of these investigations are given and discussed.Publicationtype: Journal Article101 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , An experimental method for model propeller-ice interaction in air: concept and first resultsOne of the aims of the German national funded research project ProEis is to develop a methodology for determination of ice loads on model propellers which will then aid in improving and developing software tools for their prediction. For this purpose, a prototype device has been designed at HSVA within this project which is used to guide defined ice floes with one degree of freedom into a model propeller where they are milled and the resulting forces and moments are measured. This paper focuses on the description of the ice feeding device and presents some first results with respect to the physical process as well as measured load characteristics. For now, experiments are conducted in absence of water in order to exclude all hydrodynamic effects. A podded propeller is used which allows measuring of shaft torque and shaft thrust. A high speed video camera is also employed to record the propeller-ice interaction process at 5000 frames per second, allowing to observe the milling process in detail. Two basic impact patterns are observed with respect to their relative load levels. When the greater part of the leading edge of the propeller strikes the ice from the top, i.e. it crushes the granular layer and cuts off a relatively large chunk of ice, the maximum shaft thrust is approximately 1.5 times as high as when the leading edge of the propeller makes contact at the front face of a floe, scraping off a thin layer of ice. Shaft torque is mostly unaffected by the type of impact. The performance of the ice feeding device and the findings of the first tests presented here are reviewed and discussed critically. Recommendations for the planning of such tests and possible improvements of the device are given.Publicationtype: Conference Paper80 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Methodology for investigation of ice breaking performance(International Society of Offshore and Polar Engineers (ISOPE), 2016-06); Understanding the influence of the ship hull design on the ship-ice interaction is essential for its assessment in an early design stage. Within the research project ProEis an investigation is carried out which is based on a holistic consideration of the ice breaking process. This paper aims to present an improved testing procedure to enable the development of a numerical simulation procedure that predicts the twoway coupled hydrodynamic interaction of the vessel with the turbulent nonlinear flow as well as the collision of the pre-broken ice and the ship hull and a companion tool which determines the bow ice-breaking pattern. Analysis results of the influence of different bow shape (parameters) on the breaking pattern are given followed by a first evaluation of the ice flow along the ship hull.Publicationtype: Conference Paper35