Until recent times researchers who investigated ice loads stochastic processes usually stated the... more Until recent times researchers who investigated ice loads stochastic processes usually stated the fact of normal distribution for them. In the paper the model of a stationary stochastic process with a lognormal distribution for ice loads is offered. This model relates to the strain gauge transducer ice loads measurements as well as to some examples considered in different papers that were published earlier. For this model dependencies of the autocorrelation function were found that allows to simulate the ice loads process relatively easily. The procedure of such a simulation is described in details and the example of the analysis and simulation ice loads measurements is provided.
Icebreaker construction that began to develop in Russia and Europe in the second half of the 19t... more Icebreaker construction that began to develop in Russia and Europe in the second half of the 19th century dictated the need for seafarers and shipbuilders to study the ice covers of the freezing waters as navigation environment. One of the most important characteristics on which the ships’ ice-breaking capabilities depend is ice strength. The problem of sea and freshwater ice strength was particularly urgent for Vice Admiral S. O. Makarov when he was putting the case for building the first Arctic icebreaker Yermak. It was for this reason that he initiated these studies. At about the same time, a renowned shipbuilder V. I. Afanasiev also came to the conclusion that it was necessary to study ice strength properties, and carried out a number of experiments together with his son. Makarov engaged A. N. Krylov, Superintendent of the Towing Tank, in the experimental data analysis. The article describes the history of, and analyzes the conclusions from, these experiments that for a long time remained the only source of data on strength properties of sea and freshwater ice.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2007
Paper presents outcomes of statistical analyze of published data about geometry and dimensions of... more Paper presents outcomes of statistical analyze of published data about geometry and dimensions of the grounded hummocks (GHs) in the Okhotskoe Sea and piled ice (PI) in the Bohai Sea, and also present the results of evaluation of forces applied on them by currents, wind, heaving, and drift ice. Base on the carried out evaluations and comparison of loads it is stated that grounded hummock is able to move and plough seabed not only due to loads from drift ice, but also due to loads from the wind waves which uplifts and swings GHs and PI. These effects are important for designing of pipelines and cable lines, which connect offshore constructions with coastal infrastructure.
For development of hydrocarbon deposits located in a shallow part of coastal shelf, offshore stru... more For development of hydrocarbon deposits located in a shallow part of coastal shelf, offshore structures of gravitational type are widely used. The foundations of such structures are towed to sites where they are flooded and installed directly on sea bed. During operation of offshore structures the sea bed soil around and beneath the structure foundations are exposed to external effects such as sea currents, waves and also propeller streams generated by ships approaching the structures. As a result the soil is washed out from under the structure which may cause reduction of bearing surface area and even lead to loss of stability of the structure on seabed. The model studies on soil erosion process near foundations of gravitational-type offshore platforms have been conducted at Krylov’s shallow water towing tank since 2000. This towing tank was not originally intended for such experiments, and, therefore, special experimental equipment has been developed for this purpose. These include a sandy bottom, current generation arrangements in the model test zone, instrumentation for measuring the bottom profile. Also specific model test procedures and methods for research on soil scour near the test objects have been developed and verified. The paper gives a review of these research studies at the Krylov Centre, describe the test equipment, modeling techniques and test data scaling procedures as well as the experience learned from the experiments. The paper gives some results of research studies of soil erosion near the foundations of offshore structures as a result of influence from sea currents and waves with coincident directions, and also as a result of influence from propeller streams of moored tankers and supply vessels. The paper presents the model test results regarding the efficiency of a mobile system developed for soil erosion protection near the offshore structure intended for exploratory drilling in shallow waters of the Gulf of Ob in the Kara Sea. A review of the recent Krylov’s studies in this field of research is given.
Vessels with an azimuth propulsion system (APS), including double-acting tankers (DATs) designed ... more Vessels with an azimuth propulsion system (APS), including double-acting tankers (DATs) designed for autonomous ice navigation in astern-running mode, which makes it possible to improve their icebreaking capability and operation performance in open water by means of bow shape optimisation, are considered to be promising ship types for hydrocarbon and ore material transportation along Arctic Passage routes. This paper covers
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2011
The North Caspian Sea area and the Kashagan Fields can be considered a unique environmental scena... more The North Caspian Sea area and the Kashagan Fields can be considered a unique environmental scenario which has assumed a strategical importance during this decade owing to the development of off-shore structures. In this paper is shown the analysis on ice going capability of a small unconventional vessel (an Ice Breaking Emergency Evacuation Vessel operated by Agip KCO) operating in the Kashagan field, equipped with two pulling type thrusters. The open water performance has been investigated in the shallow water tank of Krylov Shipbuilding Research Institute. The purpose of the research in the hydrodynamic basin was to study the influence of shallow water and ultra shallow water on resistance, propeller-hull interaction and propulsion. Some bow and stern shape variants have been tested in ice model tank in order to verify the ice going capability of the vessel and to reduce ice resistance. Three campaigns of full scale trials in ice were performed in North Caspian Sea during the last years. The scope of these trials was to verify the maximum performance of the vessel and to investigate its operative limitations. Ice going capability and manoeuvrability were widely investigated for different ice thickness and flexural strength. A great deal of further analysis and measurements, not discussed in this paper, were also performed during the trials as vibration on hull, machineries and propulsor, torsional vibration and hull strain measurements (strain gauges). The overall result of the conducted study is identification of the allowable combination of ice thickness and flexural strength to achieve a minimum safety speed. Moreover, some operative recommendations are given in order to preserve the vessel from any damage (failure) and assure safety operations.
At present, there is a tendency to use the large-size active ice-going ships for oil and gas tran... more At present, there is a tendency to use the large-size active ice-going ships for oil and gas transportation from the fields located in the Far North and Far East as well as from the shelf of freezing seas. Intentions for use of large-size tankers and gas carriers as a part of arctic transportation systems are mostly based on the results of cost-effectiveness calculations. However, these calculations usually do not take into account actual conditions of ship navigation in ice. In this paper, we review some main challenges related to large-size ships manoeuverability and performance in ice as well as interaction of above ships with icebreakers. In the final section of this paper, the author gives the conclusions based on the brief review of the problems arising during navigation of large-size ships in ice.
Ледяной покров на поверхности воды отличается большим разнообразием своего строения, включая лине... more Ледяной покров на поверхности воды отличается большим разнообразием своего строения, включая линейные размеры ледяных образований. Лед с наименьшими линейными размерами (менее 2 м) называется тертым. Такой лед может образовываться как в естественных условиях при замерзании воды и при динамических процессах в ледяном покрове, так и из-за хозяйственной деятельности человека. Именно такой тертый лед в последнее время начинает создавать серьезные затруднения для породившего его судоходства в замерзающих акваториях. В статье описываются основные свойства тертого льда и рассматриваются способы борьбы с этим явлением.
Труды Крыловского государственного научного центра, Jun 6, 2023
Object and purpose of research. This paper discusses the methods for determination of propeller a... more Object and purpose of research. This paper discusses the methods for determination of propeller anti-torque in ice milling conditions. The purpose of the study was to investigate existing methods for propeller anti-torque determination, analyse their respective pros and cons and to trace out the paths of further studies towards a satisfactory description of propeller anti-torque. Materials and methods. This study relies on previous publications and experimental ice milling data from both laboratory tests and field measurements, as well as on full-scale measurement data obtained on propulsion shafts of real icebreakers and ice-going ships. Main results. Currently, there is a wide variety of methods for obtaining anti-torque data: regulatory, theoretical, model testing and full-scale measurements on ship shafting. Analysis of the regulations given in the recommendations of various class societies has shown considerable drawbacks in the calculation formulae used in them. This paper proves that the most viable method for propeller anti-torque determination is its reconstruction as per the results of full-scale measurements on shaft line. Conclusion. Current methods for determination of anti-torque do not describe this phenomenon exhaustively. The most promising solution here would be to perform full-scale trials and analyse their results.
Until recent times researchers who investigated ice loads stochastic processes usually stated the... more Until recent times researchers who investigated ice loads stochastic processes usually stated the fact of normal distribution for them. In the paper the model of a stationary stochastic process with a lognormal distribution for ice loads is offered. This model relates to the strain gauge transducer ice loads measurements as well as to some examples considered in different papers that were published earlier. For this model dependencies of the autocorrelation function were found that allows to simulate the ice loads process relatively easily. The procedure of such a simulation is described in details and the example of the analysis and simulation ice loads measurements is provided.
Icebreaker construction that began to develop in Russia and Europe in the second half of the 19t... more Icebreaker construction that began to develop in Russia and Europe in the second half of the 19th century dictated the need for seafarers and shipbuilders to study the ice covers of the freezing waters as navigation environment. One of the most important characteristics on which the ships’ ice-breaking capabilities depend is ice strength. The problem of sea and freshwater ice strength was particularly urgent for Vice Admiral S. O. Makarov when he was putting the case for building the first Arctic icebreaker Yermak. It was for this reason that he initiated these studies. At about the same time, a renowned shipbuilder V. I. Afanasiev also came to the conclusion that it was necessary to study ice strength properties, and carried out a number of experiments together with his son. Makarov engaged A. N. Krylov, Superintendent of the Towing Tank, in the experimental data analysis. The article describes the history of, and analyzes the conclusions from, these experiments that for a long time remained the only source of data on strength properties of sea and freshwater ice.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2007
Paper presents outcomes of statistical analyze of published data about geometry and dimensions of... more Paper presents outcomes of statistical analyze of published data about geometry and dimensions of the grounded hummocks (GHs) in the Okhotskoe Sea and piled ice (PI) in the Bohai Sea, and also present the results of evaluation of forces applied on them by currents, wind, heaving, and drift ice. Base on the carried out evaluations and comparison of loads it is stated that grounded hummock is able to move and plough seabed not only due to loads from drift ice, but also due to loads from the wind waves which uplifts and swings GHs and PI. These effects are important for designing of pipelines and cable lines, which connect offshore constructions with coastal infrastructure.
For development of hydrocarbon deposits located in a shallow part of coastal shelf, offshore stru... more For development of hydrocarbon deposits located in a shallow part of coastal shelf, offshore structures of gravitational type are widely used. The foundations of such structures are towed to sites where they are flooded and installed directly on sea bed. During operation of offshore structures the sea bed soil around and beneath the structure foundations are exposed to external effects such as sea currents, waves and also propeller streams generated by ships approaching the structures. As a result the soil is washed out from under the structure which may cause reduction of bearing surface area and even lead to loss of stability of the structure on seabed. The model studies on soil erosion process near foundations of gravitational-type offshore platforms have been conducted at Krylov’s shallow water towing tank since 2000. This towing tank was not originally intended for such experiments, and, therefore, special experimental equipment has been developed for this purpose. These include a sandy bottom, current generation arrangements in the model test zone, instrumentation for measuring the bottom profile. Also specific model test procedures and methods for research on soil scour near the test objects have been developed and verified. The paper gives a review of these research studies at the Krylov Centre, describe the test equipment, modeling techniques and test data scaling procedures as well as the experience learned from the experiments. The paper gives some results of research studies of soil erosion near the foundations of offshore structures as a result of influence from sea currents and waves with coincident directions, and also as a result of influence from propeller streams of moored tankers and supply vessels. The paper presents the model test results regarding the efficiency of a mobile system developed for soil erosion protection near the offshore structure intended for exploratory drilling in shallow waters of the Gulf of Ob in the Kara Sea. A review of the recent Krylov’s studies in this field of research is given.
Vessels with an azimuth propulsion system (APS), including double-acting tankers (DATs) designed ... more Vessels with an azimuth propulsion system (APS), including double-acting tankers (DATs) designed for autonomous ice navigation in astern-running mode, which makes it possible to improve their icebreaking capability and operation performance in open water by means of bow shape optimisation, are considered to be promising ship types for hydrocarbon and ore material transportation along Arctic Passage routes. This paper covers
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2011
The North Caspian Sea area and the Kashagan Fields can be considered a unique environmental scena... more The North Caspian Sea area and the Kashagan Fields can be considered a unique environmental scenario which has assumed a strategical importance during this decade owing to the development of off-shore structures. In this paper is shown the analysis on ice going capability of a small unconventional vessel (an Ice Breaking Emergency Evacuation Vessel operated by Agip KCO) operating in the Kashagan field, equipped with two pulling type thrusters. The open water performance has been investigated in the shallow water tank of Krylov Shipbuilding Research Institute. The purpose of the research in the hydrodynamic basin was to study the influence of shallow water and ultra shallow water on resistance, propeller-hull interaction and propulsion. Some bow and stern shape variants have been tested in ice model tank in order to verify the ice going capability of the vessel and to reduce ice resistance. Three campaigns of full scale trials in ice were performed in North Caspian Sea during the last years. The scope of these trials was to verify the maximum performance of the vessel and to investigate its operative limitations. Ice going capability and manoeuvrability were widely investigated for different ice thickness and flexural strength. A great deal of further analysis and measurements, not discussed in this paper, were also performed during the trials as vibration on hull, machineries and propulsor, torsional vibration and hull strain measurements (strain gauges). The overall result of the conducted study is identification of the allowable combination of ice thickness and flexural strength to achieve a minimum safety speed. Moreover, some operative recommendations are given in order to preserve the vessel from any damage (failure) and assure safety operations.
At present, there is a tendency to use the large-size active ice-going ships for oil and gas tran... more At present, there is a tendency to use the large-size active ice-going ships for oil and gas transportation from the fields located in the Far North and Far East as well as from the shelf of freezing seas. Intentions for use of large-size tankers and gas carriers as a part of arctic transportation systems are mostly based on the results of cost-effectiveness calculations. However, these calculations usually do not take into account actual conditions of ship navigation in ice. In this paper, we review some main challenges related to large-size ships manoeuverability and performance in ice as well as interaction of above ships with icebreakers. In the final section of this paper, the author gives the conclusions based on the brief review of the problems arising during navigation of large-size ships in ice.
Ледяной покров на поверхности воды отличается большим разнообразием своего строения, включая лине... more Ледяной покров на поверхности воды отличается большим разнообразием своего строения, включая линейные размеры ледяных образований. Лед с наименьшими линейными размерами (менее 2 м) называется тертым. Такой лед может образовываться как в естественных условиях при замерзании воды и при динамических процессах в ледяном покрове, так и из-за хозяйственной деятельности человека. Именно такой тертый лед в последнее время начинает создавать серьезные затруднения для породившего его судоходства в замерзающих акваториях. В статье описываются основные свойства тертого льда и рассматриваются способы борьбы с этим явлением.
Труды Крыловского государственного научного центра, Jun 6, 2023
Object and purpose of research. This paper discusses the methods for determination of propeller a... more Object and purpose of research. This paper discusses the methods for determination of propeller anti-torque in ice milling conditions. The purpose of the study was to investigate existing methods for propeller anti-torque determination, analyse their respective pros and cons and to trace out the paths of further studies towards a satisfactory description of propeller anti-torque. Materials and methods. This study relies on previous publications and experimental ice milling data from both laboratory tests and field measurements, as well as on full-scale measurement data obtained on propulsion shafts of real icebreakers and ice-going ships. Main results. Currently, there is a wide variety of methods for obtaining anti-torque data: regulatory, theoretical, model testing and full-scale measurements on ship shafting. Analysis of the regulations given in the recommendations of various class societies has shown considerable drawbacks in the calculation formulae used in them. This paper proves that the most viable method for propeller anti-torque determination is its reconstruction as per the results of full-scale measurements on shaft line. Conclusion. Current methods for determination of anti-torque do not describe this phenomenon exhaustively. The most promising solution here would be to perform full-scale trials and analyse their results.
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