Krylov State Research Centre Research Articles

Применение современных конструкций винтов регулируемого шага и особенности их проектирования

Object and purpose of research. This paper discusses controllable-pitch propellers (CPPs) of various designs. The purpose of this study was to summarize the findings of CPP studies in Russia and abroad, as well as to identify current challenges in Russian CPP design and manufacturing. Materials and methods. This paper relies on the test data obtained at Deepwater Tank and cavitation tunnels of Krylov State Research Centre. It analyses the results of computational studies for CPP hydrodynamics and strength obtained as per the latest techniques of CFD and FE analysis. Main results. The history of CPP design and manufacturing in Russia clearly shows that our country has considerable expertise in design of controllable-pitch propellers that can operate in the harshest conditions. Analysis of global shipbuilding experience has shown that CPPs not only ensure optimal operational conditions for “engine-propeller” system in the conditions of variable hydrodynamic load on the propeller, but also feature better cavitation and vibroacoustic performance because the skew of CPP blades can be moderate and high: actually, it can be significantly higher than for fixed-pitch propellers (FPPs) because FPP blades in reversal conditions do not have to operate their trailing edges forward, which reduces the risk of high stresses and damage of skewed blades in crash-stop scenarios. Analysis of CPP test results obtained at Krylov State Research Centre hydrodynamic and cavitation laboratories, as well as the findings of foreign computational studies enabled justified assessment of CPP advantages. It also highlighted the challenges that require dedicated studies and special consideration in design of skewed CPPs, so as to improve their performance in partialcavitation and cavitation-inception conditions. Conclusion. Currently, Russia has all the pre-requisites for increased production and wide application of modern CPPs. Controllable blades with moderate and high skew have a certain potential in terms of improving their vibroacoustic performance as compared to FPPs. However, to design these blades correctly, with consideration of their possible operational risks, it is necessary to use state-of-the art computational and experimental methods, as well as to rely on the experience of full-scale trials.

Влияние неравномерности потока за корпусом модели одновального судна на гидродинамические и кавитационные характеристики отдельной лопасти в составе гребного винта

Object and purpose of research. This paper investigates wake non-uniformity effect of single-shafter model upon local and integral hydrodynamic and cavitation parameters of separate blade of its propeller. The study was performed on propeller models KP505 and containership models KCS. Materials and methods. Local and integral hydrodynamic parameters of propeller and container ship were obtained as per CFD methods. Viscous flow parameters are obtained through finite volume (FVM) solution of unsteady Reynolds equations (URANS) closed by biparametric semi-empirical turbulence model. Main results. The paper demonstrates that local and integral parameters of separate blade in “hull-propeller” system are considerably different from those determined in the uniform wake at the speeds obtained for the nominal wake field in behindhull conditions. Conclusion. Krylov State Research Centre experience of numerical calculations shows that 1) in many aspects of marine hydrodynamics numerical techniques are more informative than model tests and 2) in a number of cases, conventional propeller design approach based on the nominal wake field data (calculated or experimental) might lead to somewhat incorrect technical solutions.

Обоснование безопасности ядерной энергетической установки модернизированного плавучего энергоблока при внешних воздействиях

Object and purpose of research. This paper discusses an upgraded floating nuclear power plant (NPP) to justify its nuclear and radiation safety under external effects. Materials and methods. The authors follow the methods of system analysis. Main results. Following the requirements of Russian Maritime Register of Shipping (RS) and Federal Service for Ecological, Technological and Nuclear Supervision (Rostekhnadzor) to the safety of upgraded floating NPP reactors, this study explored the incidents related to external loads on floating NPPs, drawing up the list of initiating events and their respective probabilities of occurrence, as well as predicting final states of floating NPPs and their reactors as per the data on hull and equipment damage, with the assessment of corresponding radiation hazards. Conclusion. Nuclear and radiation safety justification of upgraded floating NPP was justified as per the regulations in force and Krylov State Research Centre procedures. If an icebreaker rams the reactor compartment of upgraded floating NPPs at the speed exceeding 6.5 knots, primary coolant circuit might leak, thus triggering a radioactive discharge into sea water that might create a contaminated spot up to 325 m in size. The worst-case scenario in terms of radiation hazard is a hypothetical (unlikely) off-design case of a medium-range airliner crash onto the upgraded floating NPP destroying all reactor protection barriers, so all humans within the range of 3.8 km might receive dangerous radiation doses and all population within the range of up to 20 km will have to be evacuated.

The choice of ice conditions for ice model tests to support the industrial development of the Оb’ Вay

The Ob’ Bay has long been the main center for the development of the Russian oil industry in the Arctic region. The rapid growth of shipping and the active creation of port infrastructure in this area are an integral part of the strategy for the development of the Russian Arctic. The main feature of the hydrometeorological regime of the Ob’ Bay is the annual presence of ice for a long time. Determining the ice performance of icebreakers, tugboats and heavy-tonnage vessels designed for the region, as well as ice loads on marine platforms and hydraulic structures, is a most important task in the creation thereof.The paper describes research carried out in the ice model tank of the Krylov State Research Centre over the past twenty years. The research supports the design and operation of new technical facilities intended for the industrial development of the Ob’ Bay. In the completed study, two main areas of research can be distinguished, namely the interaction of ships and engineering structures with ice formations in the Ob’ Bay. The paper emphasizes a significant dependence of the possibility of conducting ice tests and proper analysis of findings on the quality of the initial data, primarily hydrology and ice parameters.The results of ice model tests analysis, especially the ice impact on offshore and hydraulic structures for the Ob’ Bay, show the need to change approaches to determining theoretical ice loads and, as a result, to expand ice model testing programs. The simulation of the worst-case scenario, when all ice parameters are determined for a given probability and are not consistent with each other, leads to a significant overestimation of ice loads and the physical modeling of unrealistic combinations of ice conditions.Each ice impact scenario should contain the maximum value of only one main ice parameter corresponding to the probability. The main ice parameters include the thickness, the flexural strength or compression strength and the speed of ice drift. In this case, ice parameters should be selected in accordance with the chosen main one in the modeling scenario. It should not be the result of the same maximum value calculation for the given observation period as for the main ice parameter.

Новое в международной политике снижения эмиссии парниковых газов судами и необходимые мероприятия в морском секторе. Часть 2. Анализ эффективности энергосберегающих мероприятий, применяемых для снижения эмиссии парниковых газов

Object and purpose of research. This work was intended to analyse technical solutions that could contribute to power efficiency of in-service fleet in the light of new IMO policy aimed at the mitigation of greenhouse gas emissions from international marine traffic. This is the second publication in the series of articles discussing various aspects of this new IMO policy, as well as shipbuilding challenges that have to be faced in order to meet relevant requirements. Subject matter and methods. This work is an analytical review of available publications on above-mentioned topic. It relies on Krylov State Research Centre experience in the optimization of ship fuel consumption, as well as on the results of IMO correspondence group discussions on power efficiency with participation of Krylov State Research Centre and RS experts. Main results. This paper discusses the efficiency of measures taken all over the world to improve fuel efficiency of ships taking into account the experience of their implementation at the early stage of IMO regulations for greenhouse gas emissions. It is shown that each of these measures might reduce the emissions from global marine traffic by ~5%, which is not enough to achieve the final goal, i.e. 70% reduction in emissions by the year 2050 as compared to 2008. Besides, these measures cannot be implemented in full due to certain limitations. For example, in Russia the main obstacle is that practically all its ships must have an ice class, so they cannot use a whole number of various power-saving devices because of their vulnerability to ice impact. Still, provided that power-saving devices are robust enough, they might prove to be a useful (and sometimes the only possible) way to reduce gas emissions of a ship after several years of service. It is incorporated to the system rating the ships in terms of their emission score assigned as per the new provisions of MARPOL Annex VI adopted in 2021, see Part I of this series. Conclusion. Analysis of power saving measures (along with assessment of their efficiency and applicability to ice-class ships) enables a justified selection of power efficiency enhancement tools for a ship in case its annual Carbon Intensity Indicator (CII) goes beyond IMO thresholds that gradually become more and more stringent in accordance with new provisions of MARPOL Annex VI. Still, these measures will not be sufficient to achieve target levels of emission reduction prescribed by IMO. These levels could only be achieved through radical changes in marine power systems, like the transition to alternative fuels with low or zero carbon footprint. This matter will be discussed in the third article of this series.

Сравнение методик пересчета результатов буксировочных испытаний моделей подводных лодок на натурные условия

Object and purpose of research. This paper discusses towing test data extrapolation for submarines (in submerged conditions) as per two different procedures to compare the results. Subject matter and methods. The study relied on model test data for submarines and submersibles available with Krylov State Research Centre Deepwater Test Tank and performed as per Procedure [1], and on towing test data extrapolation results obtained as per References [2, 4]. Test results are extrapolated to the full-scale as per two procedures, with subsequent comparison of towing resistance values for model hull. Main results. The paper demonstrates that the deviation between the two procedures is insignificant and commensurable with acceptable measurement error, with discussion on possible reasons for this deviation. Conclusion. Despite minor deviations in towing test procedures described in [1, 4], full-scale extrapolations obtained as per References [2, 4] coincide, which indirectly confirms reliability of the results and correctness of the assumptions.

Совершенствование геометрических характеристик водометного движителя насосного типа для судов и кораблей

Object and purpose of research. This paper discusses pump jet propulsor. The purpose of the study was to improve its elements through experimental and theoretical investigation of its hydrodynamics and cavitation properties. This work is a part of the project intended to develop an application for a useful model. Subject matter and methods. To achieve its purposes, the work follows both theoretical and experimental research methods of ship theory. Numerical simulation of pump jet operation was performed in Siemens StarCCM+ commercial software package, and also as per in-house Krylov State Research Centre calculation methods for unviscous and viscous flows. Main results. The study suggests rotor and stator blade profiles that improve hydrodynamic and cavitation performance of basic pump jet versions. It also suggests updated shapes for pump jet stator and aft fairing. The study has shown that these improvements will increase the efficiency of pump jets by 3–5% as compared to the basic version, and will also eliminate several types of cavitation. Conclusion. The study was meant to improve pump jet elements so as to eliminate the flaws of the basic pump jet version. The results will be helpful in further pump jet design and development of the application for useful model.

EXPERIMENTAL STUDYING A POSSIBILITY OF CLOSE-COUPLED TOWING OF LARGE-SIZED VESSELS BY ICEBREAKER

The experimental studies in the ice model tank of the Krylov State Research Centre are described in the paper. This study aimed at researching a possibility of close-coupled towing of large-sized vessels by icebreaker. The displacement of considered commercial vessels is several times greater than the icebreaker displacement. Due to the fact that an amount of cargo transported along the Northern Sea Route is growing every year and new terminals are being constructed for the export of raw materials extracted in the Arctic, it has been shown in the paper that new transport vessels with high cargo capacity should be designed and built for the efficient operation of terminal. It has also been shown that the organization of independent year-round operation of such vessels in the Arctic region is extremely difficult, therefore, even at the stage of their design it’s important to consider the possibility of their escorting by existing icebreakers. The feasibility of close-coupled towing in the escorting of large-sized vessels with low ice class by icebreakers in the Arctic waters has been studied in the paper. The models of the greatest existing nuclear-powered icebreaker and conditional bulk carrier are used as an object of the ice model tests. The study of the close-coupled towing features in the continuous flat ice conditions is carried out at straightforward movement and gyration, as well as for the case of an emergency stop of the icebreaker. During ice model tests the ice forces acting on the hull of the model are measured, as well as the load on a towing notch with rubber fenders in the stern of icebreaker and the tension in the wire rope. The comparison of the wire rope tension with its breaking force is taken as a criterion to assess the possibility of the close-coupled towing operation. The results can be used as the basis for choosing the hull concept of the future large-sized vessels, its ice class and main dimensions and in strategic simulations of Arctic marine transport systems.

Возможности обнаружения излучения морских радиолокаторов с низкой вероятностью перехвата их излучения

Object and purpose of research. This paper presents analytical estimates for emission characteristics of foreign low-probability-of-intercept (LPI) radars. It also gives a quantitative assessment to the possibility of detecting the operation of these radars by standard naval EW tools. Subject matter and methods. This paper reviews the publications of leading foreign experts in order to analyse performance parameters of existing foreign LPI radars and ESM tools. Emission characteristics of these “stealthy” radars in marine conditions were calculated by means of the four-beam model of electromagnetic wave scattering over an underlying surface developed by Krylov State Research Centre researchers. Main results. The study yielded a quantitative estimate for the possibility to detect the emission of radar homing head for RBS-15 anti-ship missile by standard naval tools of radioelectronic surveillance. Conclusion. The study has shown that ESM tools currently available with foreign navies cannot reliably detect the operation of LPI radars.

Разработка формы обводов носовой оконечности судов типа «река – море» повышенной мореходности

Object and purpose of research. The purpose of this study was to develop a bow shape with increased block coefficient for river-sea vessels so as to improve their seakeeping at high sea states. Subject matter and methods. This paper qualitatively analyses the physics of wave effects upon a moving ship, ranking the contribution of specific factors and solving the task of improving the seakeeping performance through optimization of hull lines. Main results. The study highlighted the peculiarities of intense wave effects upon ship bow and suggested the hull lines offering a good seakeeping performance for a hull with high block coefficient. Seakeeping tests of initial and modified hull models at Krylov State Research Centre Seakeeping Basin have confirmed the theoretical results. Conclusion. The study outlined one of the ways to improve seakeeping performance of river-sea ships with increased block coefficient at high sea states.

Применение транцевого интерцептора для снижения буксировочного сопротивления быстроходных водоизмещающих судов

Object and purpose of research. This paper discusses three models of fast monohull displacement ships of various purpose and one model of fast passenger catamaran. The purpose of the study was to experimentally verify the efficiency of transom interceptor in towing resistance reduction. Subject matter and methods. The study was based on the test results available with Krylov State Research Centre Deepwater Towing Tank. Main results. This study was performed on four models and showed how their towing resistance depended on interceptor advance and static trim angle. Conclusion. The tests have confirmed the efficiency of transom interceptor in towing resistance reduction of fast displacement monohulls and catamarans with operational speeds corresponding to Froude numbers 0,4–0,6. Transom interceptor reduces towing resistance by 4,5–6,5 %.

Модификация корпусов контейнеровозов при снижении скорости хода с целью сокращения объема парниковых газов

Object and purpose of research. The objects of study are two containerships of 8100 and 8500 TEU capacities operated by Danaos Shipping Co. Ltd, Greece. The purpose is to experimentally verify alteration of bow shapes in the containerships designed to reduce hydrodynamic resistance at a lower operation speed, as well as to examine the impact of these alterations on energy efficiency design index (EEDI). Materials and methods. Experimental data from model tests were obtained in a deep-water test tank of Krylov State Research Centre. Main results. Based on the research studies the shaft power was determined versus the containership speed for the hulls with the original and modified bow shapes. Conclusion. Switchover to lower speeds combined with optimization and modernization of bow shapes will bring a possible reduction of shaft power and, accordingly, less fuel consumption and carbon dioxide emissions by about 40 %.

Особенности проектирования многоцелевого судна обеспечения

Object and purpose of research. This paper discusses a multi-role support vessel working as a supply ship, a tug and an anchor handler. The purpose of the study was to obtain an optimal design that could be of interest for potential customers, like oil and gas companies and offshore fleet operators. Materials and methods. The paper describes design peculiarities of multi-role support vessels, methodological approach to justification of main design solutions and principal results of these justifications in terms of selecting main dimensions, lines and structures for hull, architecture and arrangement of main equipment, propulsion system components, etc. It also describes model tests undertaken as part of this project in order to obtain high propulsion, seakeeping, maneuverability and ice performance parameters. The study outlines technical solutions adopted to widen the ship’s functionality, i.e. modular payloads and detachable equipment. Main results. As part of Russian State Program Development of offshore shipbuilding and technology for the years 2013-2030, Krylov State Research Centre completed a design of multi-role support vessel. This work was performed in two stages. The first stage was intended to develop the technical proposal (further transformed into the Technical Assignment for Detailed Design) and to justify principal design solutions with participation of possible customers. The second stage was dedicated to model tests, update of design solutions and detailed design development of multi-purpose support vessel in the scope sufficient to obtain the approval from Russian Maritime Register of Shipping. Conclusion. This multi-role support vessel is intended as a baseline variant for further modifications to the needs of the customers (oil and gas companies and offshore operators) which will enable its large-batch construction and eventually reduce lead ship construction costs, as well as make this ship a good replacement for the fleet of foreign service companies currently contracted for support of oil and gas facilities in Russian offshore areas.

Постановка задачи о техногенном подводном шуме как факторе государственной морской промышленной и транспортной политики

Object and purpose of research. The study addresses the technogenic underwater noise issues with a view to environmental and competitive challenges, as well as the Navy interests. Materials and methods. The issues studied in this investigation are relatively new for the Russian shipbuilding, shipping and marine activities, and the first step to systematic studies should be formulation of a technogenic noise problem as a physical phenomenon, which have to be considered in the state marine and transportation policy. The paper uses results of design studies performed in Krylov State research Centre, as well as information from mass media. The main sources of the technogenic underwater noise are coastal industries and port infrastructure, marine oil & gas structures, transport and ice-breaking vessels. Main results. It is concluded that a special-purpose integrated target program should be formulated and performed, whose result would be systematization of research and design projects aimed at the analysis, regulation and standardization of technogenic underwater noise parameters of various marine technologies. Conclusion. Technogenic underwater noise is directly related to the safety of marine ecosystems. In addition, it is a factor of commercial and large-scale economic competition in the international community. In future the technogenic underwater noise of marine facilities may become an instrument of competition for the opportunity and right to exploit Russian oil & gas deposits, as well as to use Russian Arctic routes. Against the backdrop of these two factors, the Navy interests are obviously to raise the efficiency of fixed and mobile sonar systems in the environment of high technogenic noise produced by civil marine activities.

О создании испытательного оборудования для проверки прочности и герметичности подводных технических средств исследования предельных глубин Мирового океана

Object and purpose of research. The object of study is an upgradation of the unique land-based pressure tank DK-600 of Krylov State Research Centre designed to test underwater technologies for strength and leak under external pressures from 90 to 100 MPа. The purpose is to support acceptance tests of pressure hulls and equipment for advanced manned autonomous submersibles of extreme diving depths to 11 500 m. In accordance with the world practices in development of deepwater submersibles it is required to achieve pressures of about 135–140 МPа. Materials and methods. С использованием современных численных методов Preliminary calculations of strength are performed using up-to-date numerical methods (FE analysis), the choice of structural material is validated as weldable steel forgings, strength category 750–800 МPа. Main results. The procedure and setup are suggested (Capsule DК-600) to provide the said tests by placing a special splittype intermediate Capsule capable to generate 135–140 МPа on the test object inside the pressure tank DК-600 with pressures of 85–90 МPа. The Capsule can accommodate a test object of up to 2400 mm (transverse dimension). Conclusion. Results of an exploratory design study are presented to upgrade the unique land-based pressure tank, which would put the KSRC hydrobaric tank at the world forefront in terms of proof pressures for testing the strength and reliability of extremely deep diving submersibles measuring within 2400 mm (transverse dimension).

Физическое моделирование ледовой нагрузки на протяженные гидротехнические сооружения. Откосные сооружения с наклонной гранью

he authors present the results of experimental studies of ice interaction with models of extended hydraulic constructions with a sloping wall carried out in the laboratory “Ice tank” of Krylov State Research Centre. The researchers analyze the possibilities of applying the method of physical modeling to investigate the processes of ice-structure interaction using ice tank. The results make it possible to recommend the method of physical modeling as one of the main approaches for studying the interaction of hydro-technical installations with ice. The data of the model experiment can be used to construct mathematical models of ice breaking mechanism, as well as to clarify the requirements of ragulatory documents.

Физическое моделирование ледовой нагрузки на протяженные гидротехнические сооружения. Сооружения с вертикальной стенкой

The authors present the results of studies carried out in the laboratory “Ice tank” of the Federal State Unitary Enterprise “Krylov State Research Centre”, related to the study of the ice effect on extended hydraulic constructions with a vertical wall. They analyze the possibilities of applying the method of physical modeling to investigate the processes of ice-construction interaction in ice tank. The results make it possible to recommend the method of physical modeling as one of the main approaches for studying the interaction specifics of hydraulic constructions with ice. The data of the model experiment can help to construct mathematical models of ongoing processes, as well as to clarify the requirements of regulatory documents.

Опыт специалистов ФГУП «Крыловский государственный научный центр» в разработке международных стандартов по арктическим операциям

Опыт специалистов ФГУП «Крыловский государственный научный центр» в разработке международных стандартов по арктическим операциям

Результаты исследований высокотемпературного окисления и солевой коррозии материалов лопаток газовых турбин в Крыловском государственном научном центре за 2009–2017 гг.

Результаты исследований высокотемпературного окисления и солевой коррозии материалов лопаток газовых турбин в Крыловском государственном научном центре за 2009–2017 гг.

Numerical Simulation on the Response of Moored Semi-submersible Under Ice Load

This study simulated ice load and the motion response of a moored semi-submersible rig in pack-ice conditions using a finite element method. Ice flows of random size and shape were modeled, and interactions for ice-sea, ice-structure, ice-ice were simulated using a simplified method. Parameters for the simplified method such as drag force coefficient and the pressure-penetration relation were obtained based on the result of detailed analysis using the coupled Eulerian-Lagrangian method. The mooring lines were modeled by spring elements based on their stiffness. As a result of the simulation over 1,400 seconds, the force and motion response of the rig were obtained and validated using discrete elements and compared with the results found by the Krylov State Research Centre.