Object and purpose of research. The object of research is the results of self-propelled ship tests in bollard-pull conditions. The purpose is to analyse the hydrodynamic sources giving rise to differences between propeller thrust coefficient in open-water and behind-hull conditions. Materials and methods. Analysis based on the ideal propeller theory shows that the velocity ΔV of inflow on propeller operating behind ship hull in bollard-pull conditions caused by a system of sinks, ensuring flow attachment to hull surface, has a finite value and is actually the effective wake. The wake velocity for an open-water propeller is equal to the behind hull velocity. The open-water propeller thrust coefficient at advance ratio (formula) is due to the opposed jet of its reversal. It is shown that the thrust coefficient deviations at self-propelled tests in open-water has to do with the specifics of propeller thrust variations in the operating area adjacent to bollard-pull conditions. Boundaries of the operating area where the opposed jet affects the propeller curve at self-propelled tests are defined. Practical conclusions and recommendations are given following from the obtained data. Main results. The source of discrepancies between self-propelled test results for open-water propeller in bollard pull conditions and close operating area has been found. Recommendations are given on updating the test procedures for propeller and self-propelled model tests Conclusion. The paper is expected to be useful for understanding the ambiguity of self-propelled test results.
Object and purpose of research. Ensuring the environmental safety of the Russian shelf waters requires constant development of methods and technologies related to monitoring, quantitative assessment and reduction of the harmful effects of pollution sources. During the industrial and transport development of the water area of the Northern Sea Route (NSR), an intensive increase of underwater noise is observed. Obtaining an adequate picture of the impact of underwater noise sources on representatives of the marine ecosystem creates a need to involve more and more modern and accurate measurement techniques. The article describes the draft methods for measuring the self-noise of carrier vessel and underwater noise of a selected marine equipment object, which were developed in order to identify the degree of impact of noise pollution over to the ecological situation in the considered water area. Materials and methods. An hydro acoustic signals contains the self-noise of measuring vessel, the noise of an object of marine industrial equipment (OMIE) and the noise of the water area where acoustic tests are going on. This acoustic signals are perceived by combined sound pressure and sound pressure gradient transducers, as well as by an omnidirectional hydrophone, located in the receiving system , and are converted into electrical signals transmitted via the main cable to the onboard post of the measuring vessel. Signals are sent to the hydro acoustic guidance beacon via the same cable to control the operation of this beacon. The information processing procedure is set out in the SIGAK VP Operation Manual (MGFK.411711.327 RE). The main purpose of the primary processing is to obtain 1/3-octave spectra and levels of underwater noise generated by the tested carrier vessel or OMIE, as well as the noise of the water area where these tests are carried out. In accordance with the accepted classification, the method of measuring sound pressure levels using a hydro acoustic complex according to this technique refers to indirect methods with single observations. Main results. In the course of the work, preliminary methods for measuring the self-noise of measuring vessel and underwater noise of a selected marine industrial object were developed. To measure the levels of underwater noise in 1/3-octave frequency bands in the range from 5 Hz to 10,000 Hz, within the framework of the draft methods, it is planned to use a stationary measuring hydro acoustic complex with a vector receiver from the GIK-VP. The signal processing algorithms are based on the spatial-frequency filtering of the acoustic power flux density components, which makes it possible to protect the measurement information from interference signals whose propagation direction does not coincide with the direction to the measured object. Conclusion. The results obtained in the form of implemented preliminary methods are important for the creation of regulatory documentation for the regulation of technogenic underwater noise in the waters of the Russian jurisdiction, reducing the intensity of noise pollution and the detrimental impact over to marine ecosystems. The article targeting the support at the stages of acoustical marine technical design, construction and operation of offshore industrial facilities and ships of various types, acoustic monitoring of the compliance of marine equipment with international standards for underwater noise.
Object and purpose of research. This paper discusses existing approaches to ship stability assessment in terms of steady-turning heel so as to justify the calculation procedure for its initial metacentric height. Subject matter and methods. The study relies on available literature discussing steady-turning heel calculation. It analyses current calculation expressions estimating initial transverse stability in terms of steady-turning heel angle. It has been established that so far this estimate has not been substantiated by any reliable procedure, and the literature on this topic contains a number of inaccuracies and even errors. Main results. The study presents analytical calculation expressions for initial transverse metacentric height of ship in terms of its steady-turning heel. It confirms that calculations have to be performed with a more accurate value for Z-coordinate of hydrodynamic force application point. Conclusion. The procedure developed under this study enables fast monitoring of ship stability and Z-coordinate of its CG in terms of steady-turning heel angle.
Object and purpose of research. The archival results of the study of the dependence of the concentration of saturated turbine oil vapors in the air of the ship's room on temperature in the range from 15 °С to 110 °С are presented. Subject matter and methods. The method of measuring the mass loss of an equilibrium cell containing the test sample in an air stream with a known temperature and flow rate providing saturation of the air with turbine oil vapors is used. Main results. Experimental data are theoretically justified by a dependency that provides reliable interpolation and extrapolation. Conclusion. The data obtained can be used in calculating the concentration of turbine oil in shipboard and other rooms, as well as for planning similar studies of other turbine oils and other liquids with a low saturated vapor pressure. The data can also be useful in the development of test equipment to test the effectiveness of air filters.
Object and purpose of research. Methods of biological aerosol research and technical means for their implementation. Subject matter and methods. Analysis of technical documentation for used and prospective equipment. Main results. The main parameters of foreign and domestic bioaerosol analysis devices based on the flow-optical method. Conclusion. Based on the results obtained, it can be concluded that the development of methods for the analysis of bioaerosol particles in the near future will be determined by the development of new radiation sources for the effective excitation of particle fluorescence, as well as the creation of new techniques to determine the independent quantitative and qualitative parameters of the studied particles. A typical example is the creation of a highly efficient system that combines several approaches, including destructive laser spectroscopy, which was not previously used in the flow-optical method.
Object and purpose of research. This paper discusses organization of the measures intended to enhance EMC and electromagnetic robustness of ships in accordance with regulations. The purpose is to obtain an optimal procedure for practical implementation of KSRC-developed methodology intended to ensure electromagnetic compatibility of equipment aboard marine objects and their robustness against electromagnetic attacks. Subject matter and methods. The methodology mentioned above is centered around scientific and engineering support of the object at all stages of its life cycle. It requires participation of numerous organizations and enterprises in charge of specifications development, equipment design, testing (acceptance, etc.), as well as operation of the object. Therefore, development of an optimal scenario for participation of all these organizations and enterprises at various life cycle stages of marine object becomes a relevant task. Main results. This paper discusses the whole participation scenario for all organizations and enterprises over the entire life cycle of marine objects, including the most sophisticated ones, i.e. ships, in terms of practical implementation for KSRCdeveloped methodology of EMC and electromagnetic robustness enhancement. It demonstrates that this task requires special test facilities, with enumeration of their respective key capabilities. It also describes the peculiarities of industrial degaussing/deperming/EMC test center established at KSRC in accordance with the requirements set out in this paper. Conclusion. Practical implementation of EMC and electromagnetic robustness enhancement methodology for marine objects is centered around optimal combinations of protective tools and measures (taken by both equipment manufacturers and ship designers coordinated by a dedicated agency in charge of scientific and engineering support) and requires optimal work organization, as well as optimal interaction between all stakeholders over the entire life cycle of marine object. Practical implementation scenario for this methodology relies on industrial test facilities and makes it possible to achieve EMC and electromagnetic robustness of various objects, including ships, in an optimal manner.
Object and purpose of research. This paper discusses induced noise radiation into water from spherical uniform bodies and spherical shells to estimate the acceptability of commonly used simplified approach to prediction of low-frequency acoustic signatures for marine objects. Materials and methods.The calculations were performed as per analytical expressions and numerical simulation techniques (FEM). Main results. The study has shown that increasing the density of radiating body and increasing mechanical resistance of shell at the location of exciting force reduces noise radiation. Resonant noise radiation typically occurs due to structural non-uniformities of marine objects, like local masses needed to ensure zero buoyancy, e.g. equipment or ballast. These nonuniformities create reactive forces that reach their peak values at resonant frequencies of the hull. Conclusion. The study concludes that reliable computational estimate of low-frequency acoustic signatures must take into account both mechanical resistance and non-uniform distribution of masses along hull, which can be done in numerical simulation packages.
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.
Object and purpose of research. This paper discusses thick stiffened plates for ship structures. The purpose is to determine the efficiency of vibration dampers (resonant anti-vibration straps with two reinforced vibration damping coatings installed on them). Subject matter and methods. Measurements of plate vibration spectra with and without vibration dampers stuck to the structure by means of a PVA-based self-adhesive tape. Main results. The study has established that efficient vibration damping of thick-plated structures is possible in principle. Conclusion. The study showed that vibration levels of thick-plated structure in a wide frequency band could be reduced by means of the dampers with the total weight considerably lower than the weight of the target structure itself.
Object and purpose of research. The object of scientific work is the methods of air purification of surface ships and Navy vessels from toxic substances, radioactive dust, and biological damaging agents. Materials and methods. Based on the analysis of technical documentation for the used and promising equipment of chemical ventilation. Main results. The optimal composition and main tactical and technical characteristics of a promising installation of chemical ventilation. Conclusion. An acceptable level of automation, controllability and maintainability for the Navy was obtained when using the aggregated anti-chemical ventilation unit.
Object and purpose of research. Investigation of the current and justification of the prospective technical level of emergency means of normalization and air purification of hermetic inhabited objects after the elimination of fires in them. Materials and methods. Analysis of technical documentation for used and prospective equipment. Main results. The main tactical and technical characteristics of a promising block-modular air purification system for sealed inhabited objects, mainly submarines, special structures and civil defense facilities equipped with various fire extinguishing systems, except for systems based on refrigerants. Conclusion. The data obtained can be used in the development of tactical and technical requirements for promising samples of special equipment, technical requirements for components and materials, including special testing equipment, gas control devices and non-metallic materials used in the manufacture of air purification products (sorbent, catalyst, filter paper).
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.
Object and purpose of research. This paper discusses propeller model. The purpose of the study was to understand the effect of hydrodynamic load on the propeller upon its high-frequency non-cavitation noise radiation (edge noise). Materials and methods. Comparative analysis of Russian and foreign methods for assignment of edge noise norms. Edge noise measurements for a series of propeller models with different hydrodynamic load. Main results. The study yielded certain theoretical hints suggesting the effect of hydrodynamic load (as non-dimensional thrust coefficient Kt) upon edge noise. Experimental studies performed in this work have confirmed that this approach is valid for propeller models. Conclusion. Model tests have confirmed that edge noise depends on hydrodynamic load on the propeller (i.e. its thrust coefficient), as well as indicated tentative Kt range optimal for propeller noise mitigation.
Object and purpose of research. The object of investigation is specific temperatures at the water/air interface (skin layer of water). The purpose is to study the interrelation of dynamics in humidity variations of surface atmospheric layer and particulars of the media interface. Subject matter and methods. Infrared thermal imagers are employed with monitoring of the parameters of atmospheric layer adjacent to ocean surface using a multi-channel thermal hygrometer and contact temperature sensors placed in water and near-water air layer. Laboratory rigs of different scales simulating various levels of external factors and an open water basin were used. Main results. Consistent analysis is done regarding phase-wise measurement of skin water layer characteristics, specific structure of temperature field in IR band of spectrum under laboratory and large-scale conditions, variations of humidity content at different state of skin water layer in the process of interaction between two media. Measurements of the radiation fog of different scales are taken, which possibly forms the false and real horizons being one of the interferences for transmission of IR radiation to recording channels. Parameters and specific manifestation of this interference are measured. Conclusion. Based on the analysis and experiments it is confirmed that there are abnormal localizations of humidity content of different scales, which produce radiation temperature variations.
Object and purpose of research. The control of the operating modes of the propulsion electric motor (PEM) is carried out by semiconductor frequency converters, the use of which significantly worsens the quality of electricity on the common buses of the Marine Power Systems. The main reasons are a decrease in the power factor and the appearance of higher harmonics in the consumed current. As a result of this, the reliability of consumers' operation decreases, and power losses increase. Therefore, reducing these negative consequences is an urgent task. Materials and methods. Methods of theoretical electrical engineering, power theory were used. Main results. The method of operation of the reactive power control device for ensuring the quality of electricity, increasing the power factor and filtering higher harmonics in Marine Power Systems was considered and proposed. Conclusion. To ensure the quality of electrical energy of the reactive power compensator, it is necessary to use modern pulse-modulation control algorithms with direct microprocessor control.
Object and purpose of research. The object of work is an autonomous offshore power plant designed to provide energy to the underwater docking station. The aim is to develop the basics of the methodology for calculating the electric generator of an autonomous offshore power plant, placed in a capsule with a conical nozzle – a diffuser. Materials and methods. The study was conducted on the basis of analytical methods for calculating electromechanical systems designed for energy supply of resident underwater robots and robotic complexes. Main results. The basics of the methodology for calculating the basic parameters of a synchronous generator of ring structure with magnetoelectric excitation, which converts the energy of the sea current into electrical energy transmitted to the underwater dock station for charging batteries, have been developed. The developed system of power supply of the underwater docking station is protected by a patent of the Russian Federation. Conclusion. The results of the development and research expand the possibilities of choosing the optimal option for the energy supply system of underwater docking stations and contribute to the acceleration of the process of their implementation in practice.
Object and purpose of research. This paper discusses neutral grounding switchboard of electric power system aboard Arktika icebreaker and estimates fault current for given neutral resistance. Materials and methods. The paper relies on the technical specifications of neutral grounding switchboard and follows common methods of electric engineering. Main results. Fault current estimates for neutral grounding switchboard of TPS-36-2M2 synchronous turbogenset. Design of the switchboard. Conclusion. Electric power system aboard Arktika icebreaker has neutral resistance rating of 600 Ohm, which corresponds to High-Resistance Grounding class. Neutral grounding switchboard discussed in this paper has been in operation since 2020.
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.
Object and purpose of research. Radar signatures of floating off-board decoys used by foreign navies for eluding anti-ship missiles of at sea are estimated. Materials and methods. Analysis of existing floating radar decoys are based on reviews of leading foreign experts. Signatures of these decoys at sea were calculated using a four-beam model of electromagnetic wave scattering on the underlying surface developed at KSRC. Main results. Quantitative assessments of floating decoy detection ranges by typical anti-ship missile radar seekers are made. Conclusion. The investigations showed that flying radar balloons are more effective in seduction of anti-ship missiles.
Object and purpose of research. The object is development of domestic shipbuilding to meet the needs of fishing industry in the context of incentive measures offered by the state. The purpose is to identify potential risks during implementation of state programs and the ways to resolve problems. Materials and methods. Materials are laws and regulations setting the investment program legal foundation for renewal of fishing fleet. The method is analysis of laws regulating the fishing fleet renovation. Also, the paper takes the benefit of expert assessments and opinions expressed by industry pundits. Main results. Main factors hindering successful implementation of state support measures for fishing fleet shipbuilding are identified the ways of their abatement are defined. E.g., the unfavorable factors include the lack of up-to-date design practice able to meet customer requirements, low level of industry localization, which, ultimately, affects interests of customers, shipyards and the Russian Federation budget. Conclusion. Management and economic measures being already implemented as well as suggested in future are discussed to reveal the problems in state support activities for construction of fishing vessels in an effort to protect participants of investment programs for stimulation of building the fishing vessels and crab boats.
