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This paper presents an analysis of the acceleration of a fast boat using a simulation model. Mathematical equations of ship motion dynamics with two types of propeller capabilities are developed using MATLAB and Simulink as simulation tools. The equations are extended to include the acting thrust, resistance, propeller’s performance curves, and the PID governor curve for the acceleration manoeuvre. The application models the dynamic differential equations representing the vessel dynamics in one degree of freedom. MATLAB code was used to develop the ship acceleration as a multibody system. Modules of hydrodynamic forces, resistance, moments, and propeller performances were implemented to simulate the ship manoeuvring process. A comparison of the results for the boat’s propulsion performance with two different propellers and the characteristics of the PID governor, which controls the fuel dose in the gas turbines, was carried out. We present a summary including a comparative analysis of the results for the boat dynamics with and without the PID governor. The results obtained here confirm significant discrepancies between the results of numerical simulations with and without the PID governor.

In the process of designing a marine propeller, hydroelasticity effects are neglected in most cases, due to the negligible influence of the blade’s deformation on its hydrodynamic characteristics. However, there are cases where the impact of hydroelasticity is crucial, for example in the case of high skew-back propellers or heavy-loaded composite propellers. Furthermore, the importance of composite propellers is growing due to their wide range of application, for instance in naval ships and unmanned vehicles. Although structural models and two-way fluid-structure interactions are implemented in most commercial CFD solvers, their relevance to the design process is severely limited due to the high computational cost for a single iteration. An effective solution would therefore be to implement a two-way fluid-structure interaction model in the lifting surface software, which is commonly accepted as a design tool due to its relatively low computational time and its applicability to multi-criteria optimisation. This paper presents the results of hydrodynamic analyses of an elastic propeller carried out using in-house software based on the lifting surface flow model, and extended with the FEM model for the blade structure. The results are compared with experimental measurements and computational analyses with the commercial RANS solver STAR-CCM+.

There has been a rapidly growing interest in the use of composite and polymer materials for the construction of marine propellers for over 20 years. The main advantages of these materials are a reduction in the weight of the propeller, increased efficiency due to the hydroelasticity effect, a reduction of the hydroacoustic signature, and a cost reduction for serial production. This paper presents an overview of diagnostic methods that can be applied at the design level and during the operation of marine propellers made of polymeric materials. Non-invasive contact and non-contact-based diagnostic techniques for evaluating the technical state of the propeller are reviewed, and the advantages and disadvantages of qualitative and quantitative methods are identified. Operational diagnostic procedures for propellers are areessential for the safety of vessels at sea. Finally, the structure of a diagnostic system is proposed. It combined diagnosis process with the genesis of damage and the prognosis of the technical condition, i.e. production and in-service diagnostics.

The study presents the evaluation and comparative analysis of engine shaft line performance in maritime transport ships of the same type. During its operation, a technical system performs functions for which it was designed. It goes through different states. Dynamic state changes of a rotational system can be identified by means of its vibration measurement. For this purpose, a research was carried out which involved recording vibrations of the analysed rotational systems. The recordings were used for calculating selected characteristics in the time-domain, where one of the most unique is the value of the normalized mutual correlation function. On the basis of the concentration values, the characteristics which unambiguously determine the ability state were selected for further studies. Then an identification method for rotational system non-coaxiality was proposed. The method involves using fuzzy clustering. According to this method the values of input signal characteristics were used to formulate fuzzy clusters of system ability and inability states. The method can be used for identifying the current state of the system. The study presents the results of the application of this method in engine turbine shaft lines of minesweepers, with the rotational system selected as an example. It needs to be noted that the efficiency of identifying the operating state of the system with this method is higher than with other methods described in the literature by authors who deal with this issue. The research results have a significant impact on the evaluation of mechanical properties of the studied objects and directly affect operational states of mechanical systems, including those installed in minesweepers, thus determining their reliability.

A correctly designed machine is characteristic of low vibration values. However wear processes occur during its operation. They are accompanied by a lack of balance of its rotating parts and elements, which results in non-coaxiality of shafts. For this reason energy and dynamic load resulting from machine vibrations grows. In this case cause and effect are mutually connected by feedback, that inevitably leads to occurrence of a failure. This paper presents results of investigations carried out on the basis of vibration analysis of propulsion systems installed on 207P minesweepers. In view of specific features of their operation it is very important to ensure high level of reliability for them. For this reason was done an attempt to develop a method intended for identifying non-coaxiality of shaft line systems of engines propelling the ships. 16 characteristic features of recorded vibration signals were selected. As any of them has not satisfied criteria assigned to features which unambiguously determine state of reliability of shaft line systems, the investigations have been continued and as a result a novel method for non-coaxiality identification was proposed. The method consists in determining unserviceability clusters and assumes that characteristic features are of a concentrated character. This way a non-coaxiality of main engine shaft lines of 207P minesweepers could be detected. This paper presents the proposed method and results of its application to the case in question.

The paper discusses determining crane block trajectories using the fi nite element method (FEM). The mathematical formulation for air resistance of hooks’ block is presented with kinematic analysis of the block. The three crane blocks are considered: without wind defl ector, with a spherical defl ector and a cylindrical fairing. The hook block was assumed as a physical pendulum. The FEM analysis is provided with the hook block movement consideration. Movement trajectories of hook blocks for diff erent wind speeds is depicted and the results are. At the end of the paper, the conclusions are provided with the directions of future research. [ABSTRACT FROM AUTHOR]

The development of recreational diving and the new biomimetic vehicles for civilian and military purposes indicates that fins drives' effectiveness should be a standard research procedure. The different sizes, construction and technical solutions of fin thrusters are the reason that no standard has been introduced for evaluating their efficiency. The paper presents an episode of the research carried out as part of a project financed by The National Centre for Research and Development in Poland concerning fin drives development. The first chapter presents a literature analysis of currently used research methods. A different approach to assessing efficiency was indicated, ranging from the study of the diver's respiratory efficiency to the manipulator measurement methods. The hydrodynamic parameters, which analyzed the propellers, including fins, and the fish swimming motility characteristics, were indicated. The next chapter presents the water tunnel for basic research with measuring equipment and the range of applications. The methodology for assessing the hydrodynamic and energy efficiency of fin's drives is presented in the third chapter. The fins' kinematics and dynamics analysis indicated an initial set of geometric, kinematic, and dynamic parameters for energy and functional assessment purposes. The scope of available tests covered issues complex to quantify unambiguously; hence the obtained results were initial. The form made this assessment of successive pool tests, the aim of which was to analyze the kinematics of the fin's operation. The trials of a representative fins thruster and the comments indicate the test stand’s practical use for testing various propellers. [ABSTRACT FROM AUTHOR]

The article presents main causes of malfunctions in marine diesel engines fuel injection systems. The measurement section focuses on damage to injection pumps. Measurements were carried out for three technical conditions of a given cylinder injection pump. At the same time, a simplified vibration model of the engine was presented allowing to indicate sensitive components in the frequency domain enabling identification of damages to injection pumps working with individual cylinders. Finally, the results obtained by modelling were compared with the results recorded during laboratory measurements. [ABSTRACT FROM AUTHOR]

The hulls of naval ships are exposed to forces and moments coming from internal and external sources. Usually, these are interactions that can be described mathematically by harmonic and polyharmonic functions. The shock of UNDEX type (underwater explosion) works completely differently and its time waveform is difficult to describe with mathematical functions as pressure vs. time. The paper presents a simplification of physical and mathematical models of 1-D kickoff pressure whose aim is performance the simulation of the external force of the detonation wave. The proposed models were verified and tuned on naval, sea trials. The main goals of the proposed models are to perform simulation calculations of the detonation pressure for different explosion charge weights from different distances of the UNDEX epicentre for the design process of machine foundation. The effects of pressure are transformed as impulses exposed on shock absorber mounted at light shock machine. [ABSTRACT FROM AUTHOR]

Injectors of marine engines are, apart from injection pumps, a key element of the fuel injection system. Their proper operation aff ects the quality and time of producing the fuel-air mixture in engine cylinders. The technical condition of the injectors also has an impact on engine performance and the emission of harmful compounds into the atmosphere. One of the basic injector damages occurring during their normal operation is the change of the injector opening pressure. The article presents mathematical relations indicating the occurrence of vibration diagnostic parameters that could potentially determine changes in the opening pressure of individual injectors. A twostage passive-active experiment was carried out during which an injector working with diff erent spring preload force was tested. The presented results of experimental tests confi rm the possibility of determining whether the injector opening pressure is within the permissible range. The presented method does not require interference in the engine operation. measurements can be made during regular operation. [ABSTRACT FROM AUTHOR]

The paper presents a results of vibration tests of common rail injectors operating in diesel engines. The most common methods of diagnosing common rail injectors (CR) as well as the most common damage of injectors of this type have been described. The results and analyzes of tests obtained during measurements on two different test stands were presented. Obtained results allowed for the preliminary determination of diagnostically sensitive parameters, which may allow the development of the injector diagnostics method without the need to stopping the engine. [ABSTRACT FROM AUTHOR]

The paper presents results of dynamic researches conducted on test bed of rotor system. The aim of research was to identify the impact of damping washers to natural frequency of the system. The first part of paper treats with measurements of rotor system in non-stationary states and the second one is about vibration performances parameters in stationary states. Article presents an example of approach to the problem conducted in laboratory conditions, the results of which can be easily transferred on board of a ship or vessel. [ABSTRACT FROM AUTHOR]

In recent years, diagnostics of marine reciprocating engines devote more and more attention. In principle, all methods for the diagnostics of marine engines can be divided into based on the measurement of work parameters (mostly changes in internal cylinder pressure), and measuring the residual energy. For this study the authors focused on the measurement of vibration parameters and their analyzes. Acceleration of vibration measurements was carried out on the engine head. During the tests, fatigues to the injection installation were simulated, it had affected to the value and the course of the gas pressure inside the cylinders. The results of research proving the usefulness of the proposed method. [ABSTRACT FROM AUTHOR]

In the phase of operation, a technical system accomplishes goals which were the reason of the system designing and creation. The execution of operation tasks by the system causes changes in the system state. The changes in the dynamic state of rotating systems can be early identified by means of vibrations measurement. Therefore, the operational tests were performed in order to register time histories of vibrations. Next, characteristics of the collected vibration signals were recorded and the most significant of them were taken as an input for further studies. The studies were performed to formulate a method of identifying the rotating systems misalignment with high reliability. The method consists in fuzzy clustering implementation. According to the method the input signals were used to formulate the fuzzy clusters of the ability and inability states of the system. Thanks to the method, it is possible to identify the operation position of the system on base of the vibration signals analysis. In the paper the proposed method was described. The results of the method application for a gas turbine engine as an example of a rotating system are also presented. It should be emphasized that the reliability of the described operation state identification is higher than other methods implemented by the authors previously. [ABSTRACT FROM AUTHOR]